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

The first mesoionic heavier chalcogenones, L 1 -L 3 [ L 1 = 1-(2-mesitylene)-3-methyl-4-phenyltriazolin-5-selone; L 2 = 1-(2-mesitylene)-3-methyl-4-phenyltriazolin-5-thione; L 3 = 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 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, [( L 1 )Zn(Cl) 2 (HOMe)] ( 1 ), [( L 2 )Zn(Cl) 2 (HOMe)] ( 3 ) and [( L 2 )Zn(Br) 2 (HOMe)] ( 4 ), and two dinuclear zinc complexes, [( L 1 )Zn(Br)(μ 2 -Br)] 2 ( 2 ) and [( L 3 )Zn(Br)(μ 2 -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. Mesoionic heavier chalcogenone complexes of zinc( ii ) have been isolated and utilized as catalysts in C-S cross coupling reactions between thiophenols and aryl halides under convenient reaction conditions.