Title
Probing Electronic Communications in Heterotrinuclear Fe−Ru−Fe Molecular Wires Formed by Ruthenium(II) Tetraphenylporphyrin and Isocyanoferrocene or 1,1′-Diisocyanoferrocene Ligands
Author
Victor N. Nemykin, Semyon V. Dudkin, Mahtab Fathi-Rasekh, Andrew D. Spaeth, Hannah M. Rhoda, Rodion V. Belosludov, Mikhail V. Barybin
Year
2015
Journal
Inorganic Chemistry
Abstract
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 X-ray 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(tert-butylisocyano)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/FeIIIcouples, 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.
Instrument
J-720
Keywords
Circular dichroism, Coordination chemistry, Inorganic chemistry