Aluminum Borohydride Complex with Ethylenediamine: Crystal Structure and Dehydrogenation Mechanism Studies

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• 作者：Qinfen Gu ; Zhiyang Wang ; Yaroslav Filinchuk ; Justin A. Kimpton ; Helen E. A. Brand ; Qian Li ; Xuebin Yu
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 19, 2016
• 年：2016
• 卷：120
• 期：19
• 页码：10192-10198
• 全文大小：463K
• 年卷期：0
• ISSN：1932-7455

文摘

We report the structure of an aluminum borohydride ethylenediamine complex, Al(EDA)₃·3BH₄·EDA. This structure was successfully determined using X-ray powder diffraction and was supported by first-principles calculations. The complex can be described as a mononuclear complex exhibiting three-dimensional supramolecular structure, built from units of Al[C₂N₂H₈]₃, BH₄, and ethylenediamine (EDA) molecules. Examination of the chemical bonding indicates that this arrangement is stabilized via dihydrogen bonding between the NH₂ ligand in EDA and the surrounding BH₄. The partial ionic bonding between the Al and N atoms in EDA forms a five-member ring (5MR), an Al[NCCN] unit. The calculated H₂ removal energies confirm that it is energetically favorable to remove the loosely bonded EDA and H atoms with N–H···H–B dihydrogen bonds upon heating. Our results suggest that the NH₂ terminal ligand in the EDA molecule combines with a H atom in the BH₄ group to release H₂ at elevated temperature, and our results confirm that the experimental result Al(EDA)₃·3BH₄·EDA can release 8.4 wt % hydrogen above 149 °C with detectable EDA molecules. This work provides insights into the dehydrogenation behavior of Al(EDA)₃·3BH₄·EDA and has implications for future development of promising high-performance metal borohydride ethylenediamine complexes.