Thermal Decomposition of Anhydrous Alkali Metal Dodecaborates M2B12H12 (M = Li, Na, K)

Metal dodecaborates M 2/ n B 12 H 12 are regarded as the dehydrogenation intermediates of metal borohydrides M(BH 4 ) n that are expected to be high density hydrogen storage materials. In this work, thermal decomposition processes of anhydrous alkali metal dodecaborates M 2 B 12 H 12 (M = Li, Na, K) synthesized by sintering of MBH 4 (M = Li, Na, K) and B 10 H 14 have been systematically investigated in order to understand its role in the dehydrogenation of M(BH 4 ) n . Thermal decomposition of M 2 B 12 H 12 indicates multistep pathways accompanying the formation of H-deficient monomers M 2 B 12 H 12 − x containing the icosahedral B 12 skeletons and is followed by the formation of (M 2 B 12 H z ) n polymers. The decomposition behaviors are different with the in situ formed M 2 B 12 H 12 during the dehydrogenation of metal borohydrides.