Novel Alkali Earth Borohydride Sr(BH4)(2) and Borohydride-Chloride Sr(BH4)Cl

作者：Ravn**aek D B^*; Nickels E A; Cerny R; Olesen C H; David W I F; Edwards P P; Filinchuk Y; Jensen T R

来源：Inorganic Chemistry, 2013, 52(19): 10877-10885.

DOI：10.1021/ic400862s

Two novel alkali earth borohydrides, Sr(BH4)(2) and Sr(BH4)Cl, have been synthesized and investigated by in-situ synchrotron radiation powder X-ray diffraction (SR-PXD) and Raman spectroscopy. Strontium borohydride, Sr(BH4)(2), was synthesized via a metathesis reaction between LiBH4 and SrCl2 by two complementary methods, i.e., solvent-mediated and mechanochemical synthesis, while Sr(BH4)Cl was obtained from mechanochemical synthesis, i.e., ball milling. Sr(BH4)(2) crystallizes in the orthorhombic crystal system, a = 6.97833(9) angstrom, b = 8.39651(11) angstrom, and c = 7.55931(10) angstrom (V = 442.927(10) angstrom(3)) at RT with space group symmetry Pbcn. The compound crystallizes in alpha-PbO2 structure type and is built from half-occupied brucite-like layers of slightly distorted [Sr(BH4)(6)] octahedra stacked in the a-axis direction. Strontium borohydride chloride, Sr(BH4)Cl, is a stoichiometric, ordered compound, which also crystallizes in the orthorhombic crystal system, a = 10.8873(8) angstrom, b = 4.6035(3) angstrom, and c = 7.4398(6) angstrom (V = 372.91(3) angstrom(3)) at RT, with space group symmetry Prima and structure type Sr(OH)(2). Sr(BH4)Cl dissociates into Sr(BH4)(2) and SrCl2 at similar to 170 degrees C, while Sr(BH4)(2) is found to decompose in multiple steps between 270 and 465 degrees C with formation of several decomposition products, e.g., SrB6. Furthermore, partly characterized new compounds are also reported here, e.g., a solvate of Sr(BH4)(2) and two Li-Sr-BH4 compounds.

• 出版日期2013-10-7