MOLECULAR-STRUCTURE OF GASEOUS TRIMETHYLGERMYLFORMATE FROM ELECTRON-DIFFRACTION

The molecular structure of trimethylgermylformate (TMGF) has been dete rmined by electron diffraction in the gas phase. The principal paramet ers, bond lengths (r(a), angstrom), bond and torsional angles (deg) wi th the least-squares standard deviations in parentheses, are as follow s: Ge-C, 1.919(21); Ge-O, 1.820(28); C=O, 1.213(76); C-O, 1.326(42); C -H(methyl), 1.109(80); C6-H8, 1.12(fixed); Ge-O-C, 117.6(23); O-Ge-C, 104.9(7); Ge-C-H, 109.8(80); O-C=O, 125.4(59); C-Ge-C, 113.6(7); O=C-H , 127(fixed); Ge-O-C=O, 81.2(63); C-Ge-O-C, 35.5(38); H-C-Ge-O, 73.2(5 2). It is found that the Ge-O-C=O fragment of TMGF is not planar, and the H-C=O plane is close to the perpendicular position with respect to the Ge-O-C plane. This result stands out from the series of previousl y obtained data for similar molecules and suggests that the conformati on of TMGF is controlled mainly by steric effects. The conformation of TMGF from electron diffraction is in agreement with molecular mechani cs calculations.