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

Journal Article · Tue Jan 01 04:00:00 EST 2008 · Inorganic Chemistry

DOI:https://doi.org/10.1021/ic7023633· OSTI ID:959860

Soloveichik, G; Her, J; Stephens, P; Gao, Y; Rijssenbeek, J; Andrus, M; Zhao, J

The ammonia complex of magnesium borohydride Mg(BH4)2{center_dot}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{center_dot}6NH3 (II), which crystallizes in the cubic space group Fmm with unit cell parameter a = 10.82(1) Angstroms 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) Angstroms, b = 9.4132(2) Angstroms, c = 8.7304(2) Angstroms, and Z = 8. This structure is built from individual pseudotetrahedral molecules Mg(BH4)2{center_dot}2NH3 containing one bidentate BH4 group and one tridentate BH4 group that pack into a layered crystal structure mediated by NH{center_dot}{center_dot}{center_dot}HB 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.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 959860
• Report Number(s): BNL--82846-2009-JA
• Journal Information: Inorganic Chemistry, Journal Name: Inorganic Chemistry Vol. 47; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
36 MATERIALS SCIENCE
AMMINES
AMMONIA
BORANES
BOROHYDRIDES
CRYSTAL STRUCTURE
HYDROGEN
HYDROGEN STORAGE
MAGNESIUM
PYROLYSIS
SPACE GROUPS
national synchrotron light source