Degradation of the Second‐Generation Grubbs Metathesis Catalyst with Primary Alcohols and Oxygen − Isomerization and Hydrogenation Activities of Monocarbonyl Complexes

Abstract Reaction of the second‐generation Grubbs metathesis catalyst RuCl 2 (=CHPh)(H 2 IMes)(PCy 3 ) ( 2 ) (H 2 IMes = 1,3‐dimethyl‐4,5‐dihydroimidazol‐2‐ylidene) with primary alcohols in the presence of a base produced the complexes RuClH(CO)(PCy 3 ) 2 ( 3 ) and RuClH(CO)(H 2 IMes)(PCy 3 ) ( 5 ). When benzyl alcohol was used, the ruthenium phenyl complexes RuClPh(CO)(PCy 3 ) 2 ( 4 ) and RuClPh(CO)(H 2 IMes)(PCy 3 ) ( 7 ) were formed in addition to 3 and 5 . Complex 7 , characterised by an X‐ray structure analysis, was also formed on exposure of 2 to oxygen. The isomerization and hydrogenation activity of 7 was determined and compared with that of 3 and 4 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)