Electron transfer at a dithiolate-bridged diiron assembly: Electrocatalytic hydrogen evolution
Electron transfer at a dithiolate-bridged diiron assembly: Electrocatalytic hydrogen evolution
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DOI：
10.1021/ja045281f
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发表时间：
2004-12-29
影响因子：
15
通讯作者：
Pickett, CJ
中科院分区：
文献类型：
--
作者：
Borg, SJ;Behrsing, T;Pickett, CJ
Fe-2(mu-pdt)(CO)(6) 1 (pdt = propane-1,3-dithiolate) 的电化学还原最初产生短寿命物质 1(-)，然后产生双电子还原产物，包括 CO 桥接二铁化合物 1B。 1(-) 的氧化还原能级的指定基于 EPR 和紫外可见光谱以及 1(-) 的 CO 饱和溶液衰变得到 1 和 1B 的观察结果。 1 的氢化物还原也会通过相对寿命较长的甲酰基物质 1 甲酰基形成 1B。尽管参与氢化物转移反应，但基于一系列光谱测量以及 2.527 埃的 Fe-Fe 分离 (EXAFS)，1B 被公式化为 [Fe-2(mu-S(CH2)(3)SH)(mu-CO)(CO)(6)](-)。已通过电化学和光谱电化学技术检查了在中等强酸中存在 1 时的电催化质子还原。伏安法的酸浓度依赖性通过两个电子/质子加成产生 1H(2) 的机制进行建模，其中氢气的解离导致 1 的恢复。在较高的酸浓度下，进一步的还原过程是明显的。虽然游离 CO 提高了 1 电化学的可逆性，但 CO 抑制了电催化质子还原，这是通过涉及由 1(-) 形成的二聚体物质的副反应而发生的。
Electrochemical reduction of Fe-2(mu-pdt)(CO)(6) 1 (pdt = propane-1,3-dithiolate) leads initially to a short-lived species, 1(-), then subsequently to two-electron reduced products, including a CO-bridged diiron compound, 1B. The assignment of the redox level of 1(-) is based on EPR and UV-vis spectra together with the observation that a CO-saturated solution of 1(-) decays to give 1 and 1B. Hydride reduction of 1 also results in formation of 1B via a relatively long-lived formyl species, 1 formyl. Despite its involvement in hydride transfer reactions, 1B is formulated as [Fe-2(mu-S(CH2)(3)SH)(mu-CO)(CO)(6)](-) based on a range of spectroscopic measurements together with the Fe-Fe separation of 2.527 Angstrom (EXAFS). Electrocatalytic proton reduction in the presence of 1 in moderately strong acids has been examined by electrochemical and spectroelectrochemical techniques. The acid concentration dependence of the voltammetry is modeled by a mechanism with two electron/proton additions leading to 1H(2), where dissociation of dihydrogen leads to recovery of 1. Further reduction processes are evident at higher acid concentrations. Whereas free CO improves the reversibility of the electrochemistry of 1, CO inhibits electrocatalytic proton reduction, and this occurs through side reactions involving a dimeric species formed from 1(-).