Study of precatalyst degradation leading to the discovery of a new Ru0 precatalyst for hydrogenation and dehydrogenation

• Verfasst von: Anaby, Aviel [VerfasserIn]
• Verfasst von: Rominger, Frank [VerfasserIn]
• Verfasst von: Hashmi, A. Stephen K. [VerfasserIn]
• Verfasst von: Schaub, Thomas [VerfasserIn]
• Titel: Study of precatalyst degradation leading to the discovery of a new Ru0 precatalyst for hydrogenation and dehydrogenation
• Verf.angabe: Aviel Anaby, Mathias Schelwies, Jonas Schwaben, Frank Rominger, A. Stephen K. Hashmi, Thomas Schaub
• E-Jahr: 2018
• Jahr: 20 June 2018
• Umfang: 9 S.
• Fussnoten: Im Titel ist die Zahl 0 als Hochzahl dargestellt ; Gesehen am 29.08.2018
• Titel Quelle: Enthalten in: Organometallics
• Ort Quelle: Washington, DC : ACS Publ., 1982
• Jahr Quelle: 2018
• Band/Heft Quelle: 37(2018), 13, Seite 2193-2201
• ISSN Quelle: 1520-6041
• DOI: doi:10.1021/acs.organomet.8b00353
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1580494668

Abstract

The complex Ru-MACHO (1) is a widely used precatalyst for hydrogenation and dehydrogenation reactions under basic conditions. In an attempt to identify the active catalyst form, 1 was reacted with a strong base. The formation of previously unreported species was observed by NMR and mass spectrometry. This observation indicated that complex 1 quickly degraded under basic conditions when no substrate was present. X-ray crystallography enabled the identification of three complexes as products of this degradation of complex 1. These complexes suggested degradation pathways which included ligand cleavage and reassembly, along with reduction of the ruthenium atom. One of the decomposition products, the Ru0 complex [Ru(N(CH2CH2PPh2)3)CO] (5), was prepared independently and studied. 5 was found to be active, entirely additive-free, in the acceptorless dehydrogenation of aliphatic alcohols to esters. The hydrogenation of esters catalyzed by 5 was also demonstrated under base-free conditions with methanol as an additive. Protic substrates were shown to add reversibly to complex 5, generating RuII-hydrido species, thus presenting a rare example of reversible oxidative addition from Ru0 to RuII and reductive elimination from RuII to Ru0.