Acetylide Addition to Bridging Vinyliminium Ligands in Dinuclear Complexes

Abstract

AbstractThe (vinyliminium)diiron complexes [Fe2{μ‐η1:η3‐Cγ(R′)=Cβ(R′)Cα=N(Me)(R)}(μ‐CO)(CO)(Cp)2][SO3CF3] [R = Xyl, R′ = Me (1a); R = Xyl, R′ = Et (1b); R = R′ = Me (1c); R = Me, R′ = Et (1d); R = CH2Ph, R′ = Me (1e); Xyl = 2,6‐Me2C6H3] undergo regio‐ and stereoselective addition by lithium acetylides. Addition of LiC≡CR″ (R″ = Tol, Ph, SiMe3; Tol = 4‐MeC6H4) to trans‐1a occurs at the Cβ atom of the vinyliminium ligand and results in the formation of the bis(alkylidene) complexes cis‐[Fe2{μ‐η1:η2‐C(Me)C(Me)(C≡CR″)CN(Me)(Xyl)}(μ‐CO)(CO)(Cp)2] [R″ = Tol (2a), Ph (2b), SiMe3 (2c)]. The molecular structure of 2a has been determined by X‐ray diffraction. Similarly, the diruthenium complex [Ru2{μ‐η1:η3‐C(Me)=C(Me)C=N(Me)(Xyl)}(μ‐CO)(CO)(Cp)2][SO3CF3] (3) reacts with LiC≡CTol to give the bis(alkylidene) compound[Ru2{μ‐η1:η2‐C(Me)C(Me)(C≡CTol)CN(Me)(Xyl)}(μ‐CO)(CO)(Cp)2] (4). Conversely, 1c and 1d undergo acetylide attack at the Cα atom of the vinyliminium ligand to yield the allylidenecomplexes [Fe2{μ‐η1:η3‐C(R′)C(R′)C(C≡CR″)N(Me)2}(μ‐CO)(CO)(Cp)2] [R′ = Me, R″ = Tol (5a); R′ = Me, R″ = Ph (5b); R′ = Me, R″ = SiMe3 (5c); R′ = Me, R″ = nBu (5d); R′ = Me, R″ = C(Me)=CH2 (5e); R′ = Me, R″ = H (5f); R′ = Et, R″ = Tol (5g); R′ = Et, R″ = Ph (5h); R′ = Et, R″ = SiMe3 (5i); R′ = Et, R″ = C(Me)=CH2 (5j)]. Analogously, the reaction of 1e with LiC≡CPh affords [Fe2{μ‐η1:η3‐C(Me)C(Me)C(C≡CPh)N(Me)(CH2Ph)}(μ‐CO)(CO)(Cp)2] (6). The molecular structure of 5h has been determined by X‐ray diffraction. Finally, 1b, in both its cis and trans forms, undergoes acetylide attack at the Cα atom of the vinyliminium ligand to give the complexes[Fe2{μ‐η1:η3‐C(Et)C(Et)C(C≡CR″)N(Me)(Xyl)}(μ‐CO)(CO)(Cp)2] [R″ = SiMe3 (7a), H (7b)]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)