Hydrothiolation of Alkynes Mediated by NHC-Ni Complexes

The sulfur-hydrogen bond addition to alkynes represents a convenient access to vinyl sulfides. Nolan, Beletskaya and co-workers reported a new selective hydrothiolation process induced by homogeneous NHC-Ni complexes. They showed that [(IMes)Ni(Cp)Cl] was effective in catalyzing the reaction of terminal alkynes and various aryl thiols (Equation (10.10)). The process was found highly selective and the classical transfer of two thioaryl groups did not 

From crystallographic data, the authors proposed a catalytic cycle, based on an alkyne insertion into the Ni-S bond and protonolysis of the Ni-C bond by trapping with arylthiol. 

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