9312053 Holmes University of Massachusetts - Amherst Dr. Robert R. Holmes, Chemistry Department, University of Massachusetts, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program for a US-Russia Cooperative Science Program with Dr. Rauza P. Arshinova, Kazan State Univ., Russia, to determine features which determine the properties of cyclic four- and five-coordinate silicon and five- and six-coordinate phosphorus compounds. New tri- and tetra-coordinate cyclic phosphorus and silicon compounds will be prepared by the Russian group. These will be used as precursors for five-coordinated cyclic derivatives to be synthesized by the Russian and US groups. These complexes will by studied by NMR spectroscopy and x-ray diffraction to determine ring conformational changes and ligand exchange phenomena. Theoretical calculations will be employed to model these processes and to understand the energetics of nucleophilic displacement reactions at phosphorus and silicon. Many reactions of phosphorus and silicon involve some reagent attacking a phosphorus or silicon compound to produce an intermediate containing all of the reacting species. This project will combine the expertise of a US and a Russian group to determine how these intermediates behave and what reaction pathways are open to them. The work will center particularly on reactions which are important in biochemical energy transfer processes.
