Halobismuthates with halopyridinium cations: appearance or non-appearance of unusual colouring

Abstract

A series of chloro- and bromobismuthate complexes with bromopyridinium cations was prepared and characterized by XRD analysis and diffuse reflectance spectroscopy. In one case, short Cl⋯Br contacts between 2-BrPyH⁺ and chlorobismuthate units in the solid state result in notable charge transfer and the appearance of unusual coloring. The nature of halogen⋯halogen interactions, which can be regarded as halogen bonding, in the obtained complexes was studied by QTAIM analysis, and their energies were estimated (1.3–3.6 kcal mol⁻¹) and compared with those in related bromo- and iodoplumbates(II). It is concluded that the presence of halogen bonding is not the single factor affecting the optical properties.