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

Abstract

The reaction of CuCl 2 · 2H 2O 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(κ 3-L)Cl 2]. On the other hand, the reaction of NiCl 2 · 6H 2O with 2 equivalents of L gave an octahedral complex [Ni(κ 3-L) 2] 2+, which was isolated as [Ni(κ 3-L) 2][BF 4] 2 using NH 4BF 4. The complexes have been characterized by elemental analyses, FAB-MS, IR, EPR and electronic spectral studies. Molecular structures of both the [Cu(κ 3-L)Cl 2] ( 1) and [Ni(κ 3-L) 2](BF 4) 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⋯X (X = F, Cl, π) interactions. In complex 2 ortho C–H bond from phenyl rings leads to unexpected C–H⋯π interaction with nickel α,α′-diimine chelate ring. This provides structural support for metalloaromaticity in the chelate ring of complex 2.