This award by the Inorganic, Bioinorganic, and Organometallic Chemistry Program supports the work of Professor Richard D. Adams at the University of South Carolina to design, synthesize, and characterize new, unsaturated heterometallic complexes for the reversible activation of hydrogen. The exceptionally-active targeted complexes contain platinum or palladium and highly sterically crowded phosphine ligands to induce electronic saturation and reversible hydrogen bonding. This hydrogen activation occurs at mild temperatures and may be important in hydrogen storage as well as in catalytic hydrogenation reactions for the chemical industry. The generation and utilization of hydrogen as an alternative fuel is of growing importance in the emerging hydrogen economy. As Professor Adams contributes rare expertise in both the synthesis and characterization new materials, the graduate and postdoctoral students in his group will gain unique, relevant, and highly valuable learning experiences.
Iridium, rhenium and tin are important metals that have been shown to produce substantial improvements in the catalytic activity of platinum when used for petroleum reforming reactions. Petroleum reforming reactions are used to raise the "octane" rating of gasolines in order to improve performance and increase mileage. All gasolines are treated with these catalysts before they are sold to the consumer. Our research has been focused on the preparation new bi- and multimetallic catalysts by using bi- and multimetallic complexes as catalyst precursors. The procedure involves first the chemical synthesis and characterization of new bi- and multimetallic complexes from suitable starting materials. The composition and structures of these new multimetallic complexes are determined by us by single-crystal x-ray diffraction techniques and suitable spectroscopic methods. Some of these complexes have been investigated for their reactivity toward hydrogen and hydrocarbons. Selected complexes are then placed on metal oxide supports by evaporation of solutions containing slurries of the finely divided catalyst supports. Next the supported complexes are converted to multimetallic nanoparticles on the supports by removing their ligands by heating under a vacuum. This treatment usually results in the formation of multimetallic nanoparticles on the support that are ready for catalytic testing. The catalytic tests are performed by research collaborators who have the specialized equipment for these tests. Over the last year, our research team has prepared and characterized a number of new polynuclear iridium-tin, iridium-germanium and iridium-germanium-platinum complexes and also some new rhenium-antimony, rhenium-antimony-platinum and the first examples of rhenium-bismuth and rhenium-bismuth-platinum complexes. The compounds have been found to have bonds directly between all of them metal atoms. They also exhibit novel structures and chemical properties. The catalytic activity of the iridium complexes has not yet been tested. Some of the rhenium-bismuth complexes have been shown to exhibit good catalytic activity for the conversion of 3-methylpyridine to 3-cyanopyridine by the process known as ammoxidation. The ammoxidation reaction converts methyl groups into cyano groups. 3-cyanopyridine can be hydrolyzed to the compounds known as nicotinamide and niacin by reactions with water. Niacin is a valuable human dietary supplement that is also known as vitamin B3. The nutrition industry is in need of more efficient new methods for making this life essential compound.
