1350472-23-9Relevant academic research and scientific papers
Ferrocenes containing a pendant propargylic chain obtained via addition of propargyl alcohol to μ-vinyliminium ligands in diiron complexes
Busetto, Luigi,Mazzoni, Rita,Salmi, Mauro,Zacchini, Stefano,Zanotti, Valerio
, p. 2667 - 2674 (2012)
The diiron bridging vinyliminium complexes [Fe2{μ- η1:η3-C=N(Me)2C(R′)=C(R″)} (μ-CO)(CO)(Cp)2][SO3CF3] (R′ = H, R″ = SiMe3, 3a; R′ = H, R″ = Tol =4-MeC 6H4, 3b; R′ = Me, R″ = Me, 3c; R′ = SPh, R″ = Me, 3d; R′ = H, R″ = Fc = [Fe(C5H 4)(Cp)], 6e) react with propargyl alcohol (HC≡CCH 2OH), in refluxing toluene, affording the polysubstituted ferrocenes as mixtures of two isomeric forms: [1-NMe2-2-R′-3-R″-5- CH2OCH2C≡CH-Fc] (R′ = H, R″ = SiMe 3, 6a; R′ = H, R″ = Tol, 6b; R′ = Me, R″ = Me, 6c; R′ = SPh, R″ = Me, 6d, R′ = H, R″ = Fc, 6e) and [1-NMe2-2-R′-3-R″-4-CH2OCH2C≡ CH-Fc] (R′ = H, R″ = SiMe3, 7a; R′ = H, R″ = Tol, 7b; R′ = Me, R″ = Me, 7c; R′ = SPh, R″ = Me, 7d) in overall yields of about 55-65%. Formation of the functionalized cyclopentadienyl in the ferrocene products takes place through the assembly of two propargyl units with the bridging vinyliminium ligand: one alkynol is incorporated by a [3 + 2] cycloaddition with the bridging C3 ligand; a second alkynol unit gives rise to a pendant chain through -OH substitution. Investigations show that the substitution step is catalyzed by the parent diiron complex itself or by a mononuclear iron fragment (likely the Fp+ complex). The pendant propargyl chain has been exploited to connect the ferrocene to other molecular fragments: in particular, the reaction of 6a with 4-biphenyl azide, by copper-catalyzed azide-alkyne cycloaddition (CuAAC), leads to the formation of the triazole-functionalized ferrocene [1-NMe 2-2-CH2OCH2-N3(C6H 4Ph)C2H-4-SiMe3-Fc] (12). Moreover, 6a reacts with Co2(CO)8, affording the complex [Co 2{μ-η2-HC≡CR}(CO)6] (13), (HC≡CR = 6a), where the alkyne adopts a η2 coordination to a dicobalt hexacarbonyl fragment. The molecular structure of 7a has been determined by X-ray diffraction studies.
