Electrochemical and theoretical investigations of the reduction of [Fe2(CO)5L{μ-SCH2XCH2S}] complexes related to [FeFe] hydrogenase
Electrochemical and theoretical investigations of the reduction of [Fe2(CO)5L{μ-SCH2XCH2S}] complexes related to [FeFe] hydrogenase
复制标题
DOI：
10.1039/b709273c
复制
发表时间：
2007-11
影响因子：
3.3
通讯作者：
J. Capon;Salah Ezzaher;F. Gloaguen;F. Pétillon;P. Schollhammer;J. Talarmin;Thomas J. Davin;J. McGrady;K. Muir
中科院分区：
文献类型：
--
作者：
J. Capon;Salah Ezzaher;F. Gloaguen;F. Pétillon;P. Schollhammer;J. Talarmin;Thomas J. Davin;J. McGrady;K. Muir
配合物[Fe_2（CO）_6{μ-SCH_2N（R）CH_2S}]（R = CH_2CH_2 OCH_3，1a; R = iPr，1b）和[Fe_2（CO）_6（μ-pdt）]_2（pdt = S（CH_2）_3S）是[Fe] H_2酶的[2Fe]H亚位点的结构类似物。用快速扫描循环伏安法研究了1和2在MeCN-[NBu 4][PF 6]体系中的还原过程，发现该还原过程可分解为两个单电子转移步骤。在缓慢的扫描速率的减少1倾向于对一个双电子的过程，由于快速的阴离子的partizationation，而两个电子的减少2显然有利于在CO的存在下。CO配体在2由一个N-杂环卡宾取代的结果在不稳定的阴离子。因此，在MeCN-、THF-或CH_2Cl_2-[NBu_4][PF_6]中，Fe_2（CO）_5LNHC（μ-pdt）]_3（LNHC = 1，3-bis（methyl）-imidazole-2-ylidene，3a; 1，3-bis（2，4，6-三甲基苯基）-咪唑-2-亚基，3b）在中等扫描速率下以单步双电子过程发生;在适当的条件下，该过程可以分成两个单电子步骤。密度泛函理论计算成功地合理化的影响，S-到-S键的配合物的电化学。
The complexes [Fe2(CO)6{μ-SCH2N(R)CH2S}] (R = CH2CH2OCH3, 1a; R = iPr, 1b) and [Fe2(CO)6(μ-pdt)] 2 (pdt = S(CH2)3S) are structural analogues of the [2Fe]H subsite of [FeFe]H2ases. Electrochemical investigation of 1 and 2 in MeCN–[NBu4][PF6] under Ar and under CO has demonstrated that the reduction can be resolved into two one-electron transfer steps by using fast scan cyclic voltammetry. At slow scan rates the reduction of 1 tends towards a two-electron process owing to the fast disproportionation of the anion, while the two-electron reduction of 2 is clearly favoured in the presence of CO. Substitution of a CO ligand in 2 by a N-heterocyclic carbene results in the destabilisation of the anion. Thus, in MeCN–, thf- or CH2Cl2–[NBu4][PF6], the electrochemical reduction of Fe2(CO)5LNHC(μ-pdt)] 3 (LNHC = 1,3-bis(methyl)-imidazol-2-ylidene, 3a; 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene, 3b) occurs in a single-step, two-electron process at moderate scan rates; under appropriate conditions this process can be separated into two one-electron steps. Density Functional Theory calculations successfully rationalize the effects of the S-to-S linkage on the electrochemistry of the complexes.