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

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 [(P4Mo6O31)-O-V](12-)-based manganese complex (Hbiz)(10){[Mn-1.5(mu(2)-O)(2)(H2O)(2)][Mn(H2O)(3)]{Mn[Mo6O12(OH)(3)(H2PO4)(HPO4)(3)](2)}}(2)4H(2)O (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(mu(2)-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.