Coupling of allenes with μ-alkylidyne ligands in diiron complexes:: Synthesis of novel bridging thio- and aminobutadienylidene complexes

The diiron aminocarbyne complexes [Fe-2{mu-CN(Me)(R)}(mu-CO)(CO)(2)(Cp)(2)](SO3CF3] (R = Xyl, 1a; R = 4-C6H4OMe, 1b; R = Me, 1c; Xyl = 2,6-Me2C6H3) react with allenes of the type CH2=C=CR'R '', in the presence of Me3NO/Et3N, to give the novel butadienylidene complexes [Fe-2{mu-eta(1):eta(3)-C alpha N(R)(Me)-C-beta(H)C gamma C delta(R')(R '')}(mu-CO)(CO)(Cp)(2)] (R = Xyl, R' = R '' = Me, 3a; R = Xyl, R' = Me, R '' = H, 3b; R = Xyl, R' = CO2Et, R '' = H, 3c; R = 4-C6H4OMe, R' = CO2Et, R '' = H, 3d; R = R' = R '' = Me, 3e; R = Me, R' = CO2Et, R '' = H, 3f) in high yields. Analogously, the diiron thiocarbyne complex [Fe-2([mu-CSMe)-(mu-CO)(CO)(2)(Cp)(2)][SO3CF3] (2) reacts with CH2=C=CR'R '', in the presence of Me3NO/Et3N, to afford the compounds [Fe-2{mu-eta(1):eta(3)-C alpha S(Me)C-beta(H)C gamma C delta(R')(R '')}(mu-CO)(CO)(Cp)(2)] (R' = R '' = Me, 4a; R' = CO2Et, R '' = H, 4b; R' = SiMe3, R '' = Me, 4c). Complexes 3-4 exist in solution as mixtures of cis and trans isomers. Compounds 3a and 3e, upon treatment with HSO3CF3, are transformed into the corresponding vinyliminium complexes [Fe-2{mu-eta(1):eta(3)-C-gamma(C delta HMe2)C beta HC alpha N(R)-(Me)}(mu-CO)(CO)(CP)(2)][SO3CF3] (R = Xyl, 5a; R = Me, 5b), in nearly quantitative yields. Conversely, compounds 4a,b undergo methylation (by CH3SO3CF3) at the sulfur to give the cationic complexes [Fe-2{mu-eta(1):eta(3)-C-alpha(SMe2)C-beta(H)C(gamma)C(delta)5(R')(R '')}(mu-CO)(CO)(Cp)(2)][SO3CF3] (R' = R '' = Me, 7a; R' = CO2Et, R '' = H, 7b). Protonation of 3a is not reversible: treating 5a with sodium hydride results in the formation of the 1-metalla-2-amino-cyclopenta-1, 3-dien-5-one species [Fe(Cp)(CO){CN(Me)(Xyl)CHC(CHMe2)C(O)}] (6). The molecular structures of cis-3a, cis-4b, 5a[CF3SO3]center dot CH2Cl2 and 7a[CF3SO3]center dot 0.5CH(2)Cl(2) have been determined by X-ray diffraction studies. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).