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Kinetic and thermodynamic study of thiolato and sulfenato Co(III) complexes in water–acetonitrile mixtures

“…A similar hypsochromic shift was observed for [Co(en) 2 cySO] + . The stabilization of Δ t G o [Co(en) 2 amSO] 2+ on changing the solvent from acetonitrile to water 18 shows that the Δ t G o is affected in the same manner, as can be seen from solvatochromic shift (Table V). Δ t G o and solvatochromic shift observed show the significant role of water in solvent–sulfenato ligand interaction.…”

“…In contrast to Δ t G o [Co(en) 2 amS] 2+ , the Δ t G o [Co(en) 2 amSO] 2+ and Δ t G o [Co(en) 2 cyS] + increase steadily over this region and this is due to the presence of hydrophilic group SO in sulfenato and COO − in cyS − ligand, which probably disturbs the composition balance between two microphases. The comparison of Δ t G o values of [Co(en) 2 cyS] + and [Co(en) 2 cySO] + 18 shows the dominance of COO − group in solute–solvent interaction.…”

“…The solubilities and Δ t G o values for Co(III) complexes investigated have already been published 18, but in the present work, Δ t G o values for Co(III) complex ions are recalculated. Instead of acetonitrile, water was used as reference solvent (Fig.…”

Intramolecular hydrogen bonds in thiolato‐, sulfenato‐, and sulfinato‐Co(III) complexes

“…In water–acetonitrile mixtures, the solvation of COO and SO groups by interaction of oxygen, which serves as the donor site for interaction with the acceptor site of the protic solvent molecule, was observed. The transfer Gibbs energies indicate that there is preferential solvation of the COO group 7. But even in the absence of any solvent molecule, there is a possibility for the COO group as well as the SO group to interact with a neighboring proton to form an intramolecular hydrogen bond.…”

“…Cobalt(III) complexes containing coordinated sulfur are useful model systems for studying controlled oxidation 4–6. In previous study 7, we investigated the kinetics of oxidation of thiolato Co(III) complex ions in water–acetonitrile mixtures. These complex ions contain three chelated ligands that form puckered rings around a central cobalt atom.…”