Reactivity of Phosphaalkenes toward Carbene Complexes

Reaction of phosphaalkenes RP=C(NMe 2 ) 2 (R = t -Bu, Me 3 Si), 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-MeC 6 H 4 , 2-MeOC 6 H 4 , M = Cr, W) afforded a mixture of complexes (CO) 5 M{P(R)=C(NMe 2 ) 2 }] and (CO) 5 M{P(R)=C(OEt)Ar}]. The treatment of phosphaalkene HP=C(NMe 2 ) 2 with compound (CO) 5 W=C(OEt)(2-MeOC 6 H 4 )] gives rise to the formation of an ( E / Z )-mixture of (CO) 5 W{P(CH(NMe 2 ) 2 )=C(OEt)(2-MeOC 6 H 4 )}].