Synthesis, characterization, electrochemical and magnetic study of mixed ligand mono iron and O-methoxy bridged diiron complexes

The complexes cis-[Fe(5,5'-dmbipy)(2)Cl-2]X (X is Cl in 1 and ClO4 in 2 and 5,5'-dmbipy is 5,5'-dimethyl-2,2'-bipyridine) were synthesized as precursors of new diiron complexes. The diiron complex [Fe(5,5'-dmbipy)(NCS)(2)(mu-OCH3)](2) (3) was obtained from the reaction of KSCN with 1 and 2. Complex 3 was obtained from the addition of KSCN to FeCl2 center dot 4H(2)O and then 5,5'-dmbipy. A new binuclear iron(III) complex [Fe(4bt)(NCS)(2)(mu-OCH3)](2) (4) (4bt is 4,4'-bithiazole) has also been synthesized from the reaction of [Fe(4bt)(3)](NO3)(2) with KSCN in a mixture of methanol/acetonitrile solvent. All complexes were characterized by elemental analysis, IR, UV-Vis, and H-1 NMR spectroscopy and their structures were studied by single-crystal X-ray crystallography. The H-1 NMR and magnetic investigation show that both paramagnetic centers in 3 and 4 complexes are coupled by an antiferromagnetic interaction. The electrochemical behavior of complex 3 show Fe-II/Fe-III and Fe-III/Fe-IV redox couples, in which Fe-III/Fe-IV show quasi-reversible redox behaviors in relatively low potential. (C) 2015 Elsevier B.V. All rights reserved.