Department of Materials Science, Fudan University, Shanghai, 200433, China.
Chemistry. 2010 Mar 22;16(12):3763-9. doi: 10.1002/chem.200903220.
The monoammoniate of lithium amidoborane, Li(NH(3))NH(2)BH(3), was synthesized by treatment of LiNH(2)BH(3) with ammonia at room temperature. This compound exists in the amorphous state at room temperature, but at -20 degrees C crystallizes in the orthorhombic space group Pbca with lattice parameters of a = 9.711(4), b = 8.7027(5), c = 7.1999(1) A, and V = 608.51 A(3). The thermal decomposition behavior of this compound under argon and under ammonia was investigated. Through a series of experiments we have demonstrated that Li(NH(3))NH(2)BH(3) is able to absorb/desorb ammonia reversibly at room temperature. In the temperature range of 40-70 degrees C, this compound showed favorable dehydrogenation characteristics. Specifically, under ammonia this material was able to release 3.0 equiv hydrogen (11.18 wt %) rapidly at 60 degrees C, which represents a significant advantage over LiNH(2)BH(3). It has been found that the formation of the coordination bond between ammonia and Li(+) in LiNH(2)BH(3) plays a crucial role in promoting the combination of hydridic B-H bonds and protic N-H bonds, leading to dehydrogenation at low temperature.
锂氨硼烷的单氨化物，Li(NH(3))NH(2)BH(3)，通过在室温下用氨处理 LiNH(2)BH(3)合成。该化合物在室温下处于无定形状态，但在-20°C 下以正交晶系 Pbca 空间群结晶，晶格参数为 a = 9.711(4)、b = 8.7027(5)、c = 7.1999(1) A 和 V = 608.51 A(3)。研究了该化合物在氩气和氨气氛下的热分解行为。通过一系列实验，我们证明了 Li(NH(3))NH(2)BH(3)能够在室温下可逆地吸收/解吸氨。在 40-70°C 的温度范围内，该化合物表现出良好的脱氢特性。具体而言，在氨气氛下，该材料能够在 60°C 下迅速释放 3.0 当量氢气（11.18wt%），这比 LiNH(2)BH(3)有明显的优势。研究发现，氨与 LiNH(2)BH(3)中 Li(+)形成配位键在促进氢化物 B-H 键和质子化 N-H 键的结合方面起着关键作用，从而导致低温脱氢。
