The visible light-driven catalytic water reduction by a cobalt(II) tripodal iminopyridine complex [Co(tachpy₃)](ClO₄)₂ (1) (tachpy₃ = cis,cis-1,3,5-tris(pyridine-2-carboxaldimino)-cyclohexane) has been investigated in aqueous acetonitrile. The catalysis is found to be homogeneous and an impressive H₂ TON of 16 440 has been achieved, which is far better than that by a structurally related complex [Co(trenpy₃)](ClO₄)₂ (2) (trenpy₃ = tris-[4-(2-pyridyl)-3-azabut-3-enyl]amine) bearing identical donor groups. A comparison between the two complexes reveals that the catalytic properties are sensitive to the change in ligand rigidity and thus the coordination geometry, as reflected by their respective reaction potentials and H₂ TONs. The catalysis of 1 proceeds via a penta-coordinate species formed by the protonation of the corresponding Co^I state. The results in spectroscopic and electrochemical studies are supplemented by DFT computation.

中文翻译：

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钴（ii）三脚架亚氨基吡啶络合物有效地光催化减水†

钴（II）三脚架亚氨基吡啶络合物[Co（tachpy ₃）]（ClO ₄）₂（1）（tachpy ₃ =顺式，顺式-1,3,5-三（吡啶-已经在乙腈水溶液中研究了2-羧基二氨基）-环己烷）。发现该催化是均相的，并且已经实现了令人印象深刻的H ₂ TON为16 440，这远好于结构相关的配合物[Co（trenpy ₃）]（ClO ₄）₂（2）（trenpy ₃＝带有相同供体基团的三-[4-（2-吡啶基）-3-氮杂丁-3-烯基]胺）。两种配合物之间的比较表明，催化性能对配体刚度的变化敏感，因此对配位几何形状也很敏感，这反映在它们各自的反应电势和H ₂ TONs上。的催化作用1个前进通过一个五配位通过相应的Co的质子化形成的物种^我状态。光谱和电化学研究的结果通过DFT计算得到补充。