Site‐Selective Supramolecular Complexation Activates Catalytic Ethane Oxidation by a Nitrido‐Bridged Iron Porphyrinoid Dimer

• Published in: Chemistry : a European journal Vol. 25; no. 13; pp. 3369 - 3375
• Main Authors: Mihara, Nozomi, Yamada, Yasuyuki, Takaya, Hikaru, Kitagawa, Yasutaka, Igawa, Kazunobu, Tomooka, Katsuhiko, Fujii, Hiroshi, Tanaka, Kentaro
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-03-2019
• Subjects: Alkanes; Catalysis; Catalysts; Catalytic activity; Chemistry; Complexation; Dimers; Electrochemistry; Electrostatic properties; Ethane; Hydrogen peroxide; Iron; Low temperature; Metal phthalocyanines; Organic chemistry; Oxidation; Perturbation; phthalocyanines; porphyrinoids; supramolecular chemistry
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201805580

Development of supramolecular methods to further activate a highly reactive intermediate is a fascinating strategy to create novel potent catalysts for activation of inert chemicals. Herein, a supramolecular approach to enhance the oxidizing ability of a high‐valent oxo species of a nitrido‐bridged iron porphyrinoid dimer that is a known potent molecular catalyst for light alkane oxidation is reported. For this purpose, a nitrido‐bridged dinuclear iron complex of porphyrin‐phthalocyanine heterodimer 35+, which is connected through a fourfold rotaxane, was prepared. Heterodimer 35+ catalyzed ethane oxidation in the presence of H2O2 at a relatively low temperature. The site‐selective complexation of 35+ with an additional anionic porphyrin (TPPS4−) through π–π stacking and electrostatic interactions afforded a stable 1:1 complex. It was demonstrated that the supramolecular post‐synthetic modification of 35+ enhances its catalytic activity efficiently. Moreover, supramolecular conjugates achieved higher catalytic ethane oxidation activity than nitrido‐bridged iron phthalocyanine dimer, which is the most potent iron‐oxo‐based molecular catalyst for light‐alkane oxidation reported so far. Electrochemical measurements proved that the electronic perturbation from TPPS4− to 35+ enhanced the catalytic activity.
Supramolecular activation: The ethane‐oxidation ability of an oxo species of a nitrido‐bridged iron porphyrinoid dimer was significantly enhanced by site‐selective strong supramolecular complexation of a fourfold rotaxane structure with an additional porphyrin through π–π stacking and quadruple ionic interactions.