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Background
Dr. Buffin's graduate research focused on the measurement of hydrogen-bonding constants in metallocene catalyst systems and the oxidative destruction of environmentally important carbon-halogen bonds using Group 6 metal complexes. In 1990/91 he was a Senior Chemist in the trace metals department for the City of Kalamazoo. Dr. Buffin worked as a Senior Research Chemist, and later a Project Manager, in Research and Development for World Minerals, Inc. from 1993-1995. During his tenure in these positions he performed research on diatomaceous earth products for pharmaceutical/biotechnology processing and for use as functional fillers in the paint, coatings, paper, and plastic industries. Dr. Buffin joined the faculty at the University of Detroit Mercy as an Assistant Professor in 1995. He joined the faculty of Western Michigan University in 1999.
Research Focus
The majority of my research interests are focused in the area of water-soluble organometallic chemistry and the synthesis of novel organometallic complexes which could serve as catalysts in environmentally-benign processes.
The chemistry of water-soluble organometallic compounds has lately received increased interest due in part to potential applications in industrial-scale biphasic catalysis. Previous work by others in the field has been performed on a large variety of organometallic complexes, of which most contain some form of hydrophilic phosphine as an ancillary ligand for promotion of water solubility. Somewhat surprisingly, little work has been performed on using hydrophilic nitrogen-based ligands in aqueous organometallic chemistry. Our research examines the chemistry of transition metal complexes that contain amine and imine ligands with charged and polar substituents in order to ascertain the effect these ligands, which possess steric and electronic properties that differ from their phosphine counterparts, impart to organometallic complexes in aqueous media.
Specifically, our research involves the synthesis of potentially chelating nitrogen-based ligands that contain hydrophilic sulfonate, phosphonate, or carboxylate substituents. Initial studies have focused on the coordination chemistry of these ligands with low valent transition metal complexes, such as tungsten(0) and molybdenum(0) metal carbonyls, as a means of determining the thermodynamic and kinetic stability of this new class of hydrophilic ligand and respective metal complexes in aqueous media. Continuing research has focused on the formation of catalytically active late transition metal complexes. Very little information is available on the ability of nitrogen-based ligands to form water-soluble organometallic catalysts, and information generated by this research could lead to the development of more active and selective catalysts for use in environmentally-benign biphasic processes.
Techniques Employed
Students performing research in my group employ a variety of synthetic and instrumental techniques including vacuum-line and glovebox techniques for the manipulation of air- and moisture-sensitive compounds as well as multinuclear NMR, Fourier-transform Infrared (FT-IR), and UV/visible spectrometries, gas chromatography (GC), and HPLC.
Impact of Research
Dr. Buffin's research is expected to impact chemical processing as industries continue to move towards higher levels of responsibility in environmental stewardship. The elimination of organic solvents in manufacturing remains a priority of many firms and regulatory agencies, and Dr. Buffin's work may directly impact the development of feasible strategies.
Recent Results
More recent research is focused on the formation of late transition metal olefin complexes as depicted below. This research has recently been communicated (Pulication 5 below). In addition, we are now examining routes for the aerobic oxidation of alcohols using water as the only solvent and air as the sole oxidant. These results are currently in publication (#1 below).
Publications:
1) B.P. Buffin, J.P. Clarkson, N.L. Belitz, A. Kundu "Pd(II)-Biquinoline Catalyzed Aerobic Oxidation of Alcohols in Water" J. Mol. Catal. A: Chem. 2004, accepted August 2004.
2) B.P. Buffin, P.J. Squattrito, A.O. Ojewole "The pH Dependent Phase Transfer of an Organometallic Complex: Synthesis, Characterization, and Crystal Structure of a W(0) Tetracarbonyl with an Acidic Pyridine-Imine Ligand" Inorganic Chemistry Communications 2004, 7, 14-17.
3) B.P. Buffin, E.B. Fonger, A. Kundu "Palladium(II) and Platinum(II) Complexes Containing Hydrophilic Pyridinylimine-Based Ligands" Inorganica Chimica Acta 2003, 355, 340-346.
4) B.P. Buffin, A. Kundu "Synthesis, Characterization, and Crystal Structure of Platinum(II) and Palladium(II) Chlorides with an Acidic a-Diimine Ligand" Inorganic Chemistry Communications 2003, 6, 680-684.
5) B.P. Buffin, A. Kundu "Aqueous Organometallic Chemistry with Nitrogen Ligands: Synthesis of Hydrophilic Platinum(0) Olefin Complexes" Organometallics 2001, 20, 3635-3637.
6) B.P. Buffin, "Removal of Heavy Metals from Water: An Environmentally Significant Atomic Absorption Spectrometry Experiment" J. Chem. Ed. 1999, 76, 1678.
7) B.P. Buffin, A.M. Arif, T.G. Richmond, "Carbonyl Insertion and Reductive Elimination Chemistry of Tungsten(II) Alkoxides and Aryloxides" J. Chem. Soc., Chem. Commun. 1993, 1432.
8) B.P. Buffin, M.J. Poss, T.G. Richmond, "Synthesis and Reactivity of a W(0) Anion Stabilized by Chelating Tertiary Amines. The Oxidative Addition and Reductive Elimination of a Carbon-Tin Bond at Tungsten" Inorg. Chem. 1993, 32, 3805.
9) B.P. Buffin, T. G. Richmond, "Coordination Chemistry of Chelating Nitrogen Ligands with Tungsten Carbonyl Nitriles" Polyhedron 1990, 9(24), 2887.
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Research Group Department of Chemistry Western Michigan University
