Copper(II) coordination compounds containing chiral functional groups as pendants: Syntheses, crystal structures, and physical properties

Chiral mononuclear copper(II) complexes, [Cu(LR,R)(ClO4)2] (1) and [Cu(LS,S)(ClO4)2] (2) and chiral polymeric compound, [Cu(LS,S)(CrO4)]·6H2O (3) have been synthesized (LR,R/S,S = 1,8-di((R/S)-α-methylbenzyl)-1,3,6,8,10,13-hexaazacyclotetradecane). These compounds were characterized by X-ray crystallography, circular dichroism, and molecular magnetism. The copper(II) ions in 1–3 have a distorted octahedral geometry by coordinating four nitrogens of a macrocyclic ligand in a square planar conformation and two oxygens in the axial positions. 3 exhibits weak antiferromagnetic coupling via the chromate ions within the 1D chain. The circular dichroism (CD) spectrum of 1 has shown a negative and positive peak at 474 and 562 nm, and that of 2 has displayed an enantiomeric pattern. The CD spectrum of 3 appears positive signal above 610 nm.