A new {P4Mo6}-based complex as a highly efficient heterogeneous catalyst for the oxidation of alkylbenzenes under mild conditions

Abstract

The selective oxidation of saturated C–H bonds to carbonyl compounds under mild conditions can be of high economic value. Therefore, it is of great significance to develop an efficient catalyst for activating C–H bonds. Here, a new [P₄Mo^V₆O₃₁]¹²⁻-based manganese complex (Hbiz)₁₀{[Mn_1.5(μ₂-O)₂(H₂O)₂][Mn(H₂O)₃]{Mn[Mo₆O₁₂(OH)₃(H₂PO₄)(HPO₄)₃]₂}}₂·4H₂O (biz = benzimidazole) was designed and synthesized under solvothermal conditions. Single crystal X-ray diffraction studies show that complex 1 is a three-dimensional supramolecular structure constructed from [Mn_1.5(μ₂-O)₂(H₂O)₂][Mn(H₂O)₃]{Mn[Mo₆O₁₂(OH)₃(H₂PO₄)(HPO₄)₃]₂} double chains with trinuclear manganese clusters and protonated Hbiz. As a heterogeneous catalyst, it can efficiently catalyze the selective oxidation of diphenylmethane, the conversion rate can reach 95.1% within 24 hours, and the selectivity >99%, which is higher than those of most catalysts. The mechanism study shows that the oxidation reaction involves the interaction between the molybdenum center and the manganese center in complex 1 as well as the metal–metal charge transfer (MMCT) between the trinuclear manganese clusters.