Bis(4‐benzhydryl‐benzoxazol‐2‐yl)methane – from a Bulky NacNac Alternative to a Trianion in Alkali Metal Complexes
| Autor: | Johannes Kretsch, Dietmar Stalke, Regine Herbst-Irmer, Anne-Kathrin Kreyenschmidt, Timo Schillmöller, Ivo Leito, Märt Lõkov |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Steric effects
Methanides Metalation NacNac Hot Paper 010402 general chemistry 01 natural sciences Medicinal chemistry Catalysis Ligand design chemistry.chemical_compound Deprotonation Full Paper 010405 organic chemistry Ligand Chemistry Organic Chemistry General Chemistry Full Papers Alkali metal 0104 chemical sciences Solvent Monomer Potassium s-Block chemistry |
| Zdroj: | Chemistry (Weinheim an Der Bergstrasse, Germany) |
| ISSN: | 1521-3765 0947-6539 |
| Popis: | A novel sterically demanding bis(4‐benzhydryl‐benzoxazol‐2‐yl)methane ligand 6 (4−BzhH2BoxCH2) was gained in a straightforward six‐step synthesis. Starting from this ligand monomeric [M(4‐BzhH2BoxCH)] (M=Na (7), K (81 )) and dimeric [{M(4‐BzhH2BoxCH)}2] (M=K (82 ), Rb (9), Cs (10)) alkali metal complexes were synthesised by deprotonation. Abstraction of the potassium ion of 8 by reaction with 18‐crown‐6 resulted in the solvent separated ion pair [{(THF)2K@(18‐crown‐6)}{bis(4‐benzhydryl‐benzoxazol‐2‐yl)methanide}] (11), including the energetically favoured monoanionic (E,E)‐(4‐BzhH2BoxCH) ligand. Further reaction of 4−BzhH2BoxCH2 with three equivalents KH and two equivalents 18‐crown‐6 yielded polymeric [{(THF)2K@(18‐crown‐6)}{K@(18‐crown‐6)K(4‐BzhBoxCH)}]n (n→∞) (12) containing a trianionic ligand. The neutral ligand and herein reported alkali complexes were characterised by single X‐ray analyses identifying the latter as a promising precursor for low‐valent main group complexes. Bis(4‐benzhydryl‐benzoxazol‐2‐yl)methane (4−BzhH2BoxCH2) provides a versatile platform for monomeric ligands in [M(4‐BzhH2BoxCH)] (M=Na, K) and dimeric [{M(4‐BzhH2BoxCH)}2] (M=K, Rb, Cs) alkali metal complexes. Even more remarkable the reaction of 4−BzhH2BoxCH2 with three equivalents KH and two equivalents 18‐crown‐6 yields polymeric [{(THF)2K@(18‐crown‐6)}{K@(18‐crown‐6)K(4‐BzhH2BoxCH)}]n (n→∞), containing a trianionic ligand. While the monoanions only provide N,N‐chelation like NacNac the latter trianion potentially provides C,N,N,C‐chelation and should be another promising ligand platform. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|