Synthesis and Electronic Structure of Carbene Complexes Based on a Sulfonyl-Substituted Dilithio Methandiide

The application of a sulfonyl-substituted dilithio methandiide in the synthesis of carbene complexes was examined. In all cases, the metal carbon interaction was found to be highly polar with only small π-contribution. Hence, the stability of these complexes was found to greatly rely on the coordination ability of the side-arms supporting the metal carbon interaction. As such, the sulfonyl moiety allowed the isolation of a carbene complex with the oxophilic zirconium, which is the first of its kind bearing no (bis)phosphonium ligand framework. On the contrary, complexes with the late transition metals ruthenium and palladium were found to be more labile due to the facile decoordination of the sulfonyl moiety. This results in the opening of a reactive coordination site at the metal center and hence in further reactions such as cyclometalation or sulfur transfer from the thiophosphoryl moiety to the carbenic carbon atom.