Possible Biotransformation Reactions of Polynuclear Pt(II) Complexes

Abstract

The reactions of the two complexes BBR3464 [{trans-PtCl(NH3)2}2{mu-trans-Pt(NH3)2(NH2(CH2)6NH2)2}](4+) and BBR3610 [{trans-PtCl(NH3)2}2{mu-C2H4(NH2(CH2)6NH2)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. 1H 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.

Kinetic and mechanistic investigation into the influence of chelate substituents on the substitution reactions of platinum(II) terpyridine complexes

“…Other systematic studies have also been reported by Romeo, van Eldik, Jaganyi, and their respective coworkers [16,20,27,[37][38][39][40][41][42]. These include the investigation into the influence of the bridging ligand on the substitution behavior of dinuclear Pt(II) complexes [37][38][39], the role of cyclometalation in controlling the rates of ligand substitution at platinum(II) complexes [16] and substitution reactions of analogues of cisplatin [40][41][42], and Pt(II) terpy complexes [20,27] with many biologically relevant nitrogen-and sulfur-donors.…”

Influence of the bridging azine ligand on the rate of ligand substitution in a series of dinuclear platinum(II) complexes

“…However, there is limited information in the literature with regard to the reactivity and thermodynamic properties of the two platinum centers in these types of complexes [38][39][40][41][42][43]. Some data [38,39] suggest that the reactivity and properties of the first platinum center are independent of the state of the second and vice versa.…”

Kinetics and mechanism of substitution reactions of the new bimetallic [{PdCl(bipy)}{μ-(NH2(CH2)6H2N)}{PtCl(bipy)}]Cl(ClO4) complex with important bio-molecules

“…Solution of the aqua complex was prepared by suspending a known quantity of the [{PdCl(bipy)}{l-(NH 2 (CH 2 ) 6 H 2 N)}{PtCl (bipy)}]Cl(ClO 4 ) complex in 0.1 M NaClO 4 and adding 3 equivalents of AgClO 4 (with respect to chloride) [28]. The solution was acidified with HClO 4 to pH 2 (for determination of the pK a values).…”