all other cases of substrate reduction by oxo transfer, the kinetic metal effect k(2)W > k(2)Mo holds. A proposal from primary sequence alignments suggesting that a conserved Asp residue is a likely ligand in the type II enzymes in the DMSO reductase family has been pursued by synthesis of the [Mo(IV)(O2CR)(S2C2Me2)2](1-) (R = Ph, Bu(t)) complexes. The species display symmetrical eta2-carboxylate binding
使用Mo(IV)的双(二
硫代
戊二烯)络合物开发了
硒酸还原酶的模拟反应系统,该系统可减少整个酶促反应SeO4(2-)+ 2H + + 2e--> SeO3(2-)+
H2O中的底物。和W(IV)。根据
氧化和还原酶的EXAFS分析结果,极有可能发生Mo(IV)OH + SeO4(2-)-> Mo(VI)O(OH)+ SeO3(2-)的最小反应。制备方形
金字塔状复合物[M(OMe)(
S2C2Me2)2](1-)(M = Mo,W)作为还原酶位点的结构类似物。
乙腈中的[ML(
S2C2Me2)2](1-)/ SeO4(2-)(L = OMe,OPh,SC6H2-
2,4,6-Pr(i)3)系统干净地将
硒酸还原为
亚硒酸盐活化反应的负熵暗示缔合过渡态的二阶反应。298 K时的速率常数在10(-2)-10(-4)M(-1)s(-1)范围内,DeltaS ++ = -12至-34 eu。当将速率常数与通过
氧原