Ligand lability and chirality inversion in Yb heterobimetallic catalysts

Chemistry - A European Journal

Volumn 10, Issue 18, 2004, Pages 4594-4598

  Di Bari, Lorenzo ^a   Lelli, Moreno ^b   Salvadori, Piero ^a  

^a CNR   (Italy)

^b SCUOLA NORMALE SUPERIORE   (Italy)

Author keywords

Chirality; Circular dichroism; Enantioselectivity; Heterometallic complexes

Indexed keywords

CHEMICAL BONDS; NUCLEAR MAGNETIC RESONANCE; SUBSTRATES;

CATALYTIC PROCESSES; CHIRALITY INVERSION; LANTHANOID CATALYSTS; LIGANDS;

CATALYST ACTIVITY;

BINAPHTHOL; IMINE; LANTHANIDE; LIGAND; METAL DERIVATIVE; NAPHTHOL DERIVATIVE; UNCLASSIFIED DRUG; YTTERBIUM;

ADDITION REACTION; ARTICLE; CATALYSIS; CATALYST; CHEMICAL BOND; CHEMICAL REACTION; CHEMICAL STRUCTURE; CHIRALITY; CIRCULAR DICHROISM; COMPLEX FORMATION; DYNAMICS; LIGAND BINDING; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; PROTON NUCLEAR MAGNETIC RESONANCE;

CATALYSIS; IMINES; LIGANDS; MAGNETIC RESONANCE SPECTROSCOPY; METALS, ALKALI; MOLECULAR STRUCTURE; NAPHTHOLS; ORGANOMETALLIC COMPOUNDS; STEREOISOMERISM; YTTERBIUM;

EID: 4744353743     PISSN: 09476539     EISSN: None     Source Type: Journal    
DOI: 10.1002/chem.200400302     Document Type: Article

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7. 31P, which displays a very large chemical shift range. Moreover, owing to the very short through-bond distance, the contact term may be dominant, as previously demonstrated in the case Yb and Pr β-diketonates (F. S. Mandel, R. H. Cox, R. C. Taylor, J. Magn. Reson. 1974, 14, 235-240 and T. A. Gerken, W. M. Ritchey, J. Magn. Reson. 1976, 24, 155-164). For these reasons, the observed LIS provide no reliable indication about the structure of the formed adduct.
8. 31P, which displays a very large chemical shift range. Moreover, owing to the very short through-bond distance, the contact term may be dominant, as previously demonstrated in the case Yb and Pr β-diketonates (F. S. Mandel, R. H. Cox, R. C. Taylor, J. Magn. Reson. 1974, 14, 235-240 and T. A. Gerken, W. M. Ritchey, J. Magn. Reson. 1976, 24, 155-164). For these reasons, the observed LIS provide no reliable indication about the structure of the formed adduct.
9. EXSY spectra is reported in the Supporting Information of reference [3].
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16. 2 must be added for each mmol of complex.
17. Such a small amount of heterochiral species is not observed in the NIR CD spectra, because it is overlapped with the more intense spectra of the prevalent homochiral species.
18. -c.
19. As these samples are prepared from racemic binol, each heterochiral and homochiral species is present with its enantiomer, which, of course, has the same NMR spectrum.
20. 2{(S)-binol}] is responsible for the favored formation of the heterochiral form. The alkali metal ion radius, combined to the nature of the lanthanide should be determinant in favoring this interaction (ref. [101).
21. The proton exchange between the phosphonate and the binol is necessary to get a nucleophilic phosphite (refs. [4,5]).
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