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Abstract
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Anion recognition is a topic of current interest in supramolecular chemistry [1]. Recognition refers to the selective interaction of the host system -the receptor- with the anion -the guest [2]. In this work the inclusion of halide ions into a dicopper(II) bistren cryptate complex containing 2,5- dimethylfuran spacers ([X Cu2(FuEACryp)]3+, X=Cl , Br , I ; see Fig. 1.) has been investigated, theoretically. The geometries of all species in the gas-phase were fully optimized with SVP basis set at B3LYP and BP86 levels of theory using the Gaussian 03 set of programs. The computed structural parameters for [Cl Cu2(FuEACryp)]3+ and [Br Cu2(FuEACryp)]3+ are very close to the related X-ray values [3]. The interaction, strain and formation energies were calculated for all compounds in the gas phase. NBO and AIM calculations were also performed on all complexes. The result of calculations in the gas phase showed the following trend for interaction, strain and also formation energies: [Cl Cu2(FuEACryp)]3+ > [Br Cu2(FuEACryp)]3+ > [I Cu2(FuEACryp)]3+. Moreover, there is a good agreement between the theoretical and experimental stability constants.
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