Molecular Structure and Internal Rotation of Trimethylamine-Boron Trifluoride. A Combination of Electron Diffraction and Spectroscopic Data

Abstract

Abstract The molecular structure of trimethylamine-boron trifluoride (CH3)3N·BF3 was determined from gas electron-diffraction data with vibrational and rotational spectroscopic data. The geometric parameters of the molecule were found to be very close to those inferred from the preliminary analysis of the diffraction data alone. The structural parameters and uncertainties were rg(N–B)=1.674(4) Å, rg(B–F)=1.374(2) Å, rg(C–N)=1.485(2) Å, rg(C–H)=1.100(3) Å, rg(F…F)=2.288(2) Å, and rg(C…C)=2.420(4) Å. The potential barrier about the N–B axis was estimated to be 4.3±0.3 kcal/mol in the gas phase; this value is much larger than that from NMR spectra.