Reactivity of phosphaalkenes toward carbene complexes

Reaction of phosphaalkenes RP=C(NMe2)(2) (R=t-Bu, Me3Si), featuring an inverse distribution of electron density about the P-C double bond, with Fischer carbene complexes [(CO)(5)M=C(OEt)Ar] (Ar=Ph, 2-MeC6H4, 2-MeOC6H4, M=Cr, W) afforded a mixture of complexes [(CO)(5)M{P(R)=C(NMe2)(2)}] and [(CO)(5)M{P(R)=C(OEt)Ar}]. The treatment of phosphaalkene HP=C(NMe2)(2) with compound [(CO)(5) W=C(OEt) (2-MeOC6H4)] gives rise to the formation of an (E/Z)-mixture of [(CO)(5)W{P(CH(NMe2)(2))=C(OEt)(2-MeOC6H4)}].