Synthesis, crystal structure and electronic property of a tetraoxolene bridged dinuclear cobalt(II) complex with bipyridyl blocking ligand

Abstract

The design of molecule-based systems displaying tuneable optical and/or magnetic properties under external perturbations has received a considerable interest because of their potential applications in high-performance molecule-based electronic devices, switches, sensors, and displays. Several valence tautomeric tetraoxolene bridged dinuclear cobalt complexes with tetradentate terminal ligands have been synthesized in this regard, but none was reported with bidentate terminal ligand. In order to increase the scope in this field, a new tetraoxolene bridged dinuclear cobalt(II) complex with three different lattice solvate molecules [Co2(bpy)4(DHBQ2−)](BPh4)2·2CH3COCH3 (1(BPh4)2·2CH3COCH3), [Co2(bpy)4(DHBQ2−)]·(BPh4)2·2MeCN (1(BPh4)2·2CH3CN) and [Co2(bpy)4(DHBQ2−)]·(BPh4)2·2DMF (1(BPh4)2·2DMF), where bpy is 2,2-bipyridine and DHBQ2− is deprotonated 2,5-dihydroxy-1,4-benzoquinone, have been reported. Their crystal structures were determined by single-crystal X-ray diffraction study. In the complex cation [Co2(bpy)4(DHBQ2−)]2+, cobalt(II) centers are hexa-coordinated by four nitrogen atoms from two bipyridine ligands and two oxygen atoms from dinegative tetraoxolene ligand which bridges two cobalt(II) ions in a bis-bidentate fashion. An extensive effort has been made to visualize the noncovalent interactions in the solid state. Electrochemical studies were also carried out to realize the electronic flexibility in these systems.