David C. Liles

The crystal and molecular structure of oxo-bis[tribenzylsilicon(IV)]

Abstract Crystals of oxo-bis[tribenzylsilicon(IV)], O[(PhCH2)3Si]2, are triclinic, space group P 1 , with a = 9.780(7), b = 9.938(9), c = 10.283(6) A, α = 93.35(1), β = overall symmetry close to 3 : the SiOSi skeleton is strictly linear with SiO = 1.613(4) A. The conformations of molecules and ions isoelectronic with O[(PhCH2)3Si]2 are compared and discussed.

The crystal and molecular structure of oxo-bis[tribenzylgermanium(IV)]

Abstract Crystals of oxo-bis[tribenzylgermanium(IV)], O[(PhCH2)3Ge]2, are rhombohedral, space group R 3 , having a = 9.621(2) A, α = 85.48(3)°. The structure was solved by Patterson methods using diffractometer data and refined by full-matrix least squares to R = 0.0876. The structure consists of molecules lying along the 3-fold axis of the unit cell, in which the GeOGe fragments are strictly linear and centrosymmetric. The Geue5f8O distance is 1.730(1) A and the Geue5f8C distance is 1.980(5) A.

The crystal and molecular structure of triphenyl(trifluoroacetato)germanium(IV)

Abstract Crystals of the compound Ph 3 GeOCOCF 3 are triclinic, space group P 1 , with a 9.704(5), b 9.747(2), c 10.792(4) A, α 73.30(3), β 86.68(3), γ 75.59(3)°, and Z = 2. The structure consists of monomeric molecules, with the geometry around germanium distorted towards trigonal bipyramidal by an intramolecular Ge … O interaction. There is no intermolecular association.

The crystal and molecular structure of 1,1,1,3,3,3-hexaphenyl-1,3-disilapropane

Abstract Crystals of the title compound H 2 C(SiPh 3 ) 2 are triclinic, space group P 1 , with a = 9.290(2), b = 12.128(4), c = 16.882(4) A, α = 62.08(1), β = 106.88(1), γ = 117.28(2)° and Z = 2. The central skeletal angle SiCSi is 128.8(7)°. The structures of the molecules H 2 C(SiR 3 ) 2 (R = H, CH 3 , and Ph) are compared and discussed: a simple model for the skeletal geometry of species H 2 C(MR 3 ) 2 is proposed, and tested against experimental data and theoretical calculations.

The structure of μ-oxo-bis[tribenzyltin(IV)]

Sn2(CTHT)60) , C42H42OSn2, M r = 800.14, rhombohedral, R3, a = 9.667 (2)/L a= 84.05 (3) °, U -- 889.7 A 3, z -- 1, D c = 1.493 Mg m -3, F(000) = 402, ~.(Mo Ka) = 0.71069/k, g = 1.311 mm -1. Final R = 0.0197. The structure consists of molecules lying along the threefold axis of the unit cell, in which the SnOSn fragment is linear and centrosymmetric. The Sn-O distance is 1.919 (0) ,~ and the Sn-C distance 2.167 (2) A.

The crystal and molecular structure of 4,4'-methyl-enebis(1,3.5-trimethyl-4-imidazolin-2-one)

Abstract The compound C 13 H 20 N 4 O 2 formed by reaction of 1,3-dimethylurea and butan-2,3-dione in benzene/TFA is shown by X-ray analysis to be 4,4-methylenebis(1,3,5-trimethyl-4-imidazolin-2-one).

Hexaorgano-substituted triatomics R3XYZR3: the configurations of organometallic sulphides (R3M)2S and the crystal and molecular structure of thio-bis[triphenyltin(IV)]

Abstract Crystals of thio-bis[triphenyltin(IV)], S(Ph3Sn)2, are orthorhombic, space-group P212121, with a = 18.469(5), b = 17.648(5), c = 9.848(6) A and Z = 4. The SnS distances are 2.405(9) and 2.417(7) A and SnSSn angle is 107.3(2)°: there are no anomalous features in the structure analogous to those in O(Ph3Sn)2-MNDO calculations for a series of organometallic sulphides (Me3M)2S+n (M = Be, B, C, N, Si, P) indicate that the inversion barrier to linearity increases monotonically, and the skeletal bending force constant at linearity decreases correspondingly as the group Me3M becomes more electro-negative.

Ligands of low electronegativity in the vsepr model: Isoelectronic molecules and ions (MX3)2 YE2n+

Abstract Equilibrium geometries, inversion barriers and force constants at linearity for the skeletal bending vibration have been calculated by the MNDO method for species of general type (X 3 M) 2 YE 2 n + ; in particular for twenty-eight hydrido species (H 3 M) 2 Y n + ; isoelectronic with H 3 COCH 3 in which M = Be, B, C, N, O, Si, P or S, and Y = B, C, N, O or F; and for eight fluoro analogues (F 3 M) 2 Y n + . For a given Y the force constant moves towards more negative values as the electronegativity of MX 3 increases: when M is held constant and Y is varied, the interplay of electronegativity and sp energy gap in Y causes a complex variation in observed behaviour. A structural description of MX 3 groups having less than C 3V symmetry is outlined.

Structure of N,N'-bis[2-(5-tert-butyl-3H-1,2-dithiol-3-ylidene)ethylidene]hydrazine

CIsH24N284, triclinic, Pi, a = 5.929 (3), b = 8.898(3), c = 9.954 (2) A, a = 92.05(3), fl = 102.12 (4), y = 104.73 (4) ° , U = 494.34 A 3, M r = 396.66, D c = 1.332 Mg m -3 for Z = 1, F(000) = 210, Mo Ka radiation, 2 = 0.71069 A, p(Mo Ka) = 0.428 mm -~, R = 0.0959 for 1407 reflections with F o >_ 6a(Fo). The molecule lies across a centre of inversion and is planar apart from the tert-butyl groups. Introductlon. Treatment of the Vilsmeier salt (I) with hydrazinium hydroxide gave the title compound (II). Crystals suitable for X-ray investigation were provided by Professor D. H. Reid and Mr A. McRoberts.

A neutral silicon ether, linear at oxygen: X-ray crystal and molecular structure of oxo-bis[triphenylsilicon(IV)]

Oxo-bis[triphenylsilicon(IV)], O(Ph3Si)2, has been found by X-ray analysis to contain a linear SiOSi fragment.