In-Situ Generation of the Benzylidene Complex [Cp(CO)2W=CH(Tol)]+ and its Reactions with Alkynes

Protonation of the carbyne complex Cp(CO)2W=CTol gives transient formation of the benzylidene complex [Cp(CO)2W=CH(Tol)]+ which rapidly reacts with alkynes. The benzylidene ligand couples with PhC≡CPh to form the vinylcarbene complex [Cp(CO)2W=C(Ph)C(Ph)=CH(Tol)]+, 7. This species in turn reacts with BH4 − and with PBun 3 to form the allyl derivatives Cp(CO)2W(η3-HC(Tol)C(Ph)C(X)(Ph) (X=H, Bun 3P+). The complex [Cp(CO)2W(C13H14O)]+, 10, possessing a coordinated naphthol ligand is produced when the protonation of Cp(CO)2W≡CTol is conducted in the presence of MeC≡CMe. The naphthol ligand results from combination of the benzylidene ligand with the alkyne and with a CO ligand. The free naphthol is readily released from complex 10 upon air oxidation, and the naphthol ligand can be reversibly deprotonated to form an allyl complex.