Harrop Todd C, Olmstead Marilyn M, Mascharak Pradip K
Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
J Am Chem Soc. 2004 Nov 17;126(45):14714-5. doi: 10.1021/ja045284s.
The Ni(II)-dicarboxamido-dithiolato complexes (Et4N)2[Ni(NpPepS)] (1) and (Et4N)2[Ni(PhPepS)] (2) were used as Nid metallosynthons in the construction of higher nuclearity dinuclear Ni-Cu and Ni-Ni species to model the bimetallic Mp-Nid site of the A-cluster of acetyl coenzyme A synthase/CO dehydrogenase (ACS/CODH). Reaction of 1 with [Cu(neo)Cl] and [Ni(terpy)Cl2] in MeCN affords the dinuclear complexes (Et4N)[Cu(neo)Ni(NpPepS)] (3) and [Ni(terpy)Ni(NpPepS)] (4), respectively. Reaction of 2 with [Ni(dppe)Cl2] in MeCN yields [Ni(dppe)Ni(PhPepS)] (6). The Ni-Cu complex 3 exhibits no redox chemistry at the Nid site and no reaction with CO. In contrast, the Nip sites in 4 and 6 are readily reduced (characterized by their Ni(I) EPR spectra) and bind CO, exhibiting nuco bands at 2044 and 1997 cm-1, respectively, indicating terminal CO binding. The present Ni-Ni systems replicate the structural and chemical properties of the A-cluster site in ACS/CODH and support the presence of Ni at Mp in the catalytically active enzyme.
镍（II）-二羧酰胺基二硫醇盐配合物（Et4N）2[Ni（NpPepS）]（1）和（Et4N）2[Ni（PhPepS）]（2）被用作镍金属合成子，用于构建更高核数的双核镍-铜和镍-镍物种，以模拟乙酰辅酶A合成酶/一氧化碳脱氢酶（ACS/CODH）A簇的双金属钼-镍位点。1与[Cu（neo）Cl]和[Ni（terpy）Cl2]在乙腈中反应，分别得到双核配合物（Et4N）[Cu（neo）Ni（NpPepS）]（3）和[Ni（terpy）Ni（NpPepS）]（4）。2与[Ni（dppe）Cl2]在乙腈中反应生成[Ni（dppe）Ni（PhPepS）]（6）。镍-铜配合物3在镍位点没有氧化还原化学性质，也不与CO反应。相比之下，4和6中的镍位点很容易被还原（通过它们的Ni（I）电子顺磁共振光谱表征）并结合CO，分别在2044和1997 cm-1处显示羰基伸缩振动带，表明是末端CO配位。目前的镍-镍体系复制了ACS/CODH中A簇位点的结构和化学性质，并支持在催化活性酶的钼位点存在镍。
