Synthesis, spectroscopic and structural characterization of Co(II), Ni(II) and Cu(II) complexes of substituted 2-pyridyl amine based [N,N] chelating ligand

Abstract

The reaction of N-benzylaminopyridine with the imidoylchloride of N-(2,6-iPr 2C 6H 3)acetamide in the presence of Et 3N affords a new neutral [N,N] chelating ligand, (PhCH 2)N(2-pyridyl)C{(Me)(N-2,6-iPr 2C 6H 3)} (L). The reaction of equimolar quantities of L with Cu(NO 3) 2, CuCl 2 and NiBr 2, respectively, in DCM, acetonitrile and DME yields the corresponding mononuclear complexes L·Cu(NO 3) 2 (1), L·CuCl 2 (2) and L·NiBr 2 (3). Whereas, the reaction of L with CoCl 2·6H 2O leads to the formation of [HL·CoCl 3] (4) with pyridine nitrogen coordinated to cobalt. Solid state structure of L and compounds 1-4 have been investigated by single crystal X-ray structural analysis. The ligand L shows the E-anti arrangement in the solid state and its mononuclear complex 1 shows six coordinated Cu in a quasi square planar geometry with two long distanced donors; complexes 2 and 3 show distorted tetrahedral arrangement of the substituents around metal ions. Interestingly, the solid state structure of complex 4 reveals C-H⋯Cl intra-molecular hydrogen bonding and N-H⋯Cl and C-H⋯Cl inter-molecular hydrogen bonds. These hydrogen bonding interactions in complex 4 facilitate the formation of an extended 2D network structure.