6533b858fe1ef96bd12b5925

RESEARCH PRODUCT

Spectral and structural insights of copper reduction pathways in the system of CuX2-R2S (X=Cl, Br; R=allyl, n-propyl)

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Abstract We have explored the behaviour of Cu(II)/Cu(I) redox couple in the system CuX2-R2S, X = Cl, Br; R = allyl, n-propyl, under anhydrous and anaerobic conditions, thus simulating the reduction half cycle in the copper catalyzed oxidation of thioethers. In doing so, the Cl−Br substitution was critical for tuning the reduction potentials, while the replacement of propyl group by allyl group supported the trapping of oxidation by-product, halogen molecules. It was therefore possible to use the spectrophotometric titration, thereby providing information on the distribution of complex species in acetonitrile solution. The study showed that the trinuclear mixed−valence copper (I-II-II) aggregates play a crucial role in the evolution of the redox process. The crystal structures of mixed-valence phase, [CuICuII2Cl5(dipropylsulfide)2], as well as full-reduced Cu(I) species, [Cu5Br5(dipropylsulfide)3], have been also determined by single crystal X-ray diffraction. The first one is considered as one of crystallographic “snapshots” of an intermediate involved in sulfoxide formation, while the latter represents the end product built from porous chiral networks.