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
Hauptverfasser: Chernichenko, K, Kótai, B, Nieger, M, Heikkinen, S, Pápai, I, Repo, T
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.
ISSN:1477-9226
1477-9234
DOI:10.1039/c6dt04649e