Synthesis of copper(II) and nickel(II) complexes using compartmental ligands: X-ray, electrochemical and magnetic studies

Abstract

Acyclic dicompartmental ligands suitable for the complexation of transition-metal ions which can form mononuclear, homo- or heterodinuclear complexes have been synthesised. The mononuclear complexes ML1 (M = Cu, Ni) where L1 = N,N′-bis[2-hydroxy-3-(morpholino-1-ylmethyl)-5-methylbenzyl] alkyldiimine (alkyl = ethylene, L1a; propylene, L1b; butylene, L1c; triethylenetetraamine, L1d); ML2 (M = Cu, Ni) where L2 = N,N′-bis[2-hydroxy-3-(morpholino-1-ylmethyl)-5-methylbenzyl] alkyldiamine (alkyl = ethylene, L2a; propylene, L2b); and ML3 (M = Cu, Ni) where L3 = N,N′-bis[2-hydroxy-3-(morpholino-1-ylmethyl)-5-bromobenzyl]alkyldiimine (alkyl = ethylene, L3a; propylene, L3b; butylene, L3c) have been synthesised and characterised by C, H, N analysis, IR, electronic and ESR spectra. The complexes CuH2L1a (1), CuH2L2a (4), NiH2L1a (9) and NiH2L1d (12) have been analysed by X-ray crystallography. Complexes 1 and 4 have square pyramidal geometry. The coordination geometry around the metal ion in complex 9 is square planar and in complex 12 it is octahedral. Electrochemical studies of the complexes show a single quasi-reversible electron transfer process at the negative potential region. For copper complexes (1-8) Epc= - 1.10 to - 0.70 V, for nickel complexes (9-12) Epc= - 1.0 to - 0.85 V. Copper complexes show a magnetic moment value of μcff = 1.70-1.75 BM. The square planar nickel complexes are diamagnetic whereas the nickel complex (12) with octahedral structure has a magnetic moment value of 3.12 BM. © 2001 Published by Elsevier Science Ltd.