New Cyclic and Acyclic Silicon-Germanium and Silicon-Germanium-Tin Derivatives

Abstract

New Si-Ge and Si-Ge-Sn compounds bearing the bulky groups -E(SiMe3>3 (E = Si, Ge) were obtained by treatment of MCU (M = Ge, Sn) with either (THF)3LiSi(SiMe3)3 or (THF)2.5LiGe(SiMe3)3. The cyclic tetragermane [(Me3-SOsSiGeCl^-CeHe crystallizes in the monoclinic space group C2/c with a = 21.835(7) Á, b = 26.342(9) A, c = 14.464(4) Á, ß = 103.45°, V = 8092 Á3, and Z = 4. The Ge4 ring was nonplanar with an average torsion angle of 17.2°. The tetragermane [(Me3Si)3GeGeCl2]2 was characterized by elemental analyses and NMR spectra, which were consistent with a linear tetragermane backbone for the molecule. Dichlorobis(tris(trimethylsilyl)germyl)tin(IV), ((Me3Si)3Ge)2SnCl2, crystallizes in the monoclinic space group C2/c with a = 16.106(4) A,b = 10.034(2) Á, c = 47.375(11) Á, ß = 90.02°, V = 7656 Á3, and Z = 8. The coordination geometry around tin is extremely distorted with Ge-Sn-Ge = 142.1°and Cl-Sn-Cl = 98.8°. The three compounds were stable in air except (( ß3-Si)3Ge)2SnCl2 was mildly hygroscopic. Reactions of the compounds with Li, L1AIH4, and (THF)2.5LiGe(SiMe3)3 were carried out, but no new products were identified. Treatment of LaCU with 3 equiv of (THF)3LiSi(SiMe3)3 afforded (THF)La(Si(SiMe3)3)2Cl as a very hygroscopic white solid. All attempts to substitute more than two -Si(SiMe3)3 groups on a central atom were unsuccessful.

Ge4Cl4[MCp(CO)3]4 (M = Cr, Mo, W): A Series of Transition Metal Substituted Four‐membered Cyclogermanes

“…Comparing the four‐membered ring structure of compounds 1 – 4 the obvious difference is that compounds 1 – 3 show a folded four‐membered ring, whereas an almost planar arrangement is realized for 4 . Hence, the dihedral angles are 21° ( 1 and 3 ) and 20° ( 2 ), respectively, which is in the same range of dihedral angles in four‐membered cyclogermanes bearing sterically demanding alkyl, silyl and germyl substituents (21°, 17°, and 19°) , , . In contrast, within [GeBrMn(CO) 5 ] 4 4 , a dihedral angle of only 4° is realized, leading to a nearly planar arrangement .…”

MOLECULAR STRUCTURE OF ORGANOSILICON COMPOUNDS WITH Si-M (M = Ge, Sn, Pb, Ti, Zr, Hf) BONDS

“…The structure of tris(trimethylsilyl)silylcyclotetragermane 7 (M=Si [22]) closely resembles that of its tris(trimethylsilyl)germyl counterpart 7 (M=Ge, [15]). Both compounds have all frans-geometry.…”

Germanium Coordination Compounds: Classification and Analysis of Crystallographic and Structural Data

“…The Ge4 ring is found in a red [137] and a bright yellow [138] derivative. The Ge4 ring in the former is almost a regular tetrahedron with Ge-Ge bond distances from 243.1(2) to 244.7(2) pm and Ge-Ge-Ge angles from 59.62(7)° to 60.10(7)°.…”