We report that (TMP)Ru(NH3)2 (TMP = tetramesitylporphryin) is a molecular catalyst for oxidation of ammonia to dinitrogen. An aryloxy radical, tri-tert-butylphenoxyl (ArO•) abstracts H atoms from a bound ammonia ligand of (TMP)Ru(NH3)2, leading to the discovery of a new catalytic C-N coupling to the para position of ArO•, forming 4-amino-2,4,6-tri-tert-butylcyclohexa-2,5-dien-1-one. Modification of the aryloxy radical to contain a trityl group at the para position, 2,6-di-tert-butyl-4-tritylphenoxyl radical, prevents C-N coupling and diverts the reaction to catalytic oxidation of ammonia to give N2. We achieve 125(±5) turnovers at 22 °C for oxidation of NH3, the highest reported to date for a molecular catalyst.
Revised: March 19, 2020 |
Published: February 19, 2020
Citation
Dunn P.L., S. Johnson, W. Kaminsky, and R.M. Bullock. 2020.Diversion of Catalytic C-N Bond Formation to Catalytic Oxidation of NH3 Through Modification of the Hydrogen Atom Abstractor.Journal of the American Chemical Society 142, no. 7:3361-3365.PNNL-SA-150204.doi:10.1021/jacs.9b13706