Ligand chirality-controlled selective formation of mono- and dinuclear copper complexes

Abstract

Reaction of copper(II) acetate with the ( S)-enantiomer of a tridentate binaphthyl Schiff base ligand, 2-(3,5-dichloro-2-hydroxybenzylideneamino)-2′-hydroxy-1,1′-binaphthyl (H 2L), in methanol afforded mononuclear copper(II) complex [Cu II(HL) 2] (( S, S)- 1) in 52% isolated yield. The same reaction gave dinuclear copper(II) complex [Cu II 2(L) 2] (( R, S)- 2) in 73% isolated yield when racemic-H 2L was used instead of ( S)-H 2L. Both complexes ( S, S)- 1 and ( R, S)- 2 were characterized by elemental analysis, mass spectrometry, and X-ray crystallography. The present work highlights the functioning of ligand chirality as a ‘switch’ for selective formation of mono- and dinuclear metal complexes.