Papers by Adam Tenderholt
Sulfur K-Edge X-ray Absorption Spectroscopy and Density Functional Calculations on Mo(IV) and Mo(VI)═O Bis-dithiolenes: Insights into the Mechanism of Oxo Transfer in DMSO Reductase and Related Functional Analogues
Sulfur K-edge X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculation... more Sulfur K-edge X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations have been used to determine the electronic structures of two Mo bis-dithiolene complexes, [Mo(OSi)(bdt)2]1− and [MoO(OSi)(bdt)2]1−, where OSi = [OSiPh2tBu]1− and bdt = benzene-1,2-dithiolate(2−), that model the Mo(IV) and Mo(VI)═O states of the DMSO reductase family of molybdenum enzymes. These results show that the Mo(IV) complex undergoes metal-based oxidation unlike Mo tris-dithiolene complexes, indicating that the dithiolene ligands are behaving innocently. Experimentally validated calculations have been extended to model the oxo transfer reaction coordinate using dimethylsulfoxide (DMSO) as a substrate. The reaction proceeds through a transition state (TS1) to an intermediate with DMSO weakly bound, followed by a subsequent transition state (TS2) which is the largest barrier of the reaction. The factors that control the energies of these transition states, the nature of the oxo transfer process, and the role of the dithiolene ligand are discussed.
Electronic Control of the "Bailar Twist" in Formally d0-d2 Molybdenum Tris(dithiolene) Complexes: A Sulfur K-edge X-ray Absorption Spectroscopy and Density Functional Theory Study
X-Ray Absorption Fine …, Jan 1, 2007
PySpline is a modern computer program for processing raw averaged XAS and EXAFS data using an int... more PySpline is a modern computer program for processing raw averaged XAS and EXAFS data using an intuitive approach which allows the user to see the immediate effect of various processing parameters on the resulting k-and Rspace data. The Python scripting language and Qt and Qwt widget libraries were chosen to meet the design requirement that it be cross-platform (i.e. versions for Windows, Mac OS X, and Linux). PySpline supports polynomial pre-and post-edge background subtraction, splining of the EXAFS region with a multi-segment polynomial spline, and Fast Fourier Transform (FFT) of the resulting k 3 -weighted EXAFS data.
Journal of inorganic …, Jan 1, 2007
Molybdenum-or tungsten-containing enzymes catalyze oxygen atom transfer reactions involved in car... more Molybdenum-or tungsten-containing enzymes catalyze oxygen atom transfer reactions involved in carbon, sulfur, or nitrogen metabolism. It has been observed that reduction potentials and oxygen atom transfer rates are different for W relative to Mo enzymes and the isostructural Mo/W complexes. Sulfur K-edge X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations on [Mo V O(bdt) 2 ] À and [W V O(bdt) 2 ] À , where bdt = benzene-1,2-dithiolate(2-), have been used to determine that the energies of the halffilled redox-active orbital, and thus the reduction potentials and M@O bond strengths, are different for these complexes due to relativistic effects in the W sites.
Angewandte …, Jan 1, 2008
Comparative molecular chemistry of molybdenum and tungsten and its relation to hydroxylase and oxotransferase enzymes
Coordination Chemistry …, Jan 1, 2010
The similarities and differences in the fundamental coordination chemistry of molybdenum and tung... more The similarities and differences in the fundamental coordination chemistry of molybdenum and tungsten mainly in physiological oxidation states MIV–VI are examined in relation to the properties of enzyme sites that catalyze oxygen atom transfer reactions. The comparative aspects of dithiolene complexes, which as synthetic analogues simulate structural and electronic features of these sites, are emphasized. Analogue reaction systems of enzymes
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Papers by Adam Tenderholt