Tilts and shifts in molecular perovskites

Abstract

Molecular perovskites have attracted widespread research attention for their diverse properties. Like inorganic perovskites, these systems are susceptible to displacive phase transitions of rigid octahedra. This study investigates the prevalence of the accessible rigid unit modes—conventional and unconventional tilts and columnar shifts—in the classes of molecular perovskites. Formate-based compounds prefer conventional tilting, as a result of its anti–anti binding mode. Azides, hypophosphites, and dicyanamides show a propensity for unconventional tilts and shifts, which relates to their flexible binding geometries.