Intermolecular dihydrogen- and hydrogen-bonding interactions in diammonium closo-decahydrodecaborate sesquihydrate

The asymmetric unit of the title salt, 2NH(4)(+)center dot B10H102-center dot 1.5H(2)O or (NH4)(2)B10H10 center dot 1.5H(2)O, (I), contains two B10H102- anions, four NH4+ cations and three water molecules. (I) was converted to the anhydrous compound (NH4)(2)B10H10, (II), by heating to 343 K and its X-ray powder pattern was obtained. The extended structure of (I) shows two types of hydrogen- bonding interactions (N-H center dot center dot center dot O and O-H center dot center dot center dot O) and two types of dihydrogen- bonding interactions (NH center dot center dot center dot H-B and O-H center dot center dot center dot H-B). The N-H center dot center dot center dot H-B dihydrogen bonding forms a two- dimensional sheet structure, and hydrogen bonding (N-H center dot center dot center dot O and O-H center dot center dot center dot O) and OH center dot center dot center dot H-B dihydrogen bonding link the respective sheets to form a three-dimensional polymeric network structure. Compound (II) has been shown to form a polymer with the accompanying loss of H-2 at a faster rate than (NH4)(2)B12H12 and we believe that this is due to the stronger dihydrogenbonding interactions shown in the hydrate (I).