The Molecular Structure of Disiloxane, (SiH3)2O.

Abstract

The structure of gaseous disiloxane was studied by electron diffraction. The Si-O-Si angle is extraordinarily large, in agreement with conclusions from infrared and Raman spectroscopy, and with results of an earlier electron diffraction investigation. The structural results derived from a least sqs. analysis based on intensity curves are (distance r in A., angle < in degrees, and root-mean-sq. amplitude of vibration (l in A.): rSi-H 1.486 +- 0.010, rSi-O 1.634 +- 0.002, rSi...Si 3.107 +- 0.009, rO...H 2.556 +- 0.021; lSi-H 0.0763 +- 0.0087, lSi-O 0.0389 +- 0.0020, lSi...Si 0.0932 +- 0.0082, lO...H 0.0801 +- 0.0181; < Si-O-Si 144.1 +- 0.86, < O-Si-H 109.9 +- 1.26, < H-Si-H 109.1 +- 1.29. The standard errors contain estimates of systematic errors. The large Si.sbd.O.sbd.Si bond angle and the short Si.sbd.O bond distance are due to conjugation of unshared electron pairs on the O atom with d orbitals from the Si atom. The question of whether or not the -SiY3 groups have preferred orientations cannot be settled by the diffraction data. [on SciFinder (R)]