Probing Electronic Communications in Heterotrinuclear Fe–Ru–Fe Molecular Wires Formed by Ruthenium(II) Tetraphenylporphyrin and Isocyanoferrocene or 1,1′-Diisocyanoferrocene Ligandsстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 марта 2017 г.
Аннотация:Two new heterotrinuclear Fe−Ru−Fe complexes of ruthenium(II) tetraphenylporphyrin axially coordinated with a pair of isocyanoferrocene ((FcNC)2RuTPP, 1) or 1,1′-diisocyanoferrocene (([C5H4NC]2Fe)2RuTPP, 2) ligands [Fc = ferrocenyl, TPP = 5,10,15,20-tetraphenylporphyrinato(2−) anion] were synthesized and characterized by UV−vis, magnetic circular dichroism, NMR, and FTIR spectroscopies as well as by
electrospray ionization mass spectrometry and single-crystal Xray diffraction. Isolation of insoluble polymeric {([C5H4NC]2Fe)RuTPP}n molecular wires (3) was also achieved for the first time. The redox properties of the new trinuclear complexes 1 and 2 were probed using electrochemical (cyclic voltammetry and differential pulse voltammetry), spectroelectrochemical, and chemical oxidation methods and correlated to those of the bis(tertbutylisocyano) ruthenium(II) tetraphenylporphyrin reference compound, (t-BuNC)2RuTPP (4). In all cases, the first oxidation process was attributed to the reversible oxidation of the RuII center. The second and third reversible oxidation processes in 1 are separated by ∼100 mV and were assigned to two single-electron FeII/FeIII couples, suggesting a weak long-range iron−iron coupling in this complex. Electrochemical data acquired for 2 are complicated by the interaction between the axial η1-1,1′-diisocyanoferrocene ligand and the electrode surface as well as by axial ligand dissociation in solution. Spectroelectrochemical and
chemical oxidation methods were used to elucidate the spectroscopic signatures of the [1]n+, [2]n+, and [4]n+ species in solution. DFT and time-dependent DFT calculations aided in correlating the spectroscopic and redox properties of complexes 1, 2, and 4 with their electronic structures.