Copper(I) complexes of 2-methoxy-(5-trifluoromethyl-phenyl)-pyridine-2yl-methylene-amine: Impact of phosphine ancillary ligands on luminescence and catalytic properties of the copper(I) complexes

Abstract

Some copper(I) complexes of the type [Cu(L)(PPh3)2]X (X=Cl (1a), CN (1b), ClO4 (1c), BF4 (1d)) and [Cu(L)(dppe)]X (X=Cl (2a), CN (2b), ClO4 (2c) and BF4 (2d)) [where L=2-methoxy-(5-trifluoromethyl-phenyl)-pyridine-2yl-methylene-amine; PPh3=triphenylphosphine; dppe=1,2-bis(diphenylphosphino)ethane] have been prepared and characterized on the basis of elemental analyses, IR, UV–Vis, 1H NMR and 31P NMR spectral studies. The representative complex of the series 1d and 2c are characterized by single crystal X-ray diffraction which reveal that, in each complex the central copper(I) ion assumes the irregular pseudo-tetrahedral geometry. All the complexes display a weak MLCT that varies considerably with phosphine ligands. Quasireversible redox behavior is accounted for all complexes corresponding to Cu(I)/Cu(II) couple and is sensitive to phosphine ligands. All the complexes exhibit blue-green emission originate from intra-ligand charge transfer (ILCT), ligand to ligand charge transfer (LLCT) transitions or mixture of them and vary markedly with the phosphine ligands. The copper(I) complexes with dppe ancillary ligand shows greater activity for the amination of iodobenzene as compared to PPh3 ancillary ligand in the complexes.