Faculty of Chemistry, The University of Warsaw, Pasteur 1, 02093, Warsaw, Poland.
Dalton Trans. 2010 Jan 7(1):160-6. doi: 10.1039/b910698g. Epub 2009 Nov 13.
Fourteen different synthetic approaches towards pure solvent-free Y(BH(4))(3) have been tested, thirteen of which have failed. Attempted reactions of YCl(3) or Y(OC(4)H(9))(3) with LiBH(4) in THF, those of YCl(3) with (C(4)H(9))(4)N(+) BH(4)(-), as well as between YH(x approximately 3) and R(4)NBH(3) (R = CH(3), C(2)H(5)) in the presence or absence of a solvent (n-hexane or CH(2)Cl(2)) did not lead to the expected product. The mechanochemical solid/solid reactions (MBH(4) + 3 YX(3)--> Y(BH(4))(3) + 3 LiCl, where M = Li, Na; X = F, Cl) have succeeded only for the LiBH(4) and YCl(3) reagents, but the separation of the crystalline reaction products (Y(BH(4))(3) in its Pa3 phase and LiCl) by dissolution or flotation in various solvents has not been successful. The thermal decomposition process of Y(BH(4))(3) in a mixture with LiCl has been investigated with thermogravimetric (TGA) and calorimetric analysis (DSC) combined with spectroscopic evolved gas analysis (EGA). Three major endothermic steps could be distinguished in the DSC profile at ca. 232, 282, 475 degrees C (heating rate 10 K min(-1)) corresponding to a phase transition and two steps of thermal decomposition. Solid decomposition products are amorphous except for the new cubic polymorph of Y(BH(4))(3) overlooked in previous work. The high-temperature phase forms at the onset of thermal decomposition and it may be prepared by heating of the low-temperature phase up to a narrow temperature range (194-210 degrees C) followed by rapid quenching. Y(BH(4))(3) constitutes a novel highly efficient hydrogen storage material (theor. 9.0 wt% H) but, unfortunately, the evolved H(2) is contaminated by toxic boron hydrides and products of their pyrolysis.
已经测试了 14 种不同的合成纯溶剂无 Y(BH(4))(3) 的方法，其中 13 种方法都失败了。尝试了 YCl(3) 或 Y(OC(4)H(9))(3) 与 LiBH(4) 在 THF 中的反应、YCl(3) 与 (C(4)H(9))(4)N(+) BH(4)(-) 的反应，以及 YH(x 约为 3) 和 R(4)NBH(3) (R = CH(3), C(2)H(5)) 在有或没有溶剂（正己烷或 CH(2)Cl(2)) 的情况下的反应，都没有得到预期的产物。机械化学固/固反应 (MBH(4) + 3 YX(3)--> Y(BH(4))(3) + 3 LiCl，其中 M = Li, Na；X = F, Cl) 仅对 LiBH(4) 和 YCl(3) 试剂成功，但通过在各种溶剂中溶解或浮选来分离结晶反应产物 (Y(BH(4))(3) 的 Pa3 相和 LiCl) 并不成功。Y(BH(4))(3) 在与 LiCl 的混合物中的热分解过程已经通过热重分析 (TGA) 和量热分析 (DSC) 与光谱衍生气体分析 (EGA) 结合进行了研究。在 DSC 图谱中可以区分出三个主要的吸热步骤，约在 232、282、475 摄氏度（升温速率为 10 K min(-1))，对应于一个相变和两个热分解步骤。除了以前工作中忽略的新立方多晶型体外，固体分解产物都是无定形的。高温相在热分解开始时形成，它可以通过将低温相加热到一个狭窄的温度范围（194-210 摄氏度），然后快速淬火来制备。Y(BH(4))(3) 是一种新型的高效储氢材料（理论上 9.0 重量% H），但不幸的是，释放出的 H(2) 被有毒的硼氢化物和它们的热解产物污染。
