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

摘要

New unsymmetrical binuclear copper(II) complexes of the general formula [Cu2L(X)]ClO4, (X = OH, OAc) have been prepared by in situ complexation of the compound 3-[N-methyl-N-(2-hydroxy-3,5-dichlorobenzyl)aminomethyl]-5-bromosalicylald ehyde (mhdab) with various primary amines, copper(II) perchlorate and appropriate sodium salt. Positive ion FAB mass spectral studies of the complexes show the presence of a dicopper core in the complexes. Electronic spectra of the complexes show a broad band for the d-d transition in the region around 635-685 nm. A cyclic voltammetric study of the complexes shows two quasi-reversible reduction waves in the range E-pc(1) = - 0.52 to - 0.86 V and E-pc(2) = - 1.02 to - 1.16 V, and the reduction potentials are sensitive pc pc towards the chemical environment around the copper atoms. Cryomagnetic investigation of the complexes shows a moderately strong antiferromagnetic spin exchange interaction between the two copper(II) ions (- 2J 60-170 cm(-1)). ESR spectra of the complexes show a broad band at room temperature. The electrochemical and magnetic properties of the complexes are compared on the basis of the rigidity and conjugation of the ligands H2L1, H2L2 and H2L3. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 27]