A new complex alkali metal aluminium amide borohydride, Li2Al(ND2)4BH4: synthesis, thermal analysis and crystal structure

S. Hino; T. Ichikawa; Y. Kojima; M. H. Sørby; B. C. Hauback

doi:10.1039/C6RA00931J

A new complex alkali metal aluminium amide borohydride, Li₂Al(ND₂)₄BH₄: synthesis, thermal analysis and crystal structure†

S. Hino,^a T. Ichikawa,^b Y. Kojima,^c M. H. Sørby*^a and B. C. Hauback^a

* Corresponding authors

^a Physics Department, Institute for Energy Technology, P. O. Box 40, NO-2027 Kjeller, Norway
E-mail: magnuss@ife.no
Fax: +47 6381 0920
Tel: +47 6380 6000

^b Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Japan

^c Institute for Advanced Materials Research, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Japan

Abstract

The mixtures of alkali metal aluminium amide MAl(ND₂)₄ and alkali metal borohydride MBH₄ were synthesized using ball-milling. Thermal analysis and phase identifications of the MAl(ND₂)₄–MBH₄ system were performed by differential scanning calorimetry-thermogravimetric analysis, temperature programmed desorption-residual gas analysis, in situ synchrotron radiation powder X-ray diffraction and Fourier transform infrared spectroscopy. A previously unknown phase, Li₂Al(ND₂)₄BH₄, was formed in the samples of LiAl(ND₂)₄ + 2LiBH₄ and NaAl(ND₂)₄ + 2LiBH₄. Its crystal structure was solved and refined in the monoclinic space group P2₁/c, with a = 6.8582(3) Å, b = 11.3128(5) Å, c = 11.2117(4) Å, β = 124.186(5)°. Li₂Al(ND₂)₄BH₄ is the first reported compound containing both [Al(ND₂)₄]⁻ and BH₄⁻ anions. The ball-milling of NaAl(ND₂)₄ + 2NaBH₄ and KAl(ND₂)₄ + 2KBH₄ gave mixtures of the starting materials. The synthesized samples desorbed ammonia in the temperature range between 50 and 200 °C and hydrogen above ∼300 °C.

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Article information

DOI: https://doi.org/10.1039/C6RA00931J
Article type: Paper
Submitted: 12 Jan 2016
Accepted: 12 Mar 2016
First published: 14 Mar 2016

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RSC Adv., 2016,6, 28761-28766

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A new complex alkali metal aluminium amide borohydride, Li₂Al(ND₂)₄BH₄: synthesis, thermal analysis and crystal structure

S. Hino, T. Ichikawa, Y. Kojima, M. H. Sørby and B. C. Hauback, RSC Adv., 2016, 6, 28761 DOI: 10.1039/C6RA00931J

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