Variation in coordinative property of two different N2O2 donor Schiff base ligands with nickel(II) and cobalt(III) ions: characterisation and single crystal structure elucidation

Abstract

A nickel(II) and a cobalt(III) complex of two different potentially tetradentate Schiff bases with different binding modes have been synthesised. The nickel(II) complex [NiL1] · CH3OH (1) was formed, on reacting the metal salt with a perfectly symmetrical N2O2 tetradentate Schiff base ligand H2L1, which is the 1:2 condensation product of 1,3-diamino propane and 2-hydroxyacetophenone. The cobalt(III) complex [Co(HL2)3] · (ClO4)3 · H2O (2) was synthesised using an asymmetric N2O2 tetradentate Schiff base ligand HL2 on condensing N,N-dimethyl-1,3-diamino propane with o-vanillin in 1:1 mmol ratio. Although both Schiff bases are N2O2 functionalised, they showed variation in their coordinative property with nickel(II) and cobalt(III) ions. Both the complexes were characterised by IR spectroscopy and cyclic voltammetry and their single crystal structures clearly indicate that 1 is a mononuclear species whereas 2 is a hydrogen-bonded dimer.