Synthesis of Hydroboranes and Borohydrides by Hydrogenolysis for Hydrogen Storage

To reduce anthropogenic CO₂ emissions, which have harmful effects on the environment, an energetic transition is needed. Hydrogen has emerged as a key actor, as it can be produced and used in a decarbonised way. Solid-state hydrogen storage is envisaged today, as it offers benefits such as greater compactness and safer handling. Boron compounds such as NH₃·BH₃ or LiBH₄ have shown excellent performance in this field. However, once dehydrogenated, they cannot be regenerated, and their synthesis requires energy-intensive processes. In this thesis, we have studied alternative synthetic pathways for the generation of hydroboranes and borohydrides while exploring BCl₃ reactivity. Our first study focused on a new reactivity between a hydrosilane and BCl₃ in the presence of chloride ions Cl^– to generate BH₄^– in good yields. A strategy was developed to recycle the chlorosilane formed using H₂ as a reductant and to valorise the boron hydrides produced. Mechanistic studies were conducted by combining an experimental approach, involving stoichiometric reactions and kinetic measurements, with a theoretical approach using DFT calculations. A second study utilised the Lewis-acidic properties of BCl₃ to abstract hydride from organic compounds, such as tertiary amines, with the aim of synthesising BH₃. Lastly, the use of hydroboranes for P–H bond synthesis has also been investigated.