Neutral pyridylmethylamide ligands and their mononuclear copper(II) complexes

Mononuclear copper(II) complexes of a family of pyridylmethylamide ligands HL, HLMe, HLPh, HLMe3 and HLPh3, [HL = N-(2-pyridylmethyl)acetamide; HLMe = N-(2-pyridylmethyl)propionamide; HLPh = 2-phenyl-N-(2-pyridylmethyl)acetamide; HLMe3 = 2,2-dimethyl-N-(2-pyridylmethyl)propionamide; HLPh3 = 2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide], were synthesized and characterized. The reaction of copper(II) salts with the pyridylmethylamide ligands yields complexes [Cu(HL)2(OTf)2] (1), [Cu(HLMe)2](ClO4)2 (2), [Cu(HL)2Cl]2[CuCl4] (3), [Cu(HLMe3)2(THF)](OTf)2 (4), [Cu(HLMe3)2(H2O)](ClO4)2 (5a and 5b), [Cu(HLPh3)2(H2O)](ClO4)2 (6), [Cu(HL)(2,2′-bipy)(H2O)](ClO4)2 (7), and [Cu(HLPh)(2,2′-bipy)(H2O)](ClO4)2 (8). All complexes were fully characterized, and the X-ray structures vary from four-coordinate square-planar, to five-coordinate square-pyramidal or trigonal-bipyramidal. The neutral ligands coordinate via the pyridyl N atom and carbonyl O atom in a bidentate fashion. The spectroscopic properties are typical of mononuclear copper(II) species with similar ligand sets, and are consistent their X-ray structures.

Graphical abstractMononuclear copper(II) complexes of neutral pyridylmethylamide ligands were synthesized and characterized. X-ray structures reveal geometries ranging from four-coordinate square planar to five-coordinate square-pyramidal or trigonal-bipyramidal. The neutral ligands coordinate via the pyridyl N atom and carbonyl O atom in a bidentate fashion.Figure optionsDownload full-size imageDownload as PowerPoint slide