Iron(III) and Cobalt(III) Complexes with Oxalate and Phenanthroline: Synthesis, Crystal Structure, Spectroscopy Properties and Magnetic Properties

We report herein the synthesis and physicochemical characterization of two mixed-ligand complexes of the following stoichiometric formulae: [Fe(phen) 2 (ox)](NO 3 )⋅2H 2 O (1) and [Co(phen) 2 (ox)](NO 3 )⋅4H 2 O (2) (as phen: 1,10-orthophenanthroline; ox: oxalate dianion). Both compounds have been prepared by slow evaporation at room temperature and characterized by single-crystal X-ray diffraction. They have been characterized by IR and UV–Vis spectra and thermoanalysis (TG and DTA) The structures of these compounds are highly symmetric. Indeed, the two compounds are isomorphous and crystallize in the orthorhombic space group Ibca . In each material, the M III ion has a slightly distorted square bipyramidal environment, coordinated by one oxalate ion and two 1,10-orthophenanthroline ligands. Structural cohesion is established essentially by π – π interactions between the rings of phen groups and intermolecular O–H…O hydrogen bonds connecting the ionic entities and uncoordinated water molecules. Magnetic susceptibility measurements of (1) in the range 5–300 K exhibit paramagnetic behavior at high temperature. However, at low temperature, the magnetic data show the occurrence of weak antiferromagnetic intermolecular interactions between the local spins.