Triple Alkyl C–H Bond Activation Mediated by Ruthenium(II): Preparation of Isopropenyl‐Substituted Carbene Complexes

Abstract

Abstract The reaction of [RuCl 2 (cod)] x (cod = 1,5‐cyclooctadiene), 1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene (IPr), tricyclohexylphosphane (PCy 3 ) and KO t Bu in a 1:1:2:1 ratio affords the new alkenyl carbene complex [RuCl(IPr″)(PCy 3 ) 2 ] ( 1 ) in 24 % isolated yield. Triphenylphosphane complex [RuCl(IPr″)(PPh 3 ) 2 ] ( 2 ) was isolated together with the single C–H activated complex [RuCl(IPr′)(PPh 3 ) 2 ] ( 3 ). Complexes 1 and 2 feature a metalated isopropenyl substituent on the IPr″ ligand, which results from the triple C–H activation of an isopropyl group. A stepwise mechanism for the formation of complexes 1 and 2 is proposed.