The Determination of Electron Density Distributions in Organometallic Compounds — Recent Experimental Results

Abstract

Knowledge of the electron density distribution in molecules provides direct access to information concerning the chemical bonding. This is based on the Hellmann-Feynman theorem which states that from the charge density, the forces on atomic nuclei can be derived by classical electrostatics. For a stable atomic arrangement, these forces must be zero. During recent years theoretical as well as experimental procedures have been developed which directly reproduce the changes in electron density as a result from the redistribution of the valence electrons of spherical atoms (pro-molecule) during formation of chemical bonds. Both procedures, theoretical computations as well as experimental investigations by X-X or X-N methods, give identical results in most cases. A short introduction to the present-day experimental procedures (1 a-d) of deriving deformation densities is illustrated using t-Butyl-Anthracene (1a, 2) (Fig. l) and Cyclopropane (3) (Fig.2) as examples.