The enhanced solid-phase dehydrogenation of in situ formed ethylenediamine bisborane

A solid AB-EDA composite was synthesized by evacuating an ammonia borane (AB) solution in ethylenediamine (EDA) at ambient temperature. The transformation of AB within the AB-EDA composite was investigated using thermal analysis (DTG-DTA), FTIR spectroscopy, and 11 B and 13 С MAS NMR, combined with DFT calculations. It was demonstrated that upon low-temperature heating (60°С), interactions between AB and EDA induce the formation of ethylenediamine bisborane (EDAB), followed by its dehydrogenation. We propose that the in situ preparation of EDAB within the solid composite creates specific conditions that facilitate its dehydrogenation. This effect is likely associated with a reduction in intermolecular interactions that stabilize the crystalline EDAB phase and the potentially initiating role of the ammonia evolved. • Solid was prepared by vacuum evaporation at room temperature of AB dissolved in EDA. • Heating AB-EDA solid to 60 °C led to EDAB formation followed by its dehydrogenation. • In situ EDAB preparation promotes efficient dehydrogenation under mild conditions.