Mechanistic Aspects of Ligand Substitution on the Hydroxopentaaquarhodium(III) Ion in Aqueous Solution by Sulfur‐Containing Bioactive Ligands

Abstract

The kinetics of the interactions between three sulfur-containing ligands, thioglycolic acid, 2-thiouracil, glutathione, and the title complex, have been studied spectrophotometrically in aqueous medium as a function of the concentrations of the ligands, temperature, and pH at constant ionic strength. The reactions follow a two-step process in which the first step is ligand-dependent and the second step is ligand-independent chelation. Rate constants (k 1 ß10 −3 s −1 and k 2 ß10 −5 s −1 ) and activation parameters (for thioglycolic acid:= −105 ± 3 J K −1 mol −1 ) were calculated. Based on the kinetic and activation parameters, an associative interchange mechanism is proposed for the interaction processes. The products of the reactions have been characterized from IR and ESI mass spectroscopic analysis.

Kinetic and Mechanistic Investigations on Some N,N‐Chelated Pt(II) Oxalate Complexes with Some “S” Containing Biorelevant Ligands at Physiological Condition

“…The anticancer activity of cisplatin, [cis‐Pt(NH 3 ) 2 Cl 2 ], opened novel perspectives for other types of chemotherapeutics . Still today, it is one of the most widely used drugs in the world, although its golden therapeutic activity is accompanied with rigorous side effects and the development of resistance . A wide variety of platinum(II) complexes have been synthesized and tested for antitumor activity, resulting in the identification of additional potentially active antitumor drugs in an attempt to improve the toxicity profile and particularly to design a drug that is able to overcome resistance .…”

“…± 0.01 3.03 ± 0.01 4.05 ± 0.01 6.03 ± 0.02 11.01 ± 0.0130 2.41 ± 0.013.64 ± 0.01 4.80 ± 0.02 7.22 ± 0.01 12.12 ± 0.01 35 2.98 ± 0.01 4.41 ± 0.01 6.03 ± 0.01 8.89 ± 0.01 14.97 ± 0.01 40 3.78 ± 0.01 5.60 ± 0.01 7.62 ± 0.01 11.43 ± 0.01 19.03 ± 0.01 45 4.91 ± 0.01 7.39 ± 0.01 9.78 ± 0.02 14.80 ± 0.02 24.62 ± 0.01 L 4 25 1.02 ± 0.01 1.53 ± 0.01 2.11 ± 0.02 3.02 ± 0.03 4.99 ± 0.02 30 1.26 ± 0.01 1.84 ± 0.01 2.61 ± 0.01 3.74 ± 0.01 6.44 ± 0.02 35 1.60 ± 0.01 2.47 ± 0.02 3.12 ± 0.04 4.81 ± 0.04 7.96 ± 0.02 40 2.13 ± 0.02 3.23 ± 0.02 4.31 ± 0.04 6.29 ± 0.05 10.69 ± 0.04 45 2.91 ± 0.02 4.36 ± 0.03 5.75 ± 0.02 8.78 ± 0.04 14.61 ± 0.02 L 5 25 0.56 ± 0.01 0.86 ± 0.01 1.16 ± 0.01 1.73 ± 0.01 2.86 ± 0.01 30 0.73 ± 0.01 1.12 ± 0.01 1.51 ± 0.01 2.14 ± 0.06 3.69 ± 0.04 35 0.96 ± 0.01 1.44 ± 0.01 1.87 ± 0.03 2.93 ± 0.02 4.85 ± 0.04 40 1.33 ± 0.01 1.96 ± 0.04 2.69 ± 0.05 4.06 ± 0.04 6.73 ± 0.06 45 1.91 ± 0.01 2.81 ± 0.02 3.82 ± 0.05 5.66 ± 0.02 9.67 ± 0.03 [Complex (2)] = 2 × 10 −4 mol dm −3 , pH 7.4, μ = 0.1 mol dm −3 NaClO 4 . IL) with an accuracy of ±0.01 units.…”