The formation of transient metal hydride(s) at the metallo-sulfur active sites of [FeFe]-hydrogenase is implicated in both hydrogen evolution and uptake reactions. Using a combination of time-resolved NMR, stopped-flow UV and stopped-flow IR, we have begun to unravel the mechanisms for protonation of synthetic electron-rich analogues of the di-iron subsite of the enzyme: Fe2(μ-pdt)(CO)4(PMe3)2, Fe2(μ-edt)(CO)4(PMe3)2, (NEt4)2[Fe2(μ-pdt)(CO)4(CN)2], (NEt4)2[Fe2(μ-edt)(CO)4(PMe3)2] and (NEt4)[Fe2(μ-pdt)(CO)4(CN)(PMe3)] (pdt = propane-1,3-dithiolate, edt = ethane-1,2-dithiolate). The mechanistic role of isomer interconversion and how this critically relates to steric access to the di-iron bridge are revealed.
在[FeFe]-氢酶的
金属-
硫活性位点形成瞬态
金属
氢化物与氢的析出和吸收反应有关。通过结合使用时间分辨核磁共振、停止流动紫外和停止流动红外,我们开始揭示合成富电子类似物对酶中二
铁亚基进行质子化的机理:Fe2(μ-pdt)(CO)4(PMe3)2、Fe2(μ-edt)(CO)4(PMe3)2、(NEt4)2[Fe2(μ-pdt)(CO)4(CN)2]、(NEt4)2[Fe2(μ-edt)(CO)4(PMe3)2]和(NEt4)[Fe2(μ-pdt)(CO)4(CN)(PMe3)](pdt =
丙烷-1,3-二
硫醇酸盐,edt =
乙烷-1,2-二
硫醇酸盐)。揭示了异构体相互转换的机理作用,以及这种作用与二
铁桥的空间位阻如何密切相关。