Copper(II) and silver(I) complexes with chiral N-substituted aminoacetic acid derivatives containing the natural monoterpenes (+)-3-carene and (–)-α-pinene: Synthesis and structures

Abstract

The complexes [Cu(HL)Cl] · 0.25H₂O (I), [Cu(HL¹)Cl] · 0.5H₂O (II), [Ag(HL)] · 0.5H₂O (III) were obtained; HL^– and (HL¹)^– are the anions of the chiral N-substituted aminoacetic acid derivatives containing the natural monoterpenes (+)-3-carene and (–)-α-pinene, respectively. The µ_eff values for paramagnetic complexes I and II are 1.92 and 1.81 µ_B, respectively. Single crystals of the coordination 1D polymer [Cu(HL)Cl · 2H₂O] _n (IV) were grown. According to the X-ray diffraction data (CIF file CCDC No. 1035219), the crystal structure of complex IV is made up of the zigzag chains [Cu(HL)Cl] _n and water molecules. The coordination polyhedron of the Cu atom is a distorted square pyramid (ClN₂O₂). The anion HL^– acts as a chelating and bridging tetradentate ligand coordinated through the N atoms of the NH and NOH groups as well as through the O atoms of the COO^–groups linking two adjacent Cu atoms together. The IR spectra of complexes I and II also provide evidence for the coordination of the functional COO^–, NOH, and NH groups. In complex III, the coordination sphere of the Ag atom is made up of the O atoms of the COO–group. Complex III shows weak green photoluminescence (λ_max = 530 nm).