科研之友
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摘要
We report the structure of an aluminum borohydride ethylenediamine complex, Al(EDA)(3)center dot 3BH(4)center dot 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 H-2 removal energies confirm that it is energetically favorable to remove the loosely bonded EDA and H atoms with N-H center dot center dot center dot 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)center dot 3BH(4)center dot EDA can release 8.4 wt % hydrogen above 149 degrees C with detectable EDA molecules. This work provides insights into the dehydrogenation behavior of Al(EDA)(3)center dot 3BH(4)center dot EDA and has implications for future development of promising high-performance metal borohydride ethylenediamine complexes.
