Part I: Xanthine oxidase family is a group of molybdenum-containing enzymes that catalyze the transfer of an oxygen atom from water to a substrate. Density functional theory calculations have been carried out on the intrinsic mechanism at molybdenum cofactor (Moco) active site and the mechanism involving the near-by glutamic acid (Glu) residue for the oxidation of several model substrates. It is found that the Glu residue can serve as a proton shuttle, activating the OH group by deprotonation and activating the substrate by protonation. As a result, it significantly increases the reactivity of the cofactor....[ Read more ]

Part I: Xanthine oxidase family is a group of molybdenum-containing enzymes that catalyze the transfer of an oxygen atom from water to a substrate. Density functional theory calculations have been carried out on the intrinsic mechanism at molybdenum cofactor (Moco) active site and the mechanism involving the near-by glutamic acid (Glu) residue for the oxidation of several model substrates. It is found that the Glu residue can serve as a proton shuttle, activating the OH group by deprotonation and activating the substrate by protonation. As a result, it significantly increases the reactivity of the cofactor.

Part II: Recently, the Tobita group reported stoichiometric hydrosilylation reactions of acetone and acetonitrile with a neutral hydrido(hydrosilylene)tungsten complexes The mechanism of the hydrosilylation reactions of unsaturated compounds (ketone, aldehyde and nitrile) with the tungsten complexes have been investigated with the B3LYP density functional theory method. The results indicate that the hydrosilylation of acetone proceeds via a metal hydride migration mechanism proposed by Tobita et al., while the hydrosilylation of nitrile occurs through a silyl migration mechanism. We also predict that hydrosilylation of acetonitriles and acetone catalyzed by the tungsten complexes is difficult to achieve

Part III: Reactions of d⁰ amides M(NMe₂)₄ (M = Zr, 1; Hf, 2), Ta(NMe₂)₅ and Bis(alkylidene) W complex with O₂ have been found to yield unusual complexes. Density functional theory calculations have been performed to explore the mechanistic pathways in the reactions of model metal complexes with triplet O₂.

Part IV: The photochemistry of gas-phase complexes, Mg^•+(2-fluoropyridine), Mg^•+(2,6-difluoropyridine) and Mg^•+(pentafluoropyridine) and a series of Mg^•+(fluorobenzene) complexes has been studied in the spectral range of ~230-440 nm with a molecular beam coupled with a time-of-flight mass spectrometer. Surprisingly rich chemistry has been observed. Plausible photoreaction mechanisms have been proposed and studied with DFT calculations.