A novel carboxylate-free ferromagnetic trinuclear μ < inf > 3 < /inf > -oxo-manganese(III) complex with distorted pentagonal-bipyramidal metal centers

Abstract

In methanol, the reaction of Mn(ClO4)2·6H2O and 1,2-bis(biacetylmonoximeimino)ethane (H2bamen) in the presence of triethylamine affords a trinuclear complex having the formula [Mn3(μ3-O)(μ3- bamen)3]ClO4·2H2O. The structure of this complex shows a symmetric planar central {MnIII3(μ3-O)} unit coordinated to three hexadentate bridging (via oximate groups) ligands. The N4O3 coordination sphere around each metal center is very close to pentagonal-bipyramidal. A cyclic voltammogram of the complex displays two reversible and an irreversible response due to MnIII3 → MnIII2MnIV, MnIII2MnIV → MnIIIMnIV2, and MnIIIMnIV2 → MnIV3 oxidation processes, respectively. Cryomagnetic data reveal that the complex is ferromagnetic.