Synthesis and reactivity of [PdCl(terpy)]Cl

[PdCl(terpy)]Cl . 3H(2)O has been synthesized both by interaction of [PdCl4](2-) and cis-[Pd(DMSO)(2)Cl-2] with terpy (2,2':6',2-terpyridine). Complex formation of [PdCl(terpy)(1+) with L-cysteine, S-methyl-L-cysteine, and L-methionine was studied as a function of temperature (298-308 K) using of stopped-flow spectrophotometry in methanol-water (95:5 (v/v)). The ionic strength and acidity of the solutions were adjusted to 0.10 mol . dm(-3) with CH3SO3H. The second-order rate constant for the reaction of [PdCl (terpy)](+) with L-cysteine amounts to 9.60 +/- 0.5 M(-1)s(-1). L-Methionine and S-methyl-L-cysteine are unreactive under the same experimental conditions. The entropy of activation is strongly negative, which is compatible with an associative mechanism.