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  • ASTROPHYSICS  (6,235)
  • Inorganic Chemistry  (3,618)
  • 2015-2019  (5)
  • 1990-1994  (9,848)
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  • 1
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-01-27
    Description: Polynitrogens have the potential for ultrahigh-performing explosives or propellants because singly or doubly bonded polynitrogens can decompose to triply bonded dinitrogen (N2) with an extraordinarily large energy release. The large energy content and relatively low activation energy toward decomposition makes the synthesis of a stable polynitrogen allotrope an extraordinary challenge. Many elements exist in different forms (allotropes)—for example, carbon can exist as graphite, diamond, buckyballs, or graphene. However, no stable neutral allotropes are known for nitrogen, and only two stable homonuclear polynitrogen ions had been isolated until now—namely, the N3− anion (1) and the N5+ cation (2). On page 374 of this issue, Zhang et al. (3) report the synthesis and characterization of the first stable salt of the cyclo-N5− anion, only the third stable homonuclear polynitrogen ion ever isolated. Author: Karl O. Christe
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-01-27
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2017-02-10
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-09-09
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-11-11
    Description: Author: Jake Yeston
    Keywords: Inorganic Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2019-04-02
    Description: A high-resolution mosaic of Ida shows a highly irregular body (roughly 56 km long), heavily covered with craters, with many interesting geological features, including grooves, blocks, chutes, dark-floored craters, and crater chains. A satellite of Ida, with a preliminary designation of 1993 (243) 1, was discovered in orbit around Ida. It is approximately 1.5 km in diameter, has an albedo and spectral reflectance not grossly different from Ida, and orbits Ida in a prograde direction with a period of roughly 20 hr. No other comparable-sized satellites have been found near Ida. New pictures of the opposite side of Ida reveal an irregular, dog-bone shape, with a prominent gouge that seems to separate Ida into two chief components. A V-shaped valley, well shown in the highest-resolution view of Ida returned in April, may mark a modest expression on the September face of the more dramatic feature on the back side. Ida's dense population of craters shows a wide diversity of morphologies, consistent with the surface having been subjected to saturated bombardment by smaller projectiles. Assuming the same projectile flux applies to Ida was used in deriving Gaspra's cratering age of about 200 m.y., and assuming that Gaspra and Ida both have the same impact strength, then the age of Ida's surface is calculated to be 1-2 b.y. This is considerably older than expected from other evidence concerning the Koronis family. Our favored explanation of Ida's satellite is that it (or a precursor satellite from which the present satellite was derived) formed during the catastrophic disruption event that formed Ida itself and formed the Koronis family of asteroids. Perhaps, instead, the satellite is a block ejected from a cratering impact. In any case, smaller blocks visible on some parts of Ida are more certain to be crater ejecta, whether or not they were ever temporary satellites.
    Keywords: ASTROPHYSICS
    Type: Meteoritics (ISSN 0026-1114); 29; 4; p. 455
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  • 7
    Publication Date: 2019-04-02
    Description: Many of the textures that are observed in CM chondrites have been alternately assigned nebular, parent-body, or combined nebular-parent body origins. Since it is very difficult to substantiate the production of complex textures in the nebula, an alternate approach to this problem is to rigorously determine which of the observable textures could have been produced by reasonable aqueous alteration processes on the CM parent body. Potential parent body reactions involving S deserve special attention because S-bearing phase define many important CM textures, such as rims. We have examined the possibility that the thin (about 5 microns) rinds of sulfides observed around some partially dissolved olivines within the chondrules and matrixes of CM chondrites were formed by the preferential precipitation of sulfides at or near dissolving olivine boundaries during parent-body alteration. Our model defines two infinite and parallel planes of olivine that are separated by pure water. Average separation distances between olivine grains in CM chondrites at the time of accretion (about 100-200 microns) were estimated by assuming a closed system fluid/rock ratio of 45% and varying the bimodal grain-size distribution. We restrict our calculations to the case of an isochemical system with sufficient bisulfide in solution to account for precipitation of pyrrhotite at STP. Our model examines the possibility that dissolving olivines with compositions between Fo(sub 0.9) and Fo(sub 0.4) can produce a strong gradient of Fe(2+) at pHs from 7 to 12 such that the precipitation of pyrrhotite will be initiated at the olivine-fluid boundary. Since CM phase equilibria is consistent with highly reducing conditions, Fe released by olivines would largely remain in solution as Fe(2+) until the solubility product of a Fe(2+) bearing phase was exceeded. Our calculations indicate that all examined combinations of olivine composition and pH yield a strong Fe(2+) gradient at the time the pyrrhotite solubility is exceeded near the olivine-fluid boundary. This favors the initiation of sulfide precipitation around dissolving olivines. However, sulfide rinds are not observed around all partially dissolved olivine grains in CM chondrites, which suggests that the availability of aqueous sulfide species limits the production of the thin sulfide rinds.
    Keywords: ASTROPHYSICS
    Type: Meteoritics (ISSN 0026-1114); 29; 4; p. 450
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  • 8
    Publication Date: 2019-04-02
    Description: ALH 84001 has recently been reclassified as a meteorite from Mars (SNC) and contains more than 90% orthopyroxene with minor chromite and accessory phases of augite, maskelynite, and carbonate. This meteorite represents a new class of igneous material from Mars. We have measured reflectance spectra of ALH 84001 as a chip as a powder, dry sieved to less than 125 microns to compare with previous spectral analyses of SNCs and remote observations of Mars. Spectra of the chip and powder in the visible-to-near-infrared region are shown. These spectra are composites of data measured with the RELAB bidirectional spectrometer from 0.3 to 2.55 microns and a Nicolet FTIR for longer wavelengths. As expected, the spectra of the chip have negative slopes and are significantly darker than the spectrum of the particulate sample, which has a positive slope. The strong absorptions near 1 micron and 2 microns are characteristic of low-Ca pyroxene and have band rninima of 0.925 microns and 1.930 microns. The strong absorption near 3 microns is characteristic of water. There is a distinct flattening in the spectrum between 1.0 and 1.5 microns indicating the presence of an additional absorption. This is interpreted to be the result of Fe(2+) in the M1 site of low-Ca pyroxene. Mid-infrared spectra showing the Christiansen feature and the reststrahlen bands are shown for spectra of the powder and of three different locations on the chip. These spectra exhibit several features in this range, some of which are associated with a specific region on the chip. Each of the spectra includes a doublet reststrahlen peak near 1100/cm, and peaks near 880 and 500/cm, which are typical for low-Ca pyroxenes. Weaker features at 940-1000/cm, 600-750/cm, and 530-560/cm are present in spectra from some locations on the chip, but not others, implying compositional and textural variation.
    Keywords: ASTROPHYSICS
    Type: Meteoritics (ISSN 0026-1114); 29; 4; p. 444-445
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  • 9
    Publication Date: 2019-04-02
    Description: The Long Duration Exposure Facility (LDEF), which encompassed 57 experiments with more than 10,000 test specimens, spent 69 months in Low Earth Orbit (LEO) before it was retrieved by the Space Shuttle in January 1990. Hundreds of LDEF investigators, after studying for over two years these retrieved test specimens and the onboard recorded data and systems hardware, have generated a unique first-hand view of the long-term synergistic effects that the LEO environment can have on spacecraft. These studies have also contributed significantly toward more accurate models of the LEO radiation, meteoroid, manmade debris and atomic oxygen environments. This paper provides an overview of some of the many LDEF observations and the implications these can have on future spacecraft such as Space Station Freedom.
    Keywords: ASTROPHYSICS
    Type: Life Sciences and Space Research 25 (2) Radiation Biology: Topical Meeting of the COSPAR Interdisciplinary Scientific Commission F of the COSPAR 29th Plenary Meeting, Washington, DC, Aug. 28-Sep. 5, 1 (ISSN 0273-1177); 14; 10; p. 7-16
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  • 10
    Publication Date: 2019-01-25
    Description: The sample collection technology and instrument concept for the Sample of Comet Coma Earth Return Mission (SOCCER) are described. The scientific goals of this Flyby Sample Return are to return to coma dust and volatile samples from a known comet source, which will permit accurate elemental and isotopic measurements for thousands of individual solid particles and volatiles, detailed analysis of the dust structure, morphology, and mineralogy of the intact samples, and identification of the biogenic elements or compounds in the solid and volatile samples. Having these intact samples, morphologic, petrographic, and phase structural features can be determined. Information on dust particle size, shape, and density can be ascertained by analyzing penetration holes and tracks in the capture medium. Time and spatial data of dust capture will provide understanding of the flux dynamics of the coma and the jets. Additional information will include the identification of cosmic ray tracks in the cometary grains, which can provide a particle's process history and perhaps even the age of the comet. The measurements will be made with the same equipment used for studying micrometeorites for decades past; hence, the results can be directly compared without extrapolation or modification. The data will provide a powerful and direct technique for comparing the cometary samples with all known types of meteorites and interplanetary dust. This sample collection system will provide the first sample return from a specifically identified primitive body and will allow, for the first time, a direct method of matching meteoritic materials captured on Earth with known parent bodies.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on Particle Capture, Recovery and Velocity(Trajectory Measurement Technologies; p 5-7
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  • 11
    Publication Date: 2019-01-25
    Description: Since May 1981, the National Aeronautics and Space Administration (NASA) has used aircraft to collect interplanetary dust particles (IDP's) from Earth's stratosphere. Specially designed dust collectors are prepared for flight and processed after flight in an ultraclean (Class-100) laboratory constructed for this purpose at the Lyndon B. Johnson Space Center (JSC) in Houston, Texas. Particles are individually retrieved from the collectors, examined, and cataloged, and then made available to the scientific community for research. Interplanetary dust thereby joins lunar samples and Antarctic meteorites as a critical extraterrestrial material being curated at JSC.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Analysis of Interplanetary Dust Particles; p 56-57
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  • 12
    Publication Date: 2019-01-25
    Description: The topics discussed include the following: stratospheric collection of interplanetary dust particles (IDP's); sources of interplanetary dust particles; and solar wind and noble gas isotopic ratios in IDP's.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Analysis of Interplanetary Dust Particles; p 40-43
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  • 13
    Publication Date: 2011-08-24
    Description: The Giotto ion mass spectrometer high-intensity spectrometer (IMS-HIS) measured fluxes of ions from about 260,000 km before (1008:37 UT spacecraft time) to about 86,000 km after (1701:33 UT spacecraft time) closest approach to comet P/Grigg-Skjellerup during the encounter on July 10, 1992. Although the HIS sensor was not designed to measure protons, these ions were measured far from the comet. Close in to the comet, the ions observed were probably also protons, although heavier ions cannot be completely ruled out. Considerable temporal structure appears in the data, well-correlated with the data of other instruments onboard, especially those of the magnetometer. In particular, the ion count rate correlates with the direction of the magnetic field. This strong modulation at the water group ion cyclotron period (approx. 90 s) inside the inbound bow wave indicates a very narrow ion pitch angle distribution. Hence at Grigg-Skjellerup the ions appear to experience very little pitch angle scattering. This may result from strong compression in the rapidly increasing magnetic field.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A10; p. 19,255-19,265
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  • 14
    Publication Date: 2011-08-24
    Description: Statistical uncertainties in determining the temperatures of hot (0.5-10 keV) coronal plasmas are investigated. The statistical presicion of various spectral temperature diagnostics is established by analyzing synthetic ASCA solid-state imaging spectrometer (SIS) CCD spectra. The diagnostics considered are the ratio of hydrogen-like to helium-like line complexes of Z greater than or = 14 elements, line-free portions of the continuum, and the entire spectrum. While fits to the entire spectrum yield the highest statistical precision, it is argued that fits to the line-free continuum are less susceptible to atomic data uncertainties but lead to a modest increase in statistical uncertainty over full spectral fits. Temperatures deduced from line ratios can have similar accuracy, but only over a narrow range of temperatures. Convenient estimates of statistical accuracies for the various temperature diagnostics are provided which may be used in planning ASCA SIS observations.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 435; 2; p. L149-L152
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  • 15
    Publication Date: 2011-08-24
    Description: We present Vela 5B observations of the Small Magellanic Cloud (SMC) region obtained during the years 1969 - 1979. We detect the 3.89 day orbital modulation of SMC X-1 with a false alarm probability of 4.3 x 10(exp -3) and observe a high state beginning in 1970 September and lasting approximately 100 days. We also detect three outbursts by a transient source consistent with the position of the candidate Be-neutron star system H0107-750 (= 1H 0103-762). These events occur roughly 100 days apart and last for approximately 35 days. No detections of SMC X-2 or SMC X-3 are apparent above a limit of approximately 7 x 10(exp 37) ergs/s.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 437; 2; p. 841-844
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  • 16
    Publication Date: 2011-08-24
    Description: In 1991 and 1992, the dust detector onboard the Ulysses spacecraft detected several dust streams apparently originating from the jovian system. The timing and measured speeds of the final two dust streams are compatible with dust from comet Shoemaker-Levy 9's (SL9) disruption in 1992. Our further investigations of stream characteristics and dust acceleration mechanisms, however, shed some doubt that two of the eleven dust streams are of SL9 origin. In July 1994 when SL9 impacts Jupiter, the Galileo spacecraft will be about 3500 jovian radii away from the planet. Submicronsized dust released into, and accelerated by, the jovian magnetosphere during this event may reach Galileo and impact its dust detector between September and November 1994. We also discuss the possibility of directly sampling dust from SL9 during Galileo's orbital tour.
    Keywords: ASTROPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 11; p. 1035-1038
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  • 17
    Publication Date: 2011-08-24
    Description: Three-dimensional numerical simulations of the impact of Comet Shoemaker - Levy 9 on Jupiter and the resulting vapor plume expansion were conducted using the Smoothed Particle Hydrodynamics (SPH) method. An icy body with a diameter of 2 km can penetrate to an altitude of -350 km (0 km = 1 bar) and most of the incident kinetic energy is transferred to the atmosphere between -100 km to -250 km. This energy is converted to potential energy of the resulting gas plume. The unconfined plume expands vertically and has a peak radiative power approximately equal to the total radiation from Jupiter's disk. The plume rises a few tens of atmospheric scale heights in approximately 10(exp 2) seconds. The rising plume reaches the altitude of approximately 3000 km, but no atmospheric gas is accelerated to the escape velocity (approximately 60 km/s).
    Keywords: ASTROPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 11; p. 1087-1090
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  • 18
    Publication Date: 2011-08-24
    Description: We suggest that prior to its impact with Jupiter, comet Shoemaker-Levy 9 will behave as an electrical generator in the Jovian magnetosphere, converting planetary rotational energy to electrical energy via a dust/plasma interaction. This electrical energy will then be deposited in the dayside auroral region where it may drive various auroral phenomena including cyclotron radio emission. Such emission could be detected by spacecraft like Ulysses and Galileo many hours prior to the actual comet impact with the upper atmosphere. We apply the theory originally developed to explain the spokes in Saturn's rings. This theory allows us to quantify the driving potential associated with the comet and, consequently, to determine the radio power created in the auroral region. We conclude that if enough fine dust is present in the cometary system, comet-induced auroral radio emissions will reach detectable levels. This emission should be observable in the dayside hemisphere about 12-24 hours prior to each fragment impact.
    Keywords: ASTROPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 11; p. 1067-1070
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  • 19
    Publication Date: 2011-08-24
    Description: The modulated light in the Intermediate Polar FO Aqr at the three periods P(sub spin) = 20.9 min, P(sub orb) = 4.85 hr and P(sub beat) = 22.5 min is studied in different spectral ranges to derive information on their nature. In this system the accretion geometry, with or without an accretion disk, is still a matter of debate (Hellier 1991; Norton et al. 1992). The different orbital behavior of phase coherence between the spin and beat pulses in the X-rays (Norton et al. 1992) and in the optical/IR regions cannot be easily accounted for by only a diskless dominated geometry where the accretion flow is switching from one pole to the other each half of the beat period. We therefore propose an accretion scenario where a non-axisymmetric disk is present. In such a non-standard accretion disk an azimuthal structure provides not only the source of variable mass transfer to the white dwarf, but also a reprocessing site which is mainly viewing the X-ray emission from the lower pole. Our spectral analysis shows that reprocessing is also occurring at the surface of the secondary star. The spin pulsation in the optical and IR continua can be explained by the so-called 'accretion curtain' model (Rosen et al. 1988) though an additional reprocessing component at the spin period cannot be excluded. In contrast to the X-rays, the beat optical/IR modulation is not intrinsic. Reprocessing at the surface of the secondary star and at the thickened part of the disk can also account for the orbital modulation in the UV, optical and IR regions.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 284; 1; p. 125-137
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  • 20
    Publication Date: 2011-08-24
    Description: Improved electric dipole transition matrix elements for rovibrational transitions in the ground state X(1)Sigma(+) of (12)C(6)O and (13)C(16)O are calculated for all the delta v = +1, +2, and +3 transitions for which v less than or equal to 20 and J less than or equal to 150. We have fitted polynomials to these matrix elements as a function of the parameter m which is defined in terms of the lower state angular momentum quantum number J. These convenient to use polynomial representations are given in Tables 1-4 for (12)C(16)O and in Tables 5-8 for (13)C(16)O. We observe that there is intensity enhancement due to vibration-rotation interaction for the P-branch transitions at the expense of the R-branch transitions for delta v = +1. This enhancement can be as large as 40% at the highest J. For the delta v = +2 and +3 transitions, the R-branch transitions are enhanced by as much as a factor of 2.75 and 10 at the highest J, respectively. The P-branch transitions exhibit only minor decreases. Comparisons with previous calculations show good agreement for the delta v = +1 transitions. The comparison for delta v = +2 and +3 transitions show differences as large as a factor of 5.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 91; 1; p. 483-489
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  • 21
    Publication Date: 2011-08-24
    Description: The cosmic microwave background radiation (CMBR) has a blackbody spectrum within 3.4 x 10(exp -8) ergs/sq cm/s/sr cm over the frequency range from 2 to 20/cm (5-0.5 mm). These measurements, derived from the Far-Infrared Absolute Spectrophotomer (FIRAS) instrument on the Cosmic Background Explorer (COBE) satellite, imply stringent limits on energy release in the early universe after t approximately 1 year and redshift z approximately 3 x 10(exp 6). The deviations are less than 0.30% of the peak brightness, with an rms value of 0.01%, and the dimensionless cosmological distortion parameters are limited to the absolute value of y is less than 2.5 x 10(exp -5) and the absolute value of mu is less than 3.3 x 10(exp -4) (95% confidence level). The temperature of the CMBR is 2.726 +/- 0.010 K (95% confidence level systematic).
    Keywords: ASTROPHYSICS
    Type: The Astrophysical Journal, Part 1 (ISSN 0004-637X); 420; 2; p. 439-444
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  • 22
    Publication Date: 2011-08-24
    Description: Several possible models have been suggested to explain the observed distribution of gamma-ray bursts: heliocentric distributions such as the Oort cloud, large galactic halos, and cosmological models. We report here on an investigation into the implications of the Burst and Transient Source Experiment (BATSE) gamma-ray burst distribution (Meegan et al. 1992a) data on the possible helocentric origin of gamma-ray bursts. We find no statistically significant anisotropy in the angular distribution of the bursts in a Sun-referenced coordinate system; there is no dipole moment in the direction of the Sun, and no quardrupole moment associated with the ecliptic plane. We have employed direct analytic calculations and Monte Carlo simulations of sources in the Oort cloud to constrain possible helicentric burst distributions. These can produce distributions consistent with the observed angular isotropy, the meal value of V/V(sub max), and the observed C/C(sub min) distribution of BATSE, and provide limits to burst energy of a few times approximately 10(exp 27) ergs. However, the agreement of the heliocentric C/C(sub min) distributions with the BATSE data is attributable to the relatively limited sampling of strong, nearby bursts. These bursts are known from observation to be homogeneously distributed, yet the density of sources in the Oort cloud is not constant in this region. Integral number-intensity distributions from the Oort cloud for larger numbers of bursts cannot reproduce the known homogeneity of the strong bursts without modification to the computed cometary number density and are therefore unlikely explanations of the gamma-ray burst distribution.
    Keywords: ASTROPHYSICS
    Type: The Astrophysical Journal, Part 1 (ISSN 0004-637X); 429; 1; p. 319-324
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  • 23
    Publication Date: 2011-08-24
    Description: Comet Austin was observed by the Cosmic Background Explorer (COBE)/Diffuse Infrared Background Experiment (DIRBE) with broadband photometry at 1-240 micrometers during the comet's close passage by Earth in 1990 May. A 6 deg long (6 x 10(exp 6) km) dust tail was found at 12 and 25 micrometers, with detailed structure due to variations in particle properties and mass-loss rate. The spectrum of the central 42 x 42 sq arcmin pixel was found to agree with that of a graybody of temperature 309 +/- 5 K and optical depth 7.3 +/- 10(exp -8). Comparison with IUE and ground-based obervations indicates that particles of radius greater than 20 micrometers predominate by surface area. A mass-loss rate of 510 (+510/-205) kg/s and a total tail mass of 7 +/- 2 x 10(exp 10) kg was found for a model dust tail composed of Mie spheres with a differential particle mass distribution dn/d log m approx. m(exp -0.63) and 2:1 silicate:amorphous carbon composition by mass.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 432; 1; p L71-L74
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  • 24
    Publication Date: 2011-08-24
    Description: We present a model for explaining the recent combined X-ray and low-energy gamma-ray observations of the Seyfert galaxy NGC 4151. According to this model, soft photons become Comptonized in a hot spot producing simultaneously the low-energy power law as observed by Ginga and the high-energy cutoff observed by the Oriented Scintillation Spectrometer Experiment (OSSE). Implementing recently developed theoretical calculations toward a generalized theory of Comptonization, we were able to find fits to the observations using only two parameters which characterize the physical quantities of the emission region: the plasma cloud optical depth and its temperature. We find that there is no need for additional nonthermal, reflection, or higher temperature thermal components to fit the aforementioned OSSE and Ginga observations. We derive in addition the size of the photon region and the temperature of the upscattered soft photons. We should emphasize, also, that any attempt at fitting only the high-energy parts of the spectrum (photon energies greater than 60 keV) by the Sunyaev & Titarchuk (1980) nonrelativistic Comptonization model leads to an underestimate of the Comptonization parameter y (or, equivalently, to an overestimation of the X-ray power-law spectral slope) and leads, as a result, to incorrect proportions between the low-energy and high-energy parts of the spectrum.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 433; 1; p. L33-L36
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  • 25
    Publication Date: 2011-08-24
    Description: We report a 1.7 day ASCA X-ray observation of the 2.87 day binary Algol (Beta Per), centered on the secondary eclipse. Spectra accumulated for different intensity states show a prominent He-like iron K line at 6.7 keV. A two-temperature variable abundance plasma model applied to the spectra yielded temperatures of approximately 8 and approximately 30 MK. The modeled coronal abundances of Fe, O, Mg, Si, S, Ar, and Ca were a factor of 2-3 below the solar photospheric value, and N less than 0.1. These model abundance anomalies are similar to those found from the ASCA spectra of other late-type stars and may indicate either true deviations from solar abundances or problems with the assumptions and atomic physics of the plasma models. The X-ray light curve shows a factor of 2 increase in flux over 13 hr beginning in the middle of the secondary eclipse, with a shallow eclipse centered on phase 0.45. The orbital light curve is similar to that observed by ROSAT 1 year earlier. The rise in flux is caused by an increase in the emission measure of the higher temperature component. The intensity variation is not associated with any major change in the abundances or temperature of the two components.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 436; 1; p. L83-L86
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  • 26
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    In:  Other Sources
    Publication Date: 2011-08-24
    Description: Gamma-ray bursts have always been intriguing sources to study in terms of particle acceleration, but not since their discovery two decades ago has the theory of these objects been in such turmoil. Prior to the launch of Compton Gamma-Ray Observatory and observations by Burst and Transient Source Experiment (BATSE), there was strong evidence pointing to magnetized Galactic neutron stars as the sources of gamma-ray bursts. However, since BATSE the observational picture has changed dramatically, requiring much more distant and possibly cosmological sources. I review the history of gamma-ray burst theory from the era of growing consensus for nearby neutron stars to the recent explosion of halo and cosmological models and the impact of the present confusion on the particle acceleration problem.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 90; 2; p. 863-868
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  • 27
    Publication Date: 2011-08-24
    Description: The theory of cosmic-ray acceleration by subluminal magnetohydrodynamics (MHD) astrophysical shocks according to the test particle approximation is extended to highly oblique shocks where flow speeds which appear nonrelativistic in the shock rest frame appear on transformation to the de Hoffmann-Teller or E identically equal to 0 frame to have upstream flow speeds approaching c. Monte Carlo simulation shows that relative to the predictions of diffusion theory, as the upstream E identically equal to 0 frame velocity approaches c, flatter spectra and faster acceleration rates occur. These spectral and acceleration time changes are similar to those found for relativistic, parallel MHD shocks and may affect all nonthermal active galactic nuclei emission from relativistic electrons. Also there is an additional means of increasing the upper limit of the cosmic-ray spectrum expected from active galactic nuclei, although the approximation used may not accurately reproduce the spectral shape.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 421; 1; p. 211-218
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  • 28
    Publication Date: 2011-08-24
    Description: High resolution spectra of Jupiter in the 3.3 micrometer region have so far failed to reveal either the continuum or the line emissions that can be unambiguously attributed to the nu(sub 3) band of methane (Drossart et al. 1993; Kim et al. 1991). Nu(sub 3) line intensities predicted with the help of two simple non-Local Thermodynamic Equilibrium (LTE) models -- a two-level model and a three-level model, using experimentally determined relaxation coefficients, are shown to be one to three orders of magnitude respectively below the 3-sigma noise level of these observations. Predicted nu(sub 4) emission intensities are consistent with observed values. If the methane mixing ratio below the homopause is assumed as 2 x 10(exp -3), a value of about 300 K is derived as an upper limit to the temperature of the high stratosphere at microbar levels.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 424; 1; p. L61-L64
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  • 29
    Publication Date: 2011-08-24
    Description: A simple method for deriving well-behaved temperature solutions to the equation of hydrostatic equilibrium for intracluster media with X-ray imaging observations is presented and applied to a series of generalized models as well as to observations of the Perseus cluster and Abell 2256. In these applications the allowed range in the ratio of nonbaryons to baryons as a function of radius is derived, taking into account the uncertainties and crude spatial resolution of the X-ray spectra and considering a range of physically reasonable mass models with various scale heights. Particular attention is paid to the central regions of the cluster, and it is found that the dark matter can be sufficiently concentrated to be consistent with the high central mass surface densities for moderate-redshift clusters from their gravitational lensing properties.
    Keywords: ASTROPHYSICS
    Type: The Astrophysical Journal, Part 1 (ISSN 0004-637X); 431; 1; p. 91-103
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  • 30
    Publication Date: 2011-08-24
    Description: We compute the three-point temperature correlation function of the Cosmic Background Explorer (COBE) Differential Microwave Radiometer (DMR) first-year sky maps to search for non-Gaussian temperature fluctuations. The level of fluctuations seen in the computed correlation function are too large to be attributable solely to instrument noise. However the fluctuations are consistent with the level expected to result from a superposition of istrument noise and sky signal arising from a Gaussian power-law model of initial fluctuations, with a quadrupole normalized amplitude of 17 micro K and a power-law spectral index n = 1. We place limits on the amplitude of intrinsic three-point correlations with a variety of predicted functional forms.
    Keywords: ASTROPHYSICS
    Type: The Astrophysical Journal, Part 1 (ISSN 0004-637X); 431; 1; p. 1-5
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  • 31
    Publication Date: 2011-08-24
    Description: This paper presents comprehensive results on the spectra of 30 bright gamma ray bursts (GRBs) as observed by the Spectroscopy Detectors (SDs) of the Burst And Transient Source Experiment (BATSE). The data selection was strict in including only spectra that are of high reliability for continuum shape studies. This BATSE Spectroscopy Catalog presents fluences, model fits (for five spectral models for three energy ranges), and photon spectra in a standard manner for each burst. Complete information is provided to describe the data selection and analysis procedures. The catalog results are also presented in electronic format (from the Compton Observatory Science Support Center) and CD-ROM format (AAS CD-ROM series, Vol. 2). These electronic formats also present the count spectra and detector response matrices so as to allow for independent study and fitting by researchers outside the BATSE Team. This BATSE Spectroscopy Catalog complements the catalog from BATSE Large Area Detector (LAD) data by Fishman et al. (1994).
    Keywords: ASTROPHYSICS
    Type: The Astrophysical Journal Supplement Series (ISSN 0067-0049); 92; 1; p. 285-310
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  • 32
    Publication Date: 2011-08-24
    Description: We review the magnetic locking of the white dwarf and the companion star in AM Herculis-type binaries for various white dwarf magnetic field structures, and compare the theoretical results with observations. The model in which the white dwarf has a dipole plus a quadrupole field is found to be in closest agreement with the recent observations.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of Australia, Proceedings (ISSN 0066-9997); 11; 2; p. 198-200
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  • 33
    Publication Date: 2011-08-24
    Description: Arrays of radio telescopes are now routinely used to provide increased signal-to-noise when observing faint point sources. However, calculation of the achievable sensitivity is complicated if there are sources in the field of view other than the target source. These additional sources not only increase the system temperatures of the individual antennas, but may also contribute significant 'correlated noise' to the effective system temperature of the array. This problem has been of particular interest in the context of tracking spacecraft in the vicinity of radio-bright planets (e.g., Galileo at Jupiter), but it has broader astronomical relevance as well. This paper presents a general formulation of the problem, for the case of a point-like target source in the presence of an additional radio source of arbitrary brightness distribution. We re-derive the well known result that, in the absence of any background sources, a phased array of N indentical antennas is a factor of N more sensitive than a single antenna. We also show that an unphased array of N identical antennas is, on average, no more sensitive than a single antenna if the signals from the individual antennas are combined prior to detection. In the case where a background source is present we show that the effects of correlated noise are highly geometry dependent, and for some astronomical observations may cause significant fluctuations in the array's effective system temperature.
    Keywords: ASTROPHYSICS
    Type: The Astronomical Journal (ISSN 0004-6256); 108; 1; p. 337-345
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  • 34
    Publication Date: 2011-08-24
    Description: We report the detection of 10 micrometer emission from the transient low-mass X-ray binary (LMXB) and optical nova GRO J0422+32 near the maximum of its outburst. We discuss this result in terms of (1) a 'standard' model according to which low-energy radiation of LMXB is caused by reprocessing of X-rays in an accretion disk; (2) emission from a cool secondary star; (3) emission from dust grains heated by the transient X-rays, and (4) free-free emission from an X-ray-driven wind from the accretion disk. Only the fourth alternative provides a viable explanation for the observed 10 micrometer emission, with a mass-loss rate in the disk wind that may be substantially higher than the rate of accretion onto the compact star. The presence of such a wind may have a profound effect on the evolution of the binary, and contribute to the solution of the 'birthrate problem' of millisecond ratio pulsars.
    Keywords: ASTROPHYSICS
    Type: The Astrophysical Journal (ISSN 0004-637X); 429; 1, pt; p. L19-L23
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  • 35
    Publication Date: 2011-08-24
    Description: The implications of recent near-infrared imaging and spectroscopy of the Galactic center stellar cluster are discussed. The central parsec appears to be powered by a cluster of hot, massive stars of which the IRS 16 complex is the central core. In the 1 to 2 micrometer band, the brightest members of this cluster are 10 to 15 HeI/HI emission line stars that can be characterized as approximately 20000 K, helium rich, very luminous supergiants. The He-I/H-I stars can account for a major fraction of the total and Lyman continuum luminosity of the central parsec, but hotter, earlier type stars are probably required in addition to account for the He-continuum. The brightest cool stars in the central parsec are red supergiants, and asymptotic giant branch stars. Two scenarios for the evolution of the central stellar core are presented: one involves a small star formation burst years ago that was the result of substantial prior gas influx into the core. In this scenario the Galactic center is presently in a short-lived, post-main sequence 'wind phase'. The second scenario involves the buildup of massive stars by sequential merging of lower mass stars. The intense mass loss from the hot stars probably affects strongly the gas dynamics in the central 0.1 pc and may prevent gas to accelerate onto the possible central hole.
    Keywords: ASTROPHYSICS
    Type: Max-Planck-Inst. fuer Extraterrestrische Physik, MPE Contributions to the Proceedings of the Conference on Nuclei of Normal Galaxies: Lessons Learned From the Galactic Center; 8 p
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  • 36
    facet.materialart.
    Unknown
    In:  Other Sources
    Publication Date: 2019-01-25
    Description: Comets, being considered the most primitive bodies in the solar system, command the highest priority among solar system objects for studying solar nebula evolution and the evolution of life through biogenic elements and compounds. Sample Of Comet Coma Earth Return (SOCCER), a joint effort between NASA and the Institute of Space and Astronautical Science (ISAS) in Japan, has two primary science objectives: (1) the imaging of the comet nucleus and (2) the return to Earth of samples of volatile species and intact dust. This effort makes use of the unique strengths and capabilities of both countries in realizing this important quest for the return of samples from a comet. This paper presents an overview of SOCCER's science payloads, engineering flight system, and its mission operations.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on Particle Capture, Recovery and Velocity(Trajectory Measurement Technologies; p 7-11
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  • 37
    Publication Date: 2019-01-25
    Description: Some general properties of stratospheric dust particles and unmelted Antarctic micrometeorites are outlined including a few examples of mineralogical and chemical similarities or differences of IDP's to micrometeorites and to known meteorites.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Analysis of Interplanetary Dust Particles; p 31-34
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  • 38
    Publication Date: 2019-01-25
    Description: The relative proportions of the cometary and the asteroidal contributions to the interplanetary dust have not yet been definitively established. These proportions may vary with time as a result of major catastrophic disruptions in the main belt or the appearance of fresh, active comets. Dermott et al. and Reach suggest the debris from catastrophic collisions in the main belt can account for most of the zodiacal cloud particles. Earth collection of these asteroidal particles is strongly favored by near-Earth gravitational enhancement. However, comets are observed to produce interplanetary dust particles (IDP's), and the identification of cometary IDP's would allow inferences of the compositions, mineralogies, and physical properties of the comets. The peak temperatures reached by IDP's on atmospheric entry indicate the distribution of IDP velocities. Each IDP contains many internal thermometers: minerals that transform above certain temperatures, volatile elements that are lost sequentially with increasing temperatures, solar flare tracks that anneal at different temperatures in different minerals, and solar-implanted noble gases that outgas progressively with temperature. Thus, limits on the peak temperature reached by each IDP on Earth atmospheric entry can be set. Other aspects of this investigation are covered.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Analysis of Interplanetary Dust Particles; p 21-22
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  • 39
    Publication Date: 2019-01-25
    Description: The orbital evolution of dust particles with two different sizes (diameters equal to 4 and 9 microns) originating from the Eos, Koronis, and Themis asteroidal families was studied. All the planetary perturbations, radiation pressure, Poynting-Robertson light drag, and corpuscular solar wind effects are included in the calculation. It is concluded that for particles having diameters ranging from 4 to 9 microns, Eos particles are quite different in orbital elements from Themis and Koronis particles. For Koronis and Themis particles, the best times to collect them are around April and October.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Analysis of Interplanetary Dust Particles; p 16-17
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  • 40
    Publication Date: 2019-01-25
    Description: An examination of the relation of track densities from solar energetic particles in interplanetary dust grains (IDP's) to the orbital elements of source bodies is made and the positive and negative aspects of using track densities to determine the origin of IDP's are reported. It is found from calculations that predicted track densities for a particle of given size are related logarithmically to the minimum semimajor axis of the source body. Consequently, although track densities measurements may not be capable of distinguishing cometary from asteroidal sources, they should give information on the minimum semimajor axis of the originating bodies.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Analysis of Interplanetary Dust Particles; p 9-11
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  • 41
    Publication Date: 2019-01-25
    Description: The COMRADE experiment is designed to return minimally degraded particles to earth along with complete in situ information concerning mass, velocity, and trajectory of encountered particles. The objectives of the program are very diverse. A set of flight-tested active detectors will be combined in an array to identify some of the physical properties of an incident grain, e.g., velocity vector, momentum, and mass. The use of passive detectors gives access to the chemical and isotopical properties of the grains in the micrometer size range. We are concerned simultaneously with a destructive capture, using metallic collectors, and a nondestructive capture, using a new low-density target in which the impacting grains stop, practically intact. The primary objectives for this mission are (1) to identify the particle remnants of the micrometer-sized grains having impacted on purposely designed metallic collectors, for complete and detailed chemical, isotopic, and organic analysis, thereby determining grain composition as well as the existence of organic and inorganic molecules, to be related with the possible cometary origin of the grains showing an extraterrestrial signature; (2) to return captured intact particles to earth for complete and detailed chemical, isotopic, spectral, mineralogical, and organic analysis, thereby determining grain composition as well as the existence of organic and inorganic molecules; and (3) to capture micrometer/submicrometer dust grains in a manner that ensures minimal particle degradation and guarantees state-of-the-art confidence in measurement of the in situ particle parameters including trajectory, velocity vector, mass, and flux distributions.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Analysis of Interplanetary Dust Particles; p 11-12
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  • 42
    facet.materialart.
    Unknown
    In:  Other Sources
    Publication Date: 2019-01-25
    Description: Comets are small bodies of the solar system containing primarily a mixture of frozen gases and carbonaceous and mineral grains. They are likely to preserve volatile mineral from cold regions of the protosolar nebula and remnants of interstellar dust and gas. More than 2500 mass spectra of cometary grains with masses in the range 5 x 10 exp -17 to 5 x 10 exp -12 g were measured in situ by PUMA1 and PUMA2 mass spectrometers on board the VEGA spacecraft during flyby missions to Comet Halley. In this paper, we discuss different organic and inorganic C-containing components discovered so far in Comet Halley dust particles, the nature and abundance of which provide information about possible astrophysical sources of C and constrain models of interstellar grains.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Analysis of Interplanetary Dust Particles; p 22-24
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  • 43
    Publication Date: 2019-01-25
    Description: The 'pyroxene' interplanetary dust particles (IDP's) may be the best samples for investigation of primordial grain-forming reactions because they appear to have experienced negligible post-accretional alteration. They are likely to continue to yield information about gas-to-solid condensation and other grain-forming reactions that may have occurred either in the solar nebular or presolar interstellar environments. An immediate challenge lies in understanding the nanometer-scale petrography of the ultrafine-grained aggregates in 'pyroxene' IDP's. Whether these aggregates contain components from diverse grain-forming environments may ultimately be answered by systematic petrographic studies using electron microscopes capable of high spatial resolution microanalysis. It may be more difficult to decipher evidence of grain formation and evolution in 'olivine' and 'layer silicate' IDP's because they appear to have experienced post-accretional alteration. Most of the studied 'olivine' IDPs have been subjected to heating and equilibration, perhaps during atmospheric entry, while the 'layer silicate' IDP's have experienced aqueous alteration.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Analysis of Interplanetary Dust Particles; p 12-13
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  • 44
    Publication Date: 2019-01-25
    Description: This study is the further investigation of space-exposed samples recently recovered from the American satellite LDEF and the Franco-Soviet Mir 'Aragatz' experiment. Some interesting impact features have been selected as examples to demonstrate various findings. Part of the objective of the experiments was to determine the nature and origin of particles in low earth orbit (LEO). Observations show that the 'multiple foil detectors' appear to be an effective way of retaining impactor residues of larger particles. They provide a 'witness' foil that shows the shape and dimensions of the impacting particle. Several low-velocity (less than 4 km/s) oblique craters containing significant quantities of impactor residue have been identified. Energy dispersive spectrometer (EDS) analyses of the residues show evidence of micrometeoroid and debris compositions. Similarities between the meteoroid signatures and those of Brownlee particles have been noted. Evidence of at least two different grain compositions in one impacting particle is shown. The discovery of debris impacts on the trailing edge of LDEF demonstrates that artificial debris may be found, not just in circular orbits, but also in elliptical orbits.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Workshop on the Analysis of Interplanetary Dust Particles; p 5-9
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  • 45
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 160-166 
    ISSN: 0044-2313
    Keywords: Tetraphosphorus tetraselenide, P4Se4 ; Tetraphosphorus triselenide, P4Se3 ; thermochemistry ; preparation ; structure, 31P-n.m.r. ; glass ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Results on P4Se4Preparation of P4Se4 from the elements yields always the β-modification of P4Se4. α-P4Se4 is obtained only with selenium deficient samples. However, it is also observed, when P4Se3 is annealed and then extracted with CS2. The insoluble part has the X-ray pattern of α-P4Se4. A reversible α-β transition is not observed. MAS-31P-NMR investigations on solid P4Se4 by Eckert et al. [2] reveal P2Se4/2 building units, which are, in view of our results, not dimer but linked to a polymeric network. Well-crystallized samples of β-P4Se4 are obtained only at measuring temperatures above 573 K. The structure is of monoclinic symmetry with the space group P21/n (a = 114.9, b = 729.0, c = 1211.0 pm, β = 120.80°).The reaction of α-P4Se3I2 with bis-(trimethyltin)selenide in CS2 at low temperature yields molecular α-P4Se4, which can be detected in solution by 31P-NMR spectroscopy. α-P4Se4 has D2d-symmetry like α-P4S4. It polymerizes at higher temperature. α-P4Se3I(SeSnMe3) and α-P4Se3(SeSnMe3)2 were observed in the course of this reaction, too. The analogous reaction of α-P4Se3I2 with bis-(trimethyltin)sulfide leads to comparable results.
    Notes: Bei der Synthese von P4Se4 aus den Elementen erhält man stets die aus der Literatur als β-P4Se4 bekannte Modifikation, nur mit einem Selenunterschuß wird α-P4Se4 erhalten, dessen Röntgenbeugungsmuster auch in getemperten P4Se3-Proben gefunden wird, nachdem man die löslichen Anteile extrahiert hat. Eine reversible-α-β-Umwandlung wird nicht beobachtet. MAS-31P-NMR-Messungen von Eckert et al. [2] zeigen, daß β-P4Se4 aus P2Se4/2-Einheiten aufgebaut ist, die nach unseren Untersuchungen allerdings nicht zu Dimeren verknüpft, sondern polymer vernetzt sind. β-P4Se4 kristallisiert störungsfrei nur oberhalb von 573 K mit monokliner symmetrie in der Raumgruppe P21/n (a = 1141,9 pm, b = 729,0 pm, c = 1211,0 pm, β = 120,80°).Die Reaktion von α-P4Se3I2 mit Bis-trimethylzinnselenid in CS2 bei tiefer Temperatur führt erstmals zum NMR-spektroskopischen Nachweis des molekularen α-P4Se4, das eine mit dem α-P4S4 vergleichbare D2d-Symmetrie besitzt und bei Temperaturerhöhung polymerisiert. Die bei der Reaktion eben-falls entstehenden Verbindungen α-P4Se3I(SeSnMe3) und α-P4Se3(SeSnMe3)2 können anhand der 31P-NMR-Daten nachgewiesen werden. Die analoge Reaktion von α-P4Se3I2 mit Bistrimethylzinnsulfid führt zu vergleichbaren Resultaten.
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  • 46
    ISSN: 0044-2313
    Keywords: Trigold manganese cluster ; (Ph3PAu)3Mn(CO)4 ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of (Ph3PAu)3Mn(CO)4Photolysis of (Ph3PAu)Mn(CO)5, Ph3PAuN3 and Ph3PAuNCO yields (Ph3PAu)3Mn(CO)4 (1). 1 crystallizes in the monoclinic space group P21/n with a = 1 031.3(1); b = 3 095.2(3), c = 3 386.3(3) pm; β = 97.58(3)°; Z = 8. The crystal structure contains two symmetry independent clusters 1 of the same geometry. Their inner core MnAu3 forms a rhombus with distances Mn—Au of about the same lengths between 258.4(4) and 262.0(4) pm. The distances Au—Au range from 276.6(2) to 281.3(2) pm. The bonding in 1 is discussed and compared with those of (Ph3PAu)3Co(CO)3 having the same total number of electrons but a tetrahedral framework.
    Notes: Photolyse einer Mischung von (Ph3PAu)Mn(CO)5, Ph3PAuN3 und Ph3PAuNCO in THF führt zur Bildung von (Ph3PAu)3Mn(CO)4 (1). 1 kristallisiert in der monoklinen Raumgruppe P21/n mit a = 1 031,3(1); b = 3 095,2(3), c = 3 386,3(3) pm; β = 97,58(3)°; Z = 8. Die Kristallstruktur enthält zwei symmetrieunabhängige Cluster 1 gleicher Gestalt, deren MnAu3-Gerüst die Struktur einer Raute mit nahezu gleich langen Mn—Au-Abständen zwischen 258,4(4) und 262,0(4) pm aufweist. Die Au—Au-Abstände liegen zwischen 276,6(2) und 281,3(2) pm. Die Bindungsverhältnisse in 1 werden diskutiert und mit denjenigen des Clusters (Ph3PAu)3Co(CO)3 mit gleicher Gesamtelektronenanzahl aber tetraedrischer Gerüststruktur verglichen.
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  • 47
    ISSN: 0044-2313
    Keywords: Silicate hydrate ; 1,1,4,4-tetramethylpiperazinium ; 1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane ; 1,1-dimethylpiperidinium ; clathrate ; crystal structure ; double four-ring silicate anion ; hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [TMPA]4[Si8O20] · 34 H2O und [DDBO]4[Si8O20] · 32 H2O sind Heteronetzwerk-Clathrate mit 1,1,4,4-Tetramethylpiperazinium (TMPA) und 1,4-Dimethyl-1,4-Diazoniabicyclo[2.2.2]octan (DDBO) Gastkationen[TMPA]4[Si8O20] · 34 H2O (1) und [DDBO]4[Si8O20] · 32 H2O (2) wurden durch Kristallisation aus wäßrigen Lösungen der entsprechenden quartären Alkylammoniumhydroxide und SiO2 erhalten. Die Kristallstrukturen wurden mittels Einkristallröntgenbeugung bestimmt. 1: Monoklin, a = 16,056(2), b = 22,086(6), c = 22,701(2) Å, β = 90,57(1)° (T = 210 K), Raumgruppe C2/c, Z = 4. 2: Monoklin, a = 14,828(9), b = 20,201(7), c = 15,519(5) Å, β = 124,13(4)° (T = 255 K), Raumgruppe P21/c, Z = 2. Die Polyhydrate sind strukturverwandte Wirt-Gast-Verbindungen mit dreidimensionalen Wirtstrukturen aus über Wasserstoffbrücken verknüpften oligomeren Anionen [Si8O20]8- und H2O-Molekülen. Die Silicat-Anionen haben eine würfelförmige Doppelvierring-Struktur und eine lokale Umgebung, die von 24 H2O-Molekülen und sechs Kationen (TMPA, [C8H20N2]2+, oder DDBO, [C8H18N2]2+) gebildet wird. Die Kationen befinden sich als Gastspezies in großen, unregelmäßigen, käfigartigen Hohlräumen. Untersuchungen mittels der 29Si-NMR-Spektroskopie und der Trimethylsilylierungsmethode haben gezeigt, daß die gesättigten Lösungen von 1 und 2 hohe Anteile an Doppelvierring-Anionen enthalten. Derartige Anionen sind auch in der gesättigten Lösung des Heteronetzwerk-Clathrats [DMPI]6[Si8O18(OH)2] · 48,5 H2O (3) mit 1,1-Dimethylpiperidinium-Kationen (DMPI, [C7H16N]+) als Gastspezies enthalten.
    Notes: [TMPA]4[Si8O20] · 34 H2O (1) and [DDBO]4[Si8O20] · 32 H2O (2) have been prepared by crystallization from aqueous solutions of the respective quaternary alkylammonium hydroxide and SiO2. The crystal structures have been determined by single-crystal X-ray diffraction. 1: Monoclinic, a = 16.056(2), b = 22.086(6), c = 22.701(2) Å, β = 90.57(1)° (T = 210 K), space group C2/c, Z = 4. 2: Monoclinic, a = 14.828(9), b = 20.201(7), c = 15.519(5) Å, β = 124.13(4)° (T = 255 K), space group P21/c, Z = 2. The polyhydrates are structurally related host-guest compounds with three-dimensional host frameworks composed of oligomeric [Si8O20]8- anions and H2O molecules which are linked via hydrogen bonds. The silicate anions possess a cube-shaped double four-ring structure and a characteristic local environment formed by 24 H2O molecules and six cations (TMPA, [C8H20N2]2+, or DDBO, [C8H18N2]2+). The cations themselves reside as guest species in large, irregular, cage-like voids. Studies employing 29Si NMR spectroscopy and the trimethylsilylation method have revealed that the saturated aqueous solutions of 1 and 2 contain high proportions of double four-ring silicate anions. Such anions are also abundant species in the saturated solution of the heteronetwork clathrate [DMPI]6[Si8O18(OH)2] · 48.5 H2O (3) with 1,1-dimethylpiperidinium (DMPI, [C7H16N]+) guest cations.
    Additional Material: 7 Ill.
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  • 48
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 781-785 
    ISSN: 0044-2313
    Keywords: Oxothallate(III) ; Preparation ; Structure ; MAPLE ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Oxidation of Intermetallic Phases: K4{Na2[Tl2O6]} from NaTl and K2O2The hitherto unknown K4{Na2[Tl2O6]} was prepared in form of transparent, yellow single crystals from NaTl and KO1,08 (molar ratio 1:1.3; sealed Ag-cylinder; 450°C, 30 d). The structure determination (four-circle diffractometer, MoKα, 1 280 out of 1 523 Io(hkl), R = 5.75%, Rw = 4.58%) confirms the space group P21/c with a = 641.3 pm, b = 691.1 pm, c = 1188.5 pm, β = 95.69° and Z = 2. As characteristic building units of the structure there are doubles of tetrahedra of [Tl2O6] and [Na2O6]. The compound is isotypic with Cs6[In2O6] and Rb6[Tl2O6]. The Madelung Part of Lattice Energy, MAPLE, the Mean Fictive Ionic Radii, MEFIR, Effective Coordination Numbers, ECoN, and Charge Distribution, CHARDI, are calculated.
    Notes: Bisher unbekanntes K4{Na2[Tl2O6]} wurde durch Oxydation von NaTl mit KO1,08 (1:1,3; geschlossener Ag-Zylinder; 450°C; 30 Tage) in Form transparenter, gelber Einkristalle dargestellt. Die Strukturaufklärung (Vierkreisdiffraktometerdaten, MoKα, 1 280 von 1 523 Io(hkl), R = 5,75%, Rw = 4,58%) erfolgte in der Raumgruppe P21/c mit a = 641,3 pm, b = 691,1 pm, c = 1 188,5 pm, β = 95,69° und Z = 2. Charakteristisches Motiv sind über Kanten verknüpfte, von ihresgleichen „isolierte“ Tetraederdoppel [Tl2O6] und [Na2O6]. Die Verbindung ist isotyp zu Cs6[In2O6] und Rb6[Tl2O6]. Der Madelunganteil der Gitterenergie, MAPLE, die Mittleren fiktiven Ionenradien, MEFIR, Effektive Koordinationszahlen, ECoN, sowie die Ladungsverteilung, CHARDI, werden berechnet.
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  • 49
    ISSN: 0044-2313
    Keywords: Dilithium magnesium tetrachloride ; dilithium vanadium tetrachloride ; dilithium cadmium tetrachloride ; crystal structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structures of MgCrO4-type Li2VCl4 and Spinel-type Li2MgCl4 and Li2CdCl4The crystal structures of the ternary lithium chlorides Li2MCl4 (M = Mg, V, Cd) have been determined firstly by X-ray single-crystal experiments. Li2MgCl4 and Li2CdCl4 crystallize in an inverse spinel structure (space group Fd3m, Z = 8, a = 1 040.1(2) and 1 062.06(9) pm, structural parameters u = 0.25699(2) and 0.2550(1), R = 1.7 and 3.7% for 218 and 211 unique reflections). The Li—Cl distances of the tetrahedrally coordinated Li+ ions are significantly greater than calculated with Shannon's crystal radii ( 〉 238 ± 1 instead of 233 pm). Contrary to the results of X-ray powder data reported in the literature, Li2VCl4 crystallizes in the distorted spinel structure of MgCr2O4 type (space group F43m, Z = 8, a = 1 037.49(2) pm, R = 5.9% for 217 unique reflections). The decrease of the site symmetry of the octahedrally coordinated ions (V2+, Li+) from 3m to 3m resulting in contracted and widened tetrahedral M4 entities of the spinel structure is obviously caused by V—V metal - metal bonds (shortest V—V distance 366.2(7) pm).
    Notes: Die Kristallstrukturen der ternären Lithiumchloride Li2MCl4 (M = Mg, V, Cd) wurden mittels Röntgen-Einkristallmessungen bestimmt. Li2MgCl4 und Li2CdCl4 kristallisieren in einer inversen Spinell-Struktur (Raumgruppe Fd3m, Z = 8, a = 1 040,1(2) und 1 062,06(9) pm, Lageparameter u = 0,25699(2) bzw. 0,2550(1), R = 1,7 bzw. 3,7% bei 218 bzw. 211 symmetrieunabhängigen Reflexen). Die Li—Cl-Abstände der tetraedrisch koordinierten Li+-Ionen sind signifikant größer als erwartet ( 〉 238 ± 1 anstatt 233 pm). Li2VCl4 kristallisiert entgegen Literaturangaben in der verzerrten Spinell-Struktur des MgCrO4-Typs (Raumgruppe F43m, Z = 8, a = 1 037,49(2) pm, R = 5,9% bei 217 symmetrieunabhängigen Reflexen). Die Erniedrigung der Lage-Symmetrie der oktaedrisch koordinierten Ionen (V2+, Li+) von 3m nach 3m, die alternierend zu einer Kontraktion und einer Aufweitung der tetraedrischen M4-Baueinheiten der Spinell-Struktur führt, wird von V—V—Metall - Metall-Bindungen verursacht (kürzester V—V-Abstand 366,2(7) pm).
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  • 50
    ISSN: 0044-2313
    Keywords: Cobalt(III) complexes functionalized N2S2-macrocyclic ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of Cobalt(III) Complexes of 14-Membered cis- and trans-N2S2 Dibenzo Macrocycles with two Pendant Acetato GroupsThe isomeric fourteen membered macrocyclic ligands 6,7,9,15,16,18-hexahydrodibenzo[f,m][1,8]dithia[4,11]diazacyclotetradecine-8,17-diacetic acid-0.5-hydrate (H2L3), C22H26N2O4S2 · 0.5 H2O and 6,7,13,15,16,18-hexahydrodibenzo-[e,m][1,4]dithia[8,11]diazacyclotetradecine-14,17-diacetic acid-1.5-hydrate (H2L6), C22H26N2O4S2 · 1.5 H2O with cis- and trans-N2S2 donorsets and two pendant acetato groups form the stable complexes [Co(L3)]ClO4 · 2 H2O (1) and [Co(L6)]ClO4 · H2O (2). Co(III) is octahedrally coordinated herein to all six donor centers of the respective ligand. The macrocyclic rings are folded. The metal ions are located outside the macrocyclic cavity. The mean Co—N, Co—O and Co—S distances are 196, 190 and 224 pm, respectively.Crystal data: 1, monoclinic, space group C2/c, a = 3 797.7(9), b = 763.8(3), c = 2 207.0(7) pm, β = 123.17(2), Z = 8, 3 445 reflections, R(Rw) = 0.072(0.070); 2, monoclinic, space group C2/c, a = 3 197.1(6), b = 880.4(2), c = 1 890.6(4) pm, β = 112,19(3)°, Z = 8, 4 415 reflections, R(Rw) = 0.062(0.064).
    Notes: Die beiden isomeren Liganden 6,7,9,15,16,18-Hexahydrodibenzo[f,m][1,8]dithia[4,11]diazacyclotetradecin-8,17-diessigsäure-0,5-hydrat (H2L3), C22H26N2O4S2 · 0,5 H2O bzw. 6,7,13,15,16,18-Hexahydrodibenzo[e,m][1,4]dithia-[8,11]diazacyclotetradecin-14,17-diessigsäure-1,5-hydrat (H2L6), C22H26N2O4S2 · 1,5 H2O mit cis- bzw. trans-N2S2-Donorzentren im vierzehngliedrigen makrocyclischen Ring und zwei Acetat-Seitenketten bilden die stabilen Komplexe [Co(L3)]ClO4 · 2H2O (1) und [Co(L6)]ClO4 · H2O (2). CoIII ist jeweils von allen 6 Donorzentren der Liganden oktaedrisch umgeben. Die Liganden sind gefaltet. Die Metallatome liegen außerhalb der makrocyclischen Kavität.Kristalldaten: 1, monoklin, Raumgruppe C2/c, a = 3 797,7(9), b = 763,8(3), c = 2 207,0(7) pm, β = 123,17(2)°, Z = 8, 3 445 Reflexe, R(Rw) = 0,072(0,070); 2, monoklin, Raumgruppe C2/c, a = 3 197,1(6), b = 880,4(2), c = 1 890,6(4) pm, β = 112,19(3)°, Z = 8, 4415 Reflexe, R(Rw) = 0,062(0,064).
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  • 51
    ISSN: 0044-2313
    Keywords: Cesium disodium trihydroxide hexahydrate ; deuterated material ; neutron diffraction ; hydrogen bonding ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hydrates of Weak and Strong Bases. IX. Hydrogen Bonding in CsNa2(OD)3 · 6D2O: A Single-Crystal Neutron-Diffraction Study at 120 KThe title compound is the first hydrate of a ternary alkali hydroxide reported. Its structure is related to the hexagonal perovskites and at the same time shaped by a complex system of hydrogen bonds. In a previous X-ray structure analysis at room temperature of the isotypic undeuterated material, these had been characterized only insufficiently. Therefore a complete structure determination has now been performed on a perdeuterated single crystal using low-temperature neutron-diffraction data (Pca21, Z = 4; a = 13.86, b = 6.070, c = 12.41 Å at 120 K; 1 655 observed independent reflections, R = 0.027).
    Notes: Die Titelverbindung ist das erste beschriebene Hydrat eines ternären Alkalihydroxids. Ihre Struktur ist verwandt mit der der hexagonalen Perowskite und zugleich durch ein komplexes System von Wasserstoffbrücken geprägt. Dieses war in einer vorangegangenen Röntgenstrukturanalyse bei Raumtemperatur an der isotypen nicht deuterierten Substanz nur unzureichend charakterisiert worden. Daher wurde nun eine vollständige Strukturbestimmung an einem perdeuterierten Einkristall mit Tieftemperatur-Neutronenbeugungsdaten durchgeführt (Pca21, Z = 4; a = 13,86, b = 6,070, c = 12,41 Å bei 120 K; 1 655 beobachtete unabhängige Reflexe, R = 0,027).
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  • 52
    ISSN: 0044-2313
    Keywords: Lithiumtetrahydrogenorthoperiodate monohydrate ; crystal structure ; tetrahydrogenorthoperiodate Ion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Existence of the Tetrahydrogenorthoperiodate Ion. The Crystal Structure of LiH4IO6 · H2OThe crystal structure of LiH4IO6 · H2O has been determined (P1; a = 564.74(12), b = 574.41(13), c = 970.4(6) pm, α = 101.37(2), β = 96.37(2), γ = 114.72(2)°; Z = 2; 5 731 independent reflections; R = 0.038). All hydrogen-atoms were localized from difference fourier map and refined without applying constraints. Thus the existence of the tetrahydrogenorthoperiodate-ion in the solid state is proved, unambigously. The crystal structure is discussed and compared to other alkaliorthoperiodates.
    Notes: Die Kristallstruktur von LiH4IO6 · H2O wurde bestimmt (P1; a = 564,74(12), b = 574,41(13), c = 970,4(6) pm, α = 101,37(2), β = 96,37(2), γ = 114,72(2)°; Z = 2; 5 731 unabhängige Reflexe, R = 0,038). Alle Wasserstofflagen konnten aufgefunden und frei verfeinert werden und beweisen erstmals die Existenz des Tetrahydrogenorthoperiodations im Festkörper. Die Kristallstruktur wird diskutiert und mit denjenigen anderer Alkaliorthoperiodate verglichen.
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  • 53
    ISSN: 0044-2313
    Keywords: Sodium Tetrachlorotitanate(II) ; Synthesis ; Crystal Structure ; Magnetism ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Crystal Structure and Magnetism of Sodium Tetrachlorotitanate(II), Na2TiCl4Na2TiCl4 is obtained as single crystals by metallothermic reduction of TiCl3 with sodium (525°C, 90 d, Ta container). Pure powder samples may be prepared by synproportionation of TiCl3 with Ti in the presence of NaCl (950-520°C, 21 d). The structure refinement from four-circle diffractometer data confirms that Na2TiCl4 is isotypic with Sr2PbO4 (orthorhombic, space group Pbam (No. 55), Z = 2 a = 694.2(1), b = 1 198.9(2), c = 385.6(1) pm, R = 0.055, Rw = 0,038). Ti2+ is surrounded by a distorted octahedron of Cl-. The octahedra are connected via common edges to chains, ∞1[TiCl2/1Cl4/2]2-, that run in the [001] direction. Magnetic susceptibility data were recorded in the 2 to 300 K temperature range at various field strengths. The interpretation of the data was carried out with the aid of crystal-field calculations taking magnetic interactions into account. The non-Curie behaviour of the reciprocal magnetic susceptibility of Ti2+ in Na2TiCl4 is due to the influence of spin-obit coupling.
    Notes: Na2TiCl4 entsteht in Form von Einkristallen bei der metallothermischen Reduktion von TiCl3 mit Na (525°C, 90 d, Ta-Ampulle). Reine Pulverproben von türkis-grünem Na2TiCl4 sind durch Synproportionierung von TiCl3 mit Titan in Gegenwart von NaCl zugänglich (950-520°C, 21 d). Die Strukturverfeinerung aus Vierkreis-Diffraktometer-Daten bestätigt, daß Na2TiCl4 im Sr2PbO4-Typ kristallisiert (orthorhombisch, Raumgruppe Pbam (Nr. 55), Z = 2, a = 694,2(1), b = 1 198,9(2), c = 385,6(1) pm, R = 0,055, Rw = 0,038). Ti2+ ist in Form eines verzerrten Oktaeders von Cl- umgeben. Die Oktaeder sind über gemeinsame Kanten zu Ketten ∞1[TiCl2/1Cl4/2]2- verknüpft, die längs [001] angeordnet sind. Die magnetische Suszeptibilität wurde im Bereich von 2-300 K bei verschiedenen Feldstärken bestimmt. Die Interpretation der Meßdaten erfolgte über Kristallfeld-Rechnungen unter Berücksichtigung magnetischer Wechselwirkungen. Das Nicht-Curie-Verhalten der reziproken magnetischen Suszeptibilität von Ti2+ in Na2TiCl4 ist auf den Einfluß der Spin-Bahn-Kopplung zurückzuführen.
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  • 54
    ISSN: 0044-2313
    Keywords: GdIII and SmIII octahedra complexes ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Complexes of the Lanthanoides with Bidentate Ligands. The Crystal Structures of [(C17H17N2)GdBr2(thf)2] and [(C17H17N2)3Ln] (L = Sm, Gd)Reaction of [(AIP)Li] with GdBr3 leads to a new mononuclear complex [(AIP)GdBr2(thf)2] 1. In contrast to this with SmI2 the compound [(AIP)3Sm] 2 is build up. Such complexes are also formed with Gd(OR*)3 (R* = OtBu2C6H3) and [(AIP)Li] in a 1:3 ratio, [(AIP)3Gd] 3. The structures of 1-3 were characterized by X-ray single crystal structure analysis (1: space group Pna21 (No. 33), Z = 4, a = 1 972.7(9) pm, b = 984.7(5) pm, c = 1 425.0(8) pm, α = β = γ = 90°; 2 · 2 THF: space group C2/c (No. 15), Z = 8, a = 3 644.4(9) pm, b = 1 437.5(5) pm, c = 2 334.4(7) pm, β = 1 21.07(6)°; 3: space group P2(1)/c (No. 14), Z = 4, a = 1 872.9(1) pm, b = 1 064.6(1) pm, c = 2 282.4(2) pm, β = 103.75(8)°).
    Notes: GdBr3 reagiert mit [(AIP)Li] zu dem einkernigen Komplex [(AIP)GdBr2(thf)2] 1. Mit SmI2 bildet sich dagegen überraschenderweise die Komplexverbindung [(AIP)3Sm] 2. Komplexe dieser Art bilden sich auch bei der Umsetzung von Gd(OR*)3 (R* = OtBu2C6H3) mit [(AIP)Li] im Verhältnis 1:3, [(AIP)3Gd] 3. Der Aufbau von 1-3 konnte durch Kristallstrukturanalyse geklärt werden (1: Raumgruppe Pna21 (Nr. 33), Z = 4, a = 1 972,7(9) pm, b = 984,7(5) pm, c = 1 425,0(8) pm, α = β = γ = 90°; 2 · 2 THF: Raumgruppe C2/c (Nr. 15), Z = 8, a = 3 644,4(9) pm, b = 1 437,5(5) pm, c = 2 334,4(7) pm, β = 1 21,07(6)°; 3: Raumgruppe P2(1)/c (Nr. 14), Z = 4, a = 1 872,9(1) pm, b = 1 064,6(1) pm, c = 2 282,4(2) pm, β = 103,75(8)°).
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  • 55
    ISSN: 0044-2313
    Keywords: MoIV ; GdIII ; Mo—Gd heterobimetallic complex ; X-ray structure analysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and structure of a Molybdenum-Gadolinium Heterometallic Complex. The Structure of [Li(thf)4]2[Cp2MoSGdBr4(thf)]2[Cp2MoHLi] reacts in THF with S and GdBr3 to yield the tetranuclear heterobimetallic complex [Li(thf)4]2[Cp2MoSGdBr4(thf)]2. The bonding situation and the structure of this compound were characterized by X-ray structure analysis (space group P1 (No. 2), Z = 1, a = 10.845(2) Å, b = 12.166(2) Å, c = 15.881(2) Å, α = 101.74(2)°, β = 97.62(2)°, γ = 103.97(2)°). Each S atom of the central Mo2S2-ring is coordinated by a GdBr4(thf) fragment. Additionally each Mo atom is connected to two Cp ligands. This leads to a tetrahedral coordination of the Mo atoms and a octahedral coordination of the Gd ions.
    Notes: [Cp2MoHLi] reagiert in THF mit S und GdBr3 zu dem vierkernigen Heterometallkomplex [Li(thf)4]2[Cp2MoSGdBr4(thf)]2. Die Bindungsverhältnisse und der Aufbau dieser Verbindung konnten durch eine Kristallstrukturanalyse geklärt werden (Raumgruppe P1 (Nr. 2), Z = 1, a = 10,845(2) Å, b = 12,166(2) Å, c = 15,881(2) Å, α = 101,74(2), β = 97,62(2)°, γ = 103,97(2)°). An den zentralen Mo2S2-Vierring koordiniert ein GdBr4(thf)-Fragment, so daß jedes Gd-Ion an sechs Liganden gebunden ist. Zusätzlich ist jedes Mo-Atom von zwei Cp-Liganden umgeben und erhält dadurch die Koordinationszahl 4.
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  • 56
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 833-838 
    ISSN: 0044-2313
    Keywords: Fluoromanganate(III) hydrates, Mn3F8 · 12H2O, AgMnF4 · 4 H2O ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Neue Fluoromanganat(III)-Hydrate: Mn3F8 · 12H2O and AgMnF4 · 4H2ODie Fluoridhydrate Mn3F8 · 12H2O und AgMnF4 · 4 H2O wurden in Form von Einkristallen hergestellt und durch Röntgenbeugungsmethoden charakterisiert. Mn3F8 · 12H2O kristallisiert in Raumgruppe P1 (a = 623.0(3), b = 896.7(4), c = 931.8(4) pm, α = 110.07(2)°, β = 103.18(2)°, γ = 107.54(2)°, Z = 1); AgMnF4 · 4 H2O kristallisiert in Raumgruppe P21/m (a = 700.9(2), b = 726.1(1), c = 749.4(3) pm, β = 107.17(3)°, Z = 2). Beide Strukturen enthalten Jahn-Teller-verzerrte [Mn(H2O)2F4]-Anionen und zeigen ein komplexes Wasserstoffbrücken-Netzwerk zwischen Anionen und Kationen, nämlich [Mn(H2O)6]2+ in der ersteren und einem polymeren [Ag(H2O)2]--Kation in der zweiten Verbindung.
    Notes: Single crystals of fluoride hydrates Mn3F8 · 12 H2O and AgMnF4 · 4 H2O have been prepared and characterized by X-ray methods. Mn3F8 · 12 H2O crystallizes in the space group P1 (a = 623.0(3), b = 896.7(4), c = 931.8(4) pm, α = 110.07(2)°, β = 103.18(2)°, γ = 107.54(2)°, Z = 1); AgMnF4 · 4 H2O crystallizes in the space group P21/m (a = 700.9(2), b = 726.1(1), c = 749.4(3) pm, β = 107.17(3)°, Z = 2). Both structures contain Jahn-Teller-distorted [Mn(H2O)2F4]- anions as well as crystal water molecules and exhibit a complex hydrogen bond network between anions and cations, i. e. [Mn(H2O)6]2+ for the first and a polymeric [Ag(H2O)2]- cation for the second compound.
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  • 57
    ISSN: 0044-2313
    Keywords: Single crystal structure ; Fluorzirkonates ; Fluorstannates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Crystal Structure of SmZrF7 with an Appendix on EuSnF7 and YSnF7SmZrF7 again was obtained as colourless single crystals and investigated by X-ray methods: It crystallizes in space group P 21/c-C2h5 (Nr. 14; P 21/n) with a = 1 140.9(2) pm, b = 574.6(1) pm, c = 914,4(2) pm, β = 107.32(2)°, Z = 4 but not in space group P 21-C22 (Nr. 4) [1]. In addition EuSnF7 and YSnF7 are isotypic with the following lattice constants: EuSnF7: a = 1 121.8(2) pm, b = 563.7(1) pm, c = 901.7(1) pm, β = 107.35(2)° with Z = 4; YSnF7: a = 1 106.7(2) pm, b = 556.4(1) pm, c = 884.7(1) pm, β = 107.51(1)° and Z = 4 (Powder data).
    Notes: SmZrF7 wurde erneut in Form farbloser Einkristalle dargestellt und röntgenographisch untersucht: Danach kristallisiert es in der Raumgruppe P 21/c-C2h5 (Nr. 14; Aufstellung P 21/n) mit a = 1 140,9(2) pm, b = 574,6(1) pm, c = 914,4(2) pm, β = 107,32(2)°, Z = 4, also nicht in der Raumgruppe P 21-C22 (Nr. 4) [1]. Aufgrund neuer Strukturrechnungen kristallisieren EuSnF7 und YSnF7 ebenfalls in der zentrosymmetrischen Raumgruppe P 21/c-C2h5 (Nr. 14) mit folgenden Gitterkonstanten für EuSnF7: a = 1 121,8(2) pm, b = 563,7(1) pm, c = 901,7(1) pm, β = 107,35(2)° mit Z = 4 sowie für YSnF7 a = 1 106,7(2) pm, b = 556,4(1) pm, c = 884,7(1) pm, β = 107,51(1)° und Z = 4 (Pulverdaten).
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  • 58
    ISSN: 0044-2313
    Keywords: Bis(fluorosulfonyl)difluoromethane ; gas-phase structure ; conformation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die Gasphasen-Struktur von Bis(fluorosulfonyl)difluormethan, (SO2F)2CF2Es wird über neue Syntheseverfahren und das Infrarotspektrum von Bis(fluorsulfonyl) Difluormethan, (SO2F)2CF2 berichtet. Die geometrische Struktur und die Konformationseigenschaften dieser Verbindung wurden mittels der Elektronenbeugung an Gasen untersucht. Je nach Stellung der zwei SO2F Gruppen können vier Konformere mit unterschiedlichen Symmetrien auftreten: C2v Symmetrie, falls beide S—F Bindungen auf Lücke zu CF2 stehen, C2 oder Cs Symmetrie, falls eine S=O Bindung jeder SO2F Gruppe auf Lücke zu CF2 steht und C1 Symmetrie, falls eine S—F und eine S=O Bindung auf Lücke zu CF2 stehen. Die experimentellen Elektronenbeugungsintensitäten können mit einem C1 Konformeren oder mit einem Gemisch aus C2v, C2 und Cs Konformeren im Verhältnis 3:2:5 nahezu gleich gut angepaßt werden. Die folgenden geometrischen Parameter (ra Abstände und ∠α Winkel mit 3σ Fehlergrenzen) wurden erhalten: C—F = 1,340(6) Å, S=O = 1,412(2) Å, S—F = 1,550(3) Å, C—S = 1,848(4) Å, S—C—S = 113,6(7)°, F—C—F = 110,0(10)°, O=S=O = 124,6(18)°, C—S—F = 96,5(16)° und C—S=O = 108,4(14)°.
    Notes: New synthetic pathways and the infrared spectrum of bis(fluorosulfonyl)difluoromethane, (SO2F)2CF2, are reported. The geometric structure and conformational properties of the title compound have been studied by gas electron diffraction. Depending on the rotational position of the two SO2F groups, four conformers with different symmetries can occur in this compound: C2v symmetry, if both S—F bonds stagger the CF2 group. C2 or Cs symmetry, if one S=O bond of each group staggers the CF2 group. The experimental electron diffraction intensities can be fitted equally well with a C1 conformer or with a mixture of C2v, C2 and Cs conformers, in a ratio of 3:2:5. The following geometric parameters (ra distances, ∠α angles with 3σ uncertainties) were derived: C—F = 1.340(6) Å, S=O = 1.412(2) Å, S—F = 1.550(3) Å, C—S = 1.848(4) Å, S—C—S = 113.6(7)°, F—C—F = 110.0(10)°, O=S=O = 124.6(18)°, C—S—F = 96.5(16)° and C—S=O = 108.4(14)°.
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  • 59
    ISSN: 0044-2313
    Keywords: Chromium niobate ; chemical transport reactions ; block structure ; high resolution electron microscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Investigation of Inorganic Non-Stoichiometric Compounds. XLIII. Preparation and Electron Microscopic Investigation of (Cr, Nb)12O29Transport experiments in the system Cr/Nb/O yielded the compound (Cr, Nb)12O29 as crystalline green needles. The lattice parameters of the monoclinic cell are a = 31.162(8) Å, b = 3.8324(6) Å, c = 20.579(6) Å, β = 113.22(3)°. (Cr, Nb)12O29 is isotypic with monoclinic Nb12O29 as shown by Guinier diagrams and high resolution transmission electron microscopy. Characteristic structural building elements are [3 × 4]-blocks which are columnar sections from the ReO3 structure. In the real structure one finds numerous defects. Under the influence of the electron beam we observed reversible changes of contrast which indicates that the positions of the M-particles (M = Cr, Nb) have shifted.
    Notes: Grüne, nadelförmige Kristalle von monoklinem (Cr, Nb)12O29 entstanden bei Transportexperimenten im System Cr/Nb/O. Die Gitterparameter a = 31,162(8) Å, b = 3,8324(6) Å, c = 20,579(6) Å, β = 113,22(3)° aus Guinieraufnahmen zeigen ebenso wie Strukturabbildungen mit der hochauflösenden Durchstrahlungselektronenmikroskopie Isotypie zu monoklinem Nb12O29. Auf den Aufnahmen erkennt man als charakteristisches Bauelement [3 × 4]-Blöcke, säulenförmige Ausschnitte aus der ReO3-Struktur, sowie zahlreiche Baufehler. Reversible Veränderungen des Kontrastes unter der Einwirkung des Elektronenstrahls lassen auf Änderungen der M-Positionen (M = Cr, Nb) schließen.
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  • 60
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 847-850 
    ISSN: 0044-2313
    Keywords: Diorganoindium cations ; syntheses ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diorganoindium Cations. The Crystal Structure of [Mes2In][BF4](PhCH3)2In and Mes3In react with BF3 · OEt2 in a ratio of 3:4 at 80°C in toluene to the corresponding salts [R2In][BF4] [R = PhCH2 (1), Mes (2)]. The same results could be obtained, when the diorganoindium fluorides (PhCH2)2InF and Mes2InF were treated with BF3 · OEt2 at 80°C in toluene. 1 und 2 were characterized by NMR-, IR- und MS-techniques. The arrangement of the ions in 2 could be established by an X-ray structure determination. The cations and anions of 2 are forming infinite chains. The metal centers are coordinated by two BF4--ions, so that every In atom possesses a distorted octahedral coordination sphere.
    Notes: (PhCH2)3In und Mes3In reagieren mit BF3 · OEt2 im Verhältnis 3:4 bei 80°C in Toluol zu den entsprechenden Salzen [R2In][BF4] [R = PhCH2 (1), Mes (2)]. Zum selben Ergebnis gelangt man, wenn die Diorganoindiumfluoride (PhCH2)2InF und Mes2InF mit BF3 · OEt2 bei 80°C in Toluol behandelt werden. 1 und 2 wurden mittels NMR- und IR-Spektroskopie sowie Massenspektrometrie charakterisiert. Die Anordnung der Ionen in 2 konnte durch eine Röntgenstrukturanalyse aufgeklärt werden. 2 bildet danach unendliche Ketten aus Kationen und Anionen, wobei durch eine chelatartige Anordnung zweier BF4--Ionen an jedes Metallzentrum eine verzerrt oktaedrische Koordinationssphäre der Indiumatome resultiert.
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  • 61
    ISSN: 0044-2313
    Keywords: System lithium hydroxide/lithium iodide ; crystal structure of Li2I(OH) and Li5I(OH)4 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Li2I(OH): A Compound with Onedimensional Infinite Edge Sharing [Li4/2(OH)+] PyramidsThe pseudobinary system LiOH/LiI was investigated by X-ray methods. Two compounds, Li2I(OH) and Li5I(OH)4 exist. The structure of Li2I(OH) was solved by single-crystal data. For Li5I(OH)4 lattice constants and space group symmetry are given:Li2I(OH): Pnma, Z = 4, a = 10.339(4) Å, b = 5.567(1) Å, c = 6.643(2) Å, Z(Fo) mit (Fo)2 ≧ 3σ(Fo)2 = 439, Z (parameter) = 23, R/Rw = 0.030/0.040Li5I(OH)4: Pmmn or P21mn(= Pmn21), Z = 2, a = 10.42 Å, b = 5.30 Å, c = 5.81 ÅLi2I(OH) crystallizes in a new type of structure. The motif of a distorted hexagonal close-packed arrangement of iodide ions is penetrated by chains of ∞1[Li4/2(OH)+].
    Notes: Das pseudobinäre System LiOH/LiI wurde röntgenographisch untersucht. Es gibt zwei Verbindungen, Li2I(OH) und Li5I(OH)4. Die Struktur von Li2I(OH) wurde mittels Einkristallröntgenstrukturanalyse aufgeklärt, von Li5I(OH)4 konnte die Elementarzellmetrik und Symmetrie ermittelt werden:Li2I(OH): Pnma, Z = 4, a = 10,339(4) Å, b = 5,567(1) Å, c = 6,643(2) Å, Z(Fo) mit (Fo)2 ≧ 3σ(Fo)2 = 439, Z (Parameter) = 23, R/Rw = 0,030/0,040Li5I(OH)4: Pmmn oder P21mn(= Pmn21), Z = 2, a = 10,42 Å, b = 5,30 Å, c = 5,81 ÅLi2I(OH) kristallisiert in einem eigenen Strukturtyp, dem das Motiv einer verzerrten hexagonal dichtesten Anordnung von Iodidionen zugrunde liegt, die von Strängen aus ∞1[Li4/2(OH)+] durchdrungen wird.
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  • 62
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 479-482 
    ISSN: 0044-2313
    Keywords: System lithium amide/lithium bromide ; crystal structure of Li2Br(NH2) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Li2Br(NH2): The First Ternary Alkali Metal Amide HalideThe pseudobinary system LiNH2/LiBr was investigated by X-ray methods. The crystal structure of the compound Li2Br(NH2) was solved by single crystal data:Li2Br(NH2): Pnma, Z = 8, a = 12.484(2) Å, b = 7.959(1) Å, c = 6.385(1) Å, Z(Fo) with (Fo)2 ≧ 3σ(Fo)2 = 348, Z (parameter) = 51, R/Rw = 0.019/0.021Li2Br(NH2) crystallizes in a new type of structure. To one another isolated chains of ∞1[Li2Li4/2(NH2)22+] show the motif of closest rod packing. They are connected via bromide ions in a distorted cubic primitive arrangement.
    Notes: Das pseudobinäre System LiNH2/LiBr wurde röntgenographisch untersucht. Die Struktur einer Verbindung, Li2Br(NH2), wurde mittels Einkristallröntgenstrukturanalyse aufgeklärt:Li2Br(NH2): Pnma, Z = 8, a = 12,484(2) Å, b = 7,959(1) Å, c = 6,385(1) Å, Z(Fo) mit (Fo)2 ≧ 3σ(Fo)2 = 348, Z (Parameter) = 51, R/Rw = 0,019/0,021Die Verbindung kristallisiert in einem eigenen Strukturtyp. Von ihresgleichen isolierte Stränge aus ∞1[Li2Li4/2(NH2)22+] bilden eine dem Motiv nach dichteste Stabpackung. Bromidionen verknüpfen die Stäbe in verzerrt kubisch primitiver Anordnung.
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  • 63
    ISSN: 0044-2313
    Keywords: Dithiatetrazine ; synthesis ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung und Röntgenstrukturanalyse von 1,4,2,3,5,6-DithiatetrazinDie Umsetzung von Schwefeldichlorid mit sym-EtO2CNHNHCO2Et 1 ergibt S2[N(CO2Et)]4 2, das analytisch, durch NMR und röntgenographisch charakterisiert wird. Die Strukturanalyse von 2 zeigt, daß der S2N4-Ring Sessel-Konformation hat mit allen vier Estergruppen in pseudoaxialen Positionen. Die Bindungslängen und -winkel werden mit denen in 1 und S4(NR)2 verglichen.
    Notes: Reaction of sulfur dichloride with sym-EtO2CNHNHCO2Et 1 gives the title ring system which has been characterised by microanalyses, nmr, and X-Ray crystallography. The X-ray structure of S2[N(CO2Et)]4 2 reveals that the S2N4 ring adopts a chair conformation with all four ester groups in pseudo-axial positions. Bond lengths and angles are compared with 1 and S4(NR)2.
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  • 64
    ISSN: 0044-2313
    Keywords: o-1λ5,3λ5-Diphosphaphenylene-bis(diphenylphosphane) ; nickel(II) chloride chelate complex ; crystal structure ; NMR, Ir spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: o-1λ5,3λ5-Diphosphaphenylene-bis(diphenylphosphane) and its Chelating PropertiesBis(diphenylphosphanyl)acetylene and 1,1′,3,3′-tetrakis(dimethylamino)-1λ5,3λ5-diphosphete react at higher temperatures to yield the title compound 5, which forms easily the chelate complex 6 with nickel(II) chloride.
    Notes: Bis(diphenylphosphanyl)acetylen und 1,1′,3,3′-Tetrakis(dimethylamino)-1λ5,3λ5-diphosphet reagieren bei höheren Temperaturen zur Titelverbindung 5, die mit Nickel(II)-chlorid leicht den Chelatkomplex 6 bildet.
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  • 65
    ISSN: 0044-2313
    Keywords: Thiooxalates ; 1,1-Dithiooxalate ; 1,1-Dithiooxalic ester ; transition metal complex ; Crystal structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,1-Dithiooxalic Acid Derivatives as Ligands in Transition Metal Complexes: Structure of O-Methyl-1,1-dithiooxalato-bis(triphenylphosphine)copper(I) and silver(I)Despite O-Alkyl-1,1-dithiooxalates are also tetradentate thioligands their tendency towards the formation of multi-nuclear bridged chelates as found for the basic 1,1-dithiooxalate does practically not exist because of derivatisation. The reaction with triphenylposphinemetal(I)-halogenides yields defined mono-nuclear mixed ligand complexes: O-Methyl-1,1-dithiooxalato-bis(triphenylphosphine)copper(I) (2) and silver(I) (1). X-ray analysis shows that both complexes (1 and 2) are isostructural and crystallize in the monoclinic space group P21/n: (Ph3P)2Ag(S2C2O2Me) (1) with a = 12.794(1), b = 21.314(4), c = 13.560(1) Å, β = 97.983(6)°, and (Ph3P)2Cu(S2C2O2Me) (2) with a = 12.622(1), b = 21.196(2), c = 13.426(1) Å, β = 96.533(7)°. These complexes are the first authentic examples of exclusively end-on coordinated thiooxalate.
    Notes: Obwohl potentiell auch vierzähnig, ist die Tendenz von O-Alkyl(bzw. Aryl)-1,1-dithio-oxalaten zur Ausbildung von Brücken in Mehrkern-Chelaten durch die Derivatisierung gegenüber dem Stammliganden 1,1-Dithiooxalat praktisch nicht mehr vorhanden. Durch Umsetzung mit Triphenylphosphinmetall(I)-halogeniden sind definierte einkernige Gemischtligandenkomplexe zugänglich. O-Methyl-1,1-dithiooxalato-bis(triphenylphosphin)kupfer(I) und -silber(I) konnten mittels Röntgenkristallstrukturanalyse strukturell gesichert werden. Beide Komplexe sind isostrukturell und kristallisieren in der monoklinen Raumgruppe P21/n: (Ph3P)2Ag(S2C2O2Me) (1), mit a = 12,794(1), b = 21,314(4), c = 13,560(1) Å, β = 97,983(6)° und (Ph3P)2Cu(S2C2O2Me) (2), mit a = 12,622(1), b = 21,196(2), c = 13,426(1) Å, β = 96,533(7)°. Diese beiden Komplexe sind die ersten strukturell gesicherten Vertreter mit ausschließlich end-on koordiniertem Thiooxalat.
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  • 66
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 505-508 
    ISSN: 0044-2313
    Keywords: O-methyl-1,1-dithiooxalate ; nucleophilic attack on dithiocarbon ; perthio ligand ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Surprising Reactions on O-Methyl-1,1-dithiooxalatesThe O-methyl-1,1-dithiooxalate ligand (i-dtoMe) reacts with metalII-acetylacetonates of d8 metal centers (NiII, PdII) forming mononuclear mixed ligand complexes with two remarkable aspects: The formation of a perthioligand, first time described for thiooxalates, and the first example of a nucleophilic attack of a CH-acidic compound (acetylacetonate) on dithiocarbon of coordinated dithiocompounds (here i-dtoMe). X-ray structure is shown for Ph4P[(ptoMe)Ni(i-dtoMeacac)].
    Notes: O-Methyl-1,1-dithiooxalat (i-dtoMe) reagiert mit Acetylacetonatkomplexen von d8-Metallen (NiII, PdII) unter Bildung von einkernigen Gemischtligandenkomplexen Ph4P[(ptoMe)M(i-dtoMeacac)] unerwarteter Konstitution. Durch Röntgenkristallstrukturanalyse des NiII-Komplexes konnte erstmals ein nukleophiler Angriff einer CH-aciden Verbindung (Acetylacetonat) am Dithiokohlenstoff einer koordinativ gebundenen Dithioverbindung (i-dtoMe) nachgewiesen werden.Gefunden wurde weiterhin die Entstehung einer Perthiogruppierung, die bisher für Thiooxalate bzw. deren Derivate unbekannt war.
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  • 67
    ISSN: 0044-2313
    Keywords: K2Fe[P2S6] ; Hexathiodiphosphate(IV) ; Hexathiohypodiphosphate ; Crystal Structure ; Magnetism ; Vibrational Spectrum ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese, Kristallstruktur, Magnetismus und Schwingungsspektrum von Dikaliumeisen(II)hexathiodiphosphat(IV), K2Fe[P2S6]K2Fe[P2S6] wurde aus den Elementen bei 1173 K in evakuierten, abgeschmolzenen Quarzampullen dargestellt. Die Verbindung bildet transparente, orangefarbene, luft- und feuchtigkeitsbeständige Kristalle. K2Fe[P2S6] kristallisiert monoklin, Raumgruppe P21/n (Nr. 14), mit den Gitterkonstanten (T = 298,5 K): a = 6,0622(4), b = 12,172(1) und c = 7,3787(8) Å, β = 101,113(7)°, Z = 2. Der neuartige Strukturtyp (mP22) wird durch Säulen von alternierend flächenverknüpften S6-Oktaedern und trigonalen Antiprismen (beide verzerrt) charakterisiert, die parallel zur a-Achse verlaufen und durch K+-Kationen (KZ 10; {2,6,2}-Polyeder; d(K—S) = 3,231 - 3,845 Å) miteinander verbunden sind. Die S6-Polyeder der Säulen werden alternierend durch Fe (d̄(Fe—S) = 2,577 Å) bzw. P2-Paare zentriert, die zur a-Achse um 73,4° geneigt sind. Die Bindungslängen in den Hexathiodiphosphat(IV)-Anionen [P2S6]4- mit angenäherter 32/m - D3d-Symmetrie betragen d(P—P) = 2,20 und d̄(P—S) = 2,02 Å. Die Titelverbindung ist oberhalb TN = 28 K paramagnetisch mit μ = 4,69 B.M. und ordnet unterhalb TN antiferromagnetisch. Die beobachteten inneren Moden der Raman- und Infrarotspektren von K2Fe[P2S6] stehen im Einklang mit der Faktorgruppenanalyse. Die Schwingungsbanden werden auf der Basis von [P2S6]4--Einheiten unter Berücksichtigung der Abweichungen von der D3d-Symmetrie zugeordnet.
    Notes: K2Fe[P2S6] was synthesized from the elements at 1173 K in sealed quartz tubes. The compound forms transparent orange crystals, stable against air and moisture. K2Fe[P2S6] crystallizes in the monoclinic system, space group P21/n (No. 14), with cell dimensions (T = 298.5 K) a = 6.0622(4), b = 12.172(1) and c = 7.3787(8) Å, β = 101.113(7)°, Z = 2. The novel structure type (mP22) is characterized by columns of alternating face-sharing S6 octahedra and trigonal antiprisms (both distorted) parallel to the a axis, which are interconnected by inserted K+ (CN 10; {2,6,2}-polyhedra; d(K—S) = 3.231 - 3.845 Å). The S6 polyhedra of the columns are centered alternately by Fe (d̄(Fe—S) = 2.577 Å) and P2 pairs which are inclined to the a axis by 73.4°. The bond lengths in the hexathiodiphosphate(IV) anions, [P2S6]4-, with approximate 3 2/m - D3d symmetry, are d̄(P—P) = 2.20 and d̄(P—S) = 2.02 Å. The compound is paramagnetic above TN = 28 K with μ = 4.69 B.M. and orders antiferromagnetically below TN. The internal modes of the observed Raman and FIR spectra of K2Fe[P2S6] are in accord with the factor group analysis, and the spectra are assigned on the basis of [P2S6]4- units, taking into account the deviation from D3d symmetry.
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  • 68
    ISSN: 0044-2313
    Keywords: (difluoro)methylphosphine ; (difluoro)methylphosphonium salts ; preparation ; single crystall X-ray structure ; vibrational and NMR spectra ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Crystal Structures of CH3PF2H+AsF6- and CH3PF2H+SbF6- and a simple Method for Preparation of CH3PF2A simple method for preparation of CH3PF2 from CH3PCl2 is reported. The phosphonium salts CH3PF2H+MF6- are obtained by the reaction of CH3PCl2 with superacidic systems HF/MF5 (M = As, Sb). CH3PF2H+SbF6- crystallizes in the space group P1 with a = 548.4(4) pm, b = 695.5(8) pm, c = 960.2(9) pm, α = 94.68(5)°, β = 97.19(6)°, γ = 94.41(6)° and Z = 2. CH3PF2H+SbF6- crystallizes in P1 with a = 554.3(3), b = 724.2(4), c = 970.4(5), α = 94.73(4)°, β = 96.14(5)°, γ = 95.30(4)°.
    Notes: Es wird über eine einfache Darstellung von CH3PF2 aus CH3PCl2 berichtet, welches in den supersauren Systemen HF/MF5 (M = As, Sb) zu den Phosphoniumsalzen CH3PF2H+MF6- protoniert wird. CH3PF2H+AsF6- kristallisiert in der Raumgruppe P1 mit a = 548,4(4) pm, b = 695,5(8) pm, c = 960,2(9) pm, α = 94,68(5)°, β = 97,19(6)°, γ = 94,41(6)° und Z = 2, das isostrukturelle CH3PF2H+SbF6- mit a = 554,3(3), b = 724,2(4), c = 970,4(5), α = 94,73(4)°, β = 96,14(5)°, γ = 95,30(4)°.
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  • 69
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 519-522 
    ISSN: 0044-2313
    Keywords: Zirconium complexes ; diazabutadiene ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zirconium Diazabutadiene Complexes of the Type Zr(DAD)31,4-Diazabutadienes (DAD), RN=CPh—CPh=NR 1 (R = C6H5 a, CH3C6H4 b, CH3OC6H4 c), react with ZrCl4 · 2 THF with formation of complexes of the type ZrCl4 · DAD 2. At interaction with lithium diazadienides Li2DAD deep coloured complexes of the composition Zr(DAD)3 3 are formed.The new compounds were characterized by elemental analysis, i.r., 1H- and 13C-n.m.r. spectra.
    Notes: 1,4-Diazabutadiene (DAD), RN=CPh—CPh=NR 1 (R=C6H5 a, CH3C6H4 b, CH3OC6H4 c), reagieren mit ZrCl4 · 2 THF zu Addukten der Zusammensetzung ZrCl4 · DAD 2. Diese werden bei Einwirkung von Lithiumdiazadieniden Li2DAD in tieffarbige Komplexe des Typs Zr(DAD)3 3 übergeführt.Die erhaltenen Verbindungen wurden durch Elementaranalysen sowie ihre IR-, 1H- und 13C-NMR-Spektren charakterisiert.
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