The elements of Group Seven of the Periodic Table, including oxygen, sulfur, selenium and tellurium, are known as the chalcogens. This research project is concerned with the synthesis and properties of metal chalcogenides, especially compounds of metals with sulfur. Such compounds play important roles both in biological and industrial catalysis. Metal Sulfides constitute the active sites of a number of important enzymes and are the active ingredient in the industrially important hydrodesulfurization catalysts. This project is expected to enhance understanding of these important catalysts and lead to the design of more efficient catalysts. The goals of this project are to synthesize, structurally characterize and explore in detail the reactivities of specific metal- sulfur complexes. These complexes are expected to assist in our understanding of a) The structures and reactivity of the metal sulfur active sites in the industrially important hydrodesulfurization (HDS) reaction catalysts. b) The structures and reactivity of specific early transition metal sulfur complexes and c) The structures and reactivities of a new class of heteronuclear M/Fe/S clusters. Research in the first area of interest will place emphasis in the synthesis, structure and reactivity of the binary complex anions containing molybdenum and sulfur and ternary molybdenum/sulfur/oxygen anions. Heterometallic clusters will be obtained using the Mo/S(O)complex anions as ligands for divalent transition metal ions. The structures and reactivity of the new M/Mo/S(O) complexes will be studied in detail. The effectiveness of supported or unsupported Mo/S(O) and M/Mo/S(O) complexes as catalysts for the HDS of thiophene concerns the chemistry of Zr/S, Nb/S and Lanthanides/S complexes. These complexes are expected to display exceptional reactivity, and will serve as reagents for the synthesis of specific heterometallic clusters. Finally the ability of the Fe6S6L6 clusters to serve as ligands for coordinatively unsaturated organometallic fragments, will be utilized for the synthesis of hepta- and octametallic clusters with the MFe6S6 and M2Fe6S6 cores. The importance of these clusters as templates for the activation and reduction of small molecules will be evaluated.
