Structure and magnetism of a Mn(iii)–Mn(ii)–Mn(ii)–Mn(iii) chain complex

Abstract

A novel tetranuclear manganese(II/III) complex with anions of pyridine-2,6-dicarboxylic acid (dipicolinic acid) has been synthesised and magneto-structurally characterised. The crystal structure of [Mn(II)2Mn(III)2(dipic)6(H2O)4]·2CH3OH·4H2O has been determined by single-crystal X-ray diffraction. The tetranuclear complex molecule [Mn(II)2Mn(III)2(dipic)6(H2O)4] is centrosymmetric and two manganese(II) and two manganese(III) atoms are bridged by four dipicolinate ligands. The complex molecules and uncoordinated water and methanol molecules are connected through hydrogen bonds and they form a 3D supramolecular hydrogen-bonding network.

Crystal structure of bis(μ-4-nitrobenzoato-κ2 O:O′)bis[bis(4-methylpyridine-κN)(4-nitrobenzoato-κ2 O,O′)manganese(II)]

“…Microwave-assisted alcohol oxidation with tert-butylhydroperoxide (TBHP) has been carried out (Sutradhar et al, 2014) using a Schiff base-containing Mn dimer. Manganese complexes are also recognized for their magnetic behaviour since coordination compounds of this metal often display large ground-state spin (S) values and the polynuclear manganese cluster [Mn 12 O 12 (CH 3 COO) 16 (H 2 O) 4 ]Á2CH 3 -COOHÁ4H 2 O is considered to be the first single molecule magnet (SMM) (Uhrecký et al, 2013;Sessoli et al, 1993). Complexes of manganese are also considered to be important ISSN 2056-9890 in view of the occurrence of an Mn 4 Ca unit in the active site of Photosystem II that catalyses the water-splitting reaction to evolve oxygen in nature (Nocera, 2012).…”