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Catalytic Ammonia Oxidation to Dinitrogen by Hydrogen Atom Abstraction
Author(s) -
Bhattacharya Papri,
Heiden Zachariah M.,
Chambers Geoffrey M.,
Johnson Samantha I.,
Bullock R. Morris,
Mock Michael T.
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201903221
Subject(s) - chemistry , catalysis , cyclooctane , oxidizing agent , ammonia , catalytic cycle , medicinal chemistry , hydrogen atom abstraction , hydrogen , photochemistry , inorganic chemistry , organic chemistry
Catalysts for the oxidation of NH 3 are critical for the utilization of NH 3 as a large‐scale energy carrier. Molecular catalysts capable of oxidizing NH 3 to N 2 are rare. This report describes the use of [Cp*Ru(P t Bu 2 N Ph 2 )( 15 NH 3 )][BAr F 4 ], (P t Bu 2 N Ph 2 =1,5‐di(phenylaza)‐3,7‐di(tert‐butylphospha)cyclooctane; Ar F =3,5‐(CF 3 ) 2 C 6 H 3 ), to catalytically oxidize NH 3 to dinitrogen under ambient conditions. The cleavage of six N−H bonds and the formation of an N≡N bond was achieved by coupling H + and e − transfers as net hydrogen atom abstraction (HAA) steps using the 2,4,6‐tri‐ tert ‐butylphenoxyl radical ( t Bu 3 ArO . ) as the H atom acceptor. Employing an excess of t Bu 3 ArO . under 1 atm of NH 3 gas at 23 °C resulted in up to ten turnovers. Nitrogen isotopic ( 15 N) labeling studies provide initial mechanistic information suggesting a monometallic pathway during the N⋅⋅⋅N bond‐forming step in the catalytic cycle.