9414242 Angelici Iowa State Univ. Dr. Robert J. Angelici, Chemistry Department, Iowa State University, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division for research into thermochemical and reactivity studies of basic transition metal complexes. A major goal of this project is to quantitatively determine the factors which determine the basicity, or "electron richness", of metal centers in metal-hydride complexes. The calorimetrically determined enthalpies of protonation will be measured for a series of mononuclear complexes of chromium, tungsten, rhenium, iron, ruthenium, osmium, cobalt rhodium, and iridium in order to establish contributions of the metal and its ligands to the basicities of the complexes. These enthalpies will be combined with electrochemical oxidation potentials to give bond dissociation energies. The studies will be extended to polynuclear complexes. Many transition metal hydride complexes are catalysts for a variety of industrial and laboratory processes. The activity of these catalysts is related to the ease with which the hydrogen can move from metal to a reactant species. However, there is very little quantitative information available on the factors which determine the strength of the interaction between a metal and a hydrogen atom. In this project the metal-hydrogen bond strengths will be determined for a range of metal complexes. These studies will provide a basis for understanding a broad range of reactivities of transition metal complexes and catalysts.
