Methandiide as a Non-Innocent Ligand in Carbene Complexes: From the Electronic Structure to Bond Activation Reactions and Cooperative Catalysis

The synthesis of a ruthenium carbene complex based on a sulfonyl‐substituted methandiide and its application in bond activation reactions and cooperative catalysis is reported. In the complex, the metal–carbon interaction can be tuned between a RuC single bond with additional electrostatic interactions and a RuC double bond, thus allowing the control of the stability and reactivity of the complex. Hence, activation of polar and non‐polar bonds (OH, HH) as well as dehydrogenation reactions become possible. In these reactions the carbene acts as a non‐innocent ligand supporting the bond activation as nucleophilic center in the 1,2‐addition across the metal–carbon double bond. This metal–ligand cooperativity can be applied in the catalytic transfer hydrogenation for the reduction of ketones. This concept opens new ways for the application of carbene complexes in catalysis. Not so innocent after all: The synthesis of methandiide‐based ruthenium carbene complexes and their application in bond activation reactions is reported. Depending on the co‐ligands, the metal–carbon interaction can be tuned to control reactivity and thus bond activation and dehydrogenation reactions. Thereby, the carbene acts as a non‐innocent ligand supporting these reactions as nucleophilic center. This cooperation can be applied in transfer hydrogenation, thus opening new ways for the application of carbene complexes.