Aerobic catechol oxidation catalyzed by a bis(μ-oxo)dimanganese(III,III) complex via a manganese(II)-semiquinonate complex
Aerobic catechol oxidation catalyzed by a bis(μ-oxo)dimanganese(III,III) complex via a manganese(II)-semiquinonate complex
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DOI：
10.1021/ic050109d
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发表时间：
2005-05-16
影响因子：
4.6
通讯作者：
Funabiki, T
中科院分区：
文献类型：
--
作者：
Hitomi, Y;Ando, A;Funabiki, T
通过Mn-II（TPA）Cl-2（TPA =三（吡啶-2-基甲基）胺）和DTBSQ阴离子之间的反应制备了Mn（II）的3，5-二叔丁基-1，2-半醌（DTBSQ）加合物，并分离为四苯基硼酸盐。X-射线晶体结构显示，该配合物被配制为锰（II）-半醌配合物[Mn-II（TPA）（DTBSQ）]（+）（1）。溶液中的电子光谱也表明半醌配位到Mn。1在乙腈中暴露于氧气中得到3，5-二叔丁基-1，2-苯醌和双（μ-氧代）二锰（III，III）配合物[MnIII 2（μ-氧代）（2）（TPA）（2）]（2+）（2）。在厌氧条件下，2与3，5-二叔丁基邻苯二酚（DTBCH 2）的反应定量地提供两当量的1。通过组合上述两个反应，即通过构建涉及锰络合物1和2的催化循环，实现了DTBCH 2与分子氧的高效催化氧化。结果表明，在催化循环中，分子氧被还原成水，但不还原成过氧化氢。
A 3,5-di-tert-butyl-1,2-semiquinonato (DTBSQ) adduct of Mn(II) was prepared by a reaction between Mn-II(TPA)Cl-2 (TPA = tris(pyridin-2-ylmethyl)amine) and DTBSQ anion and was isolated as a tetraphenylborate salt. The X-ray crystal structure revealed that the complex is formulated as a manganese(II)-semiquinonate complex [Mn-II(TPA)(DTBSQ)](+) (1). The electronic spectra in solution also indicated the semiquinonate coordination to Mn. The exposure of 1 in acetonitrile to dioxygen afforded 3,5-di-tert-butyl-1,2-benzoquione and a bis(μ-oxo)dimanganese(III,III) complex [MnIII2(μ-oxo)(2)(TPA)(2)](2+) (2). The reaction of 2 with 3,5-di-tert-butylcatechol (DTBCH2) quantitatively afforded two equivalents of 1 under anaerobic conditions. The highly efficient catalytic oxidation of DTBCH2 with dioxygen was achieved by combining the above two reactions, that is, by constructing a catalytic cycle involving both manganese complexes 1 and 2. It was revealed that dioxygen is reduced to water but not to hydrogen peroxide in the catalytic cycle.