[en] Structural modelling of mechanisms of inversion with central atom tetrahedral configuration in bischelate complexes of nontransitional metals, including Be, B, In, Cd and other is conducted. It is shown that in solutions the complexes mentioned undergo fast intramolecular stereoisomerization as well as reactions of intermolecular ligand exchange. Possible mechanism of these reactions are considered. 53 refs., 4 figs., 2 tabs