New low-temperature NMR studies establish the presence of a second equatorial

• Verfasst von: Castillo Molina, Dante Alberto [VerfasserIn]
• Verfasst von: Casey, Charles P. [VerfasserIn]
• Verfasst von: Müller, Imke [VerfasserIn]
• Verfasst von: Nozaki, Kyoko [VerfasserIn]
• Verfasst von: Jäkel, Christoph [VerfasserIn]
• Titel: New low-temperature NMR studies establish the presence of a second equatorial
• Titelzusatz: apical isomer of [(R,S)-Binaphos](CO)2RhH
• Verf.angabe: Dante A. Castillo Molina, Charles P. Casey, Imke Müller, Kyoko Nozaki, and Christoph Jäkel
• E-Jahr: 2010
• Jahr: 6 July 2010
• Umfang: 6 S.
• Fussnoten: Gesehen am 03.05.2023 ; Im Titel ist die Zahl 2 nach "CO" tiefgestellt
• Titel Quelle: Enthalten in: Organometallics
• Ort Quelle: Washington, DC : ACS Publ., 1982
• Jahr Quelle: 2010
• Band/Heft Quelle: 29(2010), 15, Seite 3362-3367
• ISSN Quelle: 1520-6041
• DOI: doi:10.1021/om100323q
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1844409422

Abstract

The important enantioselective hydroformylation catalyst [(R,S)-Binaphos](CO)2RhH has been reexamained by low-temperature NMR spectroscopy. Both 1H and 31P NMR spectroscopy at −90 °C allow direct observation of a mixture of two apical−equatorial chelates. The major chelate, 1eq,ap, was shown to have an equatorial phosphine and an apical phosphite. Its structure was unambiguously assigned using low-temperature 31P NMR spectroscopy with selective decoupling of aromatic hydrogens but not of the rhodium hydride, which showed a 225 Hz trans phosphite to RhH coupling. The equilibrium constant for [1eq,ap]/[1ap,eq] was determined over a wide temperature range.