Strontium Vanadium Oxide-Hydrides: 'Square-Planar' Two-Electron Phases

摘要

A series of strontium vanadium oxide-hydride phases prepared by utilizing a low-temperature synthesis strategy in which oxide ions in Sr_(n+1)V_nO_(3n+1) (n = ∞, 1, 2) phases are topochemically replaced by hydride ions to form SrVO2H, Sr2VO3H, and Sr3V2O5H2, respectively. These new phases contain sheets or chains of apex-linked V~(3+)O4 squares stacked with SrH layers/chains, such that the n = ∞ member, SrVO2H, can be considered to be analogous to "infinite-layer" phases, such as Sr_(1-x)Ca_xCuO2 (the parent phase of the high-T_c cuprate superconductors), but with a d~2 electron count. All three oxide-hydride phases exhibit strong antiferromagnetic coupling, with SrVO2H exhibiting an antiferromagnetic ordering temperature, T_N>300 K. The strong antiferromagnetic couplings are surprising given they appear to arise from π-type magnetic exchange.