The Role of Sublattices in Chemical Bonding in Molecular Ion Crystals

The sublattice method developed earlier is used to study chemical bonding in series of oxyanion compounds MAO3 (M = Li, Na, K, Rb, Tl, Mg, Ca; A = C, N, Cl, Br). It is established that electrons pass from the metal sublattice to the anion plane so that the density maxima of the metal occupy the space between the anions. This leads to the formation of the ionic component of the bond between the metal and anion planes. More complex electron redistribution occurs between sublattices A and O, leading to a covalent bond inside the molecular group AO3. For carbonates, the difference density qualitatively agrees with the experimentally determined deformation density.