Synthesis, crystal structure and magnetic characterization of a series of four phenoxo-bridged binuclear manganese(III) Schiff base complexes

Abstract

A family of four new phenoxo-bridged binuclear manganese(III) complexes of the general formula, [Mn(L)(X)] 2 where L = [ N,N′-bis(salicylidene)]propane-1,2-diamine and X = salicylaldehyde anion (sal −) ( 1); NCS − ( 2); NCO − ( 3) and [Mn(L′)(N 3)] 2·2C 2H 5OH ( 4) where L′ = [ N,N′-bis(2-hydroxyacetophenylidene)]propane-1,2-diamine has been prepared. The syntheses have been achieved by reacting manganese perchlorate with 1,2-diaminopropane and salicylaldehyde (or 2-hydroxyacetophenone for 4) or along with the respective pseudohalides so that the tetradentate Schiff base H 2L or H 2L′ is obtained in situ to bind the Mn(III) ion. The complexes have been characterized by IR spectroscopy, elemental analysis, crystal structure analysis and variable-temperature magnetic susceptibility measurements. The single crystal X-ray diffraction studies show that the compounds are isostructural containing dimeric Mn(III) units with bridging phenolate oxygen atoms. Low temperature magnetic studies indicate that the complexes 1– 3 exhibit intradimer ferromagnetic exchange as well as single-molecule magnet (SMM) behavior while complex 4 is found to undergo an intradimer antiferromagnetic coupling.