Amidoboranes of rubidium and caesium: the last missing members of the alkali metal amidoborane family

Abstract

We report the synthesis and physicochemical characterization of two ammonia borane derivatives: rubidium amidoborane (RbNH₂BH₃) and caesium amidoborane (CsNH₂BH₃). Both compounds undergo solid–solid phase transition upon heating and then evolve pure hydrogen at temperatures lower than 125 °C. The phase transition is clearly seen in the Raman spectra. We present crystal structures of both low- and high-temperature forms of the title compounds which were solved from powder X-ray data.