Kinetics and mechanism of the ligand substitution reaction of di-μ-hydroxobis(bipyridyl)dipalladium(II) ion with thiourea in aqueous solution

Abstract

The kinetics of the interaction between thiourea and the title complex has been studied spectrophotometrically in aqueous medium as a function of nucleophile concentration, temperature and pH at constant ionic strength. The reaction is a two-step process in which the first step is ligand dependent, but the second step is ligand independent and is assigned to ring closure. The rate and activation parameters, conductivity studies and IR data were used to deduce a plausible mechanism.

PdII–PdII bonding interaction in dinuclear PdII complex with non-macrocyclic (O&N) chelates: Characterization, kinetics and DFT study

“…S12). Literature reports [61][62][63][64][65][66] indicate that more negative (large) values of DS -is characteristic of an associative substitution mechanism for Pd II and Pt II complexes [67]. The enthalpy of activation (DH -) for both the steps were in fair agreement with those found for related Pd II complexes with subsequent diimine ligands.…”

A colorimetric Boolean INHIBIT logic gate for the determination of sulfide based on citrate-capped gold nanoparticles

“…With a pK a of 2.0, TU remains in the neutral form from pH ¼ 2 to pH ¼ 10. 27 Therefore, the adsorption of TU on the surface of AuNPs results in signicantly reduced overall surface charges and increased van der Waals attractive force among nanoparticles, promoting the aggregation of AuNPs. In our experiment, it was found that urea, which is structurally similar to TU, could not induce the aggregation of AuNPs, revealing that S atom rather than amino groups of TU plays a key role in the interaction between TU and AuNPs.…”