Synthesis, crystal structure, and magnetic properties of dinuclear iron(III) complexes with Methoxo Bridges

Abstract

The reaction of stoichiometric amount of FeCl2-4H2O, (2-pyridylmethyl, 3-pyridylmethyl)amine (2,3-pyma) and sodium azide/sodium thiocyanate in methanol under aerobic conditions affords the dinuclear Fe(III) complexes, [(2,3-pyma) (N3)2Fe(μ-OCH3) 2Fe(N3)2(2,3-pyma)]-CH3OH (1) and [(2,3-pyma)(NCS)2Fe(μ-OCH3)2Fe(NCS) 2(2,3-pyma)] (2) in good yield. Two bis-methoxy-bridged diiron(III) complexes are isolated and characterized. The coordination geometries around iron(III) ions in 1 and 2 are the same tetragonally distorted octahedron. The iron(III) ions are coordinated by two nitrogens of a 2,3-pyma, two nitrogens of two azide/thiocyanate ions, and two oxygens of two methoxy groups. Both compounds are isomorphous. The structures of 1 and 2 display the C-H π and/or π-π stacking interactions as well as hydrogen bonding interactions, respectively. Compounds 1 and 2 show significant antiferromagnetic couplings through the bridged methoxy groups between the iron(III) ions in the temperature range from 5 to 300 K (H=-2JS1 S2, J = -19.1 and -13.9 cm-1 for 1 and 2).