Oxidation-Reduction Mechanisms

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Dr. Henry Taube, Chemistry Department, Stanford University, supported by an award from the Inorganic, Bioinorganic, and Organometallic Program, will conduct research in three areas. First, he will study vanadium complexes in non-aqueous solvents. The effects of back-bonding on the chemistry of V(II) will be explored using acetonitrile as a solvent, but some effort will also be devoted to characterizing the higher oxidation states of vanadium and generating higher oxidation state species by aerobic oxidation. The second area is the study of mixed valence molecules. Here work on molecular hysteresis will continue. In specific systems in which electron transfer is accompanied by structural change, light of energy corresponding to that of the mixed valence band will be used to convert one isomeric form to the other and determine the efficiency of the conversion. Also, molecules based on aromatic poly-ring systems with osmiumammines bound in the eta-2, -4 or -6 modes will be investigated. Linkage isomerism in mixed valence molecules based on simple derivatives of benzene will be studied. In the third area, the mechanism of activation for substitution on a ligand by a co-ligand which is an oxidizing agent will be explored. The particular system will involve cyclopentadienone bound to Ru(II), the effect of which on the rate of substitution of co-ligand cyclopentadienide has been measured. %%% These fundamental studies involve electron transfer and substitution reactions of transition metal complexes of vanadium, ruthenium and osmium. The results of these studies are relevant to the mechanism of action of catalysts for organic reactions and to conversion of solar to electrical energy.