Hydrogen Carbonate Inhibited and Induced Substitution Reactions of Labile Square‐Planar Diethylenetriaminepalladium(II) Complexes

Abstract

The reaction of labile square-planar diethylenetriaminepaIladium(1I) complexes with hydrogen carbonate ion was studied by stopped flow spectrophotometry as a function of [HCOj] and [CI-] and constant [Pd], ionic strength and temperature to investigate the substitution behaviour with a nucleophile capable of affecting the solution pH. The kinetic results significantly deviate from those for normal square-planar substitution behaviour. The reaction comprises two consecutive equilibrations, which have complex kinetics compared to the simple two-term rate law normally encountered, and which represent hydrogen carbonate inhibited and induced substitution reactions, respectively. The suggested mechanism and data treatment account for the observed deviating kinetics and provide alternative ways of obtaining formerly determined aquation and anation rate constants with comparable accuracy, even for complexes too labile to be monitored directly.

Interaction of adenine with dichloro-[1-alkyl-2-(naphthylazo)-imidazole]palladium(II) complexes: kinetic and mechanistic studies

“…Naphthylazoimidazoles (Scheme 1, ii) are chemical analogues to phenylazoimidazoles (Scheme 1, i) but with a higher degree of steric crowding and electron donating ability. Thus, the kinetics and mechanism of the reactions involving Pd(II) complexes [19][20][21][22][23] stimulate us to study the kinetic and mechanistic aspects of palladium(II) complexes of cis-platin analogues. The reaction of DNA bases with Pd(II) complexes of the chelating N,N 0 -donor systems having cis-MCl 2 configuration constitutes a model system that allows exploration of the mechanism of the antitumor activity of the complexes.…”

Kinetic and mechanistic studies on the Pd–Cl cleavage of dichloro‐ [1‐alkyl‐2‐(naphthylazo)imidazole]palladium(II) complexes by 2,2′‐bipyridine

“…Naphthylazoimidazoles (ii) are chemical analogues to phenylazoimidazoles (i) but with a higher degree of steric-crowding and electron-donating ability. The kinetics and mechanism of the reactions involving Pd(II) complexes [23][24][25][26][27][28] stimulates us to study the kinetic and mechanistic aspects of palladium(II) complexes of cisplatin analogues. Heterocyclic compounds are very widely distributed in nature and are very much essential to many biochemical processes.…”

Mechanism of interaction of DNA bases with dichloro‐[1‐alkyl‐2‐(naphthylazo)imidazole]palladium(II) complexes: A cytosine case

“…Naphthylazoimidazoles ( ii ) are chemical analogues to phenylazoimidazoles ( i ) but with a higher degree of steric crowding and electron‐donating ability. The kinetics and mechanism of the reactions involving previously isolated Pd(II) complexes 27–31 stimulates us to study the kinetic and mechanistic aspects of palladium(II) complexes of cisplatin analogues. The reaction of DNA bases with Pd(II) complexes of the chelating N,N′‐donor systems having cis ‐MCl 2 configuration constitutes a model system that allows exploration of the mechanism of the antitumor activity of the complexes.…”