This award from the Inorganic, Bioinorganic and Organometallic Chemistry Program is in the general area of organometallic chemistry. The research is concerned with the planned synthesis of new types of stacked organometallic complexes (multiligand sandwich compounds) and metal-boron-carbon clusters. Such extended sandwich systems in which electrons are delocalized over a large number of atoms are of interest as potential precursors to novel low-dimensional electrical conductors or semiconductors wherein the current flows only parallel to the chain. An important aim of the research is to discover new materials with unusual electronic properties. The principal building blocks which will be used to synthesize new extended sandwich systems are carboranes, paramagnetic transition metal ions, and polycyclic arenes. These will be combined in complexes having two or more metal centers and designed to favor delocalization of electrons between the metals. The new complexes will be characterized by multinuclear NMR, infrared, electron spin resonance and mass spectroscopy, as well as by X-ray crystallography, where feasible. Detailed electrochemical studies will be conducted on several families of these compounds. Small carborane ligands will be combined with diborolene units to create novel mixed-ligand sandwich species which may be used to construct large multilevel sandwich systems of a novel type, and which also may undergo oxidative ligand fusion to generate new classes of carbon-rich carboranes. Attempts will be made to also synthesize (carborane)metal(metallacycle) and (carborane)metal(borazine) complexes, types of compounds which are presently unknown, and to attempt linkage or fusion between the ligands.
