Structural Chemistry of Organomercury Compounds. Role of Secondary Interactions*

The structures of the organomercury compounds have been reviewed from the point of view of the secondary bonds which mercury atom forms with the surrounding atoms. These bonds, though rather labile, exhibit a definite influence on the crystal structure which is manifested in a peculiar coordination around the mercury atom. This influence has to be studied systematically since the mercury coordination polyhedra in the crystal structure of organomercury compounds are far from being regular. The review has been restricted to the structures in which the secondary bonds of mercury are shorter than the sum of the van der Waals radii. The upper limit of the distances within the coordination polyhedron cannot be well substantiated while the distances larger than the sum of the van der Waals radii may be also influencial in the structure. The influence of the long-range contacts, both on the molecular structure as a whole as well as on the stability of the secondary bonds, may be quite essential. The long-range contacts actually reproduce the solvation effect in chemical reactions in solutions. From this point of view the X-ray diffraction data are useful for the study of the chemical reaction mechanism in the organic chemistry of mercury.