Electron diffraction analysis of charge redistribution model and structure of SeF6

Abstract

The bond length of the octahedral molecule SeF6 was found to be rg(3[sigma]) = 1.685(2) A. Mean amplitudes of vibration, measured by diffraction, were within the experimental error of those calculated from spectral data by Brunvoll. Systematic residuals in scattered intensities were examined in the light of the observation (Pulay, Bartell) that residuals for SF4 result principally from the disparity between the actual electron distribution and that of the independent atom model (IAM) of standard analyses. A modified version of IAM (MIAM), retaining spherical atoms as in IAM but shifting net charge and atomic radii, somewhat in the manner of Hehre, was tested. For reasons discussed, the MIAM approach worked too imperfectly to warrant routine incorporation in diffraction analyses.