Proton affinity studies of nickel N2S2 complexes and control of aggregation
Proton affinity studies of nickel N2S2 complexes and control of aggregation
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DOI：
10.1007/s00775-019-01671-4
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发表时间：
2019-09-01
影响因子：
3
通讯作者：
Darensbourg, Marcetta Y.
中科院分区：
文献类型：
--
作者：
Arnet, Nicholas A.;Bhuvanesh, Nattamai;Darensbourg, Marcetta Y.
[NiFe]-H（2）酶的硫醇配体被认为是H+/H-2还原/氧化的质子结合位点。本文研究了配体对NiN_2S_2配合物与一系列酸在甲醇溶液中反应性的影响。紫外-可见吸收光谱用于观察从单体物质到质子诱导配体解离后形成的三金属络合物的转化。发现具有柔性（丙基和乙基）N至N连接体的镍络合物容易与弱如铵的酸形成三金属络合物（在甲醇中pK（a）= 10.9）。具有二氮杂环庚烷N至N连接基的更受约束的镍络合物需要更强的酸如2，2-二氯乙酸（在甲醇中pK（a）= 6.38）以形成三金属络合物，并且特征在于与乙酸形成NiN 2S 2 H+络合物（在甲醇中pK（a）= 9.63）。最紧张的配体，其特征是二氮杂环己烷骨架，在与酸混合时容易从镍中心解离，具有pK（a）
The thiolate ligands of [NiFe]-H(2)ase enzymes have been implicated as proton-binding sites for the reduction/oxidation of H+/H-2. This study examines the ligand effect on reactivity of NiN2S2 complexes with an array of acids in methanol solution. UV-Vis absorption spectroscopy is utilized to observe the transformation from the monomeric species to a trimetallic complex that is formed after proton-induced ligand dissociation. Nickel complexes with a flexible (propyl and ethyl) N to N linker were found to readily form the trimetallic complex with acids as weak as ammonium (pK(a) = 10.9 in methanol). A more constrained nickel complex with a diazacycloheptane N to N linker required stronger acids such as 2,2-dichloroacetic acid (pK(a) = 6.38 in methanol) to form the trimetallic complex and featured the formation of an NiN2S2H+ complex with acetic acid (pK(a) = 9.63 in methanol). The most strained ligand, which featured a diazacyclohexane backbone, readily dissociated from the nickel center upon mixture with acids with pK(a)