Novel alkali earth borohydride Sr(BH4)2 and borohydride-chloride Sr(BH4)Cl

Ravnsbaek, D.B.;Nickels, E.A.;Cerny, R.;Olesen, C.H.;Jensen, T.R.;et.al.
(2013) Inorganic Chemistry — Vol. 52, n° 19, p. 10877-10885 (2013)

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Authors
  • Ravnsbaek, D.B.University of Aarhus (Denmark)
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  • Nickels, E.A.University of Oxford (UK)
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  • Cerny, R.University of Geneva (Switzerland)
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  • Olesen, C.H.University of Arhus (Denmark)
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  • Jensen, T.R.University of Aarhus (Denmark)
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Abstract
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) Å, b = 8.39651(11) Å, and c = 7.55931(10) Å (V = 442.927(10) Å3) at RT with space group symmetry Pbcn. The compound crystallizes in α-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) Å, b = 4.6035(3) Å, and c = 7.4398(6) Å (V = 372.91(3) Å3) at RT, with space group symmetry Pnma and structure type Sr(OH)2. Sr(BH4)Cl dissociates into Sr(BH4)2 and SrCl2 at ∼170 C, while Sr(BH4)2 is found to decompose in multiple steps between 270 and 465 C with formation of several decomposition products, e.g., SrB 6. Furthermore, partly characterized new compounds are also reported here, e.g., a solvate of Sr(BH4)2 and two Li-Sr-BH 4 compounds. © 2013 American Chemical Society.
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Citations

Ravnsbaek, D. B., Nickels, E. A., Cerny, R., Olesen, C. H., David, W. I. F., Edwards, P. P., Filinchuk, Y., & Jensen, T. R. (2013). Novel alkali earth borohydride Sr(BH4)2 and borohydride-chloride Sr(BH4)Cl. Inorganic Chemistry, 52(19), 10877-10885. https://doi.org/10.1021/ic400862s (Original work published 2013)