Magnetic, electrochemical and optical properties of a sulfate-bridged Co(ii) imidazole dimer

Abstract

The synthesis, as well as the electrochemical, optical and magnetic properties of a sulfate-bridged Co(II) dimer, [Co₂(DMIM)₄(μ₂-O²,O,O′-SO₄)₂]·2MeCN (DMIM = 1,2-dimethylimidazole) (2), are reported. The crystal structure consists of two distorted pseudo-octahedral Co(II) centres, each ligated by the μ₂-(O-O′-sulfato) and μ₂-(O²-sulfato) bridging modes of the SO₄²⁻ anions. Magnetic studies have identified significant antiferromagnetic coupling between the high spin Co(II) centres, with J = −28 cm⁻¹. Cyclic voltammetry indicated the presence of a quasi-reversible ligand centred oxidation, while the vis-NIR spectrum of 2 revealed complex splitting of the absorption bands due to the tetragonal distortion of the octahedral geometry of the Co(II) centres.