Transformation of the Chromium Coordination Environment in LaCrAsO Induced by Hydride Doping: Formation of La2Cr2As2OyHx.

We report the synthesis of La2Cr2As2OyHx (0.1 < y < 1.6) oxyhydride solid solutions using a solid-state reaction under high pressure with a solid-state hydrogen source and exhibit an example of how H- doping can also promote structural changes: H- doping in LaCrAsO results in the formation of La2Cr2As2OyHx with the La2Fe2Se2O3-type layered structure. Remarkably, this transformation includes a change of the coordination number of Cr from 4 to 6, with the some of the H- being accommodated in new sites within the CrAs layers. In this way, H- not only serves as a conventional electron dopant by the substitution of O2- but also makes new bonds to the transition metals.