Jump to main content
Jump to site search

Issue 24, 2017
Previous Article Next Article

Synthesis, structures and thermal decomposition of ammine MxB12H12 complexes (M = Li, Na, Ca)

Author affiliations

Abstract

A series of ammine metal-dodecahydro-closo-dodecaboranes, MxB12H12·nNH3 (M = Li, Na, Ca) were synthesized and their structural and thermal properties studied with in situ time-resolved synchrotron radiation powder X-ray diffraction, thermal analysis, Fourier transformed infrared spectroscopy, and temperature-programmed photographic analysis. The synthesized compounds, Li2B12H12·7NH3, Na2B12H12·4NH3 and CaB12H12·6NH3, contain high amounts of NH3, 43.3, 26.6 and 35.9 wt% NH3, respectively, which can be released and absorbed reversibly at moderate conditions without decomposition, thereby making the closo-boranes favorable ‘host’ materials for ammonia or indirect hydrogen storage in the solid state. In this work, fifteen new ammine metal dodecahydro-closo-dodecaborane compounds are observed by powder X-ray diffraction, of which six are structurally characterized, Li2B12H12·4NH3, Li2B12H12·2NH3, Na2B12H12·4NH3, Na2B12H12·2NH3, CaB12H12·4NH3 and CaB12H12·3NH3. Li2B12H12·4NH3 and Na2B12H12·4NH3 are isostructural and monoclinic (P21/n) whereas Na2B12H12·2NH3 and CaB12H12·3NH3 are both trigonal with space groups P[3 with combining macron]m1 and R[3 with combining macron]c, respectively. Generally, coordination between the metal and the icosahedral closo-borane anion is diverse and includes point sharing, edge sharing, or face sharing, while coordination of ammonia always occurs via the lone pair on nitrogen to the metal. Furthermore, a liquid intermediate is observed during heating of Li2B12H12·7NH3. This work provides deeper insight into the structural, physical, and chemical properties related to thermal decomposition and possible ammonia and hydrogen storage.

Graphical abstract: Synthesis, structures and thermal decomposition of ammine MxB12H12 complexes (M = Li, Na, Ca)

Back to tab navigation

Supplementary files

Publication details

The article was received on 19 Apr 2017, accepted on 29 May 2017 and first published on 30 May 2017


Article type: Paper
DOI: 10.1039/C7DT01414G
Citation: Dalton Trans., 2017,46, 7770-7781
  •   Request permissions

    Synthesis, structures and thermal decomposition of ammine MxB12H12 complexes (M = Li, Na, Ca)

    B. R. S. Hansen, N. Tumanov, A. Santoru, C. Pistidda, J. Bednarcik, T. Klassen, M. Dornheim, Y. Filinchuk and T. R. Jensen, Dalton Trans., 2017, 46, 7770
    DOI: 10.1039/C7DT01414G

Search articles by author

Spotlight

Advertisements