1 / 20

Literaturvortrag

Literaturvortrag. Monika Schmidt // 28. Juni. 2011. Monika Schmidt // 28. Juni. 2011. Monika Schmidt // 28. Juni. 2011. N-heterocyclic carbenes (NHC‘s)

alpha
Download Presentation

Literaturvortrag

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. Literaturvortrag Monika Schmidt // 28. Juni. 2011

  2. Monika Schmidt // 28. Juni. 2011

  3. Monika Schmidt // 28. Juni. 2011 N-heterocyclic carbenes (NHC‘s) … are interesting compounds with promising potential in many applications (catalytic activation, stabilization of instable fragments, ligands for catalytically active transition metal complexes) ... Reactivity depends on steric and electronic factors, generation and introduction not always straightforward → carbene adducts with organic molecules ( MeCN, …→ α-elimination) labile NHC-M-complex (M= Mo, Cr, Mn, Cu, Au, Ag, …)

  4. Monika Schmidt // 28. Juni. 2011 NHC Ag(I) complexes have proved especially useful because… … their synthesis is straightforward and high yielding (various silver sources, e.g. silver oxide, triflate, carbonate, acetate,…) … they are applicable to many different carbenes … the complexes are typically air- and moisture-stable compounds

  5. Monika Schmidt // 28. Juni. 2011 Synthesis In Solution Both were observed in MS, NMR

  6. Monika Schmidt // 28. Juni. 2011 Generally: Mono-NHC-Ag(I) complexes with coordinating anions, e.g. halides Bis-NHC-Ag(I) complexes with noncoordinating anions, e.g. triflates Different reactivity

  7. Monika Schmidt // 28. Juni. 2011

  8. Monika Schmidt // 28. Juni. 2011

  9. Monika Schmidt // 28. Juni. 2011

  10. Monika Schmidt // 28. Juni. 2011 The first stable Si=P (Phosphasilene) was reported by Bickelhaupt et al. in 1984 After: a number of phosphasilene derivates have been synthesized (bulky group,…) 2009: Eind groups encapsulate the reactiv Si=P moieties → coplanar π-conjugated frameworks (strong π-π* absorption)

  11. Monika Schmidt // 28. Juni. 2011 Synthesis of mononuclear complexes

  12. Monika Schmidt // 28. Juni. 2011 29Si-NMR (144.4 ppm // 1JSiP= 39 Hz) 31P-NMR (43.2 ppm) X-Ray: Ƞ1-coordination almost linear coordinated gold center (< PAuCl = 178. 828°) d(Si=P): 2.0924 Å d(Au-P): 2.2293 Å 31P-NMR (48.1 ppm) X-Ray: C2-Symmetry almost linear coordinated gold center (< PAuP= 178. 13°) d(Si=P): 2.0924 Å d(Au-P): 2.2807 Å

  13. Monika Schmidt // 28. Juni. 2011 Synthesis of dinuclear complexes 31P-NMR (52.6, 65.9 ppm // 2JPiP= 388 Hz) MS (ESI): m/z= 1843.2043 [M-2B(C6F5)4)]2+

  14. Monika Schmidt // 28. Juni. 2011 Mononuclear AuCl complexes 3a/3b show the π-π* absorption peak at 395nm/386nm (redshift) and enhanced absorption intensity

  15. Monika Schmidt // 28. Juni. 2011

  16. Monika Schmidt // 28. Juni. 2011 Only few examples of cationic dialkyl metal compounds of group 13 elements [R2E]+ without a stabilizing donor ligand are known → very electrophilic // “unique properties” Bochmann et al.: [B(C6F5)4]- + AlR3→ [R2Al]+ (transient!!) Reed et al.: (Et2Al)(HCB11H5X6) (X=Cl,Br)

  17. Monika Schmidt // 28. Juni. 2011 Synthesis: Transfer the reaction [Ph3C]2[B12Cl12] + R3SiH (R3Si)2B12Cl12

  18. Monika Schmidt // 28. Juni. 2011

  19. Monika Schmidt // 28. Juni. 2011 Reaction mechanism oft the reaction of [Ph3C]+ with Et3Al and Me3Al is completely different Competing reation pathways (ß-hydrid abstraction vs alkide transfer)

  20. Monika Schmidt // 28. Juni. 2011 Danke für die Aufmerksamkeit!

More Related