Photochemical Reactions in A₂X₂ (A = Na, Rb and X = S, Se, Te): A Path toward Nonclassical Bonds in Metastable Compounds

Materials with nonclassical bonding, such as hypervalently bonded square-net materials, can have unusual properties necessary for the development of new technologies. However, unusual bonding, oxidation states, or coordination are typically found in metastable phases, which are hard to reach using common solid-state chemistry methods. We investigate photochemical reactions as a means of reaching metastable structures. We computationally examine the photochemical conversion of A₂X₂ (A = Na, Rb, and X = S, Se, Te) from experimentally known geometries with classical bonding into metastable structures with nonclassical, hypervalently bonded chains. We identify three metastable products realized at different light intensities.