Structure,Magnetic Properties and Catalase-like Activity of Asymmetric Dimanganese(III,III) Carboxylate Complexes with Salicylaldimine Ligands

The crystal structures, magnetic properties, and catalase-like activities of assymmetric dinuclear manganese(III, III) complexes, [Mn₂^{III, III}(spa)₂(μ-Me₃CCO₂)(Me₃CCO₂)(CH₃OH)] ( 1 ) and [Mn₂^{III, III}(vpa)₂(μ-Me₃CCO₂)(Me₃CCO₂)(CH₃OH)] ( 2 ), (H₂spa = 3-salicyclideneamino-1-propanol, H₂vpa = O-vanillin), were reported. The crystal structures of complexes 1 and 2 consist of the same discrete asymmetric coordination environment of dinuclear clusters, where the two manganese atoms are bridged by two alkoxo oxygens of the spa or vpa ligands and one bidentate carboxylate ion, whereas an additional oxygen atom of monodentate carboxylate coordinated to the first metal ion, and the second metal ion was coordinated by one oxygen atom of the solvent CH₃OH. Magnetic investigations (2–300 K) reveal an intramolecular antiferromagnetic spin exchange interaction with axial-field splittings: J = ?12.3 cm^?1 (D = ?0.10 cm^?1) and J = ?13.3 cm^?1 (D = ?0.15 cm^?1) for complexes 1 and 2 , respectively. The complexes should show catalase-like activity for H₂O₂ disproportionation in CH₃OH solvent at 25° with rate constants of k = 6.35 dm³moI^?1s^?1 and 6.20 dm³mol^?1s^?1 for complexes 1 and 2 , respectively.