New macrocyclic schiff base complexes incorporating a homopiperazine unit: Synthesis of some Co(II), Ni(II),Cu(II) and Zn(II) complexes and crystal structure and theoretical studies

A new macrocyclic Schiff base ligand, L, was synthesized by condensation reaction of 1,4-bis(2-formylphenyl)homopiperazine and 1,4-diaminobutane in acetonitrile. The Schiff base ligand was characterized by using elemental analyses, FT-IR, H-1, C-13 NMR and mass spectroscopic techniques. The metal (II) complexes [ML], were synthesized from the reaction of MCl2 center dot nH(2)O (M: Co, Ni, Cu and Zn) with Schiff base ligand, L and characterized by elemental analyses and FT-IR. X-ray crystal structure of [CoLCl](+) distorted square pyramidal geometry with an N4Cl core, arising from coordination by the four donor nitrogen atoms from the macrocyclic framework and one Cl atom. It crystallizes triclinic space group, P-1 with a = 7.1777(1) angstrom, b = 11.0357 (2) angstrom, c = 15.1520(2) angstrom, V = 1183.14(3), Z = 2, D-c = 1.556 g cm(-3), mu (MoK alpha) = 0.156 mm(-1). Also, the bonding situation between the [MCl](+) and Ligand (L) fragments in [MLCl]ClO4 (M = Co(II), Ni(II), Cu(II), Zn(II)) complexes were carried out by energy-decomposition analysis (EDA). The results showed that there is an increasing trend in the case of Delta E-elstat of the complexes by changing the M from Co(II) to Zn(II). (C) 2016 Elsevier B.V. All rights reserved.