New FeII starting materials: preparation, characterisation and structural features of iron halide complexes with alcohol ligands

The new mononuclear [FeCl2(HOPri)4] (1), polymeric [{Cl3Fe(μ-Cl)Fe(HOPri)4}n] (2) and binuclear [I2Fe(μ-I)2Fe(PriOH)4] (3) iron(II) complexes have been synthesized in high yields in propan-2-ol or toluene/propan-2-ol mixtures at room temperature. Magnetic moment measurements, 57Fe Mössbauer spectroscopy data and the results of semi-empirical quantum mechanical calculations confirmed the high-spin configuration of the iron(II) centres, which were shown to be four- and/or six-coordinate by single crystal X-ray diffraction analyses. Intermolecular hydrogen bonding was observed in the solid state structure of 1, intramolecular interactions in 2, while both intra- and intermolecular association was seen in 3. Long iron–(μ-halide) bonds suggest the possibility of complex dissociation in solution and facile ligand substitution in 2 and 3.