Copper(II) Complexes with Chiral Ligands Containing Fragments of Monoterpenoids and Amino Acid Esters

Abstract

Complexes [CuL1Cl2] (I), [CuL2Cl2] · EtOH (II), and Cu2L3Cl4 (III) containing esters of the N-derivatives of optically active amino acids based on (+)-3-carene (L1, L2) and (‒)-α-pinene (L3) are synthesized. The crystal and molecular structures of compounds I and II are determined by X-ray diffraction analyses (CIF files CCDC nos. 1560071 (I), 1560072 (II)). The crystal structure of compound I consists of mononuclear complex molecules. In the structure of compound II, the unit cell contains two crystallographically independent molecules of mononuclear complex [CuL2Cl2] and two EtOH molecules. Ligands L1 and L2 perform the tridentate-chelating function by the N atoms of the NH and NOH groups and by the O atom of the C=O group. In compounds I and II, the coordination polyhedra Cl2N2O of the Cu atoms are trigonal bipyramid. According to the data of IR and electronic spectroscopy, binuclear complex III has similar coordination polyhedra. The experimental values of μeff for compounds I, II, and III at 300 K are 1.93, 1.88, and 2.71 μB. For complex III, the μeff(T) dependence in a range of 2–300 K indicates a weak ferromagnetic exchange interaction.