Comparative topological analysis of simple anhydrous borates, carbonates and nitrates

Topological analysis and comparing of the crystal structures of anhydrous inorganic salts containing triangular oxo-anions (borates, carbonates and nitrates) was performed using the program package for multipurpose crystallochemical analysis TOPOS. The examples of topological similarities between these classes of substances and 2920 framework binary compounds AyX, were revealed and discussed. It is shown that in most cases the ionic arrays constructed according to one of close packings or to a b.c.c. motif can be selected in the crystal structures of anhydrous inorganic salts. The conclusions were made about the structure-forming role of atoms and atomic groups in these substances. The crystal structures of anhydrous salts are substantiated to be correctly considered as packings of metal cations and quasi-spherical oxo-anions.