title: System with potential dual modes of metal-ligand cooperation: highly catalytically active pyridine-based PNNH-Ru pincer complexes.
abstract: Metal-ligand cooperation (MLC) plays an important role in catalysis. Systems reported so far are generally based on a single mode of MLC. We report here a system with potential for MLC by both amine-amide and aromatization-dearomatization ligand transformations, based on a new class of phosphino-pyridyl ruthenium pincer complexes, bearing sec-amine coordination. These pincer complexes are effective catalysts under unprecedented mild conditions for acceptorless dehydrogenative coupling of alcohols to esters at 35 °C and hydrogenation of esters at room temperature and 5 atm H2. The likely actual catalyst, a novel, crystallographically characterized monoanionic de-aromatized enamido-Ru(II) complex, was obtained by deprotonation of both the N-H and the methylene proton of the N-arm of the pincer ligand.
authors.affiliation: Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, 76100 (Israel).
authors.forename: Eran
authors.initials: E
authors.lastname: Fogler
authors.forename: Jai Anand
authors.initials: JA
authors.lastname: Garg
authors.forename: Peng
authors.initials: P
authors.lastname: Hu
authors.forename: Gregory
authors.initials: G
authors.lastname: Leitus
authors.forename: Linda J W
authors.initials: LJ
authors.lastname: Shimon
authors.forename: David
authors.initials: D
authors.lastname: Milstein
keywords: dehydrogenation; hydrogenation; metal-ligand cooperation; pincer complex; ruthenium