On a dual function of anions in crystallogenesis of compounds: Structure-directing and stabilizing

Abstract

The crystallogenesis of three groups of structures of fluoride-orthoborates (and their analogs) with large cations is studied from the point of view of the current cation-framework representations. Their cation frameworks are sterically templated by rigid borate anions and are built as antizeolite structures. Cavities of channel or layered types are filled with components different their composition and configuration with the main function as charge compensators. An example of different functionalities of the identical anions are Ba₃(BO₃)₂ and La₃Ca₃(BO₃)₅ structures. In these structures, two (BO₃) types generate a cation framework, and the third type stabilizes it in ready channels (!).