title: A new ammine dual-cation (Li, Mg) borohydride: synthesis, structure, and dehydrogenation enhancement.
abstract: A new ammine dual-cation borohydride, LiMg(BH(4))(3)(NH(3))(2), has been successfully synthesized simply by ball-milling of Mg(BH(4))(2) and LiBH(4)·NH(3). Structure analysis of the synthesized LiMg(BH(4))(3)(NH(3))(2) revealed that it crystallized in the space group P6(3) (no. 173) with lattice parameters of a=b=8.0002(1) Å, c=8.4276(1) Å, α=β=90°, and γ=120° at 50 °C. A three-dimensional architecture is built up through corner-connecting BH(4) units. Strong N-H···H-B dihydrogen bonds exist between the NH(3) and BH(4) units, enabling LiMg(BH(4))(3)(NH(3))(2) to undergo dehydrogenation at a much lower temperature. Dehydrogenation studies have revealed that the LiMg(BH(4))(3)(NH(3))(2)/LiBH(4) composite is able to release over 8 wt% hydrogen below 200 °C, which is comparable to that released by Mg(BH(4))(3)(NH(3))(2). More importantly, it was found that release of the byproduct NH(3) in this system can be completely suppressed by adjusting the ratio of Mg(BH(4))(2) and LiBH(4)·NH(3). This chemical control route highlights a potential method for modifying the dehydrogenation properties of other ammine borohydride systems.
authors.affiliation: Department of Materials Science, Fudan University, Shanghai 200433, P.R. China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Sun
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Chen
authors.forename: Qinfen
authors.initials: Q
authors.lastname: Gu
authors.forename: Kia S
authors.initials: KS
authors.lastname: Wallwork
authors.forename: Yingbin
authors.initials: Y
authors.lastname: Tan
authors.forename: Ziwei
authors.initials: Z
authors.lastname: Tang
authors.forename: Xuebin
authors.initials: X
authors.lastname: Yu