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-con taining macrocycles has been investigated. For this purpose, calculati ons of the complexes of halide anions with cyclic trimeric o-phenylene mercury (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 carri ed out by the MNDO method. Complexes of the half-sandwich [L-X](-), bi pyramidal [X-L-X](2-) and sandwich [L-X-L]- (X = Hal, L = mercury-cont aining macrocycle) types have been calculated. It has been established that a uniform description of the bonding in such complexes, not depe nding on the number of Hg atoms in the macrocycle, can be reached with in the framework of the concept of generalized chemical bonds. (C) 199 7 Elsevier Science S.A.