DETERMINATION OF THE MOLECULAR-STRUCTURE OF TERT-BUTYLDIMETHYLSILANE IN THE GAS-PHASE BY ELECTRON-DIFFRACTION

The molecular structure and conformation of SiHBu(t)Me2 in the gas phase have been determined by electron diffraction. Assuming local C3 symmetry within tert-butyl and methyl groups the principal refined parameters are r[Si-C(Bu)] 188.6(2), r [Si-C(Me)] 188.2(2), r(C-C) 154.6(1) pm, angle CCC 108.5(3), angle C(Bu)SiC(Me) 111.1(4) and angle C(Me)SiC(Me) 105.5(10)-degrees. A small steric effect is apparent, with the threefold axis of the tert-butyl group tilted 3.6(10)-degrees away from the Si-methyl groups, so that the three SiCC angles are 114.1(9), 109.0(6) and 108.3(8)-degrees. The conformation adopted about the Si-C(butyl) bond is almost fully staggered with the HSiCC dihedral angle 174.3(48)-degrees.