Reactivity of neutral Mo(S2C6H4)3 in aqueous media: an alternative functional model of sulfite oxidase.
The kinetics of the reaction of neutral [Mo(S2C6H4)3] with hydrogen sulfite to produce the anionic Mo(V) complex, [Mo(S2C6H4)3]-, and sulfate have been investigated. It has been shown that [Mo(S2C6H4)3] acts as the electron-proton sink in the oxygenation reaction of HSO3(-) by water. Reaction rates, monitored by UV/vis stopped-flow spectrometry, were studied in THF/water media as a function of the concentration of HSO3(-) and molybdenum complex, pH, ionic strength, and temperature. The reaction exhibits pH-dependent HSO3(-) saturation kinetics, and it is first-order in complex concentration. The kinetic data and MS-ESI spectra are consistent with the formation of [Mo O(S2C6H4)2(S2C6H5)]- (1) adduct as a crucial intermediate that transfers the oxygen atom to HSO3(-) yielding the Mo(V) species quantitatively.
Pérez Pla
Francisco
F
Instituto de Ciencia de Materiales de la Universidad de Valencia, P.O. Box 2085, Poligono La Coma, Paterna, Valencia, Spain. francisco.perez@uv.es
Cervilla
Antonio
A
Piles
María
M
Llopis
Elisa
E
D005663:Furans / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D050876:Sulfite Oxidase / Q000737:chemistry / Q000378:metabolism; D013447:Sulfites / Q000737:chemistry; D014867:Water / Q000737:chemistry
D005663:Furans; D009942:Organometallic Compounds; D013438:Sulfhydryl Compounds; D013447:Sulfites; D014867:Water; C018674:tetrahydrofuran; D008982:Molybdenum; D050876:Sulfite Oxidase; C042345:hydrogen sulfite