SUBSTITUTION REACTIONS OF INORGANIC COMPLEXES . CONCERNING PREDICTION OF ACTIVATION ENERGIES AND REACTION MECHANISMS BY CRYSTAL FIELD THEORY

The substitution reactions of octahedral or nearly octahedral inorganic complexes are briefly reviewed. If it is assumed that the observed activation energies for these reactions depend primarily upon the energy required for the particular complex to proceed to an intermediate of either enhanced or reduced coordination, then these observed activation energies may be compared to calculated crystal field stabilization energies (CFSE) for various geometries to see which model best fits the experimental data. The results of these calculations for a number of d3 and d6 systems indicate that a model with enhanced coordination number (CN) and C2v symmetry fits the data best for Cr(III) complexes while a model with reduced CN and C4v symmetry fits the data for Co(III) complexes best. Of course this analysis does not prove what the nature of the intermediate is in a particular case because many important factors have been omitted, but the results strongly suggest that the observed activation energies depend upon the CFSE in the fundamental way shown and that data available can be rationalized with one simple model. © 1968, American Chemical Society. All rights reserved.