THE HYDROLYSIS PRODUCTS OF CIS-DICHLORODIAMMINEPLATINUM(II) .3. HYDROLYSIS KINETICS AT PHYSIOLOGICAL PH

The rate of hydrolysis of cis-PtCl2(NH3)2 has been measured in non-buffered aqueous solution (I = 0.2 M NaClO4; T = 45.0 °C) at constant pH over the range pH = 4.0-8.5 using a combined pH-stat/ spectrophotometric technique. The hydrolysis rate at pH = 7.4 (T = 45.0 °C) was also determined with [Cl-] = 0.0-0.1 M (I = 0.2 M; NaCl, NaClO4). At the end of each kinetic run, the resulting solution was made 0.2 M in Cl- by the addition of NaCl and the reverse (anation) reaction was monitored, again under constant pH conditions. A knowledge of the complete pH-rate profile, with and without added chloride ion, allows current models for the hydrolysis of cis-PtCl2(NH3)2 under physiological conditions, to be tested. cis-Pt(NH3)2(OH2)22+ is considered to be the least important of all the potential hydrolysis products available to bind to replicating DNA at pH = 7.4. © 1990.