Crown compounds for anions. A new approach to the description of chemical bonds in the complexes of halide anions with polymercury-containing macrocycles

The nature of chemical bonds between halide anions and polymercury-containing macrocycles has been investigated. For this purpose, calculations of the complexes of halide anions with cyclic trimeric o-phenylenemercury (o-C6H4Hg)(3), cyclic trimeric pefluoro-o-phenylenemercury (o-C6F4Hg)(3), cyclic pentameric perfluoroisopropylidenemercury [(CF3)(2)CHg](5) and some of their simpler hypothetical analogs have been carried out by the MNDO method. Complexes of the half-sandwich [L-X](-), bipyramidal [X-L-X](2-) and sandwich [L-X-L]- (X = Hal, L = mercury-containing macrocycle) types have been calculated. It has been established that a uniform description of the bonding in such complexes, not depending on the number of Hg atoms in the macrocycle, can be reached within the framework of the concept of generalized chemical bonds. (C) 1997 Elsevier Science S.A.