Mechanistic Investigation on the Formation and Dehydrogenation of Calcium Amidoborane Ammoniate
Possessing high H{sub 2} capacities and interesting dehydrogenation behavior, metal amidoborane ammoniates were prepared by reacting Ca(NH{sub 2}){sub 2}, MgNH, and LiNH{sub 2} with ammonia borane to form Ca(NH{sub 2}BH{sub 3}){sub 2} - 2 NH{sub 3}, Mg(NH{sub 2}BH{sub 3}){sub 2} - NH{sub 3}, and Li(NH{sub 2}BH{sub 3}){sub 2} - NH{sub 3} (LiAB - NH{sub 3}). Insight into the mechanisms of amidoborane ammoniate formation and dehydrogenation was obtained by using isotopic labeling techniques. Selective {sup 15}N and {sup 2}H labeling showed that the formation of the ammoniate occurs via the transfer of one H(N) from ammonia borane to the [NH{sub 2}]{sup -} unit in Ca(NH{sub 2}){sub 2} giving rise to NH{sub 3} and [NH{sub 2}BH{sub 3}]{sup -}. Supported by theoretical calculations, it is suggested that the improved dehydrogenation properties of metal amidoborane ammoniates compared to metal amidoboranes are a result of the participation of a strong dihydrogen bond between the NH{sub 3} molecule and [NH{sub 2}BH{sub 3}]{sup -}. Our study elucidates the reaction pathway involved in the synthesis and dehydrogenation of Ca(NH{sub 2}BH{sub 3}){sub 2}-2NH{sub 3}, and clarifies our understanding of the role of NH{sub 3}, that is, it is not only involved in stabilizing the structure, but also in improving the dehydrogenation properties of metal amidoboranes.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1044479
- Report Number(s):
- PNNL-SA-88654; 36397; KC0302010
- Journal Information:
- ChemSusChem, Journal Name: ChemSusChem Journal Issue: 5 Vol. 5; ISSN 1864-5631
- Country of Publication:
- United States
- Language:
- English
Similar Records
Hydrogen Release Studies of Alkali Metal Amidoboranes
First-Principles Prediction of Intermediate Products in the Decomposition of Metal Amidoboranes
Solid-State NMR Study of Li-Assisted Dehydrogenation of Ammonia Borane
Journal Article
·
Mon Apr 19 00:00:00 EDT 2010
· Inorganic Chemistry, 49(8):3905-3910
·
OSTI ID:982297
First-Principles Prediction of Intermediate Products in the Decomposition of Metal Amidoboranes
Journal Article
·
Wed Dec 26 23:00:00 EST 2012
· Journal of Physical Chemistry. C
·
OSTI ID:1064595
Solid-State NMR Study of Li-Assisted Dehydrogenation of Ammonia Borane
Journal Article
·
Wed Mar 21 00:00:00 EDT 2012
· Inorganic Chemistry
·
OSTI ID:1044998