Selectivity of Thiolate Ligand and Preference of Substrate in Model Reactions of Dissimilatory Nitrate Reductase

摘要: Complexes analogous to the active site of dissimilatory nitrate reductase from Desulfovibrio desulfuricans are synthesized. The hexacoordinated complexes [PPh4][MoIV(PPh3)(SR)(mnt)2] (R = −CH2CH3 (1), −CH2Ph (2)) released PPh3 in solution generate model cofactor, {MoIV(SR)(mnt)2}1−, ready with a for binding. Kinetics reduction by 1 and 2 followed Michaelis−Menten saturation kinetics faster rate case (VMax 3.2 × 10−2 s−1, KM 2.3 10−4 M) than that reported earlier 4.2 10−3 4.3 (Majumdar, A., Pal, K., Sarkar, S. J. Am. Chem. Soc. 2006, 128, 4196–4197). oxidized molybdenum species may be reduced back starting complex, catalytic cycle involving [Bu4N][NO3] as oxidizing reducing substrates, respectively, is established 2. Isostructural complexes, [Et4N][MoIV(PPh3)(X)(mnt)2] (X −Br (3), −I (4)) did not show any reductive activity towa...