Synthesis, spectral, electrochemical and magnetic properties of new phenoxo-bridged dicopper(II) complexes derived from unsymmetrical binucleating ligands

New unsymmetrical binucleating ligands 4-bromo-2- [(4-methylpiperazin-1-yl) methyl]-6- [N-(3,5-dimethyl-2-hydroxy-benzyl)-N-methylaminomethyl]phenol (H 2L1) and 4-bromo-2-[(4-methyl-piperazin-1-yl)methyl]-6-[N-( 3,5-dichloro2-h ydroxybenzyl)-N-cyclo-hexylminomethyl] phenol (H2L2) and their copper(II) c omplexes [Cu2L1-2(X)]ClO4, (X=OH, Br, OAc) have been prepared. Spectral, el ectrochemical and magnetic behaviors have been studied. Electrochemical stu dy of the complexes shows two distinct quasireversible redox peaks. (E-pc(1 )=-0.35 to -0.70 V, E-pc(2)=-0.75 to -0.97 V). Variable temperature magneti c susceptibility studies of the complexes show the presence of antiferromag netic interaction between the copper atoms (-2J=69-124 cm(-1)). A compariso n of the electrochemical and magnetic behavior of the complexes derived fro m both the ligands is discussed on the basis of substitutional steric and e lectronic effects. (C) 1999 Elsevier Science Ireland Ltd. All rights reserv ed.