Stability of hypothetical AgIICl2 polymorphs under high pressure, revisited: a computational study

Abstract

A comparative computational study of stability of candidate structures for an as-yet unknown silver dichloride AgCl2 is presented. It is found that all considered candidates have a negative enthalpy of formation, but are unstable towards charge transfer and decomposition into silver(I) chloride and chlorine within the DFT and hybrid-DFT approaches in the entire studied pressure range. Within SCAN approach, several of the “true” AgIICl2 polymorphs (i.e. containing Ag(II) species) exhibit a region of stability below ca. 20 GPa. However, their stability with respect to aforementioned decomposition decreases with pressure by account of all three DFT methods, which suggests a limited possibility of high-pressure synthesis of AgCl2. Some common patterns in pressure-induced structural transitions observed in the studied systems also emerge, which further testify to an instability of hypothetical AgCl2 towards charge transfer and phase separation.

Application of Silver Compounds in Fluoroorganic Synthesis: A Minireview

“…[54] Last but not the least, AgCl 2 has been theorized but it has been computed to be unstable towards a redox reaction involving ligands, similarly to AgSO 4 . [55] The combined experimental and theoretical evidence suggests that disproportionation of Ag(II) is strongly ligand-dependent, and tends to be prevented in most strongly electronegative and the least basic ligand environment, i. e. in fluoride and complex fluoroligand one [16] as well as oxido-(but not simple oxide!) one, provided that charge density on oxo terminus is diminished by use of Lewis acid (e. g., for sulphate, fluororosulphate and triflate liagands).…”

“…Ag(I)Ag(III)O 2 [53] retains its mixed‐valent character up to at least 100 GPa [54] . Last but not the least, AgCl 2 has been theorized but it has been computed to be unstable towards a redox reaction involving ligands, similarly to AgSO 4 [55] . The combined experimental and theoretical evidence suggests that disproportionation of Ag(II) is strongly ligand‐dependent, and tends to be prevented in most strongly electronegative and the least basic ligand environment, i. e .…”