Roedern Elsa, Jensen Torben R
Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , Langelandsgade 140, DK-8000 Aarhus C, Denmark.
Inorg Chem. 2015 Nov 2;54(21):10477-82. doi: 10.1021/acs.inorgchem.5b01959. Epub 2015 Oct 21.
Iron and cobalt borohydrides stabilized by ammonia (NH3), Fe(NH3)62 and Co(NH3)62, were synthesized along with a solid solution, Co(NH3)6(2-x)Cl(x) (x ∼ 1), and a bimetallic compound, Fe(NH3)6. The compounds were prepared by new low-temperature, solvent-based synthesis methods, using dimethyl sulfide or liquid NH3, which allow for the removal of inert metal halides. The crystal structures were determined from synchrotron radiation powder X-ray diffraction (SR-PXD) data. M(NH3)62 (M = Fe, Co) and Co(NH3)6(2-x)Cl(x) crystallize in the cubic crystal system, where the transition metals are octahedrally coordinated by NH3. Polymeric chains of lithium coordinated by four bridging BH4(-) anions are found in Fe(NH3)6. The new compounds have high hydrogen densities of ∼14 wt % H2 and ∼140 g H2/L and release a mixture of hydrogen and NH3 gas at low temperatures, T < 80 °C. The decomposition mechanisms of the prepared compounds along with the composites Fe(NH3)62·nNH3BH3 (n = 2, 4, 6) were studied by thermal analysis and in situ SR-PXD.
通过氨（NH₃）稳定的铁和钴硼氢化物Fe(NH₃)₆₂和Co(NH₃)₆₂与一种固溶体Co(NH₃)₆(2 - x)Cl(x)（x ∼ 1）以及一种双金属化合物Fe(NH₃)₆一同被合成出来。这些化合物是通过新的低温、基于溶剂的合成方法制备的，使用二甲基硫醚或液态NH₃，这使得惰性金属卤化物得以去除。晶体结构是根据同步辐射粉末X射线衍射（SR - PXD）数据确定的。M(NH₃)₆₂（M = Fe、Co）和Co(NH₃)₆(2 - x)Cl(x)结晶于立方晶系，其中过渡金属由NH₃八面体配位。在Fe(NH₃)₆中发现了由四个桥连的BH₄⁻阴离子配位的锂的聚合物链。这些新化合物具有约14 wt% H₂和约140 g H₂/L的高氢密度，并在低温（T < 80 °C）下释放出氢气和NH₃气体的混合物。通过热分析和原位SR - PXD研究了所制备化合物以及复合材料Fe(NH₃)₆₂·nNH₃BH₃（n = 2、4、6）的分解机理。
