Synthesis and thermal decomposition of magnesium-, calcium- and strontium octahydrotriborates solvated with diglyme

Octahydrotriborates Mg(B3H8)2X2DG, Ca(BH4)(B3H8)x2DG and Sr(B3H8)2x3DG (DG-diglyme) are synthesized through the interaction of hydridoborates of the respective metals with diborane in diglyme medium at 55-70 deg C. In difference with Mg- and Sr hydridoborates, Ca hydridoborate reacts with one mole of diborane. It is stated from the investigation of thermal decomposition of octahydrotriborates in vacUum that pentaborane-9 is extracted following decomposition of octahydrotriborates, but hydridoborates and closododecahydrododecaborates of metals are formed. Pyrolysis of ionic octahydrotriborates is supposed to proceed through the stage of B3H8- ion disintegration with the formation of hydridoborate and pentaborane-9