The μ-aminocarbyne complexes [Fe 2 {μ-CN(Me)(R)}(μ-CO)(CO)(NCMe)(Cp) 2 ][SO 3 CF 3 ] (R=Me, 1a; Xyl, 1b; Xyl=2,6-Me 2 C 6 H 3 ) react with ethynylferrocene to give the corresponding bridging vinyliminium complexes [Fe 2 {μ-η 1 :η 3 -CN(Me)(R)CHC(Fc)}(μ-CO)(CO)(Cp) 2 ][SO 3 CF 3 ] (R=Me, 2a; R=Xyl, 2b). Insertion of the ethynylferrocene in the metal–carbyne bond is regiospecific, and leads to the formation of only one isomer.Complexes 2a and 2b undergo hydride addition (by NaBH 4 ) affording the enaminoalkylidene complex [Fe 2 {μ-η 1 :η 3 -C(H)(N(Me) 2 )CHC(Fc)}(μ-CO)(CO)(Cp) 2 ] (3a) and the bis-alkylidene [Fe 2 {μ-η 1 :η 2 -C(N(Me)(Xyl))CH 2 C(Fc)}(μ-CO)(CO)(Cp) 2 ] (3b), respectively. Upon treatment with NaH, compounds 2a and 2b undergo fragmentation, affording the 1-metalla-2-aminocyclopenta-1,3-dien-5-one complexes [Fe(CO)(Cp){C(N(Me)(R))}CHC(Fc)C(O)}] (R=Me, 4a; R=Xyl, 4b).The molecular structures of 2b, 3b and 4b have been determined by X-ray diffraction studies.