Bridging vinyliminium- and enaminoalkylidenediiron complexes as organometallic ligands

The SPh-functionalized vinyliminium complexes [Fe2{μ-η1:η3-Cγ(R′)=Cβ(SPh)Cα=N(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3](R = Xyl, R′ = Me, 3a; R = R′ = Me, 3b; R = Xyl, R′ = CH2OH, 3c; R = Me, R′ = CH2OH, 3d; Xyl = 2,6-Me2C6H3; Cp = η5C5H5) react with NaBH4, in thf solution, to afford the corresponding μ-vinylalkylidene complexes [Fe2{μ-η1:η3-Cγ(R′)Cβ(SPh)=Cα(H)N(Me)(R)}(μ-CO)(CO)(Cp)2] (5a–d). This reaction transforms the iminium into an amine group, thereby generating an N-donor functionality. Consequently, the bridging organic framework in 5a–d, which contains S and N donor atoms, can act as an ambidentate ligand toward coordinatively unsaturated metal fragments. In particular, the complexes [Fe2{μ-η1:η3-Cγ(R′)Cβ(SPh)=Cα(H)NMe2}(μ-CO)(CO)(Cp)2] (R′ = Me, 5b; R′ = CH2OH, 5d) react with [PdCl2(CH3CN)2] to give [PdCl2(N,S-5b)] (6a) and [PdCl2(N,S-5d)] (6b), respectively. The molecular structure of 6b has been determined by X-ray diffractometry. In an analogous reaction, compound 5d acts as an “organometallic ligand” for the unsaturated rhodium fragment generated upon treatment of [Rh(NBD)Cl]2 (NBD = norbornadiene) with AgClO4. This reaction affords the trinuclear complex [Rh(NBD)(κ2-N,S-5d)][ClO4] (7). The bridging ligand in the zwitterionic complex [Fe2{μ-η1:η3-Cγ(CH2OH)=Cβ(S)Cα=N(Me)(Xyl)}(μ-CO)(CO)(Cp)2] (2a) contains an OH group in addition to the N and S functionalities. This bridging framework acts as a O,S bidentate ligand and the reaction of 2a with [Ti(Cp)2(CH3CN)2](SO3CF3)2 leads to the formation of the adduct [Ti(Cp)2(κ2-O,S-2a)][SO3CF3]2 (8).