Coordination Equilibrium of Pd(II)—2,2'-Bipyridyl-3,3'-Dicarboxylic Acid—Aminoacid Ternary Complexes

The stability constants of Pd(BDA)(Aa) ternary complexes have been determined by Potentionmetric pH titration at 25 ℃ with the ionic strength 0.1 mol/L(KNO_3), where BDA=2,2'-bipyridyl-3,3'-dicarboxylic acid, Aa=Alanine,Phenylalanine, Asparatic acid, Asparagine and Glutamine. The relative stability constants of ternary complexes Δlg K, lg X have also been calculated. All the stability constants and the practical values of relative stability constants are bigger than that of expectation. The degree of stability has been discussed from the view of d～pπ electronic effect, electrical counteract and aromatic nucleus stacking.