CO cleavage promoted by acetylide additions to vinyliminium diiron complexes

The vinyliminium complex [Fe2{μ-η1:η3-C(Me)=C(Me)C=N(Me)(Xyl)}(μ-CO)(CO)(Cp)2][SO3CF3] (1; Xyl = 2,6-Me2C6H3) reacts with LiC≡CR [R = C6H4Me = Tol, Ph, H, nBu, SiMe3, C(Me)=CH2] affording the amido-functionalized allylidene complexes [Fe2{μ-κ1(O):η1(C):η3(C)-C(C≡CR)C(Me)C(Me)C(O)N(Me)(Xyl)}(μ-CO)(Cp)2] [R = C6H4Me = Tol, 2; R = Ph, 3; R = H, 4; R = nBu, 5; R = SiMe3, 6; R = C(Me)=CH2, 7] in good yields. Labelling experiments with 13CO-enriched 1 indicate that formation of 2–7 occurs through cleavage of the carbon–oxygen bond of a coordinated CO ligand. The molecular structure of 2 has been determined by an X-ray diffraction study.