DuBois, Daniel L., Tegan J. Craig, Karen A. Brooks, Arlan D. Norman. PHOSPHONIUM-SUBSTITUTED QUINONES AND ORGANOMETALLIC COMPLEXES DESIGNED FOR USE IN IONIC LIQUIDS
Basic Sciences Center, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401-3393 (dan_dubois@nrel.gov)
The design of ligands to improve the solubility of organometallic compounds in water, fluorocarbons, or CO2 has significantly advanced our understanding of catalytic reactions in these solvents. Ionic liquids have been proposed as green solvents because of their relatively low toxicity and low vapor pressures. In this presentation, we describe the synthesis of quinones and organometallic compounds modified with phosphonium substituents to enhance their solubility in ionic liquids. These substituents also provide a useful 31P NMR probe for studies in nondeuterated ionic liquids. Reactions of triphenylphosphine or tri(n-butyl)phosphine with benzoquinone result in betaines which contain phosphonium substituents attached to the quinone ring. Structural, spectroscopic, and electrochemical characterization of these compounds will be described. Similarly, the preparation and characterization of phosphine ligands with pendant phosphonium substituents and some metal complexes will be described.