This award from the Chemistry Research Instrumentation Program will assist the Department of Chemistry at the University of Pennsylvania in the purchase of an x-ray diffractometer and associated data collection and analysis system and an upgrade of an older x-ray diffractometer. This new instrument will enhance greatly research in a number of areas including the following: 1) Transition metal complexes of organosilicon compounds: New structures and catalysts, 2) Catalytic dehydrogenative coupling of alkylsilanes to carbosilanes, 3) Natural product structure determination, synthesis and organic photochemistry: Hitachimycin (a.k.a. Stubomycin), a novel antitumor agent, 4) Bioorganic chemistry: Non-peptidal peptidomimetics, 5) Materials chemistry and inorganic catalysis: New polymeric precursors to boron-based ceramics, 6) Ferroelectric metal-oxo polymers and metal-insulator transitions in metal-oxo polymers, 7) Organometallic reactivity of metallomacrocyclic complexes, 8) Strategies for synthesis of anti-tumor compounds. %%% The x-ray diffractometer is used to make accurate and precise measurements of the full three-dimensional structure of a molecule. The information obtained gives the precise values of all the bond distances and bond angles of a given molecule and it gives accurate information about the spatial arrangement of that molecule relative to the neighboring molecules.