This project in the Inorganic, Bioinorganic, and Organometallic Program is in the area of organosilicon chemistry. In addition to advancing knowledge of metal-mediated reactions of organosilicon compounds, the results of the project are expected to be useful in the synthesis of new silicon-containing advanced materials. New classes of transition metal complexes of organosilicon ligands will be synthesized by a variety of methods, emphasizing compounds which will serve as models of postulated catalytic intermediates, or which should exhibit new reaction chemistry. New synthetic routes to silicon-substituted metal-silyls and -disilyls will be developed which employ silylene transfer reactions from hexamethysilacyclopropane, cyclo-Si6Me12, and cyclo-Si3R6. Synthetic transformations involving metal-initiated silylene transfer as well as free silylenes will be explored. The conversion of substituted silyls and disilyls to silene, disilene, and metallacyclic complexes will then be studied. Structural and spectroscopic techniques will be used to determine the extent of pi-bonding in the silaolefin complexes. Insertion and ring-expansion reactions of silene and disilene complexes will be examined, and the photolytic dissociation of free silaolefins from the complexes will be attempted. Silylidene or silylenoid intermediates, generated from substituted silyls or free silylenes, will be trapped as silametallacycles with olefins and alkynes. Finally, mechanistic studies of silylene insertion reactions will focus on (1) silylene extrusion (independent of metal substrates), (2) the role of Lewis bases on silylene generation and reactivity, (3) the interactions of dimethylsilylene with metal substrates.
