Ammine Magnesium Borohydride Complex as a New Material for Hydrogen Storage: Structure and Properties of Mg(BH4)2·2NH3

The ammonia complex of magnesium borohydride Mg(BH4)2·2NH3 (I), which contains 16.0 wt % hydrogen, is a potentially promising material for hydrogen storage. This complex was synthesized by thermal decomposition of a hexaaammine complex Mg(BH4)2·6NH3 (II), which crystallizes in the cubic space group...

Full description

Saved in:
Bibliographic Details
Published in:Inorganic chemistry 2008-05, Vol.47 (10), p.4290-4298
Main Authors: Soloveichik, Grigorii, Her, Jae-Hyuk, Stephens, Peter W, Gao, Yan, Rijssenbeek, Job, Andrus, Matt, Zhao, J.-C
Format: Article
Language:English
Subjects:
08 HYDROGEN
AMMINES
AMMONIA
BORANES
BOROHYDRIDES
CRYSTAL STRUCTURE
HYDROGEN
HYDROGEN STORAGE
MAGNESIUM
MATERIALS SCIENCE
national synchrotron light source
PYROLYSIS
SPACE GROUPS
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The ammonia complex of magnesium borohydride Mg(BH4)2·2NH3 (I), which contains 16.0 wt % hydrogen, is a potentially promising material for hydrogen storage. This complex was synthesized by thermal decomposition of a hexaaammine complex Mg(BH4)2·6NH3 (II), which crystallizes in the cubic space group Fm3̅m with unit cell parameter a = 10.82(1) Å and is isostructural to Mg(NH3)6Cl2. We solved the structure of I that crystallizes in the orthorhombic space group Pcab with unit cell parameters a = 17.4872(4) Å, b = 9.4132(2) Å, c = 8.7304(2) Å, and Z = 8. This structure is built from individual pseudotetrahedral molecules Mg(BH4)2·2NH3 containing one bidentate BH4 group and one tridentate BH4 group that pack into a layered crystal structure mediated by N−H···H−B dihydrogen bonds. Complex I decomposes endothermically starting at 150 °C, with a maximum hydrogen release rate at 205 °C, which makes it competitive with ammonia borane BH3NH3 as a hydrogen storage material.
ISSN:0020-1669
1520-510X
DOI:10.1021/ic7023633