Room Temperature Activation of Aromatic CH Bonds by Non‐Classical Ruthenium Hydride Complexes Containing Carbene Ligands

Non‐classical ruthenium hydride complexes are promising lead structures for the CH bond activation and functionalization of aromatic compounds. In the present paper, the preparation and crystallographic characterisation of the first organometallic complexes bearing dihydrogen ligands and N‐heterocyclic carbene ligands in the same coordination sphere are described. The mixed phosphine/carbene complex [(IMes)Ru(H)2(H2)2(PCy3)] (IMes=1,3‐dimesityl‐1,3‐dihydro‐2H‐imidazol‐2‐ylidene; 3a) shows a unique reactivity pattern in the inter‐ and intramolecular activation of CH bonds. In particular, complex 3a effects a rapid and remarkably selective intermolecular activation of sp2 CH bonds in simple aromatic compounds at room temperature.