Spectroscopic and Electrochemical Studies of the Interaction of Some Gold(III) Complexes with Biologically Relevant Thiones

Abstract

The interaction of gold(III) complexes, [Au(cis‐DACH)Cl2]Cl and [Au(cis‐DACH)2]Cl3 complexes (DACH = cis‐1,2‐diaminocyclohexane), with 13C, 15N‐enriched thiourea (Tu) and 1,3‐diazinane‐2‐thione ligands was investigated. The progress of these reactions was monitored by NMR (1H, 13C, and 15N) and UV–vis spectroscopy as well as square wave stripping voltammetry. The kinetic studies of the substitution reactions between the above‐mentioned complexes with thiones in aqueous solutions containing 30 mM KCl, which is used to suppress the hydrolysis of the chloride complexes, were conducted. These reactions were followed under pseudo–first‐order conditions as functions of ligand concentration, pH, and temperature. The activation parameters (ΔH#, ΔS#) were calculated from Eyring plots, and the negative values of ΔS≠ lend support for an associative mechanism. The kinetic data also indicated a relatively higher reactivity of [Au(cis‐DACH)Cl2]Cl than that of [Au(cis‐DACH)2]Cl3 toward the thiones.

Cyclometalated Gold(III) Complexes Bearing DACH Ligands

“…The (1 R ,2 R )-(+)-1,2-diaminocyclohexane (DACH) ligand is featured in the FDA-approved platinum­(II) complex, oxaliplatin, which displays a different spectrum of activity from cisplatin with no cross resistance. , In catalysis, DACH and its derivatives have been employed in the prominent Pd-catalyzed asymmetric allylic alkylation reaction for the construction of stereogenic centers and C–C, C–O, C–S, C–N bond formation. , Whereas the DACH ligand has gained traction, motivated by the outlined successes in the fields of catalysis and medicine, very few gold DACH compounds exist. − Synthesis of diverse gold DACH compounds can reveal structural insights that could lead to a new class of organogold reagents for useful applications. By combining the N-donor DACH ligand and the strong σ-donating character of C, N cyclometalated ligands, distinct gold­(III) structure scaffolds can be obtained.…”

Ni-thiosaccharinate complexes: Synthesis, characterization and DFT studies. Biological properties as superoxide dismutase mimetics and as anti-carcinogenic agents

“…Thionate complexes have been used in a wide range of different applications going from the treatment of rheumatoid arthritis to anti-carcinogenic properties [3]. Coordination chemistry of heterocyclic thiones, usually in their deprotonated form, remains well studied, particularly for their potential biological use [4][5][6][7][8][9]. Some thione-metal complexes present mimetic metalloenzyme active site properties.…”