NIU Department of
Chemistry & Biochemistry
Where the study of matter...matters!
Visiting Research Associate, H. C. Ørsted Institute, Copenhagen, 1974-1975
Research Fellow, California Institute of Tehcnology, 1966-1967
Ph.D., Emory University, 1966
M.S., Emory University, 1966
B.S., Emory University, 1963
Electronic structure and spectra of heavy metal complexes; electronic and magnetic circular dichroism spectroscopy; symmetry and MO theory.
Mason authored a new book, Magnetic Circular Dichroism Spectroscopy, July 2007.
Magnetic Circular Dichroism Spectroscopy. Mason, W.R. (2007) John Wiley & Sons, Inc., New Jersey.
Magnetic circular dichroism. Mason, W. R. In Comprehensive Coordination Chemistry II: From Biology to Nanotechnology; McCleverty, J. A., Meyer, T. J., (2004) Eds.; Volume 2; Section 1.71; Oxford: Elsevier.
Electronic absorption and magnetic circular dichroism spectra for the linear two-coordinate bis(tri-tert-butyl- phosphine)platinum(0) complex in 2-methylpentane at 295 and 80 K. Mason, W. R. (2001) Inorg. Chem., 40: 6316-6319.
Magnetic circular dichroism spectra for colloidal gold nanoparticles in xerogels at 5.5 K. Zaitoun, M. A.; Mason, W. R.; Lin, C. T. (2001) J. Phys. Chem. B, 105: 6780-6784.
Electronic absorption and MCD spectra for Pt(AuPPh3)82+ and Au(AuPPh3)83+ cluster complexes in poly(methyl methacrylate) thin films at 295 and 10 K. Mason, W. R. (2000) Inorg. Chem., 39: 370-374.
Electronic absorption and MCD spectra for BiX63- (X = Cl-, Br-, and I-) in acetonitrile solution: Metal-centered vs. ligand-to-metal charge-transfer assignments. Mason, W. R. (1999) Inorg. Chem., 38: 2742-2745.
Our group's interest is coordination chemistry, particularly of complexes of platinum and coinage metals and the heavy atoms of the p block. The focus of our research, apart from the synthesis and characterization of new complexes, is in the area of electronic structure and spectra.
The experimental study of electronic structure derives mainly from electronic spectroscopy in the visible and ultraviolet region. Spectroscopic data is obtained from the analysis of high resolution absorption spectra obtained at cryogenic temperatures (1.5-20 K), magnetic circular dichroism (MCD) spectra, and polarized spectra of oriented single crystals. A high resolution MCD spectrometer has been constructed in our laboratory (see Anal. Chem. 1982, 54, 646). The spectrometer is computer controlled and features an 8/9 tesla split coil superconducting magnet, with a low-temperature sample tube.
MCD spectrum for Pt[P(t-Bu)3]2 in acetonitrile.
Electronic structural models are constructed from comparative spectral data and are described in terms of molecular orbital theory which includes perturbations due to heavy atom spin-orbit coupling and electron repulsions. Complexes of several structural types, including mononuclear octahedral six coordinate, tetrahedral four coordinate and linear two coordinate complexes, are currently being investigated. We are also investigating certain binuclear and polynuclear cluster complexes of platinum and gold which feature short metal-metal distances and strong intermetallic interaction.
Emphasis recently has been on the characterization and detailed interpretation of charge-transfer spectra of the metal-to-ligand (MLCT) and ligand-to-metal (LMCT) type in mononuclear complexes and intramolecular metal centered transitions in binuclear and cluster complexes. The goal of our studies is to increase the detail with which the electronic origins of metal-ligand bonding and metal-metal interaction are described and to characterize low-energy excited states in heavy metal complexes, especially those of low coordination number.
