Synthesis and crystal structure analysis of complex hydride Mg(BH4)(NH2)

Complex hydride Mg(BH4)(NH2), which consists of double anion BH4_ and NH2_, was synthesized and the crystal structure was analyzed by synchrotron X-ray diffraction. The mixture sample of Mg(BH4)(2) + Mg(NH2)(2) prepared by ball milling was reacted and crystallized to Mg(BH4)(NH2) by heating at about 453 K. This crystal phase transforms into amorphous phase above 473 K and subsequently the dehydrogenation begins. The crystal structure of Mg(BH4)(NH2) was determined from measurement data at 453 K (chemical formula: Mg-0.94(BH4)(1)(NH2)(0.88), crystal system: tetragonal, space group: I4(1) (No.80), Z = 8, lattice constants: a = 5.814(1), c = 20.450(4) angstrom at 453 K) . Mg(BH4)(NH2) is ionic crystal which the cation (Mg2+) and the anions (BH(4)(_)and NH2_) are stacking alternately along the c-axis direction. Two BH4_ and two NH2_ tetrahedrally coordinate around Mg2+ ion. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.