Design and synthesis of new functional compounds related to ferrocene bearing heterocyclic moieties: A new approach towards electron donor organic materials

The synthesis of heterocyclic systems incorporating more than one ferrocene unit was shown to be a facile and convenient route for the synthesis of new ferrocene-heterocycles. Hydrazide 2 was prepared and cyclized to oxadiazole, triazole, and pyrazole using the procedures described in this context with good yields. A pyrazolone derivative could not be obtained and instead a hydrazone derivative 17 was isolated. Hydrazide 2 was condensed with aromatic aldehydes and ferrocene-1,1′-dicarbaldehyde derivatives to give the corresponding hydrazones 11a–c and dihydrazones 12, 14 and 18 in high yields. Cyclic voltammetry (CV) of the selected ferrocene-heterocycles 8 and 9 was studied comparing with the parent ferrocene and acetylferrocene. The CV of the compound 8 revealed an additional, quasireversible, one-electron oxidation wave at 849 mV, corresponding to the second ferrocene unit connected to the oxadiazole ring through the SCH2CO spacer.