Acetylide Addition to Bridging Vinyliminium Ligands in Dinuclear Complexes

The (vinyliminium)diiron complexes [Fe 2 {μ‐η 1 :η 3 ‐C γ (R′)=C β (R′)C α =N(Me)(R)}(μ‐CO)(CO)(Cp) 2 ][SO 3 CF 3 ] [R = Xyl, R′ = Me ( 1a ); R = Xyl, R′ = Et ( 1b ); R = R′ = Me ( 1c ); R = Me, R′ = Et ( 1d ); R = CH 2 Ph, R′ = Me ( 1e ); Xyl = 2,6‐Me 2 C 6 H 3 ] undergo regio‐ and stereoselective addition by lithium acetylides. Addition of LiC≡CR″ (R″ = Tol, Ph, SiMe 3 ; Tol = 4‐MeC 6 H 4 ) to trans ‐ 1a occurs at the C β atom of the vinyliminium ligand and results in the formation of the bis(alkylidene) complexes cis ‐[Fe 2 {μ‐η 1 :η 2 ‐C(Me)C(Me)(C≡CR″)CN(Me)(Xyl)}(μ‐CO)(CO)(Cp) 2 ] [R″ = Tol ( 2a ), Ph ( 2b ), SiMe 3 ( 2c )]. The molecular structure of 2a has been determined by X‐ray diffraction. Similarly, the diruthenium complex [Ru 2 {μ‐η 1 :η 3 ‐C(Me)=C(Me)C=N(Me)(Xyl)}(μ‐CO)(CO)(Cp) 2 ][SO 3 CF 3 ] ( 3 ) reacts with LiC≡CTol to give the bis(alkylidene) compound[Ru 2 {μ‐η 1 :η 2 ‐C(Me)C(Me)(C≡CTol)CN(Me)(Xyl)}(μ‐CO)(CO)(Cp) 2 ] ( 4 ). Conversely, 1c and 1d undergo acetylide attack at the C α atom of the vinyliminium ligand to yield the allylidenecomplexes [Fe 2 {μ‐η 1 :η 3 ‐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″ = SiMe 3 ( 5c ); R′ = Me, R″ = n Bu ( 5d ); R′ = Me, R″ = C(Me)=CH 2 ( 5e ); R′ = Me, R″ = H ( 5f ); R′ = Et, R″ = Tol ( 5g ); R′ = Et, R″ = Ph ( 5h ); R′ = Et, R″ = SiMe 3 ( 5i ); R′ = Et, R″ = C(Me)=CH 2 ( 5j )]. Analogously, the reaction of 1e with LiC≡CPh affords [Fe 2 {μ‐η 1 :η 3 ‐C(Me)C(Me)C(C≡CPh)N(Me)(CH 2 Ph)}(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 C α atom of the vinyliminium ligand to give the complexes[Fe 2 {μ‐η 1 :η 3 ‐C(Et)C(Et)C(C≡CR″)N(Me)(Xyl)}(μ‐CO)(CO)(Cp) 2 ] [R″ = SiMe 3 ( 7a ), H ( 7b )]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)