THE MOLECULAR-STRUCTURES AND CONFORMATIONAL PREFERENCES OF BIS(DIMETHYLSTIBYL)-SULFANE AND BIS(DIMETHYLSTIBYL)-TELLURANE, E(SBME2)(2), E = S OR TE, ME = CH3, BY DENSITY-FUNCTIONAL THEORY CALCULATIONS AND GAS ELECTRON-DIFFRACTION

Density functional theory calculations on E(SbMe2)(2), E = S or Te, Me = CH3, indicate that the equilibrium structures are syn-in or near in -in conformers with overall C-2, or C-2 symmetry The calculations furt her indicate the existence of syn-anti conformers about 4 kJ mol(-1) ( E = S) or 1 kJ mol(-1) (E = Te) above the equilibrium structure. Gas e lectron diffraction data show that both conformers are present in gase ous S(SbMe2)(2), while the presence of the syn-anti conformer in gaseo us Te(SbMe2)(2) is uncertain. The Sb-S and Sb-Te bond distances are 24 1.4(4) and 278.1(3) pm, respectively, the valence angles of the syn-sy n conformers are <SbSSb = 98.7(5)degrees and <SbTeSb = 91(2)degrees.