Correlation between kinetic and thermodynamic complex-formation constants for the interaction of bis(amine)palladium(II) with inosine, inosine 5′-monophosphate and guanosine 5′-monophosphate

Abstract

The complex-formation equilibria of [Pd(amine)Cl₂](amine =N,N,N,′N′-tetramethyl- or N,N,N,′N′-tetraethyl-ethane-1,2-diamine) with inosine, inosine 5′-monophosphate, guanosine and guanosine 5′-monophosphate were investigated at different temperatures using a potentiometric technique. The stepwise formation constants of the complexes formed in solution were calculated using the non-linear least-squares program MINIQUAD 75. The mode of binding of the DNA unit to the palladium(II) complexes is discussed. Comparison of the potentiometric results with corresponding data obtained from kinetic measurements indicates that atom N⁷ constitutes the binding site in acidic media and N¹ in basic media. The concentration distribution of the various complex species was evaluated as a function of pH.