Franklin A. Schultz, Ph.D.

Research

The principal objective of our research is to understand relationships between molecular structure and electron transfer reactivity of transition metal compounds. The work has two directions. The first seeks to obtain a detailed understanding of the molecular features which control the rates and spontaneities of electron transfer reactions. To achieve this goal, we measure rates and activation parameters using electrochemical techniques and correlate findings with structural data and the results of chemical calculations. A significant conclusion is that, because electronic and nuclear motions are highly correlated, displacements of atomic nuclei constitute the largest barrier to electron transfer. This imparts important consequences to the coupling of electron transfer and structural change. Currently, we are investigating compounds characterized by large amounts of electron transfer-initiated structural reorganization and the manner in which the charge transfer event is correlated with changes in vibrational frequencies, solvent organization, ionic association, and metal atom spin state. Structural control of electron transfer is important in the function of biological redox systems and in the construction of molecular devices.

A second line of research involves electrochemical investigation of compounds that model the active sites of molybdenum-containing enzymes. There are two families of such enzymes. One contains high-valent, mononuclear oxo molybdenum centers that metabolize toxins in mammalian systems. A second contains a polynuclear Fe, Mo and S cluster that catalyzes the reduction of dinitrogen (N2) to ammonia, a process known as nitrogen fixation. A common feature of both enzyme classes is their ability to transfer more than one electron at a time. We have pursued understanding of this behavior through investigations of model systems and have identified examples in which processes such as protonation or changes in metal coordination promote multielectron transfer. A more subtle explanation may be operative in nitrogen fixation. Currently, we are conducting studies of binuclear, ligand-bridged complexes that model this important biological reaction. The compounds undergo two-electron transfer in a single step that is accompanied by reversible cleavage of a metal-metal bond. We seek to understand the molecular features that produce this behavior and to understand the energetics of multielectron transfer through a series of synthetic and electrochemical studies.

Education

• B.S., California Institute of Technology, 1963
• Ph.D., University of California, Riverside, 1967

Publications & Professional Activity

F. Hossain, M. A. Rigsby, C. T. Duncan, P. L. Milligan, Jr., R. L. Lord, M.-H. Baik and F. A. Schultz "Synthesis, structure, and properties of low-spin manganese(III)-poly(pyrazolyl)borate complexes" Inorg. Chem. 2007, 46, in press.

F. A. Schultz, C. T. Duncan and M. A. Risgby "Electrochemistry of the group 7 elements: manganese, technetium, and rhenium" in: The Encyclopedia of Electrochemistry, Volume 7b, Inorganic Electrochemistry; A. J. Bard, M Stratman, F. Scholz and C. J. Pickett, Eds.: Wiley-VCH, Weinheim, 2006, pp 399-460.

J. R. Sheets and F. A. Schultz "Coupled electron-transfer and spin- exchange reactions of metal-bis[(tris)pyrazolyl)methane complexes" Polyhedron 2004, 23, 1037-1043.

D. Uhrhammer and F. A. Schultz "Modulation of molybdenum-centered redox potentials and electron transfer rates by sulfur versus oxygen ligation" Inorg. Chem. 2004, 43, 7389-7395.

D. C. L. De Alwis and F. A. Schultz "Metal-bis[poly(pyrazolyl)borate] complexes. electrochemical, magnetic, and spectroscopic properties and coupled electron-transfer and spin exchange reactions" Inorg. Chem. 2003, 42, 3616-3622.

A.-K. Duhme-Klair, D. C. L. De Alwis and F. A. Schultz "Electrochemistry of molybdenum(VI)-catecholamide siderophore complexes in aqueous solution" Inorg. Chim. Acta 2003, 351, 150-158.

D. Uhrhammer and F. A. Schultz "Energetics of concerted two-electron transfer and metal-metal bond cleavage in phosphido-bridged molybdenum and tungsten carbonyl complexes" J. Phys. Chem. A 2002, 106, 11630-11636.

J. W. Turner and F. A. Schultz "Electrochemical activation parameters of coupled electron-transfer and spin-exchange reactions. Experimental studies of [M(Tacn)2]3+/2+ and [Fe(Pzb)2]+/0 redox systems" J. Phys. Chem. B, 2002, 106, 2009-2017.

J. W. Turner and F. A. Schultz "Coupled electron-transfer and spin- exchange reactions" Coord. Chem. Rev. 2001, 219-221, 81-97.

J. W. Turner and F. A. Schultz "Solution characterization of the iron (II) bis(1,4,7-triazacyclononane) spin-equilibrium reaction" Inorg. Chem. 2001, 40, 5296-5298.

J. U. Mondal, J. G. Zamora, M. D. Kinon and F. A. Schultz "Six- coordinate monooxo molybdenum(VI) complexes with catecholate and salicylaldelyde thiosemicarbazone ligands" Inorg. Chim. Acta 2000, 309, 147-150.

Awards

• Distinguished Teacher of the Year, 1980, and C.G. Saltarelli Sigma Xi Research Award, 1986, Florida Atlantic University
• Treasurer, Society for Electroanalytical Chemistry, 1988-94
• Chairman, Division of Organic and Biological Electrochemistry, The Electrochemical Society, 1997-99
• School of Science Research Award, 1998.