C–H Activation in Diiron Bridging Vinyliminium Ligands: Reaction with CS2 to Form New Zwitterionic Complexes Acting as Organometallic Ligands

The reactions of vinyliminium complexes [Fe2{μ-η1:η3- C(R)=C(H)C=N(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Xyl, R = Me, 1a; R = Xyl, R = Tol, 1b; R = Xyl, R = COOMe, 1c; R = Me, R = Me, 1d; R = Me, R = nBu, 1e; R = p-MeOC6H4, R = Me, 1f; Tol = 4-C6H4Me, Xyl = 2,6-Me2C6H3) with CS2 and NaH resulted in the replacement of CH hydrogen (in the bridging frame) with CS2 to give the corresponding dithiocarboxylate- vinyliminium complexes [Fe2{μ-η1:η3-C(R)=C- (CS2)C=N(Me)(R)}(μ-CO)(CO)(Cp)2] (2a–2f). Analogously, 1a and 1d reacted with NaH and SCNPh to afford the complexes [Fe2{μ-η1:η3-C(R)=C{C(NPh)S}C=N(Me)(R)}(μ-CO)(CO)(Cp)2] (R = Xyl, R = Me, 3a; R = Me, R = Me, 3b), respectively. Complex 2b was methylated at the dithiocarboxylate groupupon treatment with CH3SO3CF3 to yield [Fe2{μ-η1:η3- C(R)=C(CS2Me)C=N(Me)(Xyl)}(μ-CO)(CO)(Cp)2][SO3CF3] (4a). Likewise, the zwitterionic complexes 2d–f underwent addition of the metal fragment [Fe(CO)2Cp]+ at the dithiocarboxylategroup to yield the corresponding triiron complexes [Fe2{μ-η1:η3-C(R)=C(CS2Fp)C=N(Me)(R)}(μ-CO)(CO)(Cp)2]- [SO3CF3] [R = R = Me, 4b; R = Me, R = nBu, 4c; R = p- MeOC6H4, R = Me, 4d; Fp = Fe(CO)2Cp]. In a related reaction with [Pd(CH3CN)2Cl2], 2a binded to Pd through the dithiocarboxylate group as chelating ligand to afford the complex [PdCl2{κ2-(S,S)-2a}] (5). The X-ray structures of 2b, 3a and 4d have been determined.