The gallium hydrides (iBu)2GaH (1a), LiGaH4 (1b) and Me3N·GaH3 (1c) hydrodefluorinate vinylic and aromatic C-Fbonds when O and N donor molecules are present. 1b exhibits the highest reactivity. Quantitative conversion to the hydrodefluorination (HDF) products could be observed for hexafluoropropene and 1,1,3,3,3-pentafluoropropene, 94% conversion of pentafluoropyridine and 49%ofoctafluorotoluene. Whereas for the HDF with 1b high conversions are observed when catalytic amounts of O donor molecules are added, for 1a,the addition of N donor molecules lead to higher conversions. The E/Z selectivity of the HDF of 1,1,3,3,3-pentafluoropropene is donor-dependent. DFT studies show that HDF proceeds in this case via the gallium hydride dimer–donorspecies and a hydrometallation/elimination sequence. Selectivities are sensitive to the choice of donor, as the right donor can lead to an on/off switching during catalysis, that is, the hydrometallation step is accelerated by the presence of a donor,but the donor dissociates prior to elimination, allowing the inherently more selective donorless gallium systems to determine the selectivity.

Gallium Hydrides and O/N-Donors as Tunable Systems in C−F Bond Activation / Jaeger, Alma D.; Walter, Ruben; Ehm, Christian; Lentz, Dieter. - In: CHEMISTRY - AN ASIAN JOURNAL. - ISSN 1861-4728. - 13:19(2018), pp. 2908-2915. [10.1002/asia.201801030]

Gallium Hydrides and O/N-Donors as Tunable Systems in C−F Bond Activation

Ehm, Christian;
2018

Abstract

The gallium hydrides (iBu)2GaH (1a), LiGaH4 (1b) and Me3N·GaH3 (1c) hydrodefluorinate vinylic and aromatic C-Fbonds when O and N donor molecules are present. 1b exhibits the highest reactivity. Quantitative conversion to the hydrodefluorination (HDF) products could be observed for hexafluoropropene and 1,1,3,3,3-pentafluoropropene, 94% conversion of pentafluoropyridine and 49%ofoctafluorotoluene. Whereas for the HDF with 1b high conversions are observed when catalytic amounts of O donor molecules are added, for 1a,the addition of N donor molecules lead to higher conversions. The E/Z selectivity of the HDF of 1,1,3,3,3-pentafluoropropene is donor-dependent. DFT studies show that HDF proceeds in this case via the gallium hydride dimer–donorspecies and a hydrometallation/elimination sequence. Selectivities are sensitive to the choice of donor, as the right donor can lead to an on/off switching during catalysis, that is, the hydrometallation step is accelerated by the presence of a donor,but the donor dissociates prior to elimination, allowing the inherently more selective donorless gallium systems to determine the selectivity.
2018
Gallium Hydrides and O/N-Donors as Tunable Systems in C−F Bond Activation / Jaeger, Alma D.; Walter, Ruben; Ehm, Christian; Lentz, Dieter. - In: CHEMISTRY - AN ASIAN JOURNAL. - ISSN 1861-4728. - 13:19(2018), pp. 2908-2915. [10.1002/asia.201801030]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/739959
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