Cp*Ru-allylcarbene complexes by nucleophilic attack of cyclic Cp*Ru-dicarbenes

Phenylacetylene and its derivatives react with Cp*Ru(COD)Cl under formation of the neutral 2,5-bis-substituted dicarbene ruthenacycles chloro-Cp*ruthenacyclopenta-1,3,5-trienes (1a R=phenyl, 1b R=p-bromophenyl). Nucleophilic attack of PMe3 or P(OMe)3 occurs at one α-atom of the ruthenacyclopentatrienes 1 and leads under metal–chlorine bond cleavage to the corresponding Cp*Ru-allylcarbene complexes 2. The X-ray structures and spectroscopic data of the complexes confirm the results.