Synergistic Effect of FeII and MnII Ions in Cyano-Bridged Heterometallic Coordination Polymers on Catalytic Selectivity of Benzene Oxygenation to Phenol.

A cyano-bridged heterometallic coordination polymer with partial deficiencies of CN- ligands, [MnII(H2O)8/3]3/2[FeII(CN)5(NH3)], forms open metal sites both on MnII and FeII ions by liberation of monodentate ligands such as NH3 and H2O. [MnII(H2O)8/3]3/2[FeII(CN)5(NH3)] exhibits high catalytic activity and selectivity of benzene oxygenation to phenol in the presence of m-chloroperoxybenzoic acid as an oxidant. The postcatalytic spectroscopy of [MnII(H2O)8/3]3/2[FeII(CN)5(NH3)] and catalysis comparison with a physical mixture of [MnII(H2O)3]2[FeII(CN)6] and [Fe(H2O)3/2]4/3[Fe(CN)6], which has open metal sites on both MnII and Fe ions separately, indicated that the high activity resulted from high oxidation ability and phenol adsorption ability of FeII and MnII ions, respectively.