1 / 15

Isoelectronic BN Substitution for C 2 in Phosphine Ligands

Isoelectronic BN Substitution for C 2 in Phosphine Ligands. Triphenylphosphine. DuPhos. Dppe. Jonathan Bailey. Why study P-B ligands?. ?. P-O. P-C. P-B. P-N. P-F. electronegativity. Pringle Angew . Chem. Int. Ed. 2012 , 51. Phosphinoboranes vs. boryl phosphines.

oliana
Télécharger la présentation

Isoelectronic BN Substitution for C 2 in Phosphine Ligands

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Isoelectronic BN Substitution for C2 in Phosphine Ligands Triphenylphosphine DuPhos Dppe Jonathan Bailey

  2. Why study P-B ligands? ? P-O P-C P-B P-N P-F electronegativity Pringle Angew. Chem. Int. Ed. 2012, 51 Phosphinoboranes vs. borylphosphines ‘Phosphinoborane’ ‘Boryl Phosphine’ Examples of P-B containing ligands Nöth, 1992 Weller, 2013 Bourissou, 2012 Buchwald, 2012

  3. B-N substituted aryl ligands Initial targets vs. vs. Liu,2009 7 steps, 10% yield Dewar, 1958 Piers, 2007 Need a milder source of phosphorus

  4. B-Cl + P-Si exchange B-Cl + P-Si → B-P + SiCl? Noeth,Chem. Berichte1965, 98, 352 ≡ Advantages: • Mild conditions • No work-up needed • NH - group tolerant

  5. Electronic Properties ν(CO) = 1942 cm-1 ν(CO) = 1940 cm-1

  6. Carbon analogues vs P P

  7. Diisopropyl ligands ν(CO) = 1940 cm-1 ν(CO) = 1953 cm-1 Electron donating Electron withdrawing 1939 cm-1 Buchwald 2015 cm-1 Pringle PPh3 PCy3 1940 cm-1 1943 cm-1 1979 cm-1

  8. Phobane ligands ν(CO) = 1942 cm-1 ν(CO) = 1951 cm-1 Substituting C-C for B-N renders the ligand much more electron donating > Why? σ-donation stronger for B-N

  9. DFT calculations ≈ 90° ≈ 180° 1.993 Å 1.941 Å Good overlap of lone pair with aromatic framework Little overlap of lone pair with aromatic framework BP86/6-31G*, LACV3P on TM atoms

  10. Scope of B-Cl + P-Si exchange B-Cl + P-Si → B-P + SiCl?

  11. NBN ligand ν(Rh-CO) = 1945 cm-1 (cf. 1942 for BN analogue) P-B: 1.93 Å

  12. Electron-Poor Groups on Boron Stephan JACS 2008,12632 versus B-Cl + P-Si → B-P + SiCl? Bourissou, JACS 2012, 6560 Lose ClSiMe3 to form P=B?

  13. ? Add a source of Cl- to catalyse the loss of ClSiMe3? Sequential adduct formation and loss of ClSiMe3 to give phosphinoborane

  14. Conclusions and future work • Exploit electron donating ability of phosphine in oxidative addition reactionsand catalysis. • Investigate the stability of ligands. Route to P-B under mild conditions Substituting C2 for BN dramatically increases electron donating ability of ligand Silyl exchange route to phosphinoboranes Extremely electron rich phosphine

  15. Acknowledgments • Prof. Paul Pringle • Dr.MairiHaddow - X-Ray • Dr. Natalie Fey - DFT • Dr. Didier Bourissou and Dr.AbderrahmaneAmgoune - Toulouse • Pringles

More Related