The molecular structure of gaseous octamethyltrisilane, (CH 3) 3SiSi(CH 3) 2Si(CH 3) 3, AS determined by electron diffraction

Abstract

The molecular structure of gaseous octamethyltrisilane, Si 3Me 3, has been determined by electron diffraction at a nozzle temperature of 339 K. The diffraction data are consistent with a model with only minor distortions from C 2V symmetry, with approximately staggered SiMe 3 groups relative to the central SiMe 2 group when viewed along the SiSi bonds, and with one CSi bond (SiMe 3) nearly anti to the remote SiSi bond. Principal bond lengths ( r a) and valence angles are: SiSi 2.325(12) Å, CSi (average) 1.887(3) Å, CH 1.100(5) Å; SiSiSi 118.0(2.5)°, SiSiC (SiMe 3) 108.7(0.9)°, CSiC (SiMe 2) 109.1(1.5)° and SiCH 111.4(0.8)°. The parenthesized values are one standard deviation, corrected for experimental errors.