School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Australia.
Inorg Chem. 2009 Nov 2;48(21):10036-48. doi: 10.1021/ic9005086.
The binuclear heterovalent manganese model complex [Mn(II)Mn(III)(L1)(OAc)(2)] ClO(4) x H(2)O (H(2)L1 = 2-(((3-((bis(pyridin-2-ylmethyl)amino)methyl)-2-hydroxy-5-methylbenzyl)(pyridin-2-ylmethyl)amino)-methyl)phenol) has been prepared and studied structurally, spectroscopically, and computationally. The magnetic and electronic properties of the complex have been related to its structure. The complex is weakly antiferromagnetically coupled (J approximately -5 cm(-1), H = -2J S(1) x S(2)) and the electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) spectra identify the Jahn-Teller distortion of the Mn(III) center as predominantly a tetragonal compression, with a significant rhombic component. Electronic structure calculations using density functional theory have confirmed the conclusions derived from the experimental investigations. In contrast to isostructural M(II)Fe(III) complexes (M = Fe, Mn, Zn, Ni), the Mn(II)Mn(III) system is bifunctional possessing both catalase and hydrolase activities, and only one catalytically relevant pK(a) (= 8.2) is detected. Mechanistic implications are discussed.
双核杂价锰模型配合物[Mn(II)Mn(III)(L1)(OAc)(2)] ClO(4) x H(2)O（H(2)L1 = 2-(((3-((双(吡啶-2-基甲基)氨基)甲基)-2-羟基-5-甲基苄基)(吡啶-2-基甲基)氨基)-甲基)苯酚）已被制备并进行了结构、光谱和计算研究。该配合物的磁和电子性质与其结构有关。该配合物是弱反铁磁耦合的（J 约为-5 cm(-1)，H = -2J S(1) x S(2)），电子顺磁共振（EPR）和磁圆二色性（MCD）光谱确定 Mn(III)中心的 Jahn-Teller 畸变主要是四方压缩，具有显著的菱形分量。使用密度泛函理论的电子结构计算证实了从实验研究中得出的结论。与同构的 M(II)Fe(III)配合物（M = Fe、Mn、Zn、Ni）相比，Mn(II)Mn(III)体系是双功能的，具有过氧化氢酶和水解酶活性，仅检测到一个与催化相关的 pK(a)（= 8.2）。讨论了其机制意义。
