New Coordination Compounds Derived from Nitrone Ligands: Copper(II) Complexes with 8-Hydroxyquinoline-2-carbaldehyde- and Pyridine-2-carbaldehyde-N-methylnitrones

Abstract

Abstract New copper(II) complexes with 8-hydroxyquinoline-2-carbaldehyde-N-methylnitrone (HL1) (1) and pyridine-2-carbaldehyde-N-methylnitrone (L2) (2) have been synthesized. The crystal structure of compound 1 consists of binuclear molecules Cu2(L1)2(NO3)2 with the oxygen atoms of the hydroxy groups acting as bridges between the copper ions. The nitrone ligand in 1 is coordinated in a tridentate fashion forming five-and six-membered chelate rings, and the copper ions have a square-pyramidal environment with the bridging oxygen atoms in apical positions. In compound 2 Cu(L2)2(NO3)2, the copper atom adopts a distorted octahedral environment with bidentately coordinated nitrone ligands. In both cases the nitrone groups are involved in coordination via the oxygen atom. Compounds 1 and 2 have been studied by EPR, UV-VIS and IR spectroscopy. The free nitrone HL1 has also been studied by X-ray diffraction as well as by IR and UV spectroscopy.