The zwitterionic vinyliminium complex [Fe 2 {μ-η 1 :η 3 -C(R′)C(S)CN(Me)(Xyl)}(μ-CO)(CO)(Cp) 2 ] (2a) (R′=p-Me-C 6 H 4 (Tol), Xyl=2,6-Me 2 C 6 H 3 ) undergoes electrophilic addition at the S atom by HSO 3 CF 3 , MeSO 3 CF 3 , SiMe 3 Cl, BrCH 2 Ph, ICH 2 CHCH 2 affording the complexes [Fe 2 {μ-η 1 :η 3 -C(Tol)C(SX)CN(Me)(Xyl)}(μ-CO)(CO)(Cp) 2 ][Y] (X= H, Y=SO 3 CF 3 , 4a; X=Me, Y=SO 3 CF 3 , 4b; X=SiMe 3 , Y=Cl, 4c; X=CH 2 Ph, Y=Br, 4d; X=CH 2 CHCH 2 , Y=I, 4e).Compound 2a and the corresponding vinyliminium complexes 2b and 2c (R′=CH 2 OH, 2b; R′=Me, 2c) react also with etherated BF 3 leading to the formation of the corresponding S-adducts [Fe 2 {μ-η 1 :η 3 -C(R′)C(SBF 3 )CN(Me)(Xyl)}(μ-CO)(CO)(Cp) 2 ] (R′=Tol, 5a; R′=CH 2 OH, 5b; R′=Me, 5c).In analogous reactions, the zwitterionic vinyliminium complexes undergo S-metalation upon treatment with in situ generated [Fp] + [SO 3 CF 3 ] − [Fp=Fe(CO) 2 (Cp)], leading to the formation of [Fe 2 {μ-η 1 :η 3 -C(R′)C(S–Fp)CN(Me)(Xyl)}(μ-CO)(CO)(Cp) 2 ][SO 3 CF 3 ](R′=CH 2 OH, 6a; R′=Me, 6b; R′=Bu n , 6c).Similarly, zwitterionic vinyliminium containing Se in the place of S also undergo Se-electrophilic addition. Thus, the complexes [Fe 2 {μ-η 1 :η 3 -C(R′)C(SeX)CN(Me)(R)}(μ-CO)(CO)(Cp) 2 ][SO 3 CF 3 ] (R=X=Me, R′=Tol, 7a; R=Xyl, R′=Me, X=Fp + , 7b) are obtained upon treatment of the neutral zwitterionic precursors with MeSO 3 CF 3 and [Fp][SO 3 CF 3 ], respectively.Alkylation at the S or Se atom of the bridging ligand is also accomplished by CH 2 Cl 2 , used as solvent, although the reaction is slower compared to more efficient alkylating reagents. The complexes formed by this route are [Fe 2 {μ-η 1 :η 3 -C(R′)C(E-CH 2 Cl)CN(Me)(R)}(μ-CO)(CO)(Cp) 2 ][X] [E=S, R=Xyl, R′=Tol, X=Cl, 8a; E=S, R=Xyl, R′=Me, X=Cl, 8b; E=Se, R=R′=Me, X=BPh 4 , 8c].Finally, treatment of the zwitterionic vinyliminium complexes with I 2 results in the oxidative coupling with formation of S–S (disulfide) or Se–Se (diselenide) bond. The reactions, performed in the presence of NaBPh 4 afford the tetranuclear complexes [Fe 2 {μ-η 1 :η 3 -C(R′)C(E)CN(Me)(R)}(μ-CO)(CO)(Cp) 2 ] 2 [BPh 4 ] 2 [R=Xyl, R′=CH 2 OH, E=S, 9a; R=Xyl, R′=Me, E=S, 9b; R=Xyl, R′=Bu n , E=S, 9c; R=Xyl, R′=Me, E=Se, 9d; R=Me, R′=Bu n , E=Se, 9e].The molecular structures of 4a, 8c and 9e have been determined by X-ray diffraction studies.