Crystal Structure and Formation of TlPd3 and its new Hydride TlPd3H

TlPd₃ was synthesised from the elements in evacuated silica tubes at 600 °C. Alternatively, TlPd₃ was yielded by reduction of TlPd₃O₄ in N₂ gas atmosphere. Reduction of the oxide in H₂ gas atmosphere resulted in the formation of the new hydride TlPd₃H. The structure of tetragonal TlPd₃ (ZrAl₃ type, space group I4/mmm, a = 410.659(9) pm, c = 1530.28(4) pm) was reinvestigated by X‐ray and also by neutron powder diffraction as well as the structure of its previously unknown hydride TlPd₃H (cubic anti‐perovskite type structure, space group Pm\bar{3} m, a = 406.313(1) pm). In situ DSC measurements of TlPd₃ in hydrogen gas atmosphere showed a broad exothermic signal over a wide temperature range with two maxima at 280 °C and at 370 °C, which resulted in the product TlPd₃H. A dependency of lattice parameters of the intermetallic phase on reaction conditions is observed and discussed. Results of hydrogenation experiments at room temperature with gas pressures up to 280 bar hydrogen and at elevated temperatures with very low hydrogen gas pressures (1–2 bar) as well as results of dehydrogenation of the hydrides under vacuum will be discussed.