This paper first discloses that two heteroleptic 8-quinolinolato iron(III) complexes (Qa₁Qb₂Fe^III, Qa₂Qb₁Fe^III) could be synthesized conveniently via the coordination of FeCl₂·6H₂O with 2 equivalents of 5,7-dichloro-8-hydroxyquinoline (Qb) or 5-chloro-8-hydroxyquinoline (Qa) under N₂ and then 1 equivalent of Qa or Qb under air. In comparison with the two homoleptic counterparts (Qa₃Fe^III and Qb₃Fe^III), the proposed heteroleptic Q₃Fe^III complexes possessed similar coordination features to the Qb₃Fe^III one but showed similar catalysis performances to the Qa₃Fe^III one in the oxygenation of cyclohexane to cyclohexanol and cyclohexanone by hydrogen peroxide (H₂O₂) in acetonitrile. More importantly, both heteroleptic Q₃Fe^III complexes showed a better accelerating effect on this reaction and provided a slightly higher conversion than the Qa₃Fe^III and especially Qb₃Fe^III ones. Furthermore, this predominance in catalytic activity was more strikingly apparent upon both-catalyzed oxygenations of benzene, toluene, ethylbenzene or thioanisole by H₂O₂. This should be due to a structurally distorted effect of the heteroleptic Q₃Fe^III complexes that is induced by the different in ligand environment, as supported by DFT B3LYP/6-311G (d) calculation. Based the present reaction and UV–vis spectral characterization results, a free radical mechanism for the present catalysis system was proposed.

中文翻译：

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弱扭曲的8-喹啉基铁（III）配合物是过氧化氢氧化有机化合物的有效催化剂

本文首先公开了可以通过FeCl ₂ ·6H ₂ O与2当量5的配位，方便地合成两种杂配的8-喹啉基铁（III）配合物（Qa ₁ Qb ₂ Fe ^III，Qa ₂ Qb ₁ Fe ^III）。 N ₂下的7-二氯-8-羟基喹啉（Qb）或5-氯-8-羟基喹啉（Qa），然后在空气中1当量的Qa或Qb。与两个均质对等物（Qa ₃ Fe ^III和Qb ₃ Fe ^III）相比，拟议的杂合性Q ₃ Fe ^III该配合物具有与Qb ₃ Fe ^III相似的配位特征，但在乙腈中过氧化氢（H ₂ O ₂）将环己烷氧化为环己醇和环己酮时，显示出与Qa ₃ Fe ^III相似的催化性能。更重要的是，两种杂合Q ₃ Fe ^III配合物均对该反应具有更好的促进作用，并提供了比Qa ₃ Fe ^III尤其是Qb ₃ Fe ^III更高的转化率。那些。此外，在H ₂ O ₂催化的苯，甲苯，乙苯或硫代苯甲醚的氧合反应中，这种催化活性的优势更为明显。这应该是由于DFT B3LYP / 6-311G（d）计算所支持的，由于配体环境不同而引起的杂配Q ₃ Fe ^III络合物的结构扭曲效应。根据目前的反应和紫外可见光谱表征结果，提出了本催化体系的自由基机理。