Deprotonation of μ-Vinyliminium Ligands in Diiron Complexes:  A Route for the Synthesis of Mono- and Polynuclear Species Containing Novel Multidentate Ligands

The Cβ−H hydrogen in the diiron vinyliminium complexes [Fe2{μ-η1:η3-Cγ(R‘)CβHCαN(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Me, 1; R = Bz, 2 (Bz = CH2Ph); R = Xyl, 3 (Xyl =2,6-Me2C6H3)) is easily removed by sodium hydride; different products are consequently formed, depending on the nature of the substituents R and R‘. Thus, deprotonation of [Fe2{μ-η1:η3-C(R‘)CHCN(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Me, R‘ = COOMe, 1a; R = Me, R‘ = Me, 1b; R = Bz, R‘ = COOMe, 2a) yields the tetranuclear complexes [Fe2{μ-η1:η2-C(R‘)CCN(Me)(R)}(μ-CO)(CO)(Cp)2]2 (R = Me, R‘ = COOMe, 4a; R = Me, R‘ = Me, 4b; R = Bz, R‘ = COOMe, 4c). Conversely, treatment with NaH of the vinyliminium complexes [Fe2{μ-η1:η3-C(R‘)CHCN(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Me, R‘ = SiMe3, 1d; R = Me, R‘ = Tol, 1e; R = Bz, R‘ = SiMe3, 2b; R = Bz, R‘ = Tol, 2c (Tol = 4-MeC6H4); R = Xyl, R‘ = SiMe3, 3a; R = Xyl, R‘ = Tol, 3b; R = Xyl, R‘ = Ph, 3c) leads to the selective formation of the corresponding μ-aminocarbyne alkynyl complexes [Fe2{μ-CN(Me)(R)}(μ-CO)(CO)(C⋮CR‘)(Cp)2] (R = Me, R‘ = SiMe3, 5a; R = Me, R‘ = Tol, 5b; R = Bz, R‘ = SiMe3, 5c; R = Bz, R‘ = Tol, 5d; R = Xyl, R‘ = SiMe3, 5e; R = Xyl, R‘ = Tol, 5f; R = Xyl, R‘ = Ph, 5g). Compounds 5c,d react with methyl iodide to give the vinyliminium cations [Fe2{μ-η1:η3-C(R‘)C(Me)CN(Me)(Bz)}(μ-CO)(CO)(Cp)2]+ (R‘ = SiMe3, 6a; R‘ = Tol, 6b). Finally, the reactions of [Fe2{μ-η1:η3-C(R‘)CHCN(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Me, R‘ = Bun, 1c; R = Xyl, R‘ = Me, 3d; R = Xyl, R‘ = COOMe, 3e; R = Xyl, R‘ = CMe2OH, 3f) with NaH afford the 1-metalla-2-aminocyclopenta-1,3-dien-5-one species (R = Me, R‘ = Bun, 7a; R = Xyl, R‘ = Me, 7b; R = Xyl, R‘ = COOMe, 7c; R = Xyl, R‘ = CMe2OH, 7d). The molecular structures of 4a·CH 2 Cl 2 , 4b, 5e, and 7b have been determined by X-ray diffraction studies.