Addition of Alkynes to Zwitterionic µ-Vinyliminium Diiron Complexes: New Selenophene (Thiophene) and Vinyl Chalcogenide Functionalized Bridging Ligands

Zwitterionic vinyliminium complexes [Fe2{u-C(R’)C(E)CN(Me)(R)}(m-CO)(CO)(Cp)2][SO3CF3] (R = R’ = Me, E = Se, 1a; R = Xyl R’ = Tol, E = Se, 1b; R = Xyl, R’ = Tol, E = S, 2a; R = Xyl, R’ = Tol, E = S, 2b; Tol = 4-MeC6H4, Xyl = 2,6-Me2C6H3), undergo alkyne addition by different reaction modes. Complexes 1a and 2a undergo 1,3 dipolar cycloaddition with alkynes [HCCCO2Me, and C2(CO2Me)2], affording new 1-(2-amino)-seleno(thio)phene-alkylidene diiron complexes. The hemilabile character of the bridging ligand in 3a is investigated by reaction with CNBut, which replace NMe2 coordination affording 5. Complexes 2a, 2b react with two equivalents of HCCCO2Me, leading to the formation in formation of 6a,b. Finally, complexes 1b, 2a and 2b react with different alkynes, in the presence of NH4PF6, affording the vinyl sufide and vinyl selenide vinyliminium complexes 7a-c, 8a-b. The molecular structures of 3a, 5, and 6b have been elucidated by X-ray diffraction.