This award from the Chemistry Research Instrumentation Program will help the Department of Chemistry at Georgetown University acquire an entire new integrated single crystal x-ray diffractometer and structure analysis system, with rotating anode generator and low temperature capabilitities. Among the areas of chemical research that will be enhanced by the acquisition are the following: 1. The Bioinorganic Chemistry of Oxo-Bridged Dinuclear Iron Proteins 2. Structural Investigations in Heteropolyanion Chemistry 3. New Categories of Heteropoly Complexes and New Insights 4. Structure and Reactions of Novel Nitrones and Their Metal Complexes 5. Mixed-Valence Ruthenium Dimers Involving Less-Effective Cross-Bridge Electronic Interaction 6. Orientation-Dependent Chemistry on Molecular Crystal Surface 7. Sterochemical Control of Vitamin B-12 Functionality 8. Chiral Columns and Channels from Discotic Mesophases 9. Magneto-Structural Correlations in Di- and Trinuclear Imidazolate-Bridged Complexes of First-Row Transition Metals %%% Single crystal x-ray crystallography is the most powerful analytical method for structure determination of solids. In synthetic inorganic, organic, bioinorganic and organometallic chemistry, single crystal x-ray diffraction is an invaluable tool to characterize molecular structure. The information gained from the knowledge of the intermolecular composition and structure helps to develop new reactions of potentially general interest in catalysis or organic synthesis.