Syntheses, structures, electrochemical measurements and magnetic properties of two iron(III) complexes derived from N,N′-o-phenylenebis(3-ethoxysalicylaldimine)

The work in this paper presents syntheses, characterizations, crystal structures, electrochemical measurements and magnetic properties of two iron(III) compounds [FeIIIL(H2O)(MeOH)](ClO4) (1) and [FeIIIL(H2O)2](NO3)·H2O (2) derived from the Schiff base compartmental ligand N,N′-o-phenylenebis(3-ethoxysalicylaldimine) (H2L). The two compounds are characterized by elemental analyses, IR, electrospray ionization mass (ESI-MS positive), UV–Vis spectra and conductance values. The structures of 1 and 2 show that these are mononuclear compounds having the metal ion in the N2O2 compartment. Two mononuclear moieties in both the compounds are self-assembled due to bifurcated hydrogen bonds involving coordinated water molecule and O(phenoxo)/O(ethoxy) oxygen atoms. The neighboring dimeric self-assemblies in 2 are further interlinked due to hydrogen bonds involving coordinated and solvated water molecules and nitrate anions to generate a one-dimensional topology. Variable-temperature (2–300 K) magnetic susceptibility measurements reveal that iron(III) centers in 1 and 2 belong to high-spin state and there exist weak antiferromagnetic interactions (J = −0.25 cm−1 for 1 and −0.20 cm−1 for 2) between the metal centers in the dimeric self-assembly. Cyclic voltammetric and square wave voltammetric studies of the two compounds reveal that compounds 1 and 2 undergo reversible Fe(II)/Fe(III) reduction process at E½ = −312 mV and −311 mV, respectively.