Electron-Transfer Processes in 3,4-Diferrocenylpyrroles: Insight into a Missing Piece of the Polyferrocenyl-Containing Pyrroles Familyстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 марта 2017 г.
Аннотация:3,4-Diiodo-1-(triisopropylsilyl)-1H-pyrrole (1), 3,4-diferrocenyl-1-(triisopropylsilyl)-1H-pyrrole (2), and 3,4-diferrocenyl-1H-pyrrole (3) were prepared and characterized using spectroscopic methods and X-ray crystallography. UV−vis spectra of 2 and 3 were correlated with their density functional theory (DFT)-calculated electronic structures as well as theoretically predicted by the timedependent
(TD) DFT-calculations vertical excitation energies. Redox properties of 2 and 3 were investigated using cyclic voltammetry, differential pulse voltammetry, and spectroelectrochemical approaches. Ferrocene-centered oxidation processes in 2 and 3 were found to be separated by ∼180 and ∼300 mV in DCM/TBAP and DCM/(NBu4)[B(C6F5)4] systems, respectively. Stepwise spectroelectrochemical oxidation of 2 and 3 allowed us to obtain spectroscopic signatures of the mixed-valence [2]+ and [3]+ cations. Hush analysis of the intervalence charge-transfer band in [2]+ and [3]+ is suggestive of class II (in Robin and Day classification) mixed-valence behavior. Electronic structures of neutral and spin-localized/delocalized single-electron oxidized mixed-valence cations of 2,5-di-, 3,4-di-, and 2,3,4,5-tetraferrocenylpyrroles
were investigated by DFT calculations to resolve current uncertainties regarding the first oxidation process of tetraferrocenylpyrrole.