Synthesis, crystal structures and electrochemical properties of Co(II) and Mn(II) complexes with asymmetric bulky BIAN ligands

Abstract

Series of newly designed Co(II) and Mn(II) complexes supported by sterically encumbered asymmetric bis(imino)acenaphthene (BIAN) ligands were synthesized through the reaction of metal dichlorides with the corresponding ligands. The metal complexes were characterized by X-ray crystallography, UV–Vis, FT-IR and NMR spectroscopy. The molecular structures of Co1–Co10 all feature tetrahedral coordination geometry around cobalt. In contrast, the Mn compounds were demonstrated to show much diverse compositions and solid-state structures. By variation of the ligands and solvents used, mononuclear, binuclear or trinuclear manganese complexes could be isolated. Furthermore, the cyclic voltammograms for the Co and Mn complexes show two successive ligand-based single-electron redox processes, and the reduction potentials could be finetuned by changing the electronic property of the para-substituents on the central aryl ring of BIAN N-aryl groups.