Replacing C 6 F 5 groups with Cl and H atoms in frustrated Lewis pairs: H 2 additions and catalytic hydrogenations
2-(Dialkylamino)phenylboranes containing the BXZ group, where X, Z = C F , Cl, and H, were prepared in a few synthetic steps and demonstrated the cleavage of H under mild conditions. Depending on the nature of the dialkylamino group, X, and Z, the stability of the produced zwitterionic H adducts var...
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Veröffentlicht in: | Dalton transactions : an international journal of inorganic chemistry 2017-02, Vol.46 (7), p.2263-2269 |
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Hauptverfasser: | , , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | 2-(Dialkylamino)phenylboranes containing the BXZ group, where X, Z = C
F
, Cl, and H, were prepared in a few synthetic steps and demonstrated the cleavage of H
under mild conditions. Depending on the nature of the dialkylamino group, X, and Z, the stability of the produced zwitterionic H
adducts varies from isolated solids indefinitely stable in an inert atmosphere to those quickly equilibrating with the initial aminoborane and H
. Using a combined experimental/computational approach on a series of isostructural aminoboranes (dialkylamino = 2,2,6,6-tetramethylpiperid-1-yl), it was demonstrated that the electronegativity and the steric effect of the substituents generally follow the trend C
F
∼ Cl ≫ H. This observation is useful for designing new FLPs for practical applications. As an example, we demonstrated the hydrogenation of alkynes to cis-alkenes under mild conditions that was catalyzed by a chloro-analogue of the C
F
-substituted aminoborane developed previously. The presence of a BHCl group in the aminochloroboranes or in their H
adducts features facile redistribution of the H and Cl atoms and the formation of polychloro and polyhydrido species. |
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ISSN: | 1477-9226 1477-9234 |
DOI: | 10.1039/c6dt04649e |