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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 7 (1990), S. 30-35 
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The current state in shape analysis is distinguished by a number of characterization methods, but the great variety of specific shapes complicates the selection of parameters that are relevant for a particular problem. Therefore, the preferred approach is to characterize single particles "free of presupposition" and to select technologically relevant parameters using cluster and discriminance algorithms.Parameter vectors including elongation, bulkiness, fractal dimension and area-equivalent diameter are calculated on the basis of image analysis. First applications to bacteria and agricultural freestuffs exemplify the concept and illustrate that technologically relevant particle shape analysis permits the classification of single particles and the quantification of property functions.
    Additional Material: 8 Ill.
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  • 2
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (η6-1,3,5-Trimethylbenzene)tin(II) chloride tetrachloroaluminate(III), (η6-1,3,5-C6H3Me3)SnCl (AlCl4), has been obtained from the reaction of anhydrous SnCl2 and AlCl3 in the molar ratio 1 : 2 in excess mesitylene as a solvent. The compound crystallizes in monoclinic needles, space group P21/n, containing a coordination polymer with planar four-membered rings Sn-Cl-Sn-Cl as the fundamental structural units. Each tin(II) atom of these rings is η6-bonded to a mesitylene ring, with the metal approximately centered over the aromatic hydrocarbon at a distance of 2.71 Å. Each of the tin(II) atoms is further connected to two tetrachloroaluminate counter ions, one of these monodentate and one bidentate. Through this mono/bidentate contacts a one-dimensional coordination polymer is generated with crystallographic centers of inversion in the middle of the Sn(Cl)2Sn and Sn(AlCl4)2Sn rings. The structure is similar to that of the analogous benzene complex, but not identical owing to a different connectivity pattern. Also, the arene-Sn(II) distance is much shorter in the mesitylene complex (2.71 Å) than in the benzene complex (2.90 Å), indicating that the trimethylbenzene molecule is a much better donor than benzene.
    Additional Material: 2 Ill.
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  • 3
    ISSN: 0009-2940
    Keywords: Arene complexes / Antimony(III) complexes / Organoantimony compounds / Dihydroanthracene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystals of a 1:2 complex of 9,10-dihydroanthracene and antimony tribromide are obtained from toluene solutions of the components. In the crystal the complex forms corrugated sheets of an inorganic (SbBr3)n coordination polymer, which are cross-linked by antimony coordination to the benzene rings of the dihydroanthracene molecules are also arranged in folded layers. The dihydroanthracene molecules reside on centers of inversion and their carbon skeleton is planar within the limits of the experiment. With contacts from opposite sides of the molecular plane, the dihydroanthracene is η6,(η6)'-coordinated to the Sb(III) centers at distances of 3.25 Å. In a very irregular geometry the coordination sphere of the crystallographically equivalent antimony atoms contains bromine neighbours at different distances. - Antimony trichloride and dihydroanthracene form a complex of ambiguous stoichiometry, while bismuth trichloride again gives a 2;1 complex, the structure of which has not yet been determined.
    Additional Material: 3 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1599-1602 
    ISSN: 0009-2940
    Keywords: l-Aspartate complexes ; Strontium l-aspartate ; trihydrate ; Barium l-aspartate trihydrate ; Amino acid complexes ; Metal complexation by amino acids ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Strontium and barium l-aspartate are obtained by neutralization of aqueous solutions of l-aspartic acid with strontium or barium hydroxide, respectively. Slow crystallization from hot water affords the crystalline trihydrates, saturated solutions of which show pH values of 11.0 and 10.8 at ambient temperature. - The crystal structure of the two compounds has been determined by single crystal X-ray diffraction. The compounds are isomorphous (orthorhombic, space group P212121), and the structural parameters are very similar as expected from the small differences in the ionic radii of the two metals. - The cations are arranged in double strings parallel to the b axis. The l-aspartate dianions are bridging these double strings by chelating contacts of the two carboxylate groups with the metal atoms of different strings to give layers. While the α-carboxylate groups are only bidentate and associated with one metal atom each, the β-carboxylate oxygen atoms are also each bridging two adjacent metals of the neighbouring string. The three water molecules are all coordinated to the metal atoms, which attain coordination number 9. The amino groups are not engaged in metal coordination, but are part of a system of hydrogen bonds cross-linking the layers.
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  • 5
    ISSN: 0009-2940
    Keywords: Michaelis-Arbuzov reaction ; Nickel complexes with trimethylphosphite and dimethylphosphito ligands ; Bis(dimethylphosphito)rhodium as chelating ligand ; Organometallic diphenylborane derivative ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes Containing Metallabis(dialky1phosphito) Units, VI1. - Synthesis and Complex-Forming Properties of the Organometallic Chelating Ligand {C5Me5RhI[P(0)(OMe)2]2}-The dinuclear complexes [C5Me5NiBr]2 and [C5Me5RhI2]2 react stepwise with P(OMe)3 by cleavage of the halide bridges and a subsequent Michaelis-Arbuzov-type reaction to give the neutral compounds C5Me5Ni[P(O)(OMe)2][P(OMe)3] (3) and C5Me5RhI[P(O)(OMe)2][P(OMe)3 (6). Treatment of 6 with an equimolar amount of NaI gives the sodium salt of the {C5Me5RhI[P(O)(OMe)2]2}- anion Na[L] (7) isolated as an adduct with 0.6 NaI. Reaction 7 with H2SO4 in water leads to the formation of the protonated complex C5Me5RhI[P(O)(OMe)2][P(OH)(OMe)2] (8), from which on treatment with thallium acetylacetonate C5Me5RhI[P(O)(OMe)2]2TI (9) is obtained. The X-ray structural analysis of 9 reveals that the organometallic anion L- is coordinated as a bidentate ligand by the P = O oxygen atoms to thallium, L- also behaves as a bidentate chelating ligand in the complexes [L]2Mg(OH2)2 (12), [L]2Zn (13) and [L]2UO2 (14), whereas it is presumably coordinated as an O,O′,I-tripod ligand in the compounds [L]PtMe3 (10) and [L]2Cu (11). In acid solution 8 reacts with NaBPh4 to give the diphenylborane derivative LBPh2 (15).
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  • 6
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hinge region links the antigen binding Fab part to the constant Fc domain in immunoglobulins. For the hinge peptide derivative [AcThr(OtBu)-Cys-Pro-Pro-Cys-Pro-Ala-ProNH2]2 the assignment of the 1H and 13C resonances was achieved by two-dimensional nmr techniques: total correlation spectroscopy (TOCSY), nuclear Ovethauser enhancement spectroscopy (NOESY), rotating frame nuclear Overhauser enhancement spectroscopy (ROESY), heteronuclear multiple quantum coherence (HMQC) transfer, and a HSQC (modified Overbodenhausen experiment) with high resolution in F1, which was several times folded in F1 but still phase correctable. Conformational relevant parameters (78 nuclear Overhauser effect distance restraints, 3JHH for prochiral assignments, temperature gradients) were determined by nmr and served as input data for molecular dynamics (MD) structure refinement. A simulated model compound corresponding to the [Cys-Pro-Pro-Cys]2 core elongated by the peptide chains in the Fab and Fc direction served as a starting structure for the final MD run. The conformation calculated in in vacuo does not agree with the C2 symmetry required from nmr data, but the structure obtained by a water simulation fulfills the requirement. Here the core of the hinge peptide derivative adopts a polyproline II double helix as in the x-ray structure of IgG1. Hence, segments responsible for the internal flexibility are located outside the core as confirmed by the flexibility of the solvent exposed C termini.
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  • 7
    ISSN: 0009-2940
    Keywords: Dihydroanthracene ; Dihydroanthracene, butyl-substituted ; Tricarbonylchromium ; Chromium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complexes [9,10-dihydroanthracene][tricarbonylchromium]n [9,10-DHA][Cr(CO)3]n [n = 1 (1), 2 (2)] and the related mono- and bis(tricarbonylchromium) complexes of 2,6- and 2,7-di-tert-butyl-9,10-dihydroanthrancene [2,6-DB-9,10-DHA][Cr(CO)3]n [n = 1 (3), 2 (4)] and [2,7-DB-9,10-DHA][Cr(CO)3]n [n = 1 (5), 2 (6)] have been prepared by heating the 9,10-DHA species in the presence of hexacarbonylchromium [Cr(CO)6]. Evidence for the existence of the complex [2,6,9-tri-tert-butyl-9,10-DHA][Cr(CO)3] (7) is also presented. The complexes have been characterised spectroscopically, and for complex 1 an X-ray crystallographic structure determination has been carried out. This complex adopts the unexpected structure in which the non-coordinated arene ring is bent towards the Cr(CO)3 moiety. The syntheses and spectroscopic characterisations of 2,6- and 2,7-di-tert-butylanthracene (2,6- and 2,7-DBA), 2,6- and 2,7-di-tert-butyl-9,10-dihydroanthracene (2,6-and 2,7-DB-9,10-DHA), 2,6,9-, 2,7,9-, and 2,7,10-tri-tert-butyl-9,10-dihydroanthracene (2,6,9-, 2,7,9- and 2,7,10-TB-9,10-DHA), and 2,6,9,10- and 2,7,9,10-tetra-tert-butyl-9,10-dihydroanthracene(2,6,9,10- and 2,7,9,10-TeB-9,10-DHA) are also given.
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  • 8
    ISSN: 0009-2940
    Keywords: Ferrocenes ; Cyclopentadienes, disilyl- ; Silatropic rearrangement ; Lithium cyclopentadienides ; Metallocene, trinuclear, mixed-metal ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The tetrahydro-4,4,8,8-tetramethyl-4,8-disila-s-indacenyl anion (LH) reacts with or without cyclopentadienyl anion (Cp-) and Fe2Cl4(THF)3 to give the mixed ferrocenes CpFe(LH) and (LH)2Fe in 50 and 63% yield, respectively. Near room temperature and in solution CpFe(LH) exists as a pair of enantiomers (syn-3a/b). According to an X-ray analysis both enantiomers are present in a single crystal. Compound 3 consists of a ferrocene linked to a cyclopentadiene by two Me2Si groups such that the acidic Cp proton points towards the iron. Temperature-dependent NMR spectra show that syn-3a and syn-3b are non-rigid molecules which are interconverted by 1,2-silatropic bond shifts (Ea = 49.2 ± 2.9 kJmol-1). Three more isomers (anti-3a, anti-3b, and the spiro derivative 3c), though present only in low concentration, are engaged in the rearrangement. (LH)2Fe is also non-rigid and exists as a pair of diastereomers (4a and 4b). The isomers of 3 and 4 undergo hydrolysis (e.g., syn-3a/3b gives [(Me2SiOSiMe2)Cp]FeCp (5) among others) and deprotonation. The latter yields CpFe(L-) (7) and (L-)2Fe (8), which are characterized by NMR spectroscopy. 7 forms crystals with [Li(TMEDA)]+ as counterion, and an X-ray analysis shows that lithium and iron are located at opposite sides of the strongly folded ligand L. The reaction of 7 with CrCl2(THF) gives the trinuclear stacked metallocene 9 in 47% yield. 9 has two unpaired electrons which are located essentially in the center of the molecule.
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  • 9
    ISSN: 0009-2940
    Keywords: Gold(I) complex ; Phosphine (selenide) complexes ; Aus···Au interactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [(CO)AuCl] reacts with equimolar amounts of Ph2PCH2P(Se)Ph2 (dpmSe) to afford ClAuPh2PCH2P(Se)Ph2, in which dpmSe is bound to gold in a monodentate fashion by phosphorus. Subsequent reaction of this 1:1 complex with AgClO4 results in the formation of the 10-membered ring complex 4 which crystallizes in the monoclinic space group P21/n with approximately centrosymmetric dicationic units, in which two gold (I) atoms are doubly bridged by two dpmSe ligands coordinated by phosphorus and selenium. The coordination at the gold atoms deviates from linearity and implies an Au···Au interaction with the gold(I) atoms separated by a distance of 3.020(1) Å.
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  • 10
    ISSN: 0009-2940
    Keywords: Germanium(II) complexes ; Electron pair, „inert“ ; Spiro compounds ; Molecular fluctionality ; Phosphanylmethanide ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring Expansion of Spirocyclic Germanium(II) Di(phosphanyl)methanide Complexes by Insertion of Sulfur and Selenium into Germanium-Phosphorus BondsGermanium in the intermolecularly stabilized germylene derivative Ge[C(PMe2)2(SiMe3)]2 (2a) is not oxidized by sulfur but the latter inserts 1 to 4 chalcogenide atoms into the Ge-P bonds of the four-membered chelate (4/4-) rings to give 4/5-, 5/5-, 5/6, and 6/6-membered spirocycles Ge[C2(SPMe2)n(PMe2)4-n(SiMe3)2] (n = 1-4: 4, 5a, 6, 7). Only 5a and 7 could be obtained in pure form, whereas compounds 4 and 6 with odd-numbered chalcogenide atoms are only characterized in solution, where they exist in equilibrium with 2a and 5a or 5a and 7, respectively. All these molecules are fluctional in solution. 7 is also obtained from GeCl2 · dioxane and Li[C(SPMe2)2(SiMe3)]. The selenium compound Ge[C(SePMe2)(PMe2)(SiMe3)]2 (5b) is obtained from 2a and grey selenium in toluene. An X-ray structure determination of 5b shows a distorted sphenoidal arrangement [approximate C2 symmetry of a spirocyclic germanium center within two five-membered rings containing a nearly linear Se-Ge-Se unit (Ge-Se 2.712/2.769(1) Å)]. The angle PGeP is 95.9(1)°. A bonding model with a stereochemically non-active electron lone pair at the formal germanium(II) center may account for this geometry. As byproducts in the sulfurization reactions, bis-(phosphanyl)methane disulfides are also observed in certain cases, from which H2C(SPMe2)2 has been isolated in pure form and characterized structurally.
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