Howard Research Interests

Basic Coordination Chemistry of Rhodium

The coordination chemistry of any transition metal seems to be a complicated function that involves numerous variables.  It may be very difficult, if not impossible at times, to predict accurately the outcome of a chemical reaction, and researchers often report surprising reactions in the scientific literature.  Understanding and predicting the results of reactions involving transition metals is an ultimate goal in inorganic chemistry.

Rhodium is probably one of the most important transition metals for industrial catalysis applications, and understanding the coordination chemistry of rhodium is essential.  Much is already known.  For instance, the rhodium center is a soft Lewis acid that usually binds soft bases such as phosphines and thiolates very tightly.  Rhodium(III) complexes are nearly always six-coordinate, octahedral compounds with an 18-electron configuration, while rhodium(I) complexes are typically four-coordinate, square planar compounds with a 16-electron configuration.  It seems as though the geometries of most rhodium complexes depend directly on the crystal field stabilization energies, although there are some exceptions. 

We are interested in preparing new kinds of rhodium complexes in order to learn more of the chemistry of this metal.  We are also interested in developing quantitative relationships between the properties of rhodium complexes and important chemical parameters such as valence, electron count, and ligand bond number.


Relevant Publication

"Mer-[MCl3(Me2pzH)3] (M = Rh, Ir; Me2pzH = 3,5-Dimethylpyrazole):  X-Ray Structures, Spectroscopic Properties, and Density Functional Theory (DFT) Calculations."  Cushing, G. W.; Howard, W. A.; Pang, K.  J. Mol. Struct. 2006, In Press.

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