MECHANISTIC INFORMATION ON THE REACTION OF MODEL PALLADIUM(II) COMPLEXES WITH PURINE NUCLEOSIDES AND 5'-NUCLEOTIDES IN REFERENCE TO THE ANTITUMOR-ACTIVITY OF RELATED PLATINUM COMPLEXES

The reaction of Pd(Me,en)Cl2 (Me4en=NNN',N'-tetramethylethylenediamine) with inosine and 5'-inosine monophosphate was studied as a function of chloride concentration and pH. Evidence for the formation of a 1:1 complex with these nucleophiles is presented, and the kinetic data indicate that Pd(Me4en)(Cl)H2O+ is the only reactive species under the selected experimental conditions. The results are compared to earlier data for the reactions of Pd(R4en)(H2O)22+ (R = H, Me, Et) with a series of nucleosides and 5'-nucleotides. The dependencies studied in this investigation allow some tentative extrapolations to conditions relevant for the antitumor activity of related Pt(II) complexes.