Probing the stereo‐electronic properties of cationic rhodium complexes bearing chiral diphosphine ligands by 103Rh NMR |
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| Authors: | Amandine Fabrello Chiara Dinoi Lionel Perrin Philippe Kalck Laurent Maron Martine Urrutigoity Odile Dechy‐Cabaret |
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| Affiliation: | 1. CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F‐31077 Toulouse, France;2. Université de Toulouse, UPS, INP, LCC;3. F‐31077 Toulouse, France;4. Université de Toulouse, INSA, UPS, LPCNO (IRSAMC), 135 Avenue de Rangueil, F‐31077 Toulouse, France;5. CNRS, UMR 5215 (IRSAMC), F‐31077 Toulouse, France |
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| Abstract: | 103Rh NMR represents a powerful tool to assess the global electronic and steric contribution of diphosphine ligands on [Rh(COD)(diphosphine)]+ complexes. In the case of DIOP, BINAP and MeDUPHOS, this approach proved to be more informative than classical CO‐stretching frequency measurements. After validation, this method has been extended to a set of seven diphosphines. 103Rh NMR measurements on [Rh(COD)(diphosphine)]PF6 lead to the following order of donor properties: dppe > MeBPE > MeDUPHOS > dppb > DIOP > BINAP > Tol‐BINAP. This trend has been validated by DFT in the case of DIOP, BINAP and MeDUPHOS. In conjunction, 31P NMR chemical shift has been shown to reflect the ring constraints of the Rh‐diphosphine scaffold. This contribution is a step towards a mechanistic investigation of the catalytic hydrogenation of unsaturated substrates by 103Rh NMR and DFT. Copyright © 2010 John Wiley & Sons, Ltd. |
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| Keywords: | 103Rh NMR rhodium complexes diphosphine IR DFT |
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