Bansal Deepak, Mondal Abhishake, Lakshminarasimhan N, Gupta Rajeev
Department of Chemistry, University of Delhi, Delhi - 110 007, India.
Dalton Trans. 2019 Jun 14;48(22):7918-7927. doi: 10.1039/c9dt00966c. Epub 2019 May 15.
In this work, we present the syntheses of two μ-oxo bridged mixed-valent trinuclear MnMn complexes (1 and 2) and a μ-oxo bridged tetranuclear Mn complex (3). All the three manganese complexes have been characterized crystallographically and by using different analytical techniques. Both mixed-valent trinuclear complexes 1 and 2 exhibited Jahn-Teller distortion for the Mn(iii) ion. Variable temperature magnetic susceptibility studies of all three complexes revealed antiferromagnetic coupling between the closely placed paramagnetic manganese ions mediated via a μ-oxo bridge. Cyclic voltammetry studies displayed both Mn(iii)/Mn(ii) and Mn(iv)/Mn(iii) redox couples in 1 whereas only the Mn(iii)/Mn(ii) couple was observed for complexes 2 and 3. Importantly, complexes 2 and 3 were found to disproportionate HO, and the catalase activity has been related to their structural features and redox properties.
在本工作中，我们展示了两种μ-氧桥联混合价态三核锰锰配合物（1和2）以及一种μ-氧桥联四核锰配合物（3）的合成。所有这三种锰配合物均已通过晶体学和使用不同分析技术进行了表征。两种混合价态三核配合物1和2对Mn(III)离子表现出 Jahn-Teller 畸变。对所有三种配合物进行的变温磁化率研究表明，通过μ-氧桥介导，紧密相邻的顺磁性锰离子之间存在反铁磁耦合。循环伏安法研究显示，配合物1中存在Mn(III)/Mn(II)和Mn(IV)/Mn(III)氧化还原对，而配合物2和3仅观察到Mn(III)/Mn(II)对。重要的是，发现配合物2和3会使HO发生歧化反应，并且过氧化氢酶活性与其结构特征和氧化还原性质有关。
