Dimanganese(II) complexes of a new phenol-based dinucleating ligand with two amino chelating arms: synthesis, structure and catalase-like activity

Abstract

A new phenol-based dinucleating ligand with two amino chelating arms, 2,6-bis{[N-(2-dimethylaminoethyl)-N-methyl]aminomethyl}-4-methylphenolate (L^–), formed dinuclear manganese(II) complexes [Mn₂L(p-XC₆H₄CO₂)₂(NCS)(MeOH)](X = H 1, Cl 2, Me 3 or NO₂4). X-Ray analysis revealed that complex 1 crystallizes in the monoclinic space group P2₁/c, a= 12.607(3), b= 19.566(6), c= 16.743(5)Å and β= 107.56(2)°. The two magnese ions are bridged by the phenolic oxygen and two benzoate groups. The NCS^– ion is co-ordinated to one of the maganese ions through its nitrogen and the methonal molecule to the other, providing distorted-octahedral geometries around each maganese. Magnetic susceptibility measurements over the temperature range 4.2–300 K indicated a weak antiferromagnetic interaction (J=–3 to –5 cm^–1 based on Ĥ=–2JŜ₁·Ŝ₂). The complexes show a catalase-like activity in disproportionating H₂O₂ in dimethylformamide. The rate of dioxygen evolution was proportional to the concentration of H₂O₂ and the rate constant decreased in the order 1(X = H) > 2(Cl) > 3(Me) > 4(NO₂).