The reactions of the two complexes BBR3464 [{trans-PtCl(NH3)(2)}(2){mu-trans-Pt(NH3)(2)(NH2(CH2)(6)NH2)(2)}](4+) and BBR3610 [{trans-PtCl(NH3)(2)}(2){mu-C2H4(NH2(CH2)(6)NH2)(2)}](4+) and the corresponding diaqua complexes with the nucleophiles thiourea (tu) and L-methionine (L-Met), were investigated under pseudo-first-order conditions as a function of concentration and temperature, using UV-vis spectrophotometric and stopped-flow techniques. H-1 NMR spectroscopy was used to follow the stepwise substitution of the chloro ligands by guanosine-5'-monophosphate under second-order conditions. For the sulfur donor containing nucleophiles (tu and L-Met), a second reaction step, the displacement of the labilized amine chain linker, as a result of the strong trans-effect of tu and L-Met, was found. The activation parameters for all reactions studied suggest an associative substitution mechanism. The displacement of the chain linker by S-donor nucleophiles illustrates the limit of application of polynuclear complexes with monodentate aliphatic amine bridges and primary ammines, in agreement with previous studies reported in the literature.