Molecular structure of tetramethoxygermane, Ge(OCH 3) 4, determined by gas-phase electron diffraction and ab initio molecular orbital calculations

Abstract

The structure of tetramethoxygermane, Ge(OCH 3) 4, has been determined by gas-phase electron diffraction (GED) and ab initio molecular orbital calculations. Two distinct conformational geometries are feasible for this molecule, one having S 4 symmetry and the other D 2d symmetry. The S 4 conformer was calculated to be about 3 kcal mol −1 lower in energy than the D 2d conformer. Refinements, based upon a dynamic model with S 4 symmetry, gave a satisfactory fit to the experimental data. Results for the principal distances ( r g) and angles ∠ α from the combined GED/ab initio, with estimated 2 σ uncertainties are: r(Ge–O)=1.743(3), r(C–O)=1.413(5), r( C– H) ave =1.075(13) A ̊ ; ∠O 2GeO 7=110.1(19), ∠GeOC=122.7(8), ∠OCH ave=109.9(24), Φ(C 3O 2GeO 7)=72° (ab initio), Φ(H 6C 3O 2Ge)=176° (ab initio).