Nickel and copper complexes based on tridentate nitrogen donor ligand 2,6-bis-(1-phenyliminoethyl) pyridine: Synthesis, spectral and structural characterization

The reaction of CuCl2 center dot 2H(2)O with 2,6-bis(1-phenyliminoethyl)pyridine (referred hereafter as L) in 1: 1 molar ratio in methanol or acetronitrile at room temperature afforded distorted trigonal-bipyramidal complex [Cu(kappa(3) -L)Cl-2]. On the other hand, the reaction of NiCl2 center dot 6H(2)O with 2 equivalents of L gave an octahedral complex [Ni(kappa(3)-L)(2)](2+), which was isolated as [Ni(kappa(3)-L)(2)][BF4](2) using NH4BF4. The complexes have been characterized by elemental analyses, FAB-MS, IR, EPR and electronic spectral studies. Molecular structures of both the [Cu(kappa(3)-L)Cl-2] (1) and [Ni(kappa(3) -L)(2)](BF4)(2) (2) have been determined by single crystal X-ray analyses. Weak interaction studies on 1 and 2 revealed stabilisation of the crystal packing by inter and intra-molecular C-H center dot center dot center dot X (X = F, Cl, pi) interactions. In complex 2 ortho C-H bond from phenyl rings leads to unexpected C-H center dot center dot center dot pi interaction with nickel alpha,alpha'-diimine chelate ring. This provides structural support for metalloaromaticity in the chelate ring of complex 2. (c) 2007 Elsevier B.V. All rights reserved.