Heteroligand copper(II) complexes with citric acid and histidine: Ac polarography studies

The formation of three heteroligand copper(II) complexes Cu(H2Citr)2(Hist)x 2- (x = 1, 2, and 3) in the reaction of dicitrate complex Cu(H2Citr)2 2- and histidine in 0.1 M NaClO4 at pH 5.5-6.0 was established by ac polarography. The partial formation constants were found to be β1 = 1 × 105, β2 = 9 × 103, and β3 = 7 × 103 l/mol. Electrochemical reduction of the resulting heteroligand copper(II) complexes at a dropping mercury electrode proceeds stepwise, with the number of reduction steps equal to the number of ligands. © 1998 MAEe cyrillic signK Hayκa/Interperiodica Publishing.