Structural studies of lithium zinc borohydride by neutron powder diffraction, Raman and NMR spectroscopy

摘要

The crystal structure of LiZn_2(BH_4)_5 is studied in detail using a combination of powder neutron diffraction (PND), Raman spectroscopy, and ~(11)B MAS NMR spectroscopy on LiZn_2(BH_4)5 and LiZn_2(~(11)BD_4)_5. The aim is to obtain detailed structural knowledge of the first interpenetrated framework hydride compound, LiZn_2(BD_4)_5 which consists of doubly interpenetrated 3D frameworks built from dinuclear complex ions [Zn_2(BD_4)_5]- and lithium ions. The positions of the deuterium atoms are determined using Rietveld refinement of the PND data and the orientation of one of the four independent BD_4~ groups is revised. The current data reveal that the structure of [Zn_2(BD_4)_5]~ is more regular than previously reported, as are also the coordinations around the Zn and Li atoms. Both Zn and Li atoms are found to coordinate to the BD_4~ units via the tetrahedral edges. Some distortion of the angles within the BD_4 units is observed, relative to the expected angles of 109.4 for the ideal tetrahedral coordination.