Isolable iron(II)-porphycene derivative stabilized by introduction of trifluoromethyl groups on the ligand framework

Kazuyuki Ito, Takashi Matsuo, Isao Aritome, Yoshio Hisaeda, Takashi Hayashi

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Abstract

Two iron porphycene complexes having four trifluoromethyl groups, chloro-2,7,12,17-tetraethyl-3,6,13,16-tetrakis- (trifluoromethyl) porphycenatoiron(III) [FeIIIClEtio(CF3)4Pc] and its μ-oxo dimer [{FeIIIEtio(CF3)4Pc}2(/U,-Oj], were characterized. The μ,-oxo dimer was easily converted into the monomelic iron(II) complex via the Fe-O bond cleavage in pyridine. This is the first study to obtain a stable iron(ll) species in a series of porphycene iron complexes. The iron(II) species crystallized in the monoclinic system C2/m, and the Fe-Npyridyl (2.007 A) and Fe-Nppyrrolyl (1.958 A) bonds were remarkably short distances among the bispyridine-coordinated iron(II) porphyrins and porphyrinoids. To evaluate the influences of the CF3 substituents and framework structure on the autoreduction, we compared the reactivity of [{FeIIIEtio(CF)4Pc}2(μ-0)] in pyridine with the reference iron porphycene and porphyrins. Autoreduction of [{FemEtio(CF3)4Pc)2(μ-0)] smoothly proceeded at 20°C in pyridine, whereas the reaction of the μ-oxo-bis{2,7,12,17- tetraethyl-3,6,13,16-tetramethylporphycenatoiron(III)} [{Fe IIIEtio(CH3)4Pc}2(μ-0)] was converted into the monomeric iron(III) complex, and the iron(II) species was not available. In contrast, the μ-oxo-bis{l,3,5,7-tetrakis(trifluoromethyl)-2,4, 6,8-tetraethylporphyrinatoiron(III)}[{FeIIIEtio(CF3) 4Por}2(μ-0)] as a structural isomer of [{Fe IIIEtio(CF3)4Pc}2(μ-0)] allowed the autoreduction, although the reaction was very slow and took over one month. These results indicate that the introduction of strong electron-withdrawing groups at the pyrrole β-carbons exhibits a unique reactivity of the iron complex.

Original languageEnglish
Pages (from-to)76-83
Number of pages8
JournalBulletin of the Chemical Society of Japan
Volume81
Issue number1
DOIs
Publication statusPublished - Dec 1 2008

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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