This award in the Inorganic, Bioinorganic, and Organometallic Chemistry Program will continue support to Dr. Richard H. Holm of the Chemistry Department, Harvard University, for research in the area of bioinorganic chemistry. Three systems will be investigated: oxygen atom transfer chemistry of molybdenum and tungsten dithiolenes, which is related to the behavior of molybdenum enzymes; hydrogen evolution from reduced nickel and formation of thioesters from nickel-acyls and thiols, which are studies relevant to the behavior of hydrogenase and carbon monoxide dehydrogenase; and binuclear iron-copper bridged molecular assemblies related to the binuclear sites of heme-copper oxidases. Kinetics and other aspects of these processes will be examined to provide descriptions of reaction pathways that may be feasible in enzymatic reactions. In addition, low-temperature syntheses of metal clusters containing chalcogenides or chalcohalides will be developed. Enzymatic reactions provide rapid low-energy routes to reactions important not only in biological systems, but also in synthesis of important organic and inorganic chemicals. By investigating the detailed mechanism of fundamental reactions involving oxygen atom transfer, oxidation-reduction, and hydrogen transfer, Dr. Holm may elucidate spatial and steric requirements useful for the development of new synthetic routes, as well as increase understanding of biological action
