A Rutile-Based Homologous Series Na(PtO₂)_2n+1 Discovered by Computationally Assisted High-Pressure Synthesis

Layered transition metal oxides typified by the Ruddlesden-Popper phase have been extensively studied for their applications in high-temperature superconductivity, catalysis, and battery technologies. Despite the remarkable structural diversity and catalytic functionality of platinum oxides, the exploration of layered polymorphs has remained significantly constrained, mainly due to the high inertness of platinum. Here, we discover a new homologous series of layered ternary oxides, Na(PtO₂)_2n+1, by a combination of highly oxidizing high-pressure methods and density functional theory (DFT) calculations. This series features unprecedented layered structural motifs, rutile-based PtO₆ octahedra, and one-dimensional PtO₄ square-planar columns, which enable systematic control of dimensionality. Furthermore, we demonstrate a computationally assisted identification of isomeric and putative members of this homologous series, as confirmed by controlled synthesis and quantitative analysis of diffuse scattering data. This approach provides an effective platform for the exhaustive exploration of metastable transition metal oxides with rich structural variations.