Molecular structure of ButCl2SiSiCl2But in the gas phase by electron diffraction and ab initio calculations. Molecular structures of the compounds ButX2SiSiX2But (X = Cl, Br or I) by vibrational spectroscopy, X-ray crystallography and ab initio calculations

Abstract

The series of compounds Bu^tX₂SiSiX₂Bu^t (X = Cl, Br and I) have been studied by X-ray crystallography, vibrational spectroscopy and ab initio calculations. The solids were all found to be anti and the vibrational spectra are consistent with this observation. The molecular structure of 1,2-di-tert-butyltetrachlorodisilane, Bu^tCl₂SiSiCl₂Bu^t, has also been determined in the gas phase by electron diffraction (GED) and ab initio molecular-orbital calculations. The conformation is distorted slightly from the fully staggered arrangement, with ϕ(CSiSiC) 167.7(11)°. Important structural parameters (r_a) include: Si–Si 238.0(7) pm, Si–C 187.2(7) pm, C–C 154.3(2) pm, C–H 114.2(4) pm, Si–Si–C 119.8(6)°, Cl–Si–Cl 105.5(8)° and C–Si–Si–C 167.7(11)°. These experimental observations are supported by theoretical predictions obtained at the MP2/6-31G* level.