New low-temperature NMR studies establish the presence of a second equatorial: apical isomer of [(R,S)-Binaphos](CO)2RhH
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...
Saved in:
| Main Authors: | , , , , |
|---|---|
| Format: | Article (Journal) |
| Language: | English |
| Published: |
6 July 2010
|
| In: |
Organometallics
Year: 2010, Volume: 29, Issue: 15, Pages: 3362-3367 |
| ISSN: | 1520-6041 |
| DOI: | 10.1021/om100323q |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1021/om100323q
|
| Author Notes: | Dante A. Castillo Molina, Charles P. Casey, Imke Müller, Kyoko Nozaki, and Christoph Jäkel |
| Summary: | 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. |
|---|---|
| Item Description: | Gesehen am 03.05.2023 Im Titel ist die Zahl 2 nach "CO" tiefgestellt |
| Physical Description: | Online Resource |
| ISSN: | 1520-6041 |
| DOI: | 10.1021/om100323q |