USE OF REVERSED-PHASE HPLC FOR DETERMINATION OF THE HYDROLYSIS RATE CONSTANTS OF DICHLORO(1,2-DIARYLETHYLENEDIAMINE)PLATINUM(II) COMPLEXES

The rates of the Pt-Cl hydrolysis reactions for a series of dichloro(1,2-diarylethylenediamine)platinum(II) complexes were measured by means of a reversed-phase h.p.l.c. assay. The compounds were hydrolysed at rates comparable to those published for [PtCl2(en)]. The configuration of the 1,2-diarylethylenediamine ligand (meso versus racem), as well as the type of substituent (i.e. OMe, CN or F) in the para-position of the aromatic rings had only a marginal influence on the rates of hydrolysis; however, the introduction of ortho-chloro substituents onto the aromatic rings markedly slowed the hydrolysis reactions. In contrast to the reported pH-dependency of the hydrolysis rates of cisplatin, changes in proton concentration had no effect on the hydrolysis rates of the title compounds over a pH range of 2.2-7.2. The activation parameters Delta H-not equal and Delta S-not equal of the Pt-Cl hydrolysis rates were comparable to those reported for similar Pt-II compounds.