1,2-DI-TERT-BUTYLTETRAFLUORODISILANE, BU(T)SIF2SIF2BUT - VIBRATIONAL-SPECTRA AND MOLECULAR-STRUCTURE IN THE GAS-PHASE BY ELECTRON-DIFFRACTION AND AB-INITIO CALCULATIONS

The molecular structure of 1,2-di-tert-butyltetrafluorodisilane, (BuSi F2SiF2But)-Si-t, has been determined in the gas phase by electron diff raction (GED) and ab initio molecular orbital calculations. Together w ith infrared and Raman studies, GED shows that only a single conformer (anti, C-2h symmetry) is present in the gas phase. From normal coordi nate analysis, the Si-Si stretching force constant is 179 N m(-1), wit hin the range previously observed for other related compounds. Importa nt structural parameters (r(a)) are: Si-Si 234.6(6), Si-C 187.2(3), Si -F 160.0(2), C-C 153.7(3), C-H 113.5(2) pm, Si-Si-C 114.6(7), Si-Si-F 108.7(3) and F-Si-F 107(2)degrees. This geometry is supported by theor etical predictions obtained at the 6-31G/SCF level.