The structural characterization of (NH4)2B10H10 and thermal decomposition studies of (NH4)2B10H10 and (NH4)2B12H12

Abstract The structure of (NH 4 ) 2 B 10 H 10 ( 1) was determined through powder XRD analysis. The thermal decomposition of 1 and (NH 4 ) 2 B 12 H 12 ( 2 ) was examined between 20 and 1000 °C using STMBMS methods. Between 200 and 400 °C a mixture of NH 3 and H 2 evolves from both compounds; above 400 °C only H 2 evolves. The dihydrogen bonding interaction in 1 is much stronger than that in 2 . The stronger dihydrogen bond in 1 resulted in a significant reduction by up to 60 °C, but with a corresponding 25% decrease in the yield of H 2 in the lower temperature region and a doubling of the yield of NH 3 . The decomposition of 1 follows a lower temperature exothermic reaction pathway that yields substantially more NH 3 than the higher temperature endothermic pathway of 2 . Heating of 1 at 250 °C resulted in partial conversion of B 10 H 10 2− to B 12 H 12 2− . Both 1 and 2 form an insoluble polymeric material after decomposition. The elements of the reaction network that control the release of H 2 from the B 10 H 10 2− can be altered by conducting the experiment under conditions in which pressures of NH 3 and H 2 are either near, or away from, their equilibrium values.