Knoevenagel condensation of [NC–CH2C(O)–NH–CH(CO2Et)–S]2 with ferrocenecarbaldehyde and the activation of the σ(C–S) bond of [(η5-C5H5)Fe{(η5-C5H4)–CHC(CN)–C(O)–NH–CH(CO2Et)–CH2–S–}]2 induced by palladium(II)

The results obtained from the Knoevenagel condensation between the aldehydes R–CHO {with R=4-MeO–C6H4, 4-NO2–C6H4, 4-Cl–C6H4, C6H5, 2,4,6-Me3–C6H2 or (η5-C5H5)Fe(η5-C5H4)} and [NC–CH2C(O)–NH–CH(CO2Et)–S]2 under different experimental conditions are reported. These studies have allowed the isolation and characterisation of three optically pure polyamides of general formula [R–CHC(CN)–C(O)–NH–CH(CO2Et)–CH2–S–]2 with R=4-MeO–C6H4 (3a), 4-NO2–C6H4 (3b) or (η5-C5H5)Fe(η5-C5H4) (3f). The reactions of 3f with Na2[PdCl4] or Pd(AcO)2 are also studied. The treatment of Pd(AcO)2 with 3f in a 2:1 molar ratio in refluxing toluene leads to the formation of [(η5-C5H5)Fe{(η5-C5H4)–CHC(CN)–C(O)–NH–C(CO2Et)CH2}] (5f). Electrochemical studies based on cyclic voltammetry of compounds 3f and 5f are also reported.