Metastable Materials with Linear Chains: Photoinduced Chemical Reactions in K ₂ X ₂ (X = S, Se, Te)

Metastable materials are attractive candidates for new catalysts, electrodes, and unconventional superconductors. Their unusual properties are rooted in nonstandard bonding, oxidation states, or coordination. However, potential applications of metastable materials are understudied, as it is difficult to obtain them via standard high-temperature solid-state synthesis methods, which result in the most thermodynamically stable products. Here, we computationally model a photochemical reaction that transforms synthetically available semiconducting crystals with a general formula K₂X₂ (X = S, Se, Te) into metastable materials with hypervalently bonded chains. The proposed reactions are an extension of well-documented ultrafast light-induced phase transitions, indicating the plausibility of these transformations under similar conditions.