Synthesis and crystal structure determination of LaAuO₃

A new ternary oxide of gold and lanthanum, LaAuO₃, has been prepared from Au₂O₃ · 2H₂O and La(OH)₃ by applying high oxygen pressure and adding aqueous KOH (55%) as a mineralizer. The bright yellow and diamagnetic LaAuO₃ crystallizes in the orthorhombic crystal system, Pbcm, a = 403.35(7), b = 1307.3(2), c = 569.52(8) pm, Z = 4. The crystal structure (determined from 980 unique reflections with a final R value of 5.7% (R_w = 4.7%)) consists of a grid of cubes formed by the oxygens which are either centered by lanthanum ions or face centered by gold ions. Thus, lanthanum is coordinated eightfold, and gold fourfold, by oxygen. LaAuO₃ may be described as a CaF₂ structure sheared within the (110) plane by half a translational period along (0 0 1].