Electrochemical and EPR spectral investigations of mixed-ligand copper(n) complexes involving 2,2'-bipyridine and aminoacids

Department of Chemistry, University of Allahabad, Allahabad-211 002, India E-mail : dr_krishna_s@yahoo.co.in dr jagdish p@yahoo.co.in Manuscript received 10 August 2004, revised 5 January 2005, accepted 22 March 2005 The redox behaviours of some mixed-ligand copper(II) complexes, viz. [Cu(bipy)(gly)]Cl.1.5H2O (1), [Cu(bipy)(ala)]Cl. 1.5H2O (2), [Cu(bipy)(val)]Cl.3H2O (3), [Cu(bipy)(ser)]Cl.H2O (4) and [Cu(bipy)(IDA)H2O].5H2O (5) have been investigated in 0.1 M NaCIO4 in aqueous medium at glassy carbon electrode using cyclic voltammetry. The cyclic voltammograms of these complexes display a quasi-reversible couple corresponding to Cu2+ /Cu+ redox change with formal potential, E0' = -95 ± 5 mV in the potential range +0.40 to -0.40 V vs SCE. A second irreversible cathodic peak is also observed corresponding to cu+/cu0 in the potential region +0.40 to -0.65 Vat scan rate 50 mV s-1. The EPR spectra of these polycrystalline complexes at room temperature and liquid nitrogen temperature display a single signal with. g values in the range 2.063 to 2.076, which are greater than the free electron g value of 2.0023