This award in the Inorganic, Bioinorganic and Organometallic Chemistry Program supports research by Professor Karl O. Christe of the Department of Chemistry of the University of Southern California to synthesize previously unknown high-valent, high coordination number complexes with oxygen and fluorine ligands. These compounds are of fundamental importance in rounding out our understanding of high-energy fluorine compounds. Theoretical ab initio calculations will done along with the experimental work to analyze bonding relationships throughout entire families of fluorine complexes. A final objective is to re-examine a complex apparently containing an unusual Xe-B bond. Joining theory with careful physical characterization, particularly by x-ray crystallography, will lead to a better fundamental understanding of high-energy fluorine molecules, which are at the very limits of coordination and chemical bond formation.