Steric, geometrical and solvent effects on redox potentials in salen-type copper(II) complexes.
Steric, geometrical and solvent effects on redox potentials in salen-type copper(II) complexes.
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DOI：
10.1039/b906013h
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发表时间：
2009-09
影响因子：
4
通讯作者：
M. Hirotsu;Naoto Kuwamura;I. Kinoshita;M. Kojima;Y. Yoshikawa;K. Ueno
中科院分区：
文献类型：
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作者：
M. Hirotsu;Naoto Kuwamura;I. Kinoshita;M. Kojima;Y. Yoshikawa;K. Ueno
用席夫碱配体[N，N'-双（2'-羟基苯基）苯基甲基]-1,2-二氨基-1,2-二苯乙烷（H(2)L）]的两种非对映体分析了铜（ii）配合物[Cu(L(R,R/S，S)] （rac-）和[Cu(L(R，S))] （meso-）的氧化还原行为。这两种配合物均通过x射线晶体学研究进行了结构表征，并显示出方形平面几何形状。Cu（II）对中介-的还原电位高于rac-的还原电位。这是由于苯基取代基的空间效应和铜(i)态的几何变化，这得到了DFT计算的支持。溶剂由二氯甲烷变为吡啶，在可见光区中介体-的吸收光谱发生了红移，而rac-的吸收光谱没有明显变化。溶剂对还原电位的影响相对较小。几何效应对于理解该体系的电化学行为更为重要。
Two diastereomers of the Schiff base ligand [N,N'-bis(2'-hydroxyphenyl)phenylmethylidene]-1,2-diamino-1,2-diphenylethane (H(2)L) were used for the analyses of the redox behaviour of the copper(ii) complexes [Cu(L(R,R/S,S))] (rac-) and [Cu(L(R,S))] (meso-). Both complexes were structurally characterised by X-ray crystallographic studies and showed square planar geometries. The reduction potential of Cu(II) to Cu(I) for meso- was higher than that for rac-. This is due to the steric effect of the phenyl substituents and the geometrical change in the copper(i) state, which is supported by DFT calculations. A red shift of the absorption spectrum was observed for meso- in the visible region by the change of solvent from dichloromethane to pyridine, while rac- did not show a significant change. The effect of solvent on the reduction potential was found to be relatively small. The geometrical effect is more important for understanding the electrochemical behaviour in this system.