Abstract

The reaction of 2,2′-biimidazole with metal diiodides, PbI₂ and SnI₂, in hydriodic acid affords new organic-based layered perovskites, (C₆H₈N₄)PbI₄ and (C₆H₈N₄)SnI₄, in which non-primary ammonium organic cations were incorporated with the inorganic layered perovskites. Single crystal X-ray investigations show the aromatic heterocyclic biimidazolium cations form organic layers sandwiched between the metal iodide sheets. The metal iodide perovskite layers exhibit unusual structural features associated with one-dimensional metal halide structures. These structural features are rationalized in terms of stereoactive lone pairs that arise from the weakening of secondary bonds.