Element-element bonds. X. Studies of chloro(diphenyl)stibane, tribenzylstibane and tribenzyldibromostiborane - Molecular structures and isotypism

Chlorodiphenylstibane (Id) {P2(1)/c; Z = 4; a=1191.8(1); b=853.4(1); c=1112 .0(l)pm; beta =93.60(1)degrees; -100 +/- 2 degreesC} crystallizes isotypica lly with a series of homologous (H5C6)(2)E-X compounds (E = As, X = Cl, Br, I; E = Sb, X = Br, I); the structure type of tribenzylstibane (5d) {Pbca: Z=8; a=832.1(2); b=2681.3(5) pm: c=1600.9(3); -100 +/- 3 degreesC} is alrea dy known from tribenzylmethanol, -silanol and -silane. Tribenzyldibromostib orane (6) {P2(1)/n; Z=4: a=938.4(2); b=2292.4(5); c=1019.7(2) pm; beta =112 .71(1)degrees -100 +/-3 degreesC} does not show an analogous relationship t o known structure types. Characteristic mean bond lengths and angles are {1 d, Sb-CI 240.9(1), Sb-C 214.0 pm, CI-Sb-C 93.8 degrees, C-Sb-C 98.6(1)degre es; 5d, Sb-C 217.5(3)pml C-Sb-C 94.9(6)degrees: 6. Sb-Br 264.6; Sb-C 217.0( 8)pm, Br-Sb-Br 179.4(1)degrees; C-Sb-C 120 degrees; Br-Sb-C 84.8(2)degrees to 94.7(2)degrees}. Stiborane 6 exhibits very weak intermolecular Sb Br int eractions of 417 pm which, however. affect the molecular conformation in a striking way.