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  • Inorganic Chemistry  (861)
  • Aircraft Stability and Control
  • 1995-1999  (649)
  • 1950-1954  (263)
  • 1996  (649)
  • 1951  (263)
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Keywords
Publisher
Years
  • 1995-1999  (649)
  • 1950-1954  (263)
Year
  • 1
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    Use of the Matching Pursuit Algorithm for Flight Flutter Test Data Analysis (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The goal of flight flutter testing is to detect possibly destructive modes of aircraft vibration which may arise during flight from interaction of aerodynamic forces with structural dynamic properties of the airframe. This is typically accomplished by exciting the airframe with a time varying force and monitoring the response of the aircraft throughout its flight envelope. The data generated must be analyzed and presented so that the frequency and time of occurrence of excited modes are clearly and unambiguously displayed. Processing and display in near real time is also desirable. Display of data in the time-frequency plane is a natural choice because it is a familiar and intuitive framework. The Matching Pursuit algorithm provides a time-frequency analysis with good adaptability to signal structure and good signal representation in the time-frequency plane. Improvements in efficiency are needed before the algorithm can be used in real time, however.
    Keywords: Aircraft Stability and Control
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  • 2
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    An Overview of Controls and Flying Qualities Technology on the F/A-18 High Alpha Research Vehicle (1996)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The NASA F/A-18 High Alpha Research Vehicle (HARV) has been the flight test bed of a focused technology effort to significantly increase maneuvering capability at high angles of attack. Development and flight test of control law design methodologies, handling qualities metrics, performance guidelines, and flight evaluation maneuvers are described. The HARV has been modified to include two research control effectors, thrust vectoring, and actuated forebody strakes in order to provide increased control power at high angles of attack. A research flight control system has been used to provide a flexible, easily modified capability for high-angle-of-attack research controls. Different control law design techniques have been implemented and flight-tested, including eigenstructure assignment, variable gain output feedback, pseudo controls, and model-following. Extensive piloted simulation has been used to develop nonlinear performance guide-lines and handling qualities criteria for high angles of attack. This paper reviews the development and evaluation of technologies useful for high-angle-of-attack control. Design, development, and flight test of the research flight control system, control laws, flying qualities specifications, and flight test maneuvers are described. Flight test results are used to illustrate some of the lessons learned during flight test and handling qualities evaluations.
    Keywords: Aircraft Stability and Control
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  • 3
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    Application of pneumatic lift and control surface technology to advanced transport aircraft (1996)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The application of pneumatic (blown) aerodynamic technology to both the lifting and the control surfaces of advanced transport aircraft can provide revolutionary changes in the performance and operation of these vehicles, ranging in speed regime from Advanced Subsonic Transports to the High Speed Civil Transport, and beyond. This technology, much of it based on the Circulation Control Wing blown concepts, can provide aerodynamic force augmentations of 80 to 100 (i.e., return of 80-100 pounds of force per pound of input momentum from the blowing jet). This can be achieved without use of external mechanical surfaces. Clever application of this technology can provide no-moving-part lifting surfaces (wings/tails) integrated into the control system to greatly simplify aircraft designs while improving their aerodynamic performance. Lift/drag ratio may be pneumatically tailored to fit the current phase of the flight, and takeoff/landing performance can be greatly improved by reducing ground roll distances and liftoff/touchdown speeds. Alternatively, great increases in liftoff weights and payloads are possible, as are great reductions in wing and tail planform size, resulting in optimized cruise wing designs. Furthermore, lift generation independent of angle of attack provides much promise for increased safety of flight in the severe updrafts/downdrafts of microbursts and windshears, which is further augmented by the ability to sustain flight at greatly reduced airspeeds. Load-tailored blown wings can also reduce tip vorticity during highlift operations and the resulting vortex wake hazards near terminal areas. Reduced noise may also be possible as these jets can be made to operate at low pressures. The planned presentation will support the above statements through discussions of recent experimental and numerical (CFD) research and development of these advanced blown aerodynamic surfaces, portions of which have been conducted for NASA. Also to be presented will be predicted performance of advanced transports resulting from these devices. Suggestions will be presented for additional innovative high-payoff research leading to further confirmation of these concepts and their application to advanced efficient commercial transport aircraft.
    Keywords: Aircraft Stability and Control
    Type: Transportation Beyond 2000: Technologies Needed for Engineering Design; 371-397; NASA-CP-10184-Pt-1
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  • 4
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    Twin Tail/Delta Wing Configuration Buffet Due to Unsteady Vortex Breakdown Flow (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The buffet response of the twin-tail configuration of the F/A-18 aircraft; a multidisciplinary problem, is investigated using three sets of equations on a multi-block grid structure. The first set is the unsteady, compressible, full Navier-Stokes equations. The second set is the coupled aeroelastic equations for bending and torsional twin-tail responses. The third set is the grid-displacement equations which are used to update the grid coordinates due to the tail deflections. The computational model consists of a 76 deg-swept back, sharp edged delta wing of aspect ratio of one and a swept-back F/A-18 twin-tails. The configuration is pitched at 32 deg angle of attack and the freestream Mach number and Reynolds number are 0.2 and 0.75 x 10(exp 6) respectively. The problem is solved for the initial flow conditions with the twin tail kept rigid. Next, the aeroelastic equations of the tails are turned on along with the grid-displacement equations to solve for the uncoupled bending and torsional tails response due to the unsteady loads produced by the vortex breakdown flow of the vortex cores of the delta wing. Two lateral locations of the twin tail are investigated. These locations are called the midspan and inboard locations.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-203258 , NAS 1.26:203258 , AIAA Paper 96-2517
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  • 5
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    Modeling of Aircraft Unsteady Aerodynamic Characteristics/Part 3 - Parameters Estimated from Flight Data (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A nonlinear least squares algorithm for aircraft parameter estimation from flight data was developed. The postulated model for the analysis represented longitudinal, short period motion of an aircraft. The corresponding aerodynamic model equations included indicial functions (unsteady terms) and conventional stability and control derivatives. The indicial functions were modeled as simple exponential functions. The estimation procedure was applied in five examples. Four of the examples used simulated and flight data from small amplitude maneuvers to the F-18 HARV and X-31A aircraft. In the fifth example a rapid, large amplitude maneuver of the X-31 drop model was analyzed. From data analysis of small amplitude maneuvers ft was found that the model with conventional stability and control derivatives was adequate. Also, parameter estimation from a rapid, large amplitude maneuver did not reveal any noticeable presence of unsteady aerodynamics.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-110259 , NAS 1.15:110259
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  • 6
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    Biomechanically Induced and Controller Coupled Oscillations Experienced on the F-16XL Aircraft During Rolling Maneuvers (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: During rapid rolling maneuvers, the F-16 XL aircraft exhibits a 2.5 Hz lightly damped roll oscillation, perceived and described as 'roll ratcheting.' This phenomenon is common with fly-by-wire control systems, particularly when primary control is derived through a pedestal-mounted side-arm controller. Analytical studies have been conducted to model the nature of the integrated control characteristics. The analytical results complement the flight observations. A three-degree-of-freedom linearized set of aerodynamic matrices was assembled to simulate the aircraft plant. The lateral-directional control system was modeled as a linear system. A combination of two second-order transfer functions was derived to couple the lateral acceleration feed through effect of the operator's arm and controller to the roll stick force input. From the combined systems, open-loop frequency responses and a time history were derived, describing and predicting an analogous in-flight situation. This report describes the primary control, aircraft angular rate, and position time responses of the F-16 XL-2 aircraft during subsonic and high-dynamic-pressure rolling maneuvers. The analytical description of the pilot's arm and controller can be applied to other aircraft or simulations to assess roll ratcheting susceptibility.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-4752 , H-2031 , NAS 1.15:4752
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  • 7
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    Integrated Control Using the SOFFT Control Structure (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The need for integrated/constrained control systems has become clearer as advanced aircraft introduced new coupled subsystems such as new propulsion subsystems with thrust vectoring and new aerodynamic designs. In this study, we develop an integrated control design methodology which accomodates constraints among subsystem variables while using the Stochastic Optimal Feedforward/Feedback Control Technique (SOFFT) thus maintaining all the advantages of the SOFFT approach. The Integrated SOFFT Control methodology uses a centralized feedforward control and a constrained feedback control law. The control thus takes advantage of the known coupling among the subsystems while maintaining the identity of subsystems for validation purposes and the simplicity of the feedback law to understand the system response in complicated nonlinear scenarios. The Variable-Gain Output Feedback Control methodology (including constant gain output feedback) is extended to accommodate equality constraints. A gain computation algorithm is developed. The designer can set the cross-gains between two variables or subsystems to zero or another value and optimize the remaining gains subject to the constraint. An integrated control law is designed for a modified F-15 SMTD aircraft model with coupled airframe and propulsion subsystems using the Integrated SOFFT Control methodology to produce a set of desired flying qualities.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-4748 , NAS 1.26:4748
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  • 8
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    Structural dynamic model obtained from flight use with piloted simulation and handling qualities analysis (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The ability to use flight data to determine an aircraft model with structural dynamic effects suitable for piloted simulation. and handling qualities analysis has been developed. This technique was demonstrated using SR-71 flight test data. For the SR-71 aircraft, the most significant structural response is the longitudinal first-bending mode. This mode was modeled as a second-order system, and the other higher order modes were modeled as a time delay. The distribution of the modal response at various fuselage locations was developed using a uniform beam solution, which can be calibrated using flight data. This approach was compared to the mode shape obtained from the ground vibration test, and the general form of the uniform beam solution was found to be a good representation of the mode shape in the areas of interest. To calibrate the solution, pitch-rate and normal-acceleration instrumentation is required for at least two locations. With the resulting structural model incorporated into the simulation, a good representation of the flight characteristics was provided for handling qualities analysis and piloted simulation.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-4747 , NAS 1.15:4747 , H-2075
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  • 9
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    Stability Analysis for Constrained Principal Axis Slew Maneuvers (1996)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: This paper addresses the problem of reorienting a rigid spacecraft from arbitrary initial conditions to prescribed final conditions with zero angular velocity. The control law analyzed is based on quaternion feedback and leaves the user to choose two gains as functions of position, angular rate, and time. For arbitrary initial states, conditions on the controller gains are identified that guarantee global asymptotic stability. For the special case of rest-to-rest reorientations, the control law reduces to earlier results involving a principal axis rotation. The paper also addresses slew rate constraints, both, in terms of the two and infinity norms.
    Keywords: Aircraft Stability and Control
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  • 10
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    Lateral-Directional Eigenvector Flying Qualities Guidelines for High Performance Aircraft (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This report presents the development of lateral-directional flying qualities guidelines with application to eigenspace (eigenstructure) assignment methods. These guidelines will assist designers in choosing eigenvectors to achieve desired closed-loop flying qualities or performing trade-offs between flying qualities and other important design requirements, such as achieving realizable gain magnitudes or desired system robustness. This has been accomplished by developing relationships between the system's eigenvectors and the roll rate and sideslip transfer functions. Using these relationships, along with constraints imposed by system dynamics, key eigenvector elements are identified and guidelines for choosing values of these elements to yield desirable flying qualities have been developed. Two guidelines are developed - one for low roll-to-sideslip ratio and one for moderate-to-high roll-to-sideslip ratio. These flying qualities guidelines are based upon the Military Standard lateral-directional coupling criteria for high performance aircraft - the roll rate oscillation criteria and the sideslip excursion criteria. Example guidelines are generated for a moderate-to-large, an intermediate, and low value of roll-to-sideslip ratio.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-110306 , NAS 1.15:110306
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  • 11
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    Aeroservoelastic Modeling and Validation of a Thrust-Vectoring F/A-18 Aircraft (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An F/A-18 aircraft was modified to perform flight research at high angles of attack (AOA) using thrust vectoring and advanced control law concepts for agility and performance enhancement and to provide a testbed for the computational fluid dynamics community. Aeroservoelastic (ASE) characteristics had changed considerably from the baseline F/A-18 aircraft because of structural and flight control system amendments, so analyses and flight tests were performed to verify structural stability at high AOA. Detailed actuator models that consider the physical, electrical, and mechanical elements of actuation and its installation on the airframe were employed in the analysis to accurately model the coupled dynamics of the airframe, actuators, and control surfaces. This report describes the ASE modeling procedure, ground test validation, flight test clearance, and test data analysis for the reconfigured F/A-18 aircraft. Multivariable ASE stability margins are calculated from flight data and compared to analytical margins. Because this thrust-vectoring configuration uses exhaust vanes to vector the thrust, the modeling issues are nearly identical for modem multi-axis nozzle configurations. This report correlates analysis results with flight test data and makes observations concerning the application of the linear predictions to thrust-vectoring and high-AOA flight.
    Keywords: Aircraft Stability and Control
    Type: NASA-TP-3647 , H-2081 , NAS 1.60:3647
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  • 12
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    The Propulsive-Only Flight Control Problem (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Attitude control of aircraft using only the throttles is investigated. The long time constants of both the engines and of the aircraft dynamics, together with the coupling between longitudinal and lateral aircraft modes make piloted flight with failed control surfaces hazardous, especially when attempting to land. This research documents the results of in-flight operation using simulated failed flight controls and ground simulations of piloted propulsive-only control to touchdown. Augmentation control laws to assist the pilot are described using both optimal control and classical feedback methods. Piloted simulation using augmentation shows that simple and effective augmented control can be achieved in a wide variety of failed configurations.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-202408 , NAS 1.26:202408
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  • 13
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    The X-31A quasi-tailless flight test results (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A quasi-tailless flight investigation was launched using the X-31A enhanced fighter maneuverability airplane. In-flight simulations were used to assess the effect of partial to total vertical tail removal. The rudder control surface was used to cancel the stabilizing effects of the vertical tail, and yaw thrust vector commands were used to restabilize and control the airplane. The quasi-tailless mode was flown supersonically with gentle maneuvering and subsonically in precision approaches and ground attack profiles. Pilot ratings and a full set of flight test measurements were recorded. This report describes the results obtained and emphasizes the lessons learned from the X-31A flight test experiment. Sensor-related issues and their importance to a quasi-tailless simulation and to ultimately controlling a directionally unstable vehicle are assessed. The X-31A quasi-tailless flight test experiment showed that tailless and reduced tail fighter aircraft are definitely feasible. When the capability is designed into the airplane from the beginning, the benefits have the potential to outweigh the added complexity required.
    Keywords: Aircraft Stability and Control
    Type: NASA-TP-3624 , NAS 1.60:3624 , H-2091
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  • 14
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    On longitudinal control of high speed aircraft in the presence of aeroelastic modes (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Longitudinal control system design is considered for a linearized dynamic model of a supersonic transport aircraft concept characterized by relaxed static stability and significant aeroelastic interactions. Two LQG-type controllers are designed using the frequency-domain additive uncertainty formulation to ensure robustness to unmodeled flexible modes. The first controller is based on a 4th-order model containing only the rigid-body modes, while the second controller is based on an 8th-order model that additionally includes the two most prominent flexible modes. The performance obtainable from the 4th-order controller is not adequate, while the 8th-order controller is found to provide better performance. Frequency-domain and time-domain (Lyapunov) methods are subsequently used to assess the robustness of the 8th-order controller to parametric uncertainties in the design model.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-110254 , NAS 1.15:110254
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  • 15
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    A Higher Harmonic Optimal Controller to Optimise Rotorcraft Aeromechanical Behaviour (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Three methods to optimize rotorcraft aeromechanical behavior for those cases where the rotorcraft plant can be adequately represented by a linear model system matrix were identified and implemented in a stand-alone code. These methods determine the optimal control vector which minimizes the vibration metric subject to constraints at discrete time points, and differ from the commonly used non-optimal constraint penalty methods such as those employed by conventional controllers in that the constraints are handled as actual constraints to an optimization problem rather than as just additional terms in the performance index. The first method is to use a Non-linear Programming algorithm to solve the problem directly. The second method is to solve the full set of non-linear equations which define the necessary conditions for optimality. The third method is to solve each of the possible reduced sets of equations defining the necessary conditions for optimality when the constraints are pre-selected to be either active or inactive, and then to simply select the best solution. The effects of maneuvers and aeroelasticity on the systems matrix are modelled by using a pseudo-random pseudo-row-dependency scheme to define the systems matrix. Cases run to date indicate that the first method of solution is reliable, robust, and easiest to use, and that it was superior to the conventional controllers which were considered.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-110390 , A-961267 , NAS 1.15:110390
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  • 16
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    An Assessment of IMPAC - Integrated Methodology for Propulsion and Airframe Controls (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This report documents the work done under a NASA sponsored contract to transition to industry technologies developed under the NASA Lewis Research Center IMPAC (Integrated Methodology for Propulsion and Airframe Control) program. The critical steps in IMPAC are exercised on an example integrated flight/propulsion control design for linear airframe/engine models of a conceptual STOVL (Short Take-Off and Vertical Landing) aircraft, and MATRIXX (TM) executive files to implement each step are developed. The results from the example study are analyzed and lessons learned are listed along with recommendations that will improve the application of each design step. The end product of this research is a set of software requirements for developing a user-friendly control design tool which will automate the steps in the IMPAC methodology. Prototypes for a graphical user interface (GUI) are sketched to specify how the tool will interact with the user, and it is recommended to build the tool around existing computer aided control design software packages.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-198460 , E-10137 , NAS 1.26:198460
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  • 17
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    Performance Validation of Version 152.0 ANSER Control Laws for the F-18 HARV (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Actuated Nose Strakes for Enhanced Rolling (ANSER) Control Laws were modified as a result of Phase 3 F/A-18 High Alpha Research Vehicle (HARV) flight testing. The control law modifications for the next software release were designated version 152.0. The Ada implementation was tested in the Hardware-In-the-Loop (HIL) simulation and results were compared to those obtained with the NASA Langley batch Fortran implementation of the control laws which are considered the 'truth model.' This report documents the performance validation test results between these implementations for ANSER control law version 152.0.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-198250 , NAS 1.26:198250
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  • 18
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    Controls design with crossfeeds for hovering rotorcraft using quantitative feedback theory (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A multi-input, multi-output controls design with dynamic crossfeed pre-compensation is presented for rotorcraft in near-hovering flight using Quantitative Feedback Theory (QFT). The resulting closed-loop control system bandwidth allows the rotorcraft to be considered for use as an inflight simulator. The use of dynamic, robust crossfeeds prior to the QFT design reduces the magnitude of required feedback gain and results in performance that meets most handling qualities specifications relative to the decoupling of off-axis responses. Handling qualities are Level 1 for both low-gain tasks and high-gain tasks in the roll, pitch, and yaw axes except for the 10 deg/sec moderate-amplitude yaw command where the rotorcraft exhibits Level 2 handling qualities in the yaw axis caused by phase lag. The combined effect of the QFT feedback design following the implementation of low-order, dynamic crossfeed compensators successfully decouples ten of twelve off-axis channels. For the other two channels it was not possible to find a single, low-order crossfeed that was effective. This is an area to be investigated in future research.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-200085 , NAS 1.26:200085
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  • 19
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    Flight Evaluation of an Aircraft with Side and Center Stick Controllers and Rate-Limited Ailerons (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: As part of an ongoing government and industry effort to study the flying qualities of aircraft with rate-limited control surface actuators, two studies were previously flown to examine an algorithm developed to reduce the tendency for pilot-induced oscillation when rate limiting occurs. This algorithm, when working properly, greatly improved the performance of the aircraft in the first study. In the second study, however, the algorithm did not initially offer as much improvement. The differences between the two studies caused concern. The study detailed in this paper was performed to determine whether the performance of the algorithm was affected by the characteristics of the cockpit controllers. Time delay and flight control system noise were also briefly evaluated. An in-flight simulator, the Calspan Learjet 25, was programmed with a low roll actuator rate limit, and the algorithm was programmed into the flight control system. Side- and center-stick controllers, force and position command signals, a rate-limited feel system, a low-frequency feel system, and a feel system damper were evaluated. The flight program consisted of four flights and 38 evaluations of test configurations. Performance of the algorithm was determined to be unaffected by using side- or center-stick controllers or force or position command signals. The rate-limited feel system performed as well as the rate-limiting algorithm but was disliked by the pilots. The low-frequency feel system and the feel system damper were ineffective. Time delay and noise were determined to degrade the performance of the algorithm.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-198055 , NAS 1.26:198055
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  • 20
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    Application of QFT to the Problem of Failed In-Flight Controllers During Approach and Landing of a B720 Aircraft (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Previous studies by NASA Dryden have shown the use of throttles for emergency flight control to be extremely difficult, especially for landing. Flight control using only the throttles to achieve safe landing for a large jet transport airplane, the Boeing 720, is investigated using Quantitative Feedback Theory (QFT). Results are compared to an augmented control developed in a previous study. The controller corrected unsatisfactory open-loop characteristics by increasing system bandwidth and damping, but improving the control bandwidth substantially proved very difficult. The pitch controller is robust in conditions of no or moderate turbulence. The roll controller performed well in conditions of no turbulence, but is sensitive to moderate turbulence. Handling qualities of the augmented control for approach and landing were evaluated by piloted simulation flights.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-202410 , NAS 1.26:202410
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  • 21
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    Pilot-in-the-Loop Analysis of Propulsive-Only Flight Control Systems (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Longitudinal control system architectures are presented which directly couple flight stick motions to throttle commands for a multi-engine aircraft. This coupling enables positive attitude control with complete failure of the flight control system. The architectures chosen vary from simple feedback gains to classical lead-lag compensators with and without prefilters. Each architecture is reviewed for its appropriateness for piloted flight. The control systems are then analyzed with pilot-in-the-loop metrics related to bandwidth required for landing. Results indicate that current and proposed bandwidth requirements should be modified for throttles only flight control. Pilot ratings consistently showed better ratings than predicted by analysis. Recommendations are made for more robust design and implementation. The use of Quantitative Feedback Theory for compensator design is discussed. Although simple and effective augmented control can be achieved in a wide variety of failed configurations, a few configuration characteristics are dominant for pilot-in-the-loop control. These characteristics will be tested in a simulator study involving failed flight controls for a multi-engine aircraft.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-202409 , NAS 1.26:202409
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  • 22
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    Fuzzy Logic Decoupled Longitudinal Control for General Aviation Airplanes (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: It has been hypothesized that a human pilot uses the same set of generic skills to control a wide variety of aircraft. If this is true, then it should be possible to construct an electronic controller which embodies this generic skill set such that it can successfully control difference airplanes without being matched to a specific airplane. In an attempt to create such a system, a fuzzy logic controller was devised to control throttle position and another to control elevator position. These two controllers were used to control flight path angle and airspeed for both a piston powered single engine airplane simulation and a business jet simulation. Overspeed protection and stall protection were incorporated in the form of expert systems supervisors. It was found that by using the artificial intelligence techniques of fuzzy logic and expert systems, a generic longitudinal controller could be successfully used on two general aviation aircraft types that have very difference characteristics. These controllers worked for both airplanes over their entire flight envelopes including configuration changes. The controllers for both airplanes were identical except for airplane specific limits (maximum allowable airspeed, throttle lever travel, etc.). The controllers also handled configuration changes without mode switching or knowledge of the current configuration. This research validated the fact that the same fuzzy logic based controller can control two very different general aviation airplanes. It also developed the basic controller architecture and specific control parameters required for such a general controller.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-201639 , NAS 1.26:201639
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  • 23
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    Development and Flight Evaluation of an Emergency Digital Flight Control System Using Only Engine Thrust on an F-15 Airplane (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A propulsion-controlled aircraft (PCA) system for emergency flight control of aircraft with no flight controls was developed and flight tested on an F-15 aircraft at the NASA Dryden Flight Research Center. The airplane has been flown in a throttles-only manual mode and with an augmented system called PCA in which pilot thumbwheel commands and aircraft feedback parameters were used to drive the throttles. Results from a 36-flight evaluation showed that the PCA system can be used to safety land an airplane that has suffered a major flight control system failure. The PCA system was used to recover from a severe upset condition, descend, and land. Guest pilots have also evaluated the PCA system. This paper describes the principles of throttles-only flight control; a history of loss-of-control accidents; a description of the F-15 aircraft; the PCA system operation, simulation, and flight testing; and the pilot comments.
    Keywords: Aircraft Stability and Control
    Type: NASA-TP-3627 , H-2048 , NAS 1.60:3627
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    Guidance and Control Design for High-Speed Rollout and Turnoff (ROTO) (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A ROTO architecture, braking and steering control law and display designs for a research high speed Rollout and Turnoff (ROTO) system applicable to transport class aircraft are described herein. Minimum surface friction and FMS database requirements are also documented. The control law designs were developed with the aid of a non-real time simulation program incorporating airframe and gear dynamics as well as steering and braking guidance algorithms. An attainable objective of this ROTO system, as seen from the results of this study, is to assure that the studied aircraft can land with runway occupancy times less then 53 seconds. Runway occupancy time is measured from the time the aircraft crosses the runway threshold until its wing tip clears the near side of the runway. Turnoff ground speeds of 70 knots onto 30 degree exits are allowed with dry and wet surface conditions. Simulation time history and statistical data are documented herein. Parameters which were treated as variables in the simulation study include aircraft touchdown weight/speed/location, aircraft CG, runway friction, sensor noise and winds. After further design and development of the ROTO control system beyond the system developed earlier, aft CG MD-11 aircraft no longer require auto-asymmetric braking (steering) and fly-by-wire nose gear steering. However, the auto ROTO nose gear hysteresis must be less than 2 degrees. The 2 sigma dispersion certified for MD-11 CATIIIB is acceptable. Using this longitudinal dispersion, three ROTO exits are recommended at 3300, 4950 and 6750 feet past the runway threshold. The 3300 foot exit is required for MD-81 class aircraft. Designs documented in this report are valid for the assumptions/models used in this simulation. It is believed that the results will apply to the general class of transport aircraft; however further effort is required to validate this assumption for the general case.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-201602 , NAS 1.26:201602 , CRAD-9206-TR-1659
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  • 25
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    X-29A Lateral-Directional Stability and Control Derivatives Extracted From High-Angle-of-Attack Flight Data (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The lateral-directional stability and control derivatives of the X-29A number 2 are extracted from flight data over an angle-of-attack range of 4 degrees to 53 degrees using a parameter identification algorithm. The algorithm uses the linearized aircraft equations of motion and a maximum likelihood estimator in the presence of state and measurement noise. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics over the aircraft at angles of attack above 15 degrees. The results supported the flight-envelope-expansion phase of the X-29A number 2 by helping to update the aerodynamic mathematical model, to improve the real-time simulator, and to revise flight control system laws. Effects of the aircraft high gain flight control system on maneuver quality and the estimated derivatives are also discussed. The derivatives are plotted as functions of angle of attack and compared with the predicted aerodynamic database. Agreement between predicted and flight values is quite good for some derivatives such as the lateral force due to sideslip, the lateral force due to rudder deflection, and the rolling moment due to roll rate. The results also show significant differences in several important derivatives such as the rolling moment due to sideslip, the yawing moment due to sideslip, the yawing moment due to aileron deflection, and the yawing moment due to rudder deflection.
    Keywords: Aircraft Stability and Control
    Type: NASA-TP-3664 , NAS 1.60:3664 , H-2118
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  • 26
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    Designing Low Bandwidth Propulsive-Only Flight Controllers (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Results from an investigation of using engine commands to control flight attitude are described. In-flight operation with simulated failed flight controls is reviewed and ground simulations of piloted propulsive-only control to touchdown are analyzed. A design of an optimal control law to assist the pilot is presented. Recommendations are made for more robust design and implementation. Results to date indicate that simply and effective augmented control can be achieved in a wide variety of failed configurations.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-202407 , NAS 1.26:202407
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  • 27
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    Design Specification for a Thrust-Vectoring, Actuated-Nose-Strake Flight Control Law for the High-Alpha Research Vehicle (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Specifications for a flight control law are delineated in sufficient detail to support coding the control law in flight software. This control law was designed for implementation and flight test on the High-Alpha Research Vehicle (HARV), which is an F/A-18 aircraft modified to include an experimental multi-axis thrust-vectoring system and actuated nose strakes for enhanced rolling (ANSER). The control law, known as the HARV ANSER Control Law, was designed to utilize a blend of conventional aerodynamic control effectors, thrust vectoring, and actuated nose strakes to provide increased agility and good handling qualities throughout the HARV flight envelope, including angles of attack up to 70 degrees.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-110217 , NAS 1.15:110217
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  • 28
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    Moving base simulation evaluation of translational rate command systems for STOVL aircraft in hover (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Using a generalized simulation model, a moving-base simulation of a lift-fan short takeoff/vertical landing fighter aircraft has been conducted on the Vertical Motion Simulator at Ames Research Center. Objectives of the experiment were to determine the influence of system bandwidth and phase delay on flying qualities for translational rate command and vertical velocity command systems. Assessments were made for precision hover control and for landings aboard an LPH type amphibious assault ship in the presence of winds and rough seas. Results obtained define the boundaries between satisfactory and adequate flying qualities for these design features for longitudinal and lateral translational rate command and for vertical velocity command.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-110399 , NAS 1.15:110399 , A-961718
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  • 29
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    Simulation model of the F/A-18 high angle-of-attack research vehicle utilized for the design of advanced control laws (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The 'f18harv' six degree-of-freedom nonlinear batch simulation used to support research in advanced control laws and flight dynamics issues as part of NASA's High Alpha Technology Program is described in this report. This simulation models an F/A-18 airplane modified to incorporate a multi-axis thrust-vectoring system for augmented pitch and yaw control power and actuated forebody strakes for enhanced aerodynamic yaw control power. The modified configuration is known as the High Alpha Research Vehicle (HARV). The 'f18harv' simulation was an outgrowth of the 'f18bas' simulation which modeled the basic F/A-18 with a preliminary version of a thrust-vectoring system designed for the HARV. The preliminary version consisted of two thrust-vectoring vanes per engine nozzle compared with the three vanes per engine actually employed on the F/A-18 HARV. The modeled flight envelope is extensive in that the aerodynamic database covers an angle-of-attack range of -10 degrees to +90 degrees, sideslip range of -20 degrees to +20 degrees, a Mach Number range between 0.0 and 2.0, and an altitude range between 0 and 60,000 feet.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-110216 , NAS 1.15:110216
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  • 30
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    Design of a mixer for the thrust-vectoring system on the high-alpha research vehicle (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: One of the advanced control concepts being investigated on the High-Alpha Research Vehicle (HARV) is multi-axis thrust vectoring using an experimental thrust-vectoring (TV) system consisting of three hydraulically actuated vanes per engine. A mixer is used to translate the pitch-, roll-, and yaw-TV commands into the appropriate TV-vane commands for distribution to the vane actuators. A computer-aided optimization process was developed to perform the inversion of the thrust-vectoring effectiveness data for use by the mixer in performing this command translation. Using this process a new mixer was designed for the HARV and evaluated in simulation and flight. An important element of the Mixer is the priority logic, which determines priority among the pitch-, roll-, and yaw-TV commands.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-110228 , NAS 1.15:110228
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  • 31
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    Power-by-Wire Development and Demonstration for Subsonic Civil Transport (1996)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: During the last decade, three significant studies by the Lockheed Martin Corporation, the NASA Lewis Research Center, and McDonnell Douglas Corporation have clearly shown operational, weight, and cost advantages for commercial subsonic transport aircraft that use all-electric or more-electric technologies in the secondary electric power systems. Even though these studies were completed on different aircraft, used different criteria, and applied a variety of technologies, all three have shown large benefits to the aircraft industry and to the nation's competitive position. The Power-by-Wire (PBW) program is part of the highly reliable Fly-By-Light/Power-By-Wire (FBL/PBW) Technology Program, whose goal is to develop the technology base for confident application of integrated FBL/PBW systems for transport aircraft. This program is part of the NASA aeronautics strategic thrust in subsonic aircraft/national airspace (Thrust 1) to "develop selected high-leverage technologies and explore new means to ensure the competitiveness of U.S. subsonic aircraft and to enhance the safety and productivity of the national aviation system" (The Aeronautics Strategic Plan). Specifically, this program is an initiative under Thrust 1, Key Objective 2, to "develop, in cooperation with U.S. industry, selected high-payoff technologies that can enable significant improvements in aircraft efficiency and cost."
    Keywords: Aircraft Stability and Control
    Type: Research and Technology 1995; NASA-TM-107111
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  • 32
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    Navier-Stokes Simulation of the Canard-Wing-Body Longitudinal Dynamic Stability Characteristics (1996)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Many modern aircraft are canard-configured for aircraft control and improved aerodynamic performance. Canards can often enhance aircraft cruise performance, maneuverability and agility. For close-coupled canard configurations, the aerodynamic interaction between the canard and wing significantly changes the flow characteristics of the wing. In unsteady flow, such changes in the flow structure and performance of wings can be quite pronounced. Accurate modeling of the unsteady aerodynamics is essential for potential CFD design and analysis of such configurations. A time-accurate numerical simulation is performed to study the unsteady aerodynamic interaction between a canard and wing with emphasis on the effects of the canard on the configuration's dynamic response characteristics. The thin-layer Reynolds-averaged Navier-Stokes Equations with various turbulence models are used in this study. Computations are made on a generic, analytically-defined, close-coupled canard-wing-body configuration which has been the subject of numerous previously published experimental studies during the 1970's to mid-80's. More recently, a series of steady-flow simulations has been performed and published by the author. In the current study, the configuration is given prescribed ramp and oscillatory motions in order to predict characteristics such as the damping-in-pitch and oscillatory longitudinal stability parameters. The current computations are made at high-subsonic and transonic Mach numbers, moderate angles-of- attack from -4 to 20 degrees, and at various pitch rates and reduced frequencies. Comparisons of pressures and integrated force quantities (e.g. lift, drag, pitching moment and selected dynamic parameters) are made with other published computational results and available experimental data. Results showing the unsteady effects of the canard on surface pressures, integrated forces, canard-wing vortex interaction and vortex breakdown will be presented.
    Keywords: Aircraft Stability and Control
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  • 33
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    Advanced Air Traffic Management Research (Human Factors and Automation): NASA Research Initiatives in Human-Centered Automation Design in Airspace Management (1996)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: NASA has initiated a significant thrust of research and development focused on providing the flight crew and air traffic managers automation aids to increase capacity in en route and terminal area operations through the use of flexible, more fuel-efficient routing, while improving the level of safety in commercial carrier operations. In that system development, definition of cognitive requirements for integrated multi-operator dynamic aiding systems is fundamental. The core processes of control and the distribution of decision making in that control are undergoing extensive analysis. From our perspective, the human operators and the procedures by which they interact are the fundamental determinants of the safe, efficient, and flexible operation of the system. In that perspective, we have begun to explore what our experience has taught will be the most challenging aspects of designing and integrating human-centered automation in the advanced system. We have performed a full mission simulation looking at the role shift to self-separation on board the aircraft with the rules of the air guiding behavior and the provision of a cockpit display of traffic information and an on-board traffic alert system that seamlessly integrates into the TCAS operations. We have performed and initial investigation of the operational impact of "Dynamic Density" metrics on controller relinquishing and reestablishing full separation authority. (We follow the assumption that responsibility at all times resides with the controller.) This presentation will describe those efforts as well as describe the process by which we will guide the development of error tolerant systems that are sensitive to shifts in operator work load levels and dynamic shifts in the operating point of air traffic management.
    Keywords: Aircraft Stability and Control
    Type: 41st Annual Air Traffic Control Association Meeting; Oct 13, 1996 - Oct 17, 1996; Nashville, TN; United States
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    Full-Scale Wind-Tunnel Studies of F/A-18 Tail Buffet (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Tail buffet studies were conducted on a full-scale, production F/A-18 fighter aircraft in the 80 by 120 ft Wind Tunnel at NASA Ames Research Center. The F/A-18 was tested over an angle-of-attack range of 18-50 deg, and at wind speeds of up to 168 ft/s, corresponding to a Reynolds number of 12.3x10(exp 6) based on mean aerodynamic chord and a Mach number of 0.15. The port, vertical tail fin was instrumented and the aircraft was equipped with a removable leading-edge extension (LEX) fence. Time-averaged, power-spectral analysis results are presented for the tail fin bending moment derived from the integrated pressure field, for the zero side-slip condition, both with and without the LEX fence. The LEX fence significantly reduces the magnitude of the rms pressures and bending moments. Scaling issues are addressed by comparing full-scale results for pressures at the 60%-span and 45%-chord location with small-scale, F/A-18 tail-buffet data. The comparison shows that the tail buffet frequency scales very well with length and velocity. Root-mean-square pressures and power spectra do not scale as well. The LEX fence is shown to reduce tail buffet loads at all model scales.
    Keywords: Aircraft Stability and Control
    Type: AIAA Paper 93-3519 , Journal of Aircraft; 33; 3; 589-595|AIAA 11th Applied Aerodynamics Conference; Aug 09, 1993 - Aug 11, 1993; Monterey, CA; United States
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    Clarification of 'Turn Performance of Aircraft' (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A recent note analyzed the minimum turning radius of an airplane in terms of its airspeed and angle of bank. Unfortunately, some misconceptions concerning the underlying physics were introduced. This note is intended to clarify those areas.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-112762 , NAS 1.15:112762 , SIAM Review; 38; 2; 309-312
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    Design, Fabrication, and Calibration of an Embedded Piezoceramic Actuator for Active Control Applications (1996)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: In this presentation, the authors describe the design and fabrication processes for a PZT strain actuator that evolved during the initial stages of a research effort to synthesize and process intelligent, cost effective structures (SPICES). The actuator performance requirements were similar to those of conventional actuators, e.g., it had to be robust, highly efficient with adequate force and stroke, as lightweight as possible, and most importantly, affordable. Further, since the actuator was to be integrated within a composite structure, it had to be compatible with the host material and easily embeddable during the fabrication process. In control applications employing strain devices as actuators, a good bond between this actuator and host material is critical to their successful operation. This criterion is often difficult to achieve when attempting to join ceramics with metals or polymers with dissimilar properties such as Young's moduli, thermal expansion coefficients, etc. One unique feature of the actuator design that evolved in this project is that the need for direct bonding between the PZT ceramic and polymers was circumvented, i.e. the strain transfer to the host material was achieved via a frame surrounding the ceramic. Consequently, the frame material could be selected (or coated) for compatibility with the host material. A second feature is that the frame enclosed a co-fired, multilayered, PZT stack that was used to minimize the voltage requirements while maximizing the output strain.
    Keywords: Aircraft Stability and Control
    Type: Proceedings of the 4th Annual Workshop: Advances in Smart Materials for Aerospace Applications; 225; NASA-CP-10185
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    A Framework for Modeling Human-Machine Interactions (1996)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Modern automated flight-control systems employ a variety of different behaviors, or modes, for managing the flight. While developments in cockpit automation have resulted in workload reduction and economical advantages, they have also given rise to an ill-defined class of human-machine problems, sometimes referred to as 'automation surprises'. Our interest in applying formal methods for describing human-computer interaction stems from our ongoing research on cockpit automation. In this area of aeronautical human factors, there is much concern about how flight crews interact with automated flight-control systems, so that the likelihood of making errors, in particular mode-errors, is minimized and the consequences of such errors are contained. The goal of the ongoing research on formal methods in this context is: (1) to develop a framework for describing human interaction with control systems; (2) to formally categorize such automation surprises; and (3) to develop tests for identification of these categories early in the specification phase of a new human-machine system.
    Keywords: Aircraft Stability and Control
    Type: CHI ''96 Workshop on Formal Methods; Apr 14, 1996 - Apr 15, 1996; Vancouver; Canada
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  • 38
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    Free-flight investigation of forebody blowing for stability and control (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-27
    Description: A free-flight wind-tunnel investigation was conducted on a generic fighter model with forebody pneumatic vortex control for high angle-of-attack directional control. This is believed to be the first flight demonstration of a forebody blowing concept integrated into a closed-loop flight control system for stability augmentation and control. The investigation showed that the static wind tunnel estimates of the yaw control available generally agreed with flight results. The control scheme for the blowing nozzles consisted of an on/off control with a deadband. Controlled flight was obtained for the model using forebody blowing for directional control to beyond 45 deg. angle of attack.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-111595 , NAS 1.15:111595 , AIAA Paper 96-3444
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  • 39
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    Natural Rolling Responses of a Delta Wing in Transonic and Subsonic Flows (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The unsteady, three-dimensional, full Navier-Stokes (NS) equations and the Euler equations of rigid-body dynamics are sequentially solved to simulate the natural rolling response of slender delta wings of zero thickness at moderate to high angles of attack, to transonic and subsonic flows. The governing equations of fluid flow and dynamics of the present multi-disciplinary problem are solved using the time-accurate solution of the NS equations with the implicit, upwind, Roe flux-difference splitting, finite-volume scheme and a four-stage Runge-Kutta scheme, respectively. The main focus is to analyze the effect of Mach number and angle of attack on the leading edge vortices and their breakdown, the resultant rolling motion, and overall aerodynamic response of the wing. Three cases demonstrate the natural response of a 65 deg swept, cropped delta wing in a transonic flow with breakdown of the leading edge vortices and an 80 deg swept delta wing in a subsonic flow undergoing either damped or self-excited limit-cycle rolling oscillations as a function of angle of attack. Comparisons with an experimental investigation completes this study, validating the analysis and illustrating the complex details afforded by computational investigations.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-203246 , NAS 1.26:203246 , AIAA Paper 96-3391 , Atmospheric Flight Mechanics; Jul 29, 1996 - Jul 31, 1996; San Diego, CA; United States
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    High-Alpha Handling Qualities Flight Research on the NASA F/A-18 High Alpha Research Vehicle (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A flight research study of high-angle-of-attack handling qualities has been conducted at the NASA Dryden Flight Research Center using the F/A-18 High Alpha Research Vehicle (HARV). The objectives were to create a high-angle-of-attack handling qualities flight database, develop appropriate research evaluation maneuvers, and evaluate high-angle-of-attack handling qualities guidelines and criteria. Using linear and nonlinear simulations and flight research data, the predictions from each criterion were compared with the pilot ratings and comments. Proposed high-angle-of-attack nonlinear design guidelines and proposed handling qualities criteria and guidelines developed using piloted simulation were considered. Recently formulated time-domain Neal-Smith guidelines were also considered for application to high-angle-of-attack maneuvering. Conventional envelope criteria were evaluated for possible extension to the high-angle-of-attack regime. Additionally, the maneuvers were studied as potential evaluation techniques, including a limited validation of the proposed standard evaluation maneuver set. This paper gives an overview of these research objectives through examples and summarizes result highlights. The maneuver development is described briefly, the criteria evaluation is emphasized with example results given, and a brief discussion of the database form and content is presented.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-4773 , NAS 1.15:4773 , H-2138 , NASA Langley High-Angle-of-Attack Conference; Sep 17, 1996 - Sep 19, 1996; Hampton, VA; United States
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  • 41
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    Development and Flight Test of an Augmented Thrust-Only Flight Control System on an MD-11 Transport Airplane (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An emergency flight control system using only engine thrust, called Propulsion-Controlled Aircraft (PCA), has been developed and flight tested on an MD-11 airplane. In this thrust-only control system, pilot flight path and track commands and aircraft feedback parameters are used to control the throttles. The PCA system was installed on the MD-11 airplane using software modifications to existing computers. Flight test results show that the PCA system can be used to fly to an airport and safely land a transport airplane with an inoperative flight control system. In up-and-away operation, the PCA system served as an acceptable autopilot capable of extended flight over a range of speeds and altitudes. The PCA approaches, go-arounds, and three landings without the use of any non-nal flight controls have been demonstrated, including instrument landing system-coupled hands-off landings. The PCA operation was used to recover from an upset condition. In addition, PCA was tested at altitude with all three hydraulic systems turned off. This paper reviews the principles of throttles-only flight control; describes the MD-11 airplane and systems; and discusses PCA system development, operation, flight testing, and pilot comments.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-4745 , H-2107 , NAS 1.15:4745 , AIAA 96-3742 , AIAA Guidance, Navigation, and Control Conference; Jul 29, 1996 - Jul 31, 1996; San Diego, CA; United States
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    Computation and Validation of Fluid/Structure Twin Tail Buffet Response (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The buffet response of the flexible twin-tail/delta wing configuration, a multidisciplinary problem, is solved using three sets of equations on a multi-block grid structure. The first set is the unsteady, compressible, full Navier-Stokes equations which are used for obtaining the flow-field vector and the aerodynamic loads on the twin tails. The second set is the coupled aeroelastic equations which are used for obtaining the bending and torsional deflections of the twin tails. The third set is the grid-displacement equations which are used for updating the grid coordinates due to the tail deflections. The computational model is similar to the one used by Washburn et. al. which consists of a delta wing of aspect ratio one and twin tails with taper ratios of 0.23. The vortex of the twin tails are located at the wing trailing edge. The configuration is pitched at 30 deg angle of attack, and the freestream Mach number and Reynolds number are 0.3 and 1.25 million, respectively. With the twin tails fixed as rigid surfaces, the problem is solved for the initial flow conditions. Next, the problem is solved for the twin tail response for uncoupled bending and torsional vibrations due to the unsteady loads produced by the vortex breakdown flow of the leading-edge vortex cores. The configuration is investigated for three spanwise positions of the twin tails; inboard, midspan and outboard locations. The computational results are validated and are in very good agreement with the experimental data of Washburn, et. al.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-203259 , NAS 1.26:203259 , AIAA CP-96-2517 , Euromech Colloquium 349: Structure Fluid Interaction in Aeronautics; Sep 16, 1996 - Sep 18, 1996; Goettingen; Germany|Applied Aerodynamics; Jun 18, 1996 - Jun 20, 1996; New Orleans, LA; United States
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  • 43
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    Flight Test of a Propulsion-Based Emergency Control System on the MD-11 Airplane with Emphasis on the Lateral Axis (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A large, civilian, multi-engine transport MD-11 airplane control system was recently modified to perform as an emergency backup controller using engine thrust only. The emergency backup system, referred to as the propulsion-controlled aircraft (PCA) system, would be used if a major primary flight control system fails. To allow for longitudinal and lateral-directional control, the PCA system requires at least two engines and is implemented through software modifications. A flight-test program was conducted to evaluate the PCA system high-altitude flying characteristics and to demonstrate its capacity to perform safe landings. The cruise flight conditions, several low approaches and one landing without any aerodynamic flight control surface movement, were demonstrated. This paper presents results that show satisfactory performance of the PCA system in the longitudinal axis. Test results indicate that the lateral-directional axis of the system performed well at high attitude but was sluggish and prone to thermal upsets during landing approaches. Flight-test experiences and test techniques are also discussed with emphasis on the lateral-directional axis because of the difficulties encountered in flight test.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-4746 , H-2110 , NAS 1.15:4746 , AIAA Paper 96-3919 , Guidance, Navigation, and Control Conference; Jul 29, 1996 - Jul 31, 1996; San Diego, CA; United States
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    Aerostructural Vortical Flow Interactions with Applications to F/A-18 and F-117 Tail Buffet (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The buffet response of the flexible twin-tail configuration of the F/A-18 and a generic F-111 aircraft are computationally simulated and experimentally validated. The problem is a multidisciplinary one which requires the sequential solution of three sets of equations on a multi-block grid structure. The first set is the unsteady, compressible, full Navier-Stokes equations. The second set is the aeroelastic equations for bending and torsional twin-tail responses. The third set is the grid-displacement equations which are used to update the grid coordinates due to the tail deflections. The computational models consist of a 76 deg. swept back, sharp edged delta wing of aspect ratio of one and a swept-back F/A-18 or F-117 twin-tail. The configuration is pitched at 30 deg. angle-of-attack. The problem is solved for the initial flow conditions with the twin tails kept rigid. Next, the aeroelastic equations of the tails are turned on along with the grid-displacement equations to solve for the bending and torsional tails responses due to the unsteady loads produced by the vortex breakdown flow of the leading-edge vortex cores of the delta wing. Several spanwise locations of the twin tails are investigated. The computational results are validated using several existing experimental data.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-203245 , NAS 1.26:203245 , High-Angle-of-Attack Technology; Sep 17, 1996 - Sep 19, 1996; Hampton, VA; United States
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    Research In Nonlinear Flight Control for Tiltrotor Aircraft Operating in the Terminal Area (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The research during the first year of the effort focused on the implementation of the recently developed combination of neural net work adaptive control and feedback linearization. At the core of this research is the comprehensive simulation code Generic Tiltrotor Simulator (GTRS) of the XV-15 tilt rotor aircraft. For this research the GTRS code has been ported to a Fortran environment for use on PC. The emphasis of the research is on terminal area approach procedures, including conversion from aircraft to helicopter configuration. This report focuses on the longitudinal control which is the more challenging case for augmentation. Therefore, an attitude command attitude hold (ACAH) control augmentation is considered which is typically used for the pitch channel during approach procedures. To evaluate the performance of the neural network adaptive control architecture it was necessary to develop a set of low order pilot models capable of performing such tasks as, follow desired altitude profiles, follow desired speed profiles, operate on both sides of powercurve, convert, including flaps as well as mastangle changes, operate with different stability and control augmentation system (SCAS) modes. The pilot models are divided in two sets, one for the backside of the powercurve and one for the frontside. These two sets are linearly blended with speed. The mastangle is also scheduled with speed. Different aspects of the proposed architecture for the neural network (NNW) augmented model inversion were also demonstrated. The demonstration involved implementation of a NNW architecture using linearized models from GTRS, including rotor states, to represent the XV-15 at various operating points. The dynamics used for the model inversion were based on the XV-15 operating at 30 Kts, with residualized rotor dynamics, and not including cross coupling between translational and rotational states. The neural network demonstrated ACAH control under various circumstances. Future efforts will include the implementation into the Fortran environment of GTRS, including pilot modeling and NNW augmentation for the lateral channels. These efforts should lead to the development of architectures that will provide for fully automated approach, using similar strategies.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-203112 , NAS 1.26:203112
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    Evaluation of High-Angle-of-Attack Handling Qualities for the X-31A Using Standard Evaluation Maneuvers (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The X-31A aircraft gross-acquisition and fine-tracking handling qualities have been evaluated using standard evaluation maneuvers developed by Wright Laboratory, Wright-Patterson Air Force Base. The emphasis of the testing is in the angle-of-attack range between 30 deg and 70 deg. Longitudinal gross-acquisition handling qualities results show borderline Level 1/Level 2 performance. Lateral gross-acquisition testing results in Level 1/Level 2 ratings below 45 deg angle of attack, degrading into Level 3 as angle of attack increases. The fine-tracking performance in both longitudinal and lateral axes also receives Level 1 ratings near 30 deg angle of attack, with the ratings tending towards Level 3 at angles of attack greater than 50 deg. These ratings do not match the expectations from the extensive close-in combat testing where the X-31A aircraft demonstrated fair to good handling qualities maneuvering for high angles of attack. This paper presents the results of the high-angle-of-attack handling qualities flight testing of the X-31A aircraft. Discussion of the preparation for the maneuvers, the pilot ratings, and selected pilot comments are included. Evaluation of the results is made in conjunction with existing Neal-Smith, bandwidth, Smith-Geddes, and military specifications.
    Keywords: Aircraft Stability and Control
    Type: NASA-TM-104322 , H-2128 , NAS 1.15:104322 , AGARD Flight Vehicle Integration Panel Symposium on Advances in Flight Testing; Sep 23, 1996 - Sep 26, 1996; Lisbon; Portugal|High-Angle-of-Attack Technology; Sep 17, 1996 - Sep 19, 1996; Hampton, VA; United States
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    Far-Field Turbulent Vortex-Wake/Exhaust Plume Interaction for Subsonic and HSCT Airplanes (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Computational study of the far-field turbulent vortex-wake/exhaust plume interaction for subsonic and high speed civil transport (HSCT) airplanes is carried out. The Reynolds-averaged Navier-Stokes (NS) equations are solved using the implicit, upwind, Roe-flux-differencing, finite-volume scheme. The two-equation shear stress transport model of Menter is implemented with the NS solver for turbulent-flow calculation. For the far-field study, the computations of vortex-wake interaction with the exhaust plume of a single engine of a Boeing 727 wing in a holding condition and two engines of an HSCT in a cruise condition are carried out using overlapping zonal method for several miles downstream. These results are obtained using the computer code FTNS3D. The results of the subsonic flow of this code are compared with those of a parabolized NS solver known as the UNIWAKE code.
    Keywords: Aircraft Stability and Control
    Type: NASA-CR-203260 , NAS 1.26:203260 , AIAA Paper 96-1962 , Fluid Dynamics; Jun 17, 1996 - Jun 20, 1996; New Orleans, LA; United States
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  • 48
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    Masthead (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290101
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    Triferriothioxophosphoranes: First Structural Characterization of a μ3-P=S ComplexDedicated to Prof. Dr. M. Herberhold on the occasion of his 60th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 11-13 
    Details
    ISSN: 0009-2940
    Keywords: Triferriophosphane sulfide ; Metallothioxophosphorane ; PS complex ; Spiro compounds ; Decarbonylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The P-H-functional triferriophosphonium salts [{CpFe-(CO)2}3PH]2FeCl4 (1) and [{μ-CO(CpFeCO)2}{CpFe-(CO)2}PH]2FeCl4 (4) are easily deprotonated by DBU to the corresponding unstable triferriophosphanes 2, 5, which subsequently are oxidized by sulfur to the triferriophosphane sulfides {CpFe(CO)2}3P=S (3) and {μ-CO(CpFeCO)2}{CpFe-(CO)2}P=S (6), respectively. The photolysis of 3 results only in its decomposition by elimination of [CpFe(CO)2]2, whereas the photolysis of 6 cleaves off one CO ligand to give the new spiro compound (CpFeCO)(μ-η2-PS){μ-CO(CpFeCO)2} (7), where the P=S unit is η2-bonded to the 15-electron CpFeCO fragment, and the phosphorus atom bridges two 17-electron fragments. Compound 7 shows a new coordination mode of the PS unit where sulfur is also bound to one of the metal atoms. Compounds 6 and 7 can be regarded as first examples of a new class of PS complexes of transition metals. All compounds were characterized by IR, 31P{1H}- and 13C{1H}-NMR spectroscopy as well as mass spectrometry; for 6 the X-ray analytical data are given.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290104
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    The Chemistry of 1,3,5-Triazacyclohexane Complexes, 3Part 2: Ref.. High Yield Synthesis of [Cr{N(SiMe3)2}3] and Accurate Structure Determination by Cocrystallization with Me6Si2 (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 25-27 
    Details
    ISSN: 0009-2940
    Keywords: Triazacyclohexanes ; Chromium complexes ; Amides ; Hexamethyldisilane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of N,N′,N′′-trimethyl-1,3,5-triazacyclohexane chromium trichloride ((Me3TAC)CrCl3, 1) with LiN(SiMe3)2 or NaN(SiMe3)2 in petroleum ether yields nearly quantitatively [Cr{N(SiMe3)2}3] (2) with loss of the Me3TAC ligand. Compound 2 could be crystallized from hexamethyldisilane as [Cr{N(SiMe3)2}3] · (Me6Si2)0,5 which allowed the refinement of the X-ray crystal structure in the trigonal space group P-31c (no. 163) (a = 16.012(3) Å, c = 8.4796(12) Å, V = 1882.8(6) Å3, Z = 2) without severe disorder.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290107
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    Synthesis of Novel Tridentate N,O,S and N,N,O Ligands of the Tripod Type in Racemic and Enantiomerically Pure Form (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 59-68 
    Details
    ISSN: 0009-2940
    Keywords: Glyceraldehyde ; Ligands, tridentate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of seven chiral, tripodal N,O,S and N,N,O ligands were prepared in which N stands for a secondary amine or imidazole donor, O for a phenol, and S for a thioether or thiol metal-binding group. Key steps are (1) the construction of ortho-hydroxyacetophenones bearing the phenolic binding group and either a thioether, a protected thiol or an imidazole substituent in the α-position, and (2) subsequent reductive amination with a primary amine. The modular synthesis allows a rapid construction of a variety of structurally related ligands. In three cases, the enantiomers of the racemic products could be separated after condensation with (R)-glyceraldehyde acetonide as chiral auxiliary. The relative configurations of the cyclic N,O- and N,N-acetals thus obtained were established by NOE spectroscopy. X-ray structural analysis of two crystalline N,O- and N,N-acetals allowed the assignment of absolute configurations. Hydrolysis of the dia-stereomerically pure acetals afforded the enantiomerically pure ligands in high yield. By comparison of their CD spectra, absolute configuration could also be assigned to the third pair of enantiomerically pure ligands.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290113
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    Kinetic Investigations of the Hydrogenation of Diolefin Ligands in Catalyst Precursors for the Asymmetric Reduction of Prochiral Olefins, II[1] (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 85-89 
    Details
    ISSN: 0009-2940
    Keywords: Rhodium complexes, chiral ; Hydrogenation ; Bisolefins ; Thermodynamic stability ; Kinetic control ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Asymmetric hydrogenations of prochiral olefines by means of chiral rhodium(I) complexes of the type [Rh(L)(PP*)]A (L = COD, [(Z,Z)-cycloocta-1,5-diene], or NBD (norborna-2;5-diene), PP* = chiral bisphosphane forming seven-membered chelate rings, A = anion like BF4-) are often associated with induction periods caused by partial blocking of the catalyst. NBD complexes are hydrogenated faster than the corresponding COD complexes. Catalytic hydrogenation of COD/NBD mixtures and the determination of the ratio of the Michaelis constants showed that the steady-state concentration of the COD complex under hydrogen is higher than that of the NBD complex. However, under argon the NBD complex predominates owing to its higher thermodynamic stability compared with that of the COD complex as determined by 31P-NMR spectoscopy. This complete reversion of the ther-modynamically determined ratios of COD to NBD complex concentration under hydrogenation conditions was proven by means of UV/Vis spectroscopy.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290117
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  • 53
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    1-Bromo-3,5-bis(trifluoromethyl)benzene: A Versatile Starting Material for Organometallic Synthesis (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 233-235 
    Details
    ISSN: 0009-2940
    Keywords: Positional selectivity ; Bromination ; Halogen/lithium exchange ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Bromo-3,5-bis(trifluoromethyl)benzene (1) can be selectively prepared by treatment of 1,3-bis(fluoromethyl)benzene with N,N'-dibromo-5,5-dimethylhydantoin in strongly acidic media. A number of synthetically useful reactions via 3,5-bis(trifluoromethyl)phenylmagnesium, -lithium, and -copper intermediates were accomplished.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290219
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    Lithiierte Phosphanimine. Synthese und Kristallstrukturen von [LiCH2PMe2NSiMe3]4 und [LiCMe2P(iPr)2NSiMe3]2 (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 253-257 
    Details
    ISSN: 0009-2940
    Keywords: Lithiated phosphane imines ; Phosphane imines, lithiated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lithiated Phosphane Imines. Synthesis and Crystal Structures of [LiCH2PMe2NSiMe3]4 and [LiCMe2P(iPr)2NSiMe3]2The title compounds were prepared by the reaction of Me3-SiNPMe3 and Me3SiNP(iPr)3, respectively, with n-Butylli-thium at 20°C in n-hexane solution. They form white, moisture- and oxygen-sensitive crystals, which were characterized by IR spectroscopy and by crystal structure determinations. - [LiCH2PMe2NSiMe3]4 (1) forms a Li4 tetrahedron, the faces of which are capped with CH2 groups with average Li-C distances of 233 and 251 pm, while the nitrogen atoms occupy the corners of the Li4 tetrahedron. - [LiCMe2P(iPr)2N-SiMe3]2 (2) forms molecules of symmetry C2 in which the lithium atoms have coordination number three by two carbon atoms and one nitrogen atom with Li-C distances of 215.2 and 237.9 pm and Li-N of 192.8 pm.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290223
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    Synthesis and Characterization of a Novel Cyclobutadiene-octatetrayne Polymer (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 269-273 
    Details
    ISSN: 0009-2940
    Keywords: Organometallic polymers ; Coupling reactions ; Butadiynyl complexes ; Cobalt compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of 3a starting from compound 1 is described. Copper-catalyzed oxidative coupling of 3b under Hay conditions gives the novel polymer 9 with octatetrayne-cyclobutadiene units.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290304
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    A Study on Electronic Interaction Between two [2.2]Metacyclophane Systems Connected with a C=C Bond: Preparation, Structure and Complexation of (E)- and (Z)-8,8′-(Ethene-1,2-diyl)bis(5-tert-butyl[2.2]metacyclophane) (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 289-296 
    Details
    ISSN: 0009-2940
    Keywords: Bis[2.2]metacyclophanes ; Stilbenes ; π-π Interaction ; Tricarbonylchromium complexes ; Charge-transfer ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (E)-8,8′-(Ethene-1,2-diyl)bis(5-tert-butyl[2.2]metacyclo-phane) (2) was obtained from a McMurry reaction of 5-tert-butyl-8-formyl[2.2]metacyclophane (1). Irradiation of 2 with a high-pressure mercury lamp gave the corresponding (Z) isomer 3. X-ray crystallographic analyses of 2 and 3 show a certain degree of twisting of the bond connecting the meta-cyclophane unit and the central π system due to steric crowding. UV spectra of 2 and 3 and of the charge-transfer complexes [2/TCNE] and [3/TCNE] allow for a discussion of π-π interaction between the central stilbene subunit and the outer benzene rings of the metacyclophane units. Bis[2.2]meta-cyclophanes 2 and 3 reacted regioselectively with hexacar-bonylchromium on the outer benzene rings giving 1:1 and 1:2 complexes 9-14 with tricarbonylchromium. No 1:3 and 1:4 complexes formed due to steric restrictions. Analysis of UV spectral data of the complexed [2.2]metacyclophanes was performed for an indication of π-π interactions in the complexes.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290308
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    Thermally Stable Self-assembling Open-Frameworks: Isostructural Cs+ and (CH3)4N+ Iron Germanium Sulfides (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 283-287 
    Details
    ISSN: 0009-2940
    Keywords: Self-assembling frameworks ; Thermal stability ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Here we report on investigations that have revealed for the first time that the Cs+ ion templates the same metal germanium sulfide open-framework as (CH3)4N+ (TMA+), and that metal complexing agents enhance crystal size by at least two orders of magnitude. The synthesis, structures and thermal properties of Cs2FeGe4S10 ·× H2O and TMA2FeGe4S10 are also described. Both have 3D zinc blende-type open-framework structures. These materials have the same connectivity as TMA2MnGe4S10. The tetrahedral sites in the lattice are alternately substituted by pseudo-tetrahedral Fe2+ and adamantanoid Ge4S104- building blocks, covalently linked together by Fe(μ-S)Ge bridge bonds, to give a tetragonal unit cell. The charge-balance of the anionic framework [Fe-Ge4S10]2- is maintained by either Cs+ or TMA+ ions in the cavity spaces. Synthesis of these materials demonstrates an interesting example of a self-assembly process in which a 3D framework is built from molecular precursors. Water adsorption-desorption cycling from room temperature to 200 °C reveals framework flexibility between larger and smaller tetragonal unit cell 14 isotypes. The compound TMA2FeGe4S10 is stable in nitrogen at 350 °C and under vacuum at 450 °C. The corresponding temperatures for Cs2FeGe4S10 are 530 °C and 630°C; it is stable on cooling to room temperature under vacuum, and after subsequent exposure to air. Six hundred thirty degrees celsius is the highest recorded temperature at which the integrity of a non-oxide framework has been maintained. The framework stability and flexibility of “all-inorganic” Cs2FeGe4S10 provides an encouraging example for researchers interested in developing sulfide-based framework materials with practical applications.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290307
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    Complexes with S-Donor Ligands, 4Part 3: J. Vicente, M. T. Chicote, P. González-Herrero, P. G. Jones, J. Chem. Soc., Chem. Commun. 1995, 745.. Mono- and Di-Homo- and -Hetero-Nuclear Gold(I), Silver(I), and Palladium(II) Complexes with 2-(Methylthio)pyridine, Pyridine-2(1H)-thione, and Benzoxazole-2(3H)-thione. Some Examples of the Use of Complexes as Ligands (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 327-330 
    Details
    ISSN: 0009-2940
    Keywords: Gold complexes ; Silver complexes ; Palladium complexes ; S-Donor ; Thiones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: AgClO4 reacts with bidentate ligands 2-(methylthio)pyridine (SMepy) or complexes PPN[Au(Spy)2] [PPN = N(PPh3)2, HSpy = pyridine-2(1H)-thione) or PPN[Au(Sbz)2] (HSbz = benzoxazole-2(3H)-thione), themselves acting as ligands, to give dinuclear complexes [Ag2(μ-SMepy)2](ClO4)2 (1), [AgAu(μ-Spy)2] (2), or [AgAu(μ-Sbz)2] (3), respectively. By treating 1 with [AuCl(tht)] (tht = tetrahydrothiophene), [Au(SMepy)(tht)]ClO4 (4) is obtained which, in turn, reacts with SMepy to give [Au(SMepy)2]ClO4 (5). Similarly, [PdCl2(NCPh)2] reacts with SMepy in 1:1 molar ratio to give [Pd2Cl2(μ-Cl)2(SMepy)2] (6) which reacts with SMepy in 1:2 molar ratio to give [PdCl2(SMepy)2] (7). On the other hand, HSpy reacts with Ag2CO3 to give [Ag2(μ-Spy)2] (8), and (SMepyH)ClO4 reacts with [Au(acac)PPh3] (acacH = acetyl-acetone) to give [Au(SMepy)PPh3]ClO4 (9).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290313
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    Zinc Complexes of Amino Acids and Peptides, 6. Zinc Complexes of Oligopeptides Containing Histidine at Both Termini (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 347-353 
    Details
    ISSN: 0009-2940
    Keywords: Histidine peptides ; Zinc complexes ; EXAFS analysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: One tripeptide, five tetrapeptides, and one pentapeptide, all containing His-Xn-His sequences and being blocked at the N and C termini with acyl and amide functions, respectively, were synthesized by solid-phase methods. With one exception their reaction with various zinc salts led to the precipitation of 1:1 (zinc/peptide) complexes. Analytically pure compounds were obtained from zinc tetrafluoroborate and His-Gly-His (1), from zinc chloride (resp. bromide) and His-Gly -Gly-His (2), His-Ala-Gly-His (3), His-Leu-Gly-His (4), His-Pro-Gly-His (5), and His-Pro-Asn-His (6) as well as from zinc sulfate and His-Leu-Gly-His (4) and His-Ala-Pro-Gly-His (7). 1H-NMR data, when available, indicate the coordination of both histidine units to zinc in all cases. The low solubility of the complexes points to their polymeric nature. The only 1:2 (zinc/peptide) complex in this series was obtained from zinc perchlorate and His-Gly-Gly-His (2). An EXAFS study revealed that it contains zinc symmetrically coordinated by four histidine imidazole ligands. Based on the available information it is proposed that all complexes are one-dimensional polymers containg [-Zn-His-Xn-His-Zn-]x backbones.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290316
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    Masthead (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290401
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    Silanediols Derived from Silanetriols. X-ray Crystal Structures of (2,4,6-Me3C6H2)N(SiMe3)Si(OSiMe3)(OH)2 and (2,4,6-Me3C6H2)N(SiMe3)Si(OSiMe2R)(OH)2 [R = CH2 (2-NH2-3,5-Me2C6H2)] (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 391-395 
    Details
    ISSN: 0009-2940
    Keywords: Silanediols ; Silanetriols ; Siloxanes ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The silanediols RN(SiMe3)Si(OSiMe3)(OH)2 (R = 2,4,6-Me3C6H2 4, 2,6-Me2C6H3 5, and 2,6-iPr2C6H3 6) were prepared by the reactions of the respective silanetriols RN(SiMe3)-Si(OH)3 1 - 3 with SiMe3Cl in THF/hexane. Silanetriol 1 in CH2Cl2/hexane solution converts over a period of 4 weeks into the silanediol (2,4,6-Me3C6H2)N(SiMe3)Si(OSiMe2 R)-(OH)2 [R = CH2(2-NH2-3,5-Me2C6H2)] (7). Compounds 4 - 7 were characterized by means of mass, IR and NMR (1H and 29Si) spectroscopy. Additionally, the molecular structures of 4 and 7 were determined by single-crystal X-ray diffraction studies. Compound 4 forms O — H…O hydrogen-bonded tetramers in the solid state. A nine-membered ring formed by an intermolecular O—H…N hydrogen bond is found in the solid-state structure of 7.
    Additional Material: 3 Ill.
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    Novel trialkylstibane iridium(I) and iridium(III) complexes including the x-ray crystal structure of five-Coordinate [IrCl(C2H4)2(SbiPr3)2]Dedicated to Professor Erwin Weiss on the occasion of his 70th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 411-417 
    Details
    ISSN: 0009-2940
    Keywords: Iridium complexes ; Stibane complexes ; Hydrido complexes ; Ethene complexes ; Ligand displacement reactions ; Alkyne-to-vinylidene rearrangement ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of [IrCl(C8H14)2]2 (2) with SbiPr3 in the presence of H2 yields the dihydridoiridium(III) complex cis,mer-[IrH2Cl(SbiPr3)3] (3) which on treatment with CO and with HC≡CR (R = Ph, CO2Me) affords the octahedral derivatives [IrH2Cl(CO)(SbiPr3)2] (4) and [IrHCl(C≡CR)(SbiPr3)3] (5, 6), respectively. The stibane ligand trans to hydride in 5 and 6 is rather labile and, therefore, 5 and 6 react with pyridine to give [IrHCl(C≡CR)(py)(SbiPr3)2] (7, 8). Five-coordinate bis-(stibane)iridium(I) complexes [IrCl(C2H4)2(SbR3)2] (10-12) were prepared from [IrCl(C2H4)2]2 (9) and four equiv. of SbR3 (R = iPr, Me, Ph). The X-ray crystal structural analysis of 10 reveals a distorted trigonal-bipyramidal geometry around the metal center with one stibane ligand and the two olefinic ligands in the equatorial plane. Compound 10 reacts with NaC5H5 to yield [C5H5Ir(C2H4)(SbiPr3)] (13) and with different alkynes by partial or complete displacement of the ethene ligands to give trans-[IrCl(PhC≡CPh)(SbiPr3)2] (14), [IrHCl(C≡CTol)(C2H4)(SbiPr3)2] (15), and trans-[IrCl-{=C=C(SiMe3)R}(SbiPr3)2] (16, 17), respectively.
    Additional Material: 1 Ill.
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    Azolylborane adducts. Structural and conformational analysis by x-ray diffraction and NMR. Protic-hydric (C=Hδ+-δ-H=B) and Protic-Fluoride (C=Hδ+-δ-F=B) interactions (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 441-449 
    Details
    ISSN: 0009-2940
    Keywords: Azolylborane adducts ; Boron-imidazole adducts ; Boron-pyridine adducts ; Protic-hydric interactions ; Protic-fluoride interactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation, NMR and X-ray diffraction studies of a series of azolylboron hydrides derived from pyrrole, indole, and carbazole coordinated with tetrahydrofuran, pyridine, and imidazole are reported. The azolyl substituents are very electroattractive leading to an acidic boron atom which strongly coordinates with the Lewis bases. The stabilization of the =BH2=groups against disproportionation could be explained in terms of the interactions found between the acidic hydrogen atoms of the heterocycles (C=Hδ+ acceptor) and the hydrides (B=Hδ- donors).
    Additional Material: 8 Ill.
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    Masthead (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290501
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    The Synthesis of Stabilized Dimetallated Thioimidate Complexes by the Insertion of Ethoxycarbonylisothiocyanate into a Rhenium-Rhenium Bond (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 485-487 
    Details
    ISSN: 0009-2940
    Keywords: Dimetallations ; Insertions ; Rhenium ; Isothiocyanates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecules containing dimetallated hydrocarbyl groupings are of great chemical interest[1-3]. These groupings often represent intermediates in important catalytic processes[4]. Recently, we have shown that substituted dimetallated olefins can be formed by alkyne insertion into the metal-metal bonds of certain dinuclear complexes[2,5]. Complexes having dimetallated hydrocarbyl groups combined with heteroatoms are quite rare[6]. Herein is described the formation of a dimetallathioimidate grouping by the insertion of an organic isothiocyanates into an unsupported metal-metal bond. Organic isothiocyanates are useful reagents in organic synthesis[7], but the organometallic chemistry of these molecules is not yet well developed[8].
    Additional Material: 3 Ill.
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    Supermolecules Containing a Tetrahedral Core: A New Class of Liquid-Crystalline Siloxanes (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 521-525 
    Details
    ISSN: 0009-2940
    Keywords: Liquid crystals ; Siloxanes ; Phase behaviors ; Defined topology ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that supermolecules with a tetrahedral symmetry and appropriate side-chains exhibit liquid-crystalline phase behaviour. The use of an optimised hydrosylation reaction allows for the synthesis of materials that have four mesogenic groups attached to a siloxane core, where the conformation and the configuration are unambiguous. The materials show low glass transition temperatures and, depending on the spacer length, complex liquid-crystalline morphologies.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290508
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    Transition Metal Complexes with Sulfur Ligands, Part 119Part 118: D. Sellmann, H.-J. Kremitzl, F. Knoch, M. Moll, J. Biol. Anorg. Chem., in press.. Synthesis of Water Soluble Fe and Ru Complexes with Novel Multidentate Thioether Thiolate Ligands Containing Carboxylate Substituents (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 509-519 
    Details
    ISSN: 0009-2940
    Keywords: Iron and ruthenium complexes ; Water soluble complexes ; Sulfur ligands ; X-ray structure analyses ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In search of water soluble transition metal complexes with sulfur dominated coordination spheres that model key reactions of nitrogenases, the benzenedithiol derivatives ‘CO2HS2’-H2 (1) and ‘CO2Me-S2’-H2 (2) were synthesized as precursors for multidentate sulfur ligands. The template alkylation of 2 by C2H4Br2 at [Fe(CO)2] fragments yielded a mixture of two diastereomeric C2 symmetrical [Fe(CO)2(‘CO2Me-S4’)] complexes (4a and 4b), which were separated by crystallization. The hydrolysis of the mixture of the diastereomers 4a and 4b led to the isomerically pure tetradentate thioether thiol ligand ‘CO2Me-S4’-H2 (5) proving the regioselectivity of the template alkylation of the asymmetrical dithiol 2. The C1 symmetrical [Fe(‘CO2Me-S2’)2]2- anion is an intermediate of the template alkylation and was isolated as (AsPh4)2 [Fe(‘CO2Me-S2’2] (11), 4a, 5 and 11 were characterized by X-ray structural analysis. Saponification of the methyl ester groups of 5 yielded ‘CO2H-S4’-H2 (7). Treatment of 7 with FeCl2 · 4 H2O in the presence of CO and LiOMe gave a mixture of two C2 symmetrical and water soluble diastereomers of Li2[Fe(CO)2(‘CO2-S4’)] (8). Upon treatment with [RuCl2 (PPh3)3] 7 yielded isomerically pure [Ru(PPh3)2-(‘CO2H-S4’)] (9). 9 also exhibits C2 symmetry and could be reversibly deprotonated to form the water soluble complex K2[Ru(PPh3)2 (‘CO2-S4’)] (10). Treatment of (NBu4)2 (‘CO2MeS2’) with “Ru(NO)Cl3” led to isomerically pure (NBu4)[Ru(NO)(‘CO2Me-S2’)2] (12).
    Additional Material: 6 Ill.
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    Syntheses and Photochemistry of Fluorinated and Chlorinated Titanium Porphyrinates: Crystal Structure of Oxotitanium meso-Tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrinate (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 833-836 
    Details
    ISSN: 0009-2940
    Keywords: Oxotitanium(IV) porphyrinate ; Peroxotitanium(IV) porphyrinate ; Photochemistry ; Singlet oxygen ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of oxotitanium(IV) meso-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrinate O=Ti(TPPF20) (1), oxotitanium(IV) meso-tetrakis(2,6-difluorophenyl)porphyrinate O=Ti-(TPPF8) (3), and oxotitanium(IV) meso-tetrakis(2,6-dichlorophenyl)porphyrinate O=Ti(TPPCl8) (5) from titanium tetrachloride and the corresponding porphine are described. The structure of 1 was determined by single-crystal X-ray diffraction. The reaction of oxotitanium porphyrinates with aqueous hydrogen peroxide leads to the corresponding light-sensitive peroxotitanium(IV) complexes: Ti(O2)(TPPF20) (2), Ti(O2)-(TPPF8) (4), Ti(O2)(TPPCl8) (6). All complexes are efficient and stable photosensitizers for the generation of singlet oxygen.
    Additional Material: 2 Ill.
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    Syntheses of Hetero-sila-closo-boranes (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 837-839 
    Details
    ISSN: 0009-2940
    Keywords: Boron compounds ; Silaboranes ; Dihetero-closo-borane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of 3 equivalents of KH · BEt3 to [Me3NH][Me-SiB10H12] followed by addition of one equivalent of SnCl2 or SbI3 affords the stanna-sila-closo-borate(1-) 3 and stiba-sila-closo-borane 4, respectively. [MePh3P] · 3 crystallizes in the orthorhombic space group P212121.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290716
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    Intramolekular stabilisierte Übergangsmetallamide: 2-(Dimethylaminomethyl)pyrrolyl-Komplexe des Titan(III), Vanadium(III), Chrom(III), Cobalt(II) und Nickel(II) (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 853-857 
    Details
    ISSN: 0009-2940
    Keywords: Amides ; Pyrrolyl complexes ; Chelate complexes ; Transition-metal complexes ; Metallacycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intramolecularly Stabilized Metal Amides: 2-(Dimethylaminomethyl)pyrrolyl Complexes of Titanium(III), Vanadium(III), Chromium(III), Cobalt(II) and Nickel(II)By the metallation of 2-(dimethylaminomethyl)pyrrol (HL) with butyllithium the lithium pyrrolide LiL (1) was obtained. The reactions of 1 with TiBr3 · 3 THF, VBr3 · 3 THF, CrBr3 · 3 THF, CoBr2 · 2 THF, and NiBr2 · 1.67 THF result in the formation of the 2-(dimethylaminomethyl)pyrrolyl complexes of type ML3 (2-4), and ML2 (5, 6), respectively. The structures of these new compounds are discussed on the basis of magnetic and visible absorption measurements. An X-ray crystal structure determination of 4 reveals a strongly distorted octahedral environment of the chromium atom with facial arrangement of the ligands.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961290719
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    Stepwise Insertion of Alkylisocyanides into the Metal-Alkyne Bond of Half-Sandwich Type Rhodium Complexes: Synthesis and Structural Characterization of Metallacyclobutenes and MetallacyclopentenesDedicated to Professor Gerhard E. Herberich on the occasion of his 60th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 903-910 
    Details
    ISSN: 0009-2940
    Keywords: Rhodium complexes ; Alkyne complexes ; Insertion reactions ; Alkyl isocyanides ; Metallacycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cyclopentadienyl complexes [C5H5Rh(RC≡CR′)(SbiPr3)] (5-8), which were prepared from trans-[RhCl-(RC≡CR′)(SbiPr3)2] (1-4) and NaC5H5 and which contain a labile Rh-SbiPr3 bond, reacted with CO and CNR″ (R″ = Me, tBu) to give the carbonyl and isocyanide derivatives [C5H5Rh(RC≡CR′)(CO)] (9-11) and [C5H5Rh(RC≡CR′)-(CNR″)] (12-16), respectively. On treatment of 12 (R = R′ = Ph; R″ = Me) with SbiPr3, the metallacyclobutene complex [C5H5Rh{κ2(C,C}-C( = NMe)CPh=CPh}(SbiPr3)] (17) was formed; it reacts with excess CNMe or CNtBu to yield the metallacyclopentenes [C5H5Rh{κ2(C,C)-C(=NMe)CPh=CPhC-(=NR)}(CNR)] (18, 19). Similar compounds 20-23 containing a five-membered RhC4 metallacycle were prepared either from [C5H5Rh(RC≡CR′)(SbiPr3)] (7, 8) or [C5H5Rh-(PhC≡CPh)(CNtBu)] (14) and excess isocyanide. The crystal and molecular structures of 17 and 18 (R = Me) have been determined.
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    Isolation and Spectroscopic Characterization of Heteroleptic, Anionic and Neutral (Phthalocyaninato)(tetra-4-pyridylporphyrinato)lanthanide(III) Double-DeckersDedicated to Professor Shang-Wai Tam on the occasion of his retirement from The Chinese University of Hong Kong. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 933-936 
    Details
    ISSN: 0009-2940
    Keywords: Phthalocyanines ; Porphyrins ; Lanthanide(III) compounds ; Macrocyclic ligands ; Double-decker complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of 5,10,15,20-tetra-4-pyridylporphyrin [(TPyP)H2] with europium(III) or gadolinium(III) acetylacetonate [Ln(acac)3 · nH2O] (Ln = Eu, Gd) in 1,2,4-trichlorobenzene produced Ln(acac)(TPyP), which reacted with dilithium phthalocyaninate [Li2(Pc)] to give Li[Ln(Pc)(TPyP)] in moderate yields. Upon exposure to air, solutions of these compounds converted slowly to the corresponding neutral complexes Ln(Pc)(TPyP). The new compounds were spectroscopically characterized.
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    Synthesis, Spectroscopic Characterization, and Crystal Structure Determination of Cationic [(Cyclopentadienyl)dicarbonyliron](alkynyl)-aminocarbene Complexes (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 937-944 
    Details
    ISSN: 0009-2940
    Keywords: Iron acyl complexes ; (Alkynyl)carbene ligand ; Cationic aminocarbene complexes ; Iron (2-methoxyvinyl)aminocarbene complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Alkynoyl)iron complexes 1, Cp(CO)2Fe(O=CC≡CR) (R = CH3, Ph, SiMe3), were synthesized by applying a mixed anhydride procedure and transformed into the cationic methoxycarbene complexes 2, [Cp(CO)2 Fe(C(OMe)C≡CR)+]-[PF6-]. Primary amines H2NR′ react with the methoxycarbene complexes to furnish exclusively cationic aminocarbene complexes 3, [Cp(CO)2 Fe(C(NHR′)C≡CR)+][PF6-], or (2-methoxyvinyl)aminocarbene complexes 5. The spectroscopic properties of the new complexes are discussed. The (alkynyl)-aminocarbene complexes 3e and 3f were characterized by X-ray crystal structure analysis.
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    URL: http://dx.doi.org/10.1002/cber.19961290810
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    Synthesis and Characterization of Novel Phthalocyanines with Four 16-Membered Diazadithia Macrocycles (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 967-971 
    Details
    ISSN: 0009-2940
    Keywords: Phthalocyanines, sulphonated ; Diazadithiamacrocycles ; Pentanuclear complex ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal phthalocyanines (M = Cu, Ni, Co) 3-5 bearing four 16-membered diazadithia macrocycles at the peripheral positions were prepared. Detosylation with concentrated sulfuric acid afforded products containing both sulfonated groups on the aromatic rings of the macrocyclic substituents which are excellently soluble in water and donor sites for binding four CuII ions to give a pentanuclear complex.
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    A Search for Thionitrosyl Chloride (Cl-N=S) in the Gas Phase (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1379-1381 
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    ISSN: 0009-2940
    Keywords: Thionitrosyl chloride ; Thiazyl chloride ; Neutralization-reionization mass spectrometry ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio MO calculations at the QCISD(T)/6-311++G(3df,2p) + ZPE level show that the thionitrosyl chloride ion, ClNS+•, is 36 kJ/mol more stable than the thiazyl chloride ion, NSCl+•, whereas neutral NSCl is 77 kJ/mol more stable than ClNS [IEa (ClNS) = 9.2 ± 0.3 eV, IEa (NSCl) = 10.5 ± 0.3 eV]. Mild flash-vacuum pyrolysis of the thiazyl chloride trimer (NSCl)3 followed by electron impact ionization resulted in the formation of [N,S,Cl]+• ions (m/z 81). The fragments observed in the CA spectrum of these ions indicate the formation of both NSCl+• and ClNS+• ions. A very weak recovery signal is observed in a neutralizationreionization experiment. This signal is tentatively assigned to the neutral thionitrosyl chloride.
    Additional Material: 4 Ill.
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    Synthesis and Reactivity of Some Nitroaryl Complexes of HgII and AuIII  -  Synthesis of a Substituted Biphenyl by C-C Coupling - Crystal Structure of [Hg(C6H4NO2-3, OnBu-6)2] (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1395-1399 
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    ISSN: 0009-2940
    Keywords: Gold ; Mercury ; Nitroaryl ; Transmetallation ; Biaryl ; C-C Coupling ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-Butoxynitrobenzene reacts with [Hg(O2CCF3)2] and LiCl to give [Hg(R)Cl] [R = C6H3NO2-3, OnBu-6 (1)] which is symmetrized by Me4NCl to give [HgR2] (2), the crystal structure of which has been determined. The reaction of 2 with Me4N[AuCl4] affords Me4N[Au(R)Cl3] (3) by a facile transmetallation process. Complex 3 reacts with PPh3 (1:1) to give cis-[Au(R)(PPh3)Cl2] (4). The diaryl complex [-Ph-2)(R)Cl] (5) is obtained by reaction of 3 with [Hg-(C6H4N=NPh-2)2] through a second transmetallation reaction. Complex 5 and PPh3 (1:1) give [AuClPPh3] and the C-C coupling biphenyl RC6H4N=NPh-2 (6).
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    URL: http://dx.doi.org/10.1002/cber.19961291114
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    Sulfenato, Thiosulfinato, and Thiosulfonato Transition Metal ComplexesDedicated to Professor M. Herberhold on the occasion of his 60th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1409-1419 
    Details
    ISSN: 0009-2940
    Keywords: Sulfenic acid anions ; Thiosulfinic acid anions ; Thiosulfonic acid anions ; Transition metal complexes ; Stereochemistry ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and coordination chemistry of sulfenic, thiosulfinic, and thiosulfonic acid anions are reviewed. Different approaches, which yield the platinum(II) and ruthenium(II) complexes containing the anionic sulfur(0), sulfur(II), and sulfur(IV) oxid ligands, are described. The oxidative addition of thiosulfinates or N-sulfinyl phthalimides to platinum(0) complexes L2Pt(C2H4) [L = PPh3, 1/2 PPh2CH2CH2PPh2, 1/2 (R,R)-(-)-DIOP, 1/2 (C5H4PPh2)Fe(C5H4PPh2) leads to sulfenato complexes; those of N-thiosulfinyl phthalimidies or trisulfid 1-oxides afford the thiosulfinato complexes. Moreover, the reactions of CpRu(PPh3)(L)(SH) (L = CO, PPh3) with N-sulfinyl phthalimides forming the thiosulfinato moiety, are reported. The spectroscopic, structural and chemical properties of these complexes are discussed.
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    URL: http://dx.doi.org/10.1002/cber.19961291202
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    Cationic Iron Aminocarbene Complexes as Dienophiles in Diels-Alder Reaction with Cyclopentadiene (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1057-1059 
    Details
    ISSN: 0009-2940
    Keywords: (Alkynyl)carbene ligands ; Iron acyl complexes ; Cationic iron aminocarbene complexes ; Diels-Alder reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cationic iron (alkynyl)aminocarbene complexes [Cp(CO)2Fe(C(NHR)C≡CSiMe3][PF6], (R = C6H5, p-CH3C6H4) 1 derived from aromatic amines smoothly react with cyclopentadiene in dichloromethane to yield the cycloadducts 2. No reaction was observed for complexes derived from sterically demanding aliphatic amines, like L-alanine tert-butyl ester. For comparison, the alkynyl-substituted acyl iron compounds Cp(CO)2Fe(C=O)C≡C̊ (R = SiMe3, C6H5) 3 were investigated, requiring TiCl4 catalysis to undergo the cycloaddition reaction. The structures of the cycloadducts 4 were determined by X-ray crystallography.
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    Synthesis, Structure and Reactions of the Homoleptic Alkyne Nickel(0) Complex (Alkyne)4Ni3 (Alkyne: 2-methyl-4-trimethylsilyl-3-butyn-2-ol)Dedicated to Professor Walter Siebert on the occasion of his 60th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1457-1461 
    Details
    ISSN: 0009-2940
    Keywords: Nickel(0) ; Alkyne complexes ; Hydrogen bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of (cdt)Ni (cdt: cyclododeca-1,5,9-triene) with 2 equivalents of 2-methyl-4-trimethylsilyl-3-butyn-2-ol leads to the selective formation of the homoleptic complex (alkyne)4Ni3 (compound 3), which can be isolated in excellent yields. The solid-state structure of 3 exhibits three Ni centers, forming a bent Ni3 chain connected by two bridging alkynes. The other two alkynes are terminally coordinated. Additionally, the trimeric units are stabilized by three intramolecular hydrogen bonds. Two intermolecular hydrogen bonds connect the trimeric units to form a polymer rope. According to the 13C- and 1H-NMR spectra in THF the structure of the complex 3 in solution is very similar to that in the solid state. The reaction of 3 with some alkynediols and with 2,5,5-trimethylhex-3-yn-2-ol affords compounds of the type (alkyne)2Ni. Cot (cot: 1,3,5,7-cyclooctatetraene) converts 3 into [(cot)Ni]2, which in turn reacts with 2,5-dimethylhex-3-yne-2,5-diol to form the dimeric complex (alkyne)2Ni2(cot) 6. X-ray analysis of 6 reveals a very symmetrical structure in which cot connects both Ni(0) centers at opposite sides of the ring system.
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    Control of the SO2 Coordination Mode at the (Monochelate)rhodium Complex ClRh(P∼O) with the Hemilabile Ligand Cy2PCH2CH2OCH3Dedicated to Professor Michael Hanack on the occasion of his 65th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1103-1105 
    Details
    ISSN: 0009-2940
    Keywords: Sulfur dioxide ; Rhodium complexes ; Ether-phosphanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The SO2 coordination mode at the rhodium complex [ClRh(P∼O)()] (1) [ = η2(O,P)-chelated Cy2PCH2CH2OCH3 ligand; P∼O = =1(P)-coordinated] is controlled by the hemilabile ligand Cy2PCH2CH2OCH3 and shows a dependence on the polarity of the solvent. In polar organic solvents (e.g. acetone) the addition of sulfur dioxide results in the formation of a trigonal-pyramidal oriented SO2 group in [ClRh(η1-SO2)(P∼O)()] (2a). However, in nonpolar media (e.g. n-hexane) a trigonal-coplanar geometry of the SO2 unit in [ClRh(η1-SO2)(P∼O)2] (2b) is favored.
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    Masthead (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/cber.19961291001
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    1,3-Heterobinuclear Cyclobutenylidene Complexes with an Exocyclic C=C bond  -  Synthesis, Structure, and Spectroscopic Properties (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1475-1482 
    Details
    ISSN: 0009-2940
    Keywords: Allenylidene complexes ; Alkynyl complexes ; Cyclobutenylidene complexes ; Cycloadditions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pentacarbonyl(allenylidene)chromium and -tungsten, [(CO)5—M=C=C=CR2] (M=Cr, R=C6H4CH3-p(1a), C6H4OCH3 (1b); M=W, R=C6H4CH3-p (1c), react with the alkynyl complexes [Cp(CO)2Fe—C≡CR′] (R′ = nBu (2), Ph (4)), [Cp*(CO)2Fe—C≡CnBu] (6), [Cp(CO){P(OMe)3}-Fe—C≡CnBu] (8) and [Cp(PPh3)Ni—C≡CnBu] (10) by cycloaddition of the C≡C bond of the alkynyl complexes to the Cα=Cβ bond of the allenylidene ligand to give 3a-c), (5), (7), and respectively. The cycloaddition is highly selective. The spectroscopic data of these 1,3-heterobinuclear complexes indicate a delocalized π-system (M=Cr, W; Y=[Fe(CO)2Cp], [Fe(CO)(P{OMe}3)Cp], [Fe(CO)2Cp*], [Ni(PPh3)-Cp]). X-ray structural analyses of the compounds 3a, 9a, and 11c reveal a “butterfly” conformation of the four-membered ring. Its puckering angle is 142° (3a), 152° (9a), and 151° (11c). All Complexes exhibit a moderate to strong negative solvatochromic behavior. The extent of the solvatochromic effect depends on [(CO)5M] and Y and considerably decreases when C=CR2 is replaced by e.g. CMe2.
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    The Phosphonate-Phosphate- and Phosphate-Phosphonate Rearrangement and Their Applications, 4Part 3: Ref.[1].. Deprotonation of Secondary Benzylic Phosphates  -  Configurationally Stabile Benzylic Carbanions with a Diethoxyphosphoryloxy Substituent and Their Rearrangement to Optically Active Tertiary α-Hydroxyphosphonates (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1503-1508 
    Details
    ISSN: 0009-2940
    Keywords: Phosphate - Phosphonate rearrangement ; Carbanions, benzylic, configurational stability of ; α-Hydroxyphosphonates, tertiary, chiral, non-racemic ; t-Butyl(phenyl)phosphinothioic acid, homochiral ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optically active alcohols (ee ≥ 98%) such as 1-phenylpropanol, 1-(2-naphthyl)ethanol, 1-tetralol, and 1-indanol were transformed into diethyl phosphates 7a-d. sBuLi/TMEDA  -  induced phosphate - phosphonate rearrangement in diethyl ether furnished tertiary α-hydroxyphosphonates 8a-d of high enantiomeric purity (ee 94-98%) in yields of 43-83% with retention of configuration. The enantiomeric excesses were determined by using homochiral t-butyl(phenyl)phosphinothioic acid as chiral solvating agent.
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    Hydride Addition to Coordinated S2CPR3 Ligands in Mononuclear Mn and Re Complexes: Phosphane-dithioformate Adducts as Five-electron Bridging Ligands (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1535-1540 
    Details
    ISSN: 0009-2940
    Keywords: 1,1-Dithiolate ; Manganese complexes ; Rhenium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cationic tetracarbonyl complex cis-[Mn(CO)4-(S2CPCy3)]+ undergoes addition of hydride ion to the central carbon of the S2CPR3 ligand to afford, after spontaneous dimerization with loss of CO, the dimer [Mn2(CO)6{μ-S2C(H)PCy3}2] (5a), which was characterized by analytical and spectroscopic methods as well as by X-ray diffraction. In the molecule of 5a each S2C(H)PCy3- ligand is coordinated to one manganese in an η2-S,S′ chelate fashion, and one sulfur of each ligand serves as a bridge to bind the other manganese atom, thus forming a distorted Mn2S2 square. This appears to be a very stable arrangement. Compound 5a can be more easily prepared by treating the perchlorato complex [Mn(CO)3(S2CPCy3)(OClO3)] (2a) with NaBH4. This procedure is general and can be used for the preparation of several derivatives containing either manganese or rhenium [M2(CO)6{μ-S2C(H)PR3}2] 5a-d. The reaction of cationic tricarbonyl complexes [M(CO)3(S2CPR3)(PPh3)]PF6 (M = Mn, Re) with NaBH4 produced the same dimers 5a or 5c by displacement of the PPh3 ligand. Treatment of the dimer 5a with excess PEt3 or P(OMe)3 leads to the cleavage of the bridges and loss of one CO and the PR3 group from the S2C(H)PR3 unit to afford ultimately the dithioformate complexes [Mn(CO)2(S2CH)(L)2] [L = PEt3, P(OMe)3].
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    Zinkorganische Phosphaniminato-Komplexe mit Heterocuban-StrukturHerrn Prof. Dr. Armin Berndt zum 60. Geburtstag gewidmet. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1621-1625 
    Details
    ISSN: 0009-2940
    Keywords: Organo-zinc compounds ; Phosphaneiminato complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organo-Zinc Phosphaneiminato Complexes with Heterocubane StructureThe organo-zinc heterocubanes [ZnR(NPMe3)]4 with R = CH3 (1) and n-C4H9 (2) were prepared by the reaction of [ZnBr(NPMe3)]4 with MeLi and nBuLi, respectively, in hexane solution. In a similar reaction of nBuLi with [ZnI(NPMe3]4 the phosphaneiminato complex [Zn4I(nBu)4(NPMe3)3] (3) is formed. 1-3 were characterized by IR, NMR and MS spectroscopy, and by crystal-structure determinations. 1 and 2 possess heterocubane structures in which the zinc atoms are linked via μ3-N bridges of the phosphaneiminato groups, and all bond angles in the Zn4N4 core are close to 90°. A distorted heterocubane structure is observed for 3 with one of the NPMe3 moieties replaced by an iodine atom.
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    On the Synthesis of Sulfoxonium Ylides: New Aspects of the Chemistry of 1,3-Dithietane 1,1,3,3-Tetraoxide and 1,3,5-Trithiane 1,1,3,3,5,5-Hexaoxide (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 161-167 
    Details
    ISSN: 0009-2940
    Keywords: Sulfoxonium ylides ; 1,3-Dithietane 1,1,3,3-tetraoxide, silylated ; 1,3,5-Trithiane 1,1,3,3,5,5-hexaoxide, silylated ; Disulfenes, unsaturated ; Disulfenes, dianions of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sulfoxonium ylides 3a-h were synthesized by silylation of the cyclic methylene disulfones 1,3-dithietane 1,1,3,3-tetraoxide (1) and 1,3,5-trithiane 1,1,3,3,5,5-hexaoxide (4) with the silylating agents silyl nonafluorobutanesulfonates. The structure and constitution of the ylides were established with 1H-NMR, 13C-NMR, 29Si-NMR spectroscopy, mass spectrometry, and elemental analysis. On the route to the sulfoxonium ylides a new class of unsaturated disulfenes 7, 8, 12, 13 of 1 and 4 were synthesized via Knoevenagel and substitution reactions. Dianions of newly formed alkyl disulfenes 16a, b, e, f, and the trianion 17 were prepared and characterized by 1H-NMR and 13C-NMR spectroscopy and compared with the results of the ylides.
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    URL: http://dx.doi.org/10.1002/cber.19961290209
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    Addition von CS2 und anderen Heteroallenen an die 16-Elektronen-Osmium(0)-Komplexe trans-[OsCl(NO)(PiPr2R)2] (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 405-410 
    Details
    ISSN: 0009-2940
    Keywords: Osmium(0) complexes ; Nitrosyl complexes ; CS2, COS, SCNPh, and Ph2C=C=O as bidentate ligands ; Protonation and methylation reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of CS2 and Other Heteroallenes to the 16-Electron Osmium(0) Complexes trans-[OsCl(NO)(PiPr2R)2]The coordinatively unsaturated 16-electron compounds trans-[OsCl(NO)(PiPr2R)2] (1: R = iPr; 2: R = Ph) react with CS2 and COS to form the 1:1 adducts [OsCl(NO){κ2(C,S)-S=C=S}(PiPr2R)2)] (3, 4) and [OsCl(NO){κ2(C,S)-S=C=O}-(PiPr2R)2] (6, 7), respectively. While compounds 3, 4 are inert toward PMe3, the Os(COS) complexes 6, 7 react with tri-methylphosphane by abstraction of sulfur to give (OsCl(NO)-(CO)(PiPr2R)2] (8, 9). From 1 or 2 and phenylisothiocyanate the corresponding 1:1 adducts (OsCl(NO){κ2(C,S)-S=C=NPh}(PiPr2R)2] (10, 11) are obtained. Protonation and methylation reactions of 10 (R = iPr) with HBF4 or CF3SO3Me lead, by addition of the electrophile to the C=N nitrogen atom, to the formation of [OsCl(NO){κ2(C,S)-S=CNHPh}-(PiPr3)2]BF4 (12) and [OsCl(NO){κ2(C,S)-S=CN(Me)Ph}-(PiPr3)2]CF3SO3 (13). Treatment of 1 with diphenylketene yields [OsCl(NO){κ2(C,O)-O=C=CPh2}(PiPr3)2] (14). The X-ray structure analyses of 10 and 14 confirm the coordination of phenylisothiocyanate via S and C and of diphenylketene via O and C, respectively.
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    8-quinolylcyclopentadienyl, a ligand with a tailored fit for chelate complexes (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 459-463 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopentadienes ; Half-sandwich complexes ; Intramolecular nitrogen donors ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 8-Lithioquinoline reacts with 2,3,4,5-tetramethylcyclopentenone to give 8-quinolylcyclopentadiene (1/2) after acidic workup and treatment with ammonia. Two of the possible three isomers are formed; the acidic protons on the Cp rings show unusual downfield shifts in the 1H-NMR spectra. Treatment with strong bases led to the intensely coloured anionic 4 which was converted into the trimethylsilyl derivative 5. This is a suitable starting compound for the trihalotitanium and -zirconium compounds 6 and 7. The two complexes were investigated by crystal structure analyses. In both cases the quinolyl nitrogen atom is coordinated to the metal.
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    Über das Silaethen tBu2Si=C(SiMe3)2 und die Struktur sowie Reaktivität seines [4 + 2]-Cycloaddukts mit Ph2C=OFrau Prof. Marianne Baudler zum 75. Geburtstag gewidmet. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 471-478 
    Details
    ISSN: 0009-2940
    Keywords: Silaethenes ; [4 + 2] Cycloadditions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Silaethene tBu2Si=C(SiMe3)2, and the Structure and Reactivity of Its [4 + 2] Cycloadduct with Ph2C=OFrom tBu2SiF—CLi(SiMe3)2 by LiF elimination only Me2Si= C(SiMe3)(SiMetBu2) (1b) instead of tBu2Si=C(SiMe3)2 (1a) is isolated. With benzophenone, silaethene 1b (from its THF adduct 1b · THF) forms at -78 °C a yellow [4 + 2] cycloadduct (5) and a colorless [2 + 2] cycloadduct (6). With increasing temperature 5 transforms into 6, and 6 transforms -more slowly - into the yellow [4 + 2] cycloadduct (7) of 1a and Ph2CO. It follows from this that the migration equilibrium 1a ⇄ 1b really exists. The structure of 7 shows a planar —O—CPh=C6H5-framework with the cycloadded atoms Si and C from -tBu2Si—C(SiMe3)2- located above the plane. The =C6H5—C bond (1.62 Å) is exceptionally long. 7 is a source for 1a which is trapped by acetone (formation of an ene product) and by benzaldehyde [formation of a [2 + 2] cycloadduct, unstable against cycloreversion into PhHC=C(SiMe3)2 and tBu2SiO-containing substances]. Reaction of 7 with trimethylsilyl azide, less reactive than acetone or benzaldehyde, leads - by way of 1a which transforms into 1b - to a trapping product of 1b (formation of a [3 + 2] cycloadduct, unstable against transformation into (RMe2Si)(Me3Si)CN2 with R = (Me3Si)2N, or cycloreversion into (tBu2MeSi)(Me3Si)CN2 and Me2SiNSiMe3-containing substances). Reaction of 1b or 1b · THF with acetone leads only to an ene reaction product of 1b. This means, that only undetectable amounts of 1a or 1a · THF are in equilibrium with 1b or 1b · THF. A minor substance which is shown by NMR at low temperatures besides 1b or 1b · THF is interpreted as a rotamer of 1b or 1b · THF.
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    Organophosphorus Compounds, 112Part 111: Ref.[1].. Lewis Acid Mediated Spirocyclotrimerization of Kinetically Stabilized Phosphaalkynes - Key Step for the Selective Generation and Trapping of Triphospha Dewar BenzenesDedicated to Professor H. W. Roesky on the occasion of his 60th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 489-494 
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    ISSN: 0009-2940
    Keywords: Phosphaalkynes ; Phosphaalkenes ; Spirocyclotrimerization ; Triphospha Dewar benzenes ; Phosphaalkyne cyclooligomers ; Cage compounds, phosphorus-carbon ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the presence of Lewis acidic derivatives of group 13 elements, phosphaalkynes 7 undergo spirocyclotrimerization with incorporation of the corresponding Lewis acids to form 10a-f. Scope and limitations of this novel cyclooligomerization process are examined. Starting from the spirocyclotrimer 10a reaction with the Lewis base dimethyl sulfoxide, we have in hand for the first time a method for the selective generation of two isomeric triphospha Dewar benzene derivatives (18, 19). Both can be trapped efficiently by further reaction with the phosphaalkyne to furnish the two novel phosphaalkyne cyclotetramers 20 and 21, both still possessing a phosphorus-carbon double bond. In the case of 21, further functionalization of the phosphaalkene unit is possible by [3 + 2] cycloaddition with a nitrile oxide (→ 23).
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    Self-Assembly of Substituted 6-Hydroxy-trans-3-hexenoic Acids - Formation of Extended Ribbon-Like Structures by Hydrogen Bonds (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1029-1034 
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    ISSN: 0009-2940
    Keywords: Hydrogen bonding ; Hydroxy carboxylic acids, self-assembly of ; Crystal engineering ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The substituted 6-hydroxy-trans-3-hexenoic acids 2a and 2b are prepared by an organometallic template reaction involving a sequence of CC coupling reactions between a CO2 equivalent, butadiene, and 3-cyclopenten-1-one or 3,4-diphenyl-3-cyclopenten-1-one, respectively. In the crystal 2a assembles to form an infinite ribbon-type structure, exhibiting an alternating array of 12 and 18 atom-containing loops. The former are each constructed by an alternating CO2H/OH/CO2H/OH sequence, originating from four different monomeric units, that are linked together by means of hydrogen bonds. Two complementary ribbons of 2a are connected by van der Waals interactions to form staples that constitute the microscopic building blocks of the true (2a)n structure in the crystal. Stacks of cyclopentene π bonds are oriented inside the columnar structure of 2a. Acid 2b also forms a related ribbon-like assembly in the solid state. Here the bulky 3,4-diphenylcyclopentadienylidene moieties are oriented laterally at the ribbons, and van-der-Waals interactions with adjacent ribbons construct a three-dimensional hydroxyhexenoic acid network.
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    Preparation and Structure of Dithioxo- and Diselenoxophosphoranes Stabilized by Intramolecular Coordination with a Dialkylamino GroupDedicated to Prof. Dr. Marianne Baudler on the occasion of her 75th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1049-1055 
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    ISSN: 0009-2940
    Keywords: Dithioxophosphoranes ; Diselenoxophosphoranes ; Internal coordination ; Steric protection ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some dithioxophosphoranes 3 stabilized by intramolecular coordination with a dialkylamino group were prepared, and their structures were analyzed by X-ray crystallography involving [2,4-di-tert-butyl-6-(isopropylmethylamino)phenyl]- (3c), {2,4-di-tert-butyl-6-[(dimethylamino)methyl]phenyl}- (3f), and {2,4-di-tert-butyl-6-[2-(dimethylamino)-1,1-dimethylethyl]phenyl}dithioxophosphorane (3h). The bond between the phosphorus atom and the aromatic ring is flexible and the angle narrows with decreasing ring size of the intramolecular coordination. The 31P-NMR signals are shifted to higher field with increasing ring size of the intramolecular coordination or strength of coordination. Similarly, the corresponding diselenoxophosphoranes 4 were prepared. Both their 31P- and 77Se-NMR signals are shifted to higher field with increasing contribution of intramolecular coordination.
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    Structural Studies on Indium and Tin Thiobenzoates (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1093-1098 
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    ISSN: 0009-2940
    Keywords: Indium tris(thiobenzoate) ; Triethylammonium tetrakis(thiobenzoato)indate ; Tin, butyl-, tris(thiobenzoate) ; Tin, dichloro-, bis(thiobenzoate) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Indium(III) and tin(IV) thiocarboxylates were prepared and characterized on the basis of their IR, 13C- and 19Sn-NMR data. Indium tris(thiobenzoate) (1) decomposes into a sulfido complex In (S)[S(O)CPh] (2a). The corresponding tris(thioacetate) In[S(O)CMe]3 is thermally too unstable to be isolated. The anionic tetrakis complex [Et3NH]{In[S(O)CPh]4} (3) was characterized by X-ray crystallography which revealed a distorted tetrahedral coordination at the In atom. X-ray diffraction analysis of the complexes BuSn[S(O)CPh]3 (4) and Cl2Sn[S(O)CPh]2 (7) showed distorted tetrahedral and cis-octahedral structures, respectively.
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    URL: http://dx.doi.org/10.1002/cber.19961290918
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    Reaktionen des Tripod-Co-Templats CH3C(CH2PPh2)3Co(II) mit funktionalisierten HydrazinenMax Herberhold zum 60. Geburtstag gewidmet. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1107-1113 
    Details
    ISSN: 0009-2940
    Keywords: Tripod ligands ; Hydrazines, substituted ; Diazenes ; Cobalt(III), fivefold coordination of ; Cobalt(II), fivefold coordination of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The coordination behaviour of ligands having the same basic constitution RN=NC(=X)R′ (X = O, NR″, S) in their tripod cobalt derivatives has been analyzed. The ligands themselves may be considered as neutral heterodiene compounds and are in this respect vinylogues to diazenes RN=NRy′. Two- electron reduction of these neutral species results in dianionic heterosubstituted heteroolefins RN- -N=C(X-)R′. Due to their redox ambiguity the oxidation state of the metal M in chelate complexes is not a priori evident. Compounds tripod [5: X, R′ = O, Ph; 6; (X, R′) = (py); 7: X, R′ = S, NH2] are best described as containing low-spin Co(III) and dianionic ligands. Co(II) species are obtained with diethyl azodicarboxylate EtOOCN=NCOOEt as the ligand. In the mononuclear compound, with only one nitrogen and one carbonyl oxygen of the ligand acting as donor groups, the neutral ligand is coordinated to give the high-spin cobalt(II) species tripod (8). In the dinuclear compound 9 with both of the nitrogen atoms and carbonyl groups involved in coordination the dianionic ligand bridges two high-spin cobalt(II) centers to give tripod (9) as a derivative with two fused five-membered chelate rings. In addition to the conventional analytical techniques X-ray structure analyses, cyclovoltametric measurements, magnetic susceptibility and ESR data are used to characterize the compounds.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19961290921
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    Übergangsmetall-Stannyl Komplexe, 10[1]. Molybdocen- und Wolframocen-Derivate mit zwei unterschiedlichen Liganden der 4. Hauptgruppe (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1131-1142 
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    ISSN: 0009-2940
    Keywords: Stannyl complexes ; Plumbyl complexes ; Tungsten complexes ; Molybdenum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal Stannyl Complexes, 10 - Molybdocen and Wolframocen Derivatives with Two Different Main-Group-4 LigandsReactions of Li[Cp2MSnPh3] (M = Mo, W) with CH3I, BuBr, PhCH2Br, PhC(O)Cl or Br(CH2)nBr (n = 4,5) yield Cp2M(R)SnPh3 [R = CH3, Bu, CH2Ph, C(O)Ph, (CH2)nBr], while tBuBr or CH3C(O)Cl give the hydrido complexes Cp2M(H)SnPh3. A silyl stannyl complex is only obtained from Li[Cp2WSnPh3] and Me3SiOSO2CF3, but not with Me3SiCl or from the anionic Mo complex. In contrast, the reactions of chlorostannanes provide the bis(stannyl) complexes Cp2M(SnR′3)SnPh3 or Cp2M(SnR′2Cl)SnPh3. R/Cl exchange at the tin atom is observed when an excess of the chlorostannane is used. Upon reaction of Li[Cp2MSnPh3] with Ph3PbCl only Cp2M(PbPh3)SnPh3 is formed, while a mixture of Cp2M(PbMe3)SnPh3 and Cp2M(PbMe2Cl)SnPh3 is obtained with Me3PbCl due to redistribution reactions. The structures of Cp2W(SnPh3)C(O)Ph, Cp2W(SnPh3)SntBu2Cl and Cp2W(SnPh3)PbMe2Cl were determined by X-ray structure analyses.
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    URL: http://dx.doi.org/10.1002/cber.19961290924
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    Thietane and Selenetane Complexes by Thermal Cycloaddition of Vinyl Ethers to Transition-Metal-Coordinated Thio- and Selenoaldehydes - Crystal Structure of Pentacarbonyl(7-phenyl-2-oxa-8-thiabicyclo[4.2.0]octane-S)tungsten(0)Dedicated to Professor Max Herberhold on the occasion of his 60th birthday (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1169-1175 
    Details
    ISSN: 0009-2940
    Keywords: Thioaldehyde complexes ; Selenoaldehyde complexes ; Thietane complexes ; Selenetane complexes ; Rearrangements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pentacarbonyl(thiobenzaldehyde)tungsten und pentacarbonyl(selenobenzaldehyde)tungsten (1a and 1b) undergo a thermal [2 + 2] cycloaddition with several vinyl ethers to give highly substituted transition metal-coordinated thietanes and selenetanes. The addition is highly regio- and stereospecific. The products undergo acid-catalyzed rearrangements, which lead to thermodynamically more stable diastereomers of the thietanes and selenetanes. The stereochemistry of both addition and rearrangement was established by reaction of deuterium-labeled vinyl ethers and by reaction of the cis and trans isomers of ethyl propenyl ether. The crystal structure of the bicyclic addition product of 1a and 3,4-dihydro-2H-pyran is reported.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961291005
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  • 97
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    Zinc Complexes of Amino Acids and Peptides, 9[Part 8: Ref.[1].]. Coordination of Cysteine and Histidine Derivatives to the Pyrazolylborate-Zinc Unit (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1251-1257 
    Details
    ISSN: 0009-2940
    Keywords: Zinc complexes ; Cysteine ligands ; Histidine ligands ; Imidazole ligands ; Pyrazolylborate ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Highly substituted pyrazolylborate ligands TpR,Me were used to limit the coordination number of zinc towards cysteine- and histidine-derived coligands. Monodentate thiolate attachment (→ 1a-f) was achieved with N- and C-protected cysteine, monodentate carboxylate attachment (→ 3) with N-protected histidine. C-protected cysteine was found to form a five-membered N,S-chelate ring (2). While imidazole coordination with N- and C-protected histidine could not be achieved, cationic pyrazolylborate-zinc-coligand complexes [TpZn-L]+ (4a, b) were obtained for L = 2-methylimidazole. The new complexes were characterized by their spectra and three structure determinations.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961291017
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  • 98
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    Organmetallic Selenolates, IVPart III: Ref.[1].. Reactions of MSeW(CO)3cp (M=Li, Na) with Organodi- and -tetrahalides - X-ray Crystal Structures of C6H5CH2W(CO)3(η5-C5H 5), μ-[m-C6H4{CH2SeW(CO)3(η5-C5H5)}2], μ-[p-C6H4{CH2SeW(CO)3- (η5-C5H5)}2], and C6H5CH[SeW(CO)3(η5-C5H5)]2 (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1275-1279 
    Details
    ISSN: 0009-2940
    Keywords: Organotungsten selenolates ; 77Se NMR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organotungsten-selenolato complexes were prepared in moderate yields by insertion of selenium into the alkali metaltungsten bonds of MSeW(CO)3cp (M = Li, Na) and subsequent reactions with the organohalides o-, m-, and p- C6H4(CH2Br)2, C6H5CHBr2, m-C6H4(CHBr2)2 and C6H5CCl3. The 77Se-NMR data of the new complexes are discussed and compared with those of related complexes derived from organomonohalides. Moreover, the X-ray crystal structures of C6H5CH2W(CO)3cp (1), μ-[m-C6H4{CH2SeW(CO)3cp}2] (3), μ-[p-C6H4{CH2SeW(CO)3cp}2] (4), and C6H5CH[SeW-(CO)3cp]2 (5) were determined. In complex (1), the W-CH2 bond length is 2.374 Å; the W-Se bond lengths in the complexes 3, 4 and 5 are all in the range 2.625-2.655 Å, corresponding to W-Se single bonds.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961291021
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    Masthead (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961291101
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    Suzuki-Coupling of Cp*Ru(para-C6H4Br2) with Phenyl Boronic Acid: A Model Reaction for the Synthesis of Organometallic PolymersDedicated to Professor Günter Szeimies with gratitude on the occasion of his 60th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1323-1325 
    Details
    ISSN: 0009-2940
    Keywords: Suzuki coupling ; π Complexes, organometallic ; π Complexes, dihaloarene ; Ruthenium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a terphenyl derivative complexed by the cationic moiety Cp*Ru+ by Suzuki coupling of [Cp*Ru(BrC6H4Br)]OTf with phenyl boronic acid under catalysis of Pd(PPh3)4 in a DME-water mixture at 85°C in quantitative yield is reported. The stable coupling product 3 was characterized by X-ray crystal structure analysis.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19961291103
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