Synthesis of Li2PtH6 using high pressure: Completion of the homologous series A2PtH6 (A=alkali metal)

Li2PtH6, the missing member of the complex transition metal hydride series A(2)PtH(6) (A=alkali metal), was prepared by reacting mixtures of LiH and Pt in the presence of BH3NH3 as hydrogen source at pressures above 8 GPa. According to powder X-ray diffraction analysis, Li2PtH6 is isostructural to its heavier homologues and crystallizes in the cubic K2PtCl6 structure (space group Fm (3) over barm, a=6.7681(3), Z=4). However, PtH62- octahedral complexes in Li2PtH6 approach each other closely and its structure may likewise be regarded as a defective perovskite structure where half of the octahedrally coordinated atoms (cations) are missing. The IR spectrum of Li2PtH6 reveals the Pt-H T-1u stretch and bend at 1840 and 889 cm(-1), respectively. (C) 2010 Elsevier Inc. All rights reserved.