title: Ammonia Synthesis from a Pincer Ruthenium Nitride via Metal-Ligand Cooperative Proton-Coupled Electron Transfer.
abstract: The conversion of metal nitride complexes to ammonia may be essential to dinitrogen fixation. We report a new reduction pathway that utilizes ligating acids and metal-ligand cooperation to effect this conversion without external reductants. Weak acids such as 4-methoxybenzoic acid and 2-pyridone react with nitride complex [(H-PNP)RuN]+(H-PNP = HN(CH2CH2PtBu2)2) to generate octahedral ammine complexes that are κ2-chelated by the conjugate base. Experimental and computational mechanistic studies reveal the important role of Lewis basic sites proximal to the acidic proton in facilitating protonation of the nitride. The subsequent reduction to ammonia is enabled by intramolecular 2H+/2e-proton-coupled electron transfer from the saturated pincer ligand backbone.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Lindley
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Quinton J
authors.initials: QJ
authors.lastname: Bruch
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Peter S
authors.initials: PS
authors.lastname: White
authors.affiliation: Department of Chemistry, American University of Beirut , Beirut 1107 2020, Lebanon.
authors.forename: Faraj
authors.initials: F
authors.lastname: Hasanayn
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Alexander J M
authors.identifier: 0000-0001-9390-3951
authors.initials: AJM
authors.lastname: Miller