Rapid-scan time-resolved FT-IR spectroelectrochemistry – Study on the electron transfer of ferrocene-substituted thiophenes

A series of ferrocene-substituted thiophenes, 2-ferrocenylthiophene, 2,5-diferrocenylthiophene and 2,3,5-triferrocenylthiophene have been synthesized. The electron transfer mechanism during redox process of the ferrocenyl complexes was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and rapid-scan time-resolved FT-IR spectroelectrochemistry (RS-TRS FT-IR). Electrochemistry and RS-TRS FT-IR spectroelectrochemistry results indicated the redox process of 2,5-diferrocenylthiophene and 2,3,5-triferrocenylthiophene involved two and three consecutive one-electron steps, respectively. IR absorption peaks arisen from intermediate appearing and disappearing on the experimental time scale in the oxidation and reduction process of 2,5-diferrocenylthiophene and 2,3,5-triferrocenylthiophene were clearly observed by the RS-TRS FT-IR spectroelectrochemistry. A kinetics simulation experiment, based on the results of RS-TRS FT-IR spectroelectrochemistry, was conducted to give the kinetics parameters of 2,5-diferrocenylthiophene.