Cooperative (De-)Hydrogenation of Small Molecules

by Arne Glüer
Doctoral thesis
Date of Examination:2018-12-11
Date of issue:2019-01-25
Advisor:Prof. Dr. Sven Schneider
Referee:Prof. Dr. Sven Schneider
Referee:Prof. Dr. Franc Meyer
Persistent Address: http://dx.doi.org/10.53846/goediss-7217

 

 

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Abstract

English

Ammonia borane dehydrocoupling to mainly linear polyaminoborane is reported at room temperature using a bifunctional iron catalyst. Mechanistic studies suggest that both hydrogen release and B−N coupling are metal-catalyzed and proceed via free aminoborane. Catalyst deactivation results from reaction with free borane that is formed by aminoborane rearrangement. Importantly, borane trapping with a simple amine allows for the observation of a TON that is unprecedented for a well-defined base metal catalyst. Additionally, hydrogenolysis of chlorosilanes and silyl triflates (triflate = trifluoromethanesulfonate) to hydrosilanes at mild conditions (4 bar of dihydrogen, room temperature) is reported using low loadings (1 mol-%) of a bifunctional ruthenium catalyst. Endergonic chlorosilane hydrogenolysis can be driven by chloride removal. Alternatively, conversion to silyl triflates enables facile hydrogenolysis, giving the corresponding silanes in high yields. These protocols provide key steps for synthesis of valuable hydrochlorosilanes, which can also be directly obtained by hydrogenolysis of chlorosilane/silyl triflate mixtures.
Keywords: ammonia borane, dehydrocoupling, chlorosilane, silyl triflate, hydrogenolysis
 
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