ABSTRACTION OF METHYL FROM NEUTRAL FISCHER-TYPE CARBENE COMPLEXES - ANEW SITE FOR NUCLEOPHILIC-ATTACK

Reactions of Fischer-type carbene complexes, M(CO)(5)(C(OMe)Ph) (M = C r, W), with metal carbonyl anions (M'(-) = CpFe(CO)(2)(-), Re(CO)(5)(- ), Mn(CO)(4)PPh(3)(-) Co(CO)(3)PPh(3)(-), CpCr(CO)(3)(-), CpMo(CO)(3) (-)) result in demethylation of the carbene complexes. The products ar e M(CO)(5)C(O)Ph(-) and M'-Me, characterized by infrared and MMR spect roscopy. A slower rate for reaction with W(CO)(5)(C(OEt)Ph) in compari son to the methyl analogue is consistent with nucleophilic attack of t he metal carbonyl anion on the methyl of the methoxy group of the carb ene. This is a new type of nucleophilic attack on a Fischer-type carbe ne.