Department of Chemistry , National Institute of Technology Durgapur , Mahatma Gandhi Avenue , Durgapur 713209 , India.
Department of Chemistry , Indian Institute of Technology Kanpur , Kanpur 208016 , India.
Inorg Chem. 2018 Nov 5;57(21):13713-13727. doi: 10.1021/acs.inorgchem.8b02276. Epub 2018 Oct 19.
Aliphatic thiolato-S-bridged tri- and binuclear nickel(II) complexes have been synthesized and characterized as models for the Ni site of the A cluster of acetyl coenzyme A synthase (ACS)/carbon monooxide (CO) dehydrogenase. Reaction of the in situ formed NS donor ligands with Ni(HO) afforded the trinuclear complexes Ni{(L)Ni}·CHCN (1·CHCN) and Ni{(L)Ni}·5HO (2·5HO) following self-assembly. Complexes 1 and 2 react with [Ni(dppe)Cl] and dppe [dppe = 1,2-bis(diphenylphosphino)ethane] to afford the binuclear Ni(dppe)Ni(L)·2HO (3·2HO) and Ni(dppe)Ni(L)·0.75O(CH) [4·0.75O(CH)], respectively. The X-ray crystal structures of 1-4 revealed a central NiS moiety in 1 and 2 and a NiPS moiety in 3 and 4; both moieties have a square-planar environment around Ni and may mimic the properties of the Ni site of ACS. The electrochemical reduction of both terminal Ni ions of 1 and 2 occurs simultaneously, which is further confirmed by the isolation of Ni{(L)Ni(NO)} (5) and Ni{(L)Ni(NO)} (6) following reductive nitrosylation of 1 and 2. Complexes 5 and 6 exhibit ν at 1773 and 1789 cm, respectively. In the presence of O, both 5 and 6 transform to nitrite-bound monomers (L)Ni(NO) (7) and (L)Ni(NO) (8). The nature of the ligand modification is evident from the X-ray crystal structure of 7. To understand the origin of multiple reductive responses of 1-4, complex (L)Ni (9) is considered. The central NiS part of 1 is labile like the Ni site of ACS and can be replaced by phenanthroline. The treatment of CO to reduce 3 generates a 3-(CO) species, as confirmed by Fourier transform infrared (ν = 1997 and 2068 cm) and electron paramagnetic resonance ( g = 2.18, g = 2.13, g = 1.95, and A = 30-80 G) spectroscopy. The CO binding to Ni of 3 is relevant to the ACS activity.
脂肪族硫醇-S-桥联三核和双核镍(II)配合物已被合成并表征为乙酰辅酶 A 合酶 (ACS)/一氧化碳 (CO) 脱氢酶 A 簇中 Ni 位的模型。原位形成的 NS 供体配体与 [Ni(HO)] (ClO) 反应，在自组装后得到三核配合物 Ni{(L)Ni}·CHCN (1·CHCN) 和 Ni{(L)Ni}·5HO (2·5HO)。配合物 1 和 2 与 [Ni(dppe)Cl] 和 dppe [dppe = 1,2-双(二苯基膦)乙烷]反应，分别得到双核 Ni(dppe)Ni(L)·2HO (3·2HO) 和 Ni(dppe)Ni(L)·0.75O(CH) [4·0.75O(CH)]。1-4 的 X 射线晶体结构显示，1 和 2 中存在中心 NiS 部分，3 和 4 中存在 NiPS 部分；这两种部分在 Ni 周围都具有平面四方环境，可能模拟 ACS 的 Ni 位的性质。1 和 2 的两个末端 Ni 离子的电化学还原同时发生，这进一步通过 1 和 2 的还原亚硝化为随后分离出 Ni{(L)Ni(NO)} (5) 和 Ni{(L)Ni(NO)} (6) 得到证实。5 和 6 分别在 1773 和 1789 cm 处表现出 ν。在 O 的存在下，5 和 6 都转化为亚硝酸盐结合的单体 (L)Ni(NO) (7) 和 (L)Ni(NO) (8)。配体修饰的性质从 7 的 X 射线晶体结构中显而易见。为了了解 1-4 的多个还原响应的起源，考虑了配合物 (L)Ni (9)。1 的中心 NiS 部分像 ACS 的 Ni 位一样不稳定，可以被邻菲咯啉取代。CO 处理以还原 3 生成 3-(CO) 物种，这通过傅里叶变换红外 (ν = 1997 和 2068 cm) 和电子顺磁共振 (g = 2.18、g = 2.13、g = 1.95 和 A = 30-80 G) 光谱得到证实。3 中 Ni 与 CO 的结合与 ACS 活性有关。
