Synthesis of Li$_{2}$MgIr and LiMgIrH$_{6}$: Guidance from DFT

Formation of Li$_{2}$MgIr was suggested by theoretical modeling of Li$_{2}$MgX systems and their hydrides with density functional theory (DFT). Verifying our DFT results, we have synthesized Li$_{2}$MgIr and determined its crystal structure and hydrogen sorption behavior. The phase crystallizes in the cubic $P\bar {4}3m$ space group and is isostructural to the known ternary Li$_{2}$MgSi. Its reaction with hydrogen proceeds according to Li$_{2}$MgIr + $\textstyle{7 \over 2}$H$_{2}\to $ LiMgIrH$_{6}$ + LiH. The hydride LiMgIrH$_{6}$ also features $P\bar {4}3m$ symmetry; its detailed crystal structure is established via a combination of x-ray diffraction and DFT analyses. A metal $\to $ insulator transition accompanies formation of the hydride.