Iron complex of a quadruply fused porphyrin: Synthesis, structure and redox properties

Tomoya Ishizuka, Keiyu Komamura, Yuta Saegusa, Shogo Tanaka, Yoshihito Shiota, Kazunari Yoshizawa, Takahiko Kojima

Research output: Contribution to journalArticle

Abstract

An iron(II) complex of a quadruply ring-fused porphyrin (QFP), Fe-1, in which four mesityl groups were introduced at the periphery to improve the solubility in organic solvents, has been newly synthesized and characterized. In the pyridine solution, two pyridine molecules bind to the low-spin FeII center of Fe-1 as axial ligands to make the complex stable even under air. Characterization of Fe-1 was performed using 1H NMR spectroscopy, MALDI-TOF-MS spectrometry and single-crystal X-ray diffraction analysis. The 1H NMR signals of Fe-1 were observed in the diamagnetic region, reflecting the low-spin state of the FeII center. In the differential pulse voltammogram of Fe-1, three oxidation waves and four reduction waves were observed in pyridine; the first oxidation wave at-0.08 V vs. Fc/Fc+ can be ascribed to the oxidation process of the FeII center, FeII/FeIII, and other six waves can be assigned to the redox processes of the QFP ligand. Furthermore, the ESR measurement of 1e-reduced Fe-1 upon controlled-potential bulk electrolysis in pyridine exhibited a signal at g = 2.003 with a well-resolved 45-line hyperfine splitting at room temperature, due to the coupling with four nitrogen nuclei and twelve hydrogen ones of the QFP ligand. This indicates that the ligand radical anion of Fe-1 is stabilized by delocalization of the spin density owing to the peripheral ring fusion and resultant expansion of the π-conjugation.

Original languageEnglish
JournalJournal of Porphyrins and Phthalocyanines
DOIs
Publication statusAccepted/In press - Jan 1 2019

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Porphyrins
Iron
Ligands
Oxidation
Electrolysis
Organic solvents
X ray diffraction analysis
Spectrometry
Nuclear magnetic resonance spectroscopy
Anions
Paramagnetic resonance
Hydrogen
Nitrogen
Fusion reactions
Solubility
Nuclear magnetic resonance
Single crystals
Molecules
pyridine
Oxidation-Reduction

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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Iron complex of a quadruply fused porphyrin : Synthesis, structure and redox properties. / Ishizuka, Tomoya; Komamura, Keiyu; Saegusa, Yuta; Tanaka, Shogo; Shiota, Yoshihito; Yoshizawa, Kazunari; Kojima, Takahiko.

In: Journal of Porphyrins and Phthalocyanines, 01.01.2019.

Research output: Contribution to journalArticle

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AU - Ishizuka, Tomoya

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AU - Saegusa, Yuta

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AU - Shiota, Yoshihito

AU - Yoshizawa, Kazunari

AU - Kojima, Takahiko

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