Highly active mesoionic chalcogenone zinc(ii) derivatives for C–S cross-coupling reactions

Vaddamanu, Moulali and Velappan, Kavitha and Prabusankar, G (2020) Highly active mesoionic chalcogenone zinc(ii) derivatives for C–S cross-coupling reactions. New Journal of Chemistry, 44 (1). pp. 129-140. ISSN 1144-0546

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Abstract

The first mesoionic heavier chalcogenones, L1-L3 [L1 = 1-(2-mesitylene)-3-methyl-4-phenyltriazolin-5-selone; L2 = 1-(2-mesitylene)-3-methyl-4-phenyltriazolin-5-thione; L3 = 1-(benzyl)-2-3(methyl)-4-phenyltriazolin-5-selone], were isolated and characterised. Density functional theory was used to obtain insights into the σ donor and π accepting nature of mesoionic chalcogenones. Using these new ligands, a series of the first zinc(ii) mesoionic chalcogenone complexes were isolated. Three mono nuclear zinc(ii) chalcogenone complexes, [(L1)Zn(Cl)2(HOMe)] (1), [(L2)Zn(Cl)2(HOMe)] (3) and [(L2)Zn(Br)2(HOMe)] (4), and two dinuclear zinc complexes, [(L1)Zn(Br)(μ2-Br)]2 (2) and [(L3)Zn(Br)(μ2-Br)]2 (5), containing mesoionic thione and selone ligands were synthesized and characterised. These new complexes 1-5 represent the first structurally characterized mesoionic chalcogenone supported metal derivatives. Furthermore, all zinc complexes were characterized by thermogravimetric analysis and UV-vis spectroscopy. The solid-state structures of all zinc complexes were determined by single-crystal X-ray diffraction. The catalytic activities of the zinc(ii) complexes in thioetherification reactions were investigated without scrubbing of oxygen. The scope of the catalytic reactions was explored with a wide range of thiophenols and aryl halides. The diaryl thioethers were obtained in very good yield under mild conditions. The present protocol furnishes a synthetic route for the C-S cross-coupling of thiophenols and aryl halides without scrubbing oxygen and moisture. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

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