Electron Diffraction Study of Monomethyl- and Dimethylphosphine

Abstract

The structural parameters of gaseous monomethyl‐ and dimethylphosphine were determined by the sector‐microphotometer method of electron diffraction. Center of gravity bond distances and standard errors for the two molecules were, respectively: r_CP=1.858±0.003 A and 1.853±0.003 A; r_CH=1.094±0.008 A and 1.097±0.007 A; r_PH=1.423±0.007 A and 1.445±0.02 A. The angles P–C–H were 109.6±1° and 109.8±0.7°. In dimethylphosphine the angle C–P–C was 99.2±0.6°. The methyl groups were found to be in staggered conformations. The distances and root‐mean‐square amplitudes of vibration agreed well with the values determined in recent studies of phosphine and trimethylphosphine.