Analysis of diborane X-ray diffraction data utilizing structure factors calculated from molecular wave functions

Abstract

Crystal unit-cell structure factors for diborane, B2H6, have been calculated for four possible molecular geometries, using densities obtained from self-consistent field molecular wavefunctions. These structure factors were fitted for various B–H distances to the experimental X-ray data for B2H6 by varying the parameters of several thermal vibration models. B–H bond lengths so determined have values about 0.05 Å longer than those determined by the usual spherical atom analysis of the X-ray data. Consideration of additional factors, such as the X-ray B–H bond shortening due to rigid rotation of the molecule in the crystal, leads to the conclusion that the bond length correction given by this treatment accounts for about two-thirds of the observed discrepancy between X-ray and electron diffraction values for the B–H bond lengths in diborane.