Coordination Chemistry of the Chiral, Facially Coordinating Tridentate Ligand 1,2-Bis(benzimidazol-2-yl)ethanol with 3d Transition Metals: Coordination Chemistry of the Chiral, Facially Coordinating Tridentate Ligand 1,2-Bis(benzimidazol-2-yl)ethanol with 3d Transition Metals

1,2-Bis(benzimidazol-2-yl)ethanol (1) and its bis-N-methylated derivative (2) act as chiral tridentate facially coordinating ligands capable of binding metals right across the d-series. Octahedral complexes of divalent and trivalent metal ions are synthesised and characterised by X-ray crystallography. Only two of the three possible diastereomers are observed in complexes of the type [M(1,2)(2)] and appear to be close in energy. In complexes of M-II ions, the alcohol function of the ligand stays protonated, but the proton is lost in complexes of M-III ions. Electronic and CD spectra are reported. Slow oxidation of the vanadium(III) complex leads to a mixed valence compound where one ligand has been oxidised.