LaMg2PdH7, a new complex metal hydride containing tetrahedral [PdH4]4− anions

Hydrogenation of the intermetallic compound LaMg2Pd at 200 °C and 10 bar leads to a complex metal hydride of composition LaMg2PdH7. Its structure has orthorhombic symmetry and displays tetrahedral [PdH4]4− anions. The Pd–H bond distances as measured on the deuteride range from 1.71 to 1.78 Å and the H–Pd–H bond angles from 95° to 122°. Three additional hydride anions H− occupy La2Mg2-type interstices having tetrahedral metal configurations. Band structure calculations suggest the hydride to be non-metallic and to have a band gap of ∼1.0 eV. The compound desorbs hydrogen at 125 °C yielding a pressure of more than 1 bar absolute.