Anion Redox as a Means to Derive Layered Manganese Oxychalcogenides with Exotic Intergrowth Structures

Topochemistry enables step-by-step conversions of solid-state materials often leading to metastable structures that retain initial structural motifs. Recent advances in this field revealed many examples where relatively bulky anionic constituents were actively involved in redox reactions during (de)intercalation processes. Such reactions are often accompanied by anion-anion bond formation, which heralds possibilities to design novel structure types disparate from known precursors, in a controlled manner. Here multistep conversion is presented of layered oxychalcogenides Sr2MnO2Cu1.5Ch2 (Ch = S, Se) into Cu-deintercalated phases where antifluorite type (Cu1.5Ch2)2.5- slabs collapsed into 2D arrays of chalcogen dimers. The collapse of the sulphide layers on deintercalation led to various stacking types of Sr2MnO2Ch2 slabs, which formed unprecedented polychalcogenide structures unattainable by conventional high-temperature syntheses. Anion-redox topochemistry is demonstrated to be of interest not only for electrochemical applications but also to design of complex novel layered architectures.