The use of a cis-dioxomolybdenum(VI) dinuclear complex with quadradentate 1,4-benzenediylbis(benzyldithiocarbamate)(2−) as model compound for the active site of oxo transfer molybdoenzymes: Reactivity, kinetics, and catalysis

摘要: Abstract Dinuclear cis -dioxomolybdenum(VI) complex [{MoO 2 (Bz Benzenediyldtc)} ] coordinated by a quadradentate dithiocarbamate Benzenediyldtc 2−  = 1,4-benzenediylbis(benzyldithiocarbamate)(2−)) has been prepared and characterized elemental analysis, 13 C NMR, IR UV–vis spectroscopy. The kinetics of the oxygen atom transfer between PPh 3 was studied spectrophotometrically in CH Cl medium at 520 nm four different temperatures, 288, 293, 298 303 K, respectively. reaction follows second order with rate constant k  = 0.163(2) M −1  S its increasingly strong absorption clearly indicate formation μ-oxo molybdenum(V) species as product. Despite steric restrictions imposed ligand structure to prevent Mo(V) species, experimental evidence confirms interference during process. product can then be formulated [MoO Benzenediyldtc) Mo O MoO which one μ-oxomolybdenum(V) moiety. An Eyring plot allows activation parameters Δ H ‡  = 64.2(1) kJ mol S  = −45.1(6) J K  mol determined from temperature dependence constant, suggesting an associative transition state for oxo reaction. Catalytic DMSO also followed monitoring chemical shift changes 31 P NMR substrate oxidation process well-defined catalytic cycle capable 100% conversion without intervention about 36 h.