An Electron Diffraction Determination of the Molecular Structure of Hexamethylcarbodiphosphorane in the Gas Phase

Abstract

Abstract The molecular structure of hexamethylcarbodiphosphorane, (CH 3 ) 3 PCP(CH 3 ) 3 , in the gas phase has been determined by electron diffraction. Principle bond lengths ( r a ) are: PC, 181.4(3) pm, PC, 159.4(3) pm; CH, 108.9(4) pm. The angles between the PC (methyl) bonds are 101.4(3)°, and the apparent PCP angle is 147.6(5)°. The single structure that fits the experimental data closest has C 2 overall symmetry, but an even closer fit is obtained if free rotation about the PC bonds is assumed. This and other evidence indicates that the molecule is probably a symmetric top, and that the PCP unit is linear in the average structure, with shrinkage caused by a low frequency bending vibration giving rise to the apparent non‐linearity.