Experimental electron density distribution of molecular chlorine

Abstract

The electron density distribution of solid chlorine is determined from high resolution X-ray diffraction intensity measurements at 90 K. Deformation densities are calculated from the observed X-ray data and parameters obtained from a high order refinement of data with sin ϑ/λ > 0·65 Å^-1. Refinements including the population of multipole density functions are used to calculate model deformation densities and the asymmetry of the electric field gradient. Inclusion of third and fourth cumulant thermal parameters results in a significant improvement in the fit to the experimental data. The deformation density reveals a torus of non-bonding density at 0·31–0·37 e/ų encircling the Cl-Cl bond somewhat in the back of each of the Cl atoms. A double peak of 0·22 e/ų is found in the bonding region of the experimental deformation density similar to the bonding density found in S₈. This feature is not properly reproduced in density maps based on the atom-centred multipole functions. The calculated distribution of errors in the experimental densities is included.