Relativistic effects in chemical interactions: Symmetry and polymorphism of inorganic heavy-metal compounds

Relativistic effects on the properties and interactions of heavy elements i n inorganic compounds are considered. The emphasis is on the interpretation of structural and symmetry manifestations of interactions of elements havi ng closed electron shells with the 5d(10), 6s(,)(2) 6p(1/2)(2) etc. configu rations, including the problem of inert and stereochemically active 6s2 ele ctron pairs. In many cases, consideration of relativistic effects makes it possible to qualitatively describe polymorphism and the lowering of symmetr y in the simplest heavy-metal compounds.