Lithium Borohydride Ethylenediaminates: A Case Study of Solid-State LiBH4鈥揙rganic Amine Complexes

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• 作者：Juner Chen ; Teng He ; Guotao Wu ; Zhitao Xiong ; Lin Liu ; Xiaohua Ju ; Ping Chen
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：June 26, 2014
• 年：2014
• 卷：118
• 期：25
• 页码：13451-13459
• 全文大小：395K
• ISSN：1932-7455

文摘

Nitrogen (N) containing ligands, such as ammonia (NH₃), hydrazine (N₂H₄), and ethylenediamine (en), can form a series of complexes with common features in crystal structures and thermal behaviors by coordinating with LiBH₄. Two newly synthesized lithium borohydride ethylenediaminates were investigated in this work. Through comparing the crystal structures of LiBH₄鈥揺n, LiBH₄鈥揘H₃, and LiBH₄鈥揘₂H₄ complexes, similar coordination environments of Li were observed in which they have the same Li/N molar ratios. Meanwhile, the establishment of dihydrogen bonding networks, together with the Li⁺/N containing ligand interactions, may be important reasons for the structural stabilization and are expected to have profound impacts on their thermal behaviors. When heated under Ar flow, LiBH₄鈥揘 containing complexes decompose via desorption of N containing ligands followed by dehydrogenation. The coordination strength is affected by the number of ligands, i.e., with the increase of N/Li ratio the ligands can be released more easily. For dehydrogenation, the complex with the shortest NH路路路HB distance gave rise to the lowest initial temperature. When heated in a closed system, direct dehydrogenation can be achieved at relatively low temperatures with Co-based catalyst. About 8.5 and 7.7 wt % of hydrogen can be released from Co-catalyzed LiBH₄路en and (LiBH₄)₂路en at 180 掳C, respectively.