A series of Mn(II) complexes of differently substituted pyridinophane ligands, (Py₂NR₂)MnCl₂ (R = ⁱPr, Cy) and [(Py₂NR₂)MnF₂](PF₆) (R = ⁱPr, Cy, ^tBu) are synthesized and characterized. The electrochemical properties of these complexes are investigated by cyclic voltammetry, along with those of previously reported (Py₂NMe₂)MnCl₂ and the Mn(III) complex [(Py₂NMe₂)MnF₂](PF₆). The electronic structure of this and other Mn(III) complexes is probed experimentally and theoretically, via high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy ab initio quantum chemical theory (QCT), respectively. These studies show that the complexes contain relatively typical six-coordinate Mn(III). The catalytic activity of these complexes toward both H₂O₂ disproportionation and H₂O oxidation has also been investigated. The rate of H₂O₂ disproportionation decreases with increasing substituent size. Some of these complexes are active for electrocatalytic H₂O oxidation; however this activity cannot be rationalized in terms of simple electronic or steric effects.

中文翻译：

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锰吡啶鎓配合物中的配体取代基效应：对析氧催化的影响。

（Py ₂ NR ₂）MnCl ₂（R = ⁱ Pr，Cy）和[（Py ₂ NR ₂）MnF ₂ ]（PF ₆）（R = ⁱ Pr ，Cy，^t Bu）被合成和表征。通过循环伏安法研究了这些络合物的电化学性质，以及先前报道的（Py ₂ NMe ₂）MnCl ₂和Mn（III）络合物[（Py ₂ NMe ₂）MnF ₂ ]（PF ₆）的电化学性质。）。分别通过高频和场电子顺磁共振（HFEPR）光谱从头计算量子化学原理（QCT），通过实验和理论方法探索了这种和其他Mn（III）配合物的电子结构。这些研究表明，该配合物包含相对典型的六坐标Mn（III）。还研究了这些配合物对H ₂ O ₂歧化和H ₂ O氧化的催化活性。H ₂ O ₂歧化速率随取代基尺寸的增加而降低。这些络合物中的一些对电催化H ₂具有活性O氧化；但是，就简单的电子或立体效果而言，不能合理地进行这项活动。