Thermodynamics of the CuII μ‑Thiolate and CuI Disulfide Equilibrium: A Combined Experimental and Theoretical Study
journal contributionposted on 18.08.2014 by Erica C.M. Ording-Wenker, Martijn van der Plas, Maxime A. Siegler, Sylvestre Bonnet, F. Matthias Bickelhaupt, Célia Fonseca Guerra, Elisabeth Bouwman
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The redox equilibrium between dinuclear CuII μ-thiolate and CuI disulfide structures has been analyzed experimentally and via DFT calculations. Two new ligands, L2SSL2 and L4SSL4, and their CuII μ-thiolate and CuI disulfide complexes were synthesized. For L2SSL2, these two redox-isomeric copper species are shown to be in equilibrium, which depends on both temperature and solvent. For L4SSL4 the μ-thiolate species forms as the kinetic product and further evolves into the disulfide complex under thermodynamic control, which creates the unprecedented possibility to compare both species under the same reaction conditions. The energies of the μ-thiolate and disulfide complexes for two series of related ligands have been calculated with DFT; the results rationalize the experimentally observed structures, and emphasize the important role that steric requirements play in the formation of the CuII thiolate structure.