Preparation of ‘unto-ordinated’ hydridoaluminium tetrahydroborate compounds, Al(BH4)3–xHx(x= 1 or 2), and alane (AlH3) species

Abstract

The action of aluminium tris(tetrahydroborate) on diethylalane, in appropriate molar ratios, yields the liquid hydridoaluminium tetrahydroborates, Al(BH₄)_3–xH_x(X= 1 or 2), after removal of the accompanying Al(BH₄)_3–xEt_x(x= 1 or 2) compounds formed in the redistribution reaction. The Al(BH₄)₂H is the more stable compound, but in vacuo both compounds disproportionate evolving Al(BH₄)³ to afford a residue which becomes increasingly rich in Al–H bonds, and eventually becomes solid when the concentration of AlH₃ units exceeds ca. 78 mol %.