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A Simple and Efficient Approach to Synthesize Amidoborane Ammoniates: Case Study for Mg(NH2BH3)2(NH3)3 with Unusual Coordination Structure



Xiangdong Kang, Hui Wu, Junhong Luo, Wei Zhou, Ping Wang


Metal amidoborane ammoniates are a new type of promising hydrogen storage materials consisting of metal cation, [NH2BH3] anionic unit and NH3 ligand. Herein, we report a new reactive ball milling approach for preparation of magnesium amidoborane ammoniate, Mg(NH2BH3)2(NH3)3. Our study found that mechanically milling the NH3BH3/MgH2 mixture in a 2:1 molar ration under NH3 atmosphere can readily produce Mg(NH2BH3)2(NH3)3. Its crystal structure was successfully determined by a combination of X-ray diffraction (XRD) analysis and first-principles calculations. This compound possesses a novel ordered structure with alternating layers of Mg(NH3)66+ hexamminemagnesium cations and Mg(NH2BH3)42- complex anions, in which Mg2+ exhibits both VI and IV coordinations. Property measurements found that Mg(NH2BH3)2(NH3)3 can release 7 equivalent (10.6 mass%) of H6d2^ upon heating up to 300 ° C in a closed system. A combination of XRD, Fourier transformation infrared spectroscopy (FTIR), and solid-state 11B MAS NMR techniques has been employed to characterize Mg(NH2BH3)2(NH3)3 and its dehydrogenation product. A series of control experiments have also been conducted to gain insight into the formation mechanism of Mg(NH2BH3)2(NH3)3.
Journal of Materials Chemistry


hydrogen storage


Kang, X. , Wu, H. , Luo, J. , Zhou, W. and Wang, P. (2012), A Simple and Efficient Approach to Synthesize Amidoborane Ammoniates: Case Study for Mg(NH<sub>2</sub>BH<sub>3</sub>)<sub>2</sub>(NH<sub>3</sub>)<sub>3</sub> with Unusual Coordination Structure, Journal of Materials Chemistry, [online], (Accessed February 25, 2024)
Created July 13, 2012, Updated October 12, 2021