Redox‐Driven Symmetry Change for Terbium(III) Bis(porphyrinato) Double‐Decker Complexes by the Azimuthal Rotation of the Porphyrin Macrocycles |
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Authors: | Dr Ken‐ichi Yamashita Takayo Yamanaka Naoya Sakata Prof?Dr Takuji Ogawa |
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Institution: | Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Osaka, Japan |
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Abstract: | Molecular structures for three oxidation forms (anion, radical, and cation) of terbium(III) bis(porphyrinato) double‐decker complexes have been systematically studied. We found that the redox state controls the azimuthal rotation angle (φ) between the two porphyrin macrocycles. For TbIII(tpp)2]n (tpp: tetraphenylporphyrinato, n=?1, 0, and +1), φ decreases at each stage of the oxidation process. The decrease in φ is due to the higher steric repulsion between the phenyl rings on the porphyrin macrocycle and the β hydrogen atoms on the other porphyrin macrocycle, which results from the shorter interfacial distance between the two porphyrin macrocycles. Conversely, φ=45° for both TbIII(oep)2]?1 and TbIII(oep)2]0 (oep: octaethylporphyrinato), but φ=36° for TbIII(oep)2]+1. Theoretical calculations suggest that the smaller azimuthal rotation angle of the cation form is due to the electronic interaction in the doubly oxidized ligand system. |
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Keywords: | lanthanides porphyrinoids redox chemistry sandwich complexes structure elucidation |
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