Magnetic and spectroscopic studies on nickel(II) and copper(II) complexes of some neutral tridentate ONS ligands

Abstract

New Schiff base ligands formed from 2-methoxybenzaldehyde and 2,4-dimethoxybenzaldehyde with N-methyl-S-alkyldithiocarbazates and their nickel(II) and copper(II) complexes have been prepared and characterised by elemental analysis and magnetic and spectroscopic measurements. The Schiff bases behave as neutral tridentate chelating agents forming stable nickel(II) complexes of stoichiometry NiLX2•xC2H5OH (L = 2-methoxy- or 2,4-dimethoxybenzaldehyde Schiff bases of N-methyl-S-methyldithiocarbazate; X = I−, SCN−; x = 0, 1). Conductivity, magnetic, and spectral data support an octahedral structure for the nickel(II) complexes. The CuLCl2 complexes were also isolated. Magnetic and spectral evidence are in accord with a chloro-bridged dimeric structure. The chloro-complex of copper(II) with the 2-methoxybenzaldehyde Schiff base displays a room-temperature magnetic moment of 1.81 BM, which remains virtually constant over the temperature range 343–123 K.Hydrated copper(II) chloride promotes complete hydrolysis of the 2,4-dimethoxybenzaldehyde and 2-methoxybenzaldehyde Schiff bases of N-methyl-S-benzyldithiocarbazate with the concomitant formation of copper(II) complexes of the parent N-methyl-S-benzyldithiocarbazate of general formula, Cu(N—SR)Cl2 (R = C6H5CH2—).