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The structure of phosphonic acid H 3 PO 3 has been redetermined by single crystal neutron diffraction (λ = 104.22 pm) at 15.0 ± 0.1 K yielding lattice parameters {Pna21; Z = 8; a = 716.6(3); b = 1201.3(5); c = 674.3(3) pm} and bond lengths {mean values from two crystallographically independent molecules: P-O 155; P=O 150; P-H 139; O-H 101 pm} of high reliability (R = 0.053). Each molecule is involved in four asymmetric hydrogen bonds (O...H 155 to 160pm; O-H...O 168 to 177°) with either hydroxyl group donating and the phosphoryl fragment acting as a twofold acceptor. Thus a complex, three-dimensional net, consisting of four- and eight-point circuits in a 1:2 ratio, is put up although the molecules are packed in a comparatively simple way to form an almost cubic closest arrangement. An X-ray crystal structure determination (R = 0.0...
In the reaction of 2,2-dimethylpropionyl chloride with bis[bis(trimethylsilyl)-phosphano]methane bis[(-2,2-dimethyl-1-trimethylsiloxypropyliden)phosphano]methane is formed. The structure of the compound (m.p.39°C) was determined at -95 ±5°C by X-ray diffraction. It crystallizes in the non-centrosymmetric space group Pca21 with a = 15.61(1); b = 12.84(1); z = 11.84(2) Å. Z = 4; R = 0.039.N.m.r. and i.r. spectroscopic investigations show the trimethylsilyl groups to be bound to the oxygen atoms and the third valence of the twofold coordinated phosphorus atoms engaged in double bonds to the neighbouring carbon atoms. This is confirmed by the X-ray structure determination. All bonds leading to the PC group lie in a plane; both planes of the molecules are mutually inclined by 85.1°. The arrangement of substituents corresponds to a Z/Z-isome...
1H-1,3-Benzazaphosphole synthesized by Issleib and coworkers [2], crystallizes in the orthorhombic space group Pna2 1 with following dimensions of the unit cell determined at a temperature of measurement of -80 ± 3°C: a = 828.6(2); b = 557.1(1); c = 1433.5(4) pm; Z = 4. An X-ray Structure Determination (Rg = 0.061) shows the molecule to be characterized by a rather narrow C-P=C angle of 88.2(4)° as well as a shortened single {180.7(7)} and a typical double bond {169.5(9) pm} between the carbon atoms and the twofold coordinate phosphorus. All the other bond lengths differ only scarcely from corresponding values of the homologues benzimidazole 2a [3, 4] and 1H-1,3-benzazarsole 2c [5]. In spite of the fact that all three solids crystallize in the same space group, only the heterocycles 2b and 2c are isotypic; intermolecular hydrogen bonds...
Studies of Fritz et al. [10] showed methylphosphane to be lithiated at -60°C in 1,2-dimethoxyethane or bis(2-methoxyethyl) ether solution by stoichiometric amounts of lithium n-butanide in n-hexane. After removing the hydrocarbons almost completely by distillation and cooling the solutions to -60°C again, colourless square crystals of (1,2-dimethoxyethane-O,O)lithium (1) and (2,5,8-trioxanonane-O2,O5)lithium methylphosphanide (2) precipitate. As shown by an X-ray structure determination (monoclinic, P21/n; a = 805.5(1); b = 1820.6(2); c = 851.5(1) pm; β = 116.76(1)° at -100 ± 3°C; Z = 4 formula units; R = 0.034) complex 2 forms a polymer which has the shape of an up to now scarcely noted meso-helix. Four-coordinated lithium is bound to two phosphorus (P-Li 252.9 and 253.2 pm; P-Li-P 131.8°; Li-P-Li 132.1°) and to two oxygen atoms ...
The photoelectron (PE) spectra of methyl and silyl ethers are assigned and correlated on the basis of CNDO/2-SCF-MO calculations. The dynamic behavior of the individual orbitals is discussed in terms of electronic and geometric perturbations of the ether system.
At −25°C bis(trimethylsilyl)phosphine 1b and 2,2-dimethylpropionyl chloride form (2,2-dimethylpropionyl)trimethylsilylphosphine 2b. As this compound is thermally more stable than similar acyltrimethylsilylphosphines, it might be treated at −55°C with methyllithium to form the correspondig lithium phosphide 2d; after the addition of chlorotrimethylsilane [2,2-dimethyl-1-(trimethylsiloxy)propylidene]-trimethylsilylphosphine 3c is obtained. At +20°C 2b rearranges to the E and Z isomer of [2,2-dimethyl-1-(trimethylsiloxy)propylidene]phosphine 3b. The NMR data of E-3b and Z-3b differ mostly in the coupling constants. Kept in the diffuse daylight for several days 3b dimerizes to form 2,4-di(tert.butyl)-2,4-bis(trimethylsiloxy)-1,3-diphosphetane 10. In solution 10 is unstable and decomposes again to a mixture of the E und Z isome...
Im Kontext unserer Arbeiten über die Chemie von Metall-Metall-Mehrfachbindungen haben wir insbesondere im Hinblick auf mögliche Cycloadditions- und/oder Metathese-Reaktionen das nach Becker und Uhl bequem zugängliche 2,2-Dimethylpropylidinphosphan exemplarisch auf sein Verhalten gegenüber Metall-Metall-Mehrfachbindungen geprüft.
Kept at 20°C in diffuse daylight the mixture of the E and Z isomer of [2,2-dimethyl-1-(trimethylsiloxy)propylidene]phosphine is not stable; within several weeks the dimer 2,4-di(tert.-butyl)-2,4-bis(trimethylsiloxy)-1,3-diphosphetane 1 precipitates. The compound crystallizes triclinic in the space group P1 with a = 1044.5(3); b = 647.8(2); c = 883.8(2) pm; α = 100.39(2); β = 102.84(2); γ = 93.70(2)°; Z = 1. As shown by an x-ray structure determination (R = 3.7%) the molecule has a centre of symmetry. The long P-C distances (189.5 and 190.3 pm) indicate a strained ring-system; in solution the diphosphetane decomposes again to form the E and Z isomeric monomer. Further characteristic bond distances and angles are: C1-O 140.8; Si-O 163.5 pm as well as P-C1-P' 92.7; C1-P-C1′ 87.3; C1-O-Si 146.2°.
Bis[bis(trimethylsilyl)methyl]gallium bromide GaBr[CH(SiMe3)2]2 (4), prepared from Ga2Br4 · 2 dioxane and bis(trimethylsilyl)-methyllithium in the molar ratio of 1:3, reacts with the sterically high-shielded lithium tris(trimethylsilyl)silyltelluride · DME to yield [(Me3Si)2CH]2Ga–TeSi(SiMe3)3 (5). 5 can also be synthesized by a metathetic reaction between tetrakis-[bis(trimethylsilyl)methyl]digallium(4) and bis[tris(trimethylsilyl)silyl]ditellane in toluene at 100°C. A crystal structure determination shows the compound to be monomeric in the solid state and the atoms of the central C2Ga–TeSi moiety to lie in the mirror plane of the molecule. The short Ga–Te distance of 253.5(1) pm as well as a hindered rotation (ΔErot ≈ 50 kJ · mol-1) as detected by NMR measurements might be interpreted in terms of a π interaction bet...
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