SrFe0.5Ru0.5O2: Square-Planar Ru2+ in an Extended Oxide

Low-temperature topochemical reduction of the cation disordered perovskite phase SrFe0.5Ru0.5O3 with CaH2 yields the infinite layer phase SrFe0.5Ru0.5O2. Thermogravimetric and X-ray absorption data confirm the transition metal oxidation states as SrFe0.52+Ru0.52+O2; thus, the title phase is the first reported observation of Ru2+ centers in an extended oxide phase. DFT calculations reveal that, while the square-planar Fe2+ centers adopt a high-spin S = 2 electronic configuration, the square-planar Ru2+ cations have an intermediate S = 1 configuration. This combination of S = 2, Fe2+ and S = 1, Ru2+ is consistent with the observed spin-glass magnetic behavior of SrFe0.5Ru0.5O2.