Starobrat A, Jaroń T, Grochala W
College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences (MISMaP), University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland.
Dalton Trans. 2018 Mar 26;47(13):4442-4448. doi: 10.1039/c7dt03926c.
Three metal-ammonium borohydrides, NH4[M(BH4)4] M = Y, Sc, Al, denoted 1, 2, 3, respectively, were prepared via a low temperature mechanochemical synthesis and characterized using PXRD, FTIR and TGA/DSC/MS. The compounds 1 and 2 adopt the P21/c space group while the compound 3 crystallizes in an orthorhombic unit cell (Fddd). The first decomposition step of all three derivatives of ammonium borohydride has the maximum rate at 48 °C, 53 °C and 35 °C for 1, 2 and 3, respectively, which are comparable to that for NH4BH4 (53 °C). The thermal decomposition of these metal-ammonium borohydrides is a multistep process, with predominantly exothermic low-temperature stages. The compound 1 decomposes via known Y(BH4)3, however, some of the solid decomposition products of the other two compounds have not been fully identified. In the system containing compound 2, a new, more dense polymorph of the previously reported LiSc(BH4)4 has been detected as the intermediate of slow decomposition at room temperature.
通过低温机械化学合成制备了三种金属-硼氢化铵，分别为NH4[M(BH4)4]（M = Y、Sc、Al），分别记为1、2、3，并使用粉末X射线衍射（PXRD）、傅里叶变换红外光谱（FTIR）和热重/差示扫描量热/质谱（TGA/DSC/MS）对其进行了表征。化合物1和2采用P21/c空间群，而化合物3结晶于正交晶胞（Fddd）中。硼氢化铵的这三种衍生物的第一步分解在48℃、53℃和35℃时速率最大，分别对应1、2和3，这与NH4BH4的情况（53℃）相当。这些金属-硼氢化铵的热分解是一个多步过程，主要是低温放热阶段。化合物1通过已知的Y(BH4)3分解，然而，其他两种化合物的一些固体分解产物尚未完全鉴定出来。在含有化合物2的体系中，已检测到先前报道的LiSc(BH4)4的一种新的、密度更大的多晶型物，作为室温下缓慢分解的中间体。
