Triller Michael U, Hsieh Wen-Yuan, Pecoraro Vincent L, Rompel Annette, Krebs Bernt
Institut für Anorganische und Analytische Chemie der Westfälischen Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 8, 48149 Münster, Germany.
Inorg Chem. 2002 Oct 21;41(21):5544-54. doi: 10.1021/ic025897a.
The series of compounds Mn(bpia)(mu-OAc)(ClO(4))(2) (1), Mn(2)(bpia)(2)(muO)(mu-OAc)(3).CH(3)CN (2), Mn(bpia)(mu-O)(ClO(4))(2)(PF(6)).2CH(3)CN (3), Mn(bpia)(Cl)(2)(4) (4), and (Mn(bpia)(Cl))(2)(mu-O)(2).2CH(3)CN (5) (bpia = bis(picolyl)(N-methylimidazol-2-yl)amine) represents a structural, spectroscopic, and functional model system for manganese catalases. Compounds 3 and 5 have been synthesized from 2 via bulk electrolysis and ligand exchange, respectively. All complexes have been structurally characterized by X-ray crystallography and by UV-vis and EPR spectroscopies. The different bridging ligands including the rare mono-mu-oxo and mono-mu-oxo-mono-mu-carboxylato motifs lead to a variation of the Mn-Mn separation across the four binuclear compounds of 1.50 A (Mn(2)(II,II) = 4.128 A, Mn(2)(III,III) = 3.5326 and 3.2533 A, Mn(2)(III,IV) = 2.624 A). Complexes 1, 2, and 3 are mimics for the Mn(2)(II,II), the Mn(2)(III,III), and the Mn(2)(III,IV) oxidation states of the native enzyme. UV-vis spectra of these compounds show similarities to those of the corresponding oxidation states of manganese catalase from Thermus thermophilus and Lactobacillus plantarum. Compound 2 exhibits a rare example of a Jahn-Teller compression. While complexes 1 and 3 are efficient catalysts for the disproportionation of hydrogen peroxide and contain an N(4)O(2) donor set, 4 and 5 show no catalase activity. These complexes have an N(4)Cl(2) and N(4)OCl donor set, respectively, and serve as mimics for halide inhibited manganese catalases. Cyclovoltammetric data show that the substitution of oxygen donor atoms with chloride causes a shift of redox potentials to more positive values. To our knowledge, complex 1 is the most efficient binuclear functional manganese catalase mimic exhibiting saturation kinetics to date.
系列化合物[Mn(bpia)(μ - OAc)]₂(ClO₄)₂ (1)、Mn₂(bpia)₂(μO)(μ - OAc)₃·CH₃CN (2)、[Mn(bpia)(μ - O)]₂(ClO₄)₂(PF₆)·2CH₃CN (3)、Mn(bpia)(Cl)₂ (4)以及(Mn(bpia)(Cl))₂(μ - O)₂·2CH₃CN (5)（bpia = 双(吡啶甲基)(N - 甲基咪唑 - 2 - 基)胺）代表了锰过氧化氢酶的结构、光谱和功能模型体系。化合物3和5分别通过大量电解和配体交换由2合成。所有配合物均通过X射线晶体学以及紫外 - 可见光谱和电子顺磁共振光谱进行了结构表征。不同的桥连配体，包括罕见的单 - μ - 氧和单 - μ - 氧 - 单 - μ - 羧基配体基序，导致四种双核化合物中Mn - Mn间距有所变化，分别为1.50 Å（Mn₂(II,II) = 4.128 Å，Mn₂(III,III) = 3.5326 Å和3.2533 Å，Mn₂(III,IV) = 2.624 Å）。配合物1、2和3分别模拟了天然酶的Mn₂(II,II)、Mn₂(III,III)和Mn₂(III,IV)氧化态。这些化合物的紫外 - 可见光谱与嗜热栖热菌和植物乳杆菌中锰过氧化氢酶相应氧化态的光谱相似。化合物2展现出一个罕见的 Jahn - Teller 压缩实例。虽然配合物1和3是过氧化氢歧化反应的有效催化剂，且含有N₄O₂供体集，但4和5没有过氧化氢酶活性。这些配合物分别具有N₄Cl₂和N₄OCl供体集，可作为卤化物抑制的锰过氧化氢酶的模拟物。循环伏安数据表明，用氯取代氧供体原子会使氧化还原电位向更正的值移动。据我们所知，配合物1是迄今为止表现出饱和动力学的最有效的双核功能性锰过氧化氢酶模拟物。
