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 [Fe-2{mu-eta(1):eta(3)-C(R`)=C(H)C=N(Me)(R)}(mu-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 [Fe-2{mu-eta(1):eta(3)-C(R`)=C-(CS2)C=N(Me)(R)}(mu-CO)(CO)(Cp)(2)] (2a-2f). Analogously, 1a and 1d reacted with NaH and SCNPh to afford the complexes [Fe-2{mu-eta(1):eta(3)-C(R`)=C{C(NPh)S}C=N(Me)(R)}(mu-CO)(CO)(Cp)(2)] (R = Xyl, R` = Me, 3a; R = Me, R` = Me, 3b), respectively. Complex 2b was methylated at the dithiocarboxylate group upon treatment with CH3SO3CF3 to yield [Fe-2{mu-eta(1):eta(3)-C(R`)=C(CS2Me)C=N(Me)(Xyl)}(mu-CO)(CO)(Cp)(2)][SO3CF3] (4a). Likewise, the zwitterionic complexes 2d-f underwent addition of the metal fragment [Fe(CO)(2)Cp](+) at the dithiocarboxylate group to yield the corresponding triiron complexes [Fe-2{mu-eta(1):eta(3)-C(R`)=C(CS(2)Fp)C=N(Me)(R)}(mu-CO)(CO)( Cp)(2)][SO3CF3] [R = R` = Me, 4b; R = Me, R` = nBu, 4c; R = p-MeOC6H4, R` = Me, 4d; Fp = Fe(CO)(2)Cp]. In a related reaction with [Pd(CH3CN)(2)Cl-2], 2a binded to Pd through the dithiocarboxylate group as chelating ligand to afford the complex [PdCl2{kappa(2)-(S,S)-2a}] (5). The X-ray structures of 2b, 3a and 4d have been determined.