Synthesis of new Cu(II), Ni(II) and Co(II) complexes with a bis-amide ligand functionalized with pyridine moieties: Spectral, magnetic and electrochemical studies

Abstract Three new copper(II), nickel(II) and cobalt (II) dinuclear complexes with a bis-amide ligand derived from tartaric acid have been prepared and characterized. For this purpose, the ligand ( R , R )-(+)-di- N , N ′-methylpyridino-tartramide (dmpt) was synthesized via the classical aminolysis of ( R , R )-(+)-dimethyltartrate with pyridylmethylamine. The molecular structures of the complexes Na[Cu 2 (dmptH −3 )(CO 3 )] · 8H 2 O ( 1 ) and [Ni 2 (dmptH −2 ) 2 ] · 9.75H 2 O ( 2 ) were elucidated by X-ray diffraction, and the complex [Co 2 (dmptH −3 )(μ-OH)] · NaClO 4  · 5H 2 O ( 3 ) by XAS. The crystal structure of ( 1 ) shows that the two metallic centres are in a square planar environment. Each copper(II) is bound to pyridyl and deprotonated amidic nitrogen atoms and to the oxygen atoms of hydroxyl and carbonato groups. In complex ( 2 ), both nickel atoms are in a distorted octahedral environment with an identical set of donors atoms, N 4 O 2 , coming from four nitrogen atoms of two pyridylmethylamido moieties and two oxygen donor atoms of alcohol groups. XAS analysis of complex ( 3 ) allows us to propose a CoN 2 O 4 chromophore, with two nitrogen atoms coming from pyridyl and amidic groups and two bridged oxygen atoms from a deprotonated alcohol group and an hydroxyl group; the hexacoordination is achieved by two water molecules. The spectroscopic, electrochemical and magnetic properties of these complexes were investigated.