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Title
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A theoretical study on encapsulation of halide anions within the cavity of hexaprotonated aliphatic azacryptand 1,4,8,11,14,18,23,27- octaazabicyclo[9.9.9]nonacosane in the gas phase and solution
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Abstract
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Anion coordination chemistry also arose as a scientific topic with the conceptual development of supramolecular chemistry [1]. Aliphatic azacryptands are one of the bicyclic receptors family that have been used as hosts for anions [2]. Herein we report a density functional theory (DFT) study as well as natural bond orbital (NBO) and atoms in molecules (AIM) analysis on encapsulation of halide anions within the cavity of hexaprotonated aliphatic azacryptand 1,4,8,11,14,18,23,27- octaazabicyclo[9.9.9]nonacosane (232) in the gas phase and solution. The geometries of all species in the gas-phase were fully optimized with TZVP basis set at B3LYP and BP86 levels of theory using the Gaussian 03 set of programs. The computed N H···X distances for [Cl H6232]5+ in most cases are close to the related X-ray values [3]. The calculated root mean squares (RMS) are 0.234 and 0.215 Å at BP86/TZVP and B3LYP/TZVP levels of theory, respectively. The interaction, strain and formation energies were calculated for all compounds. NBO and AIM calculations were also performed on all complexes. The result of calculations in the gas phase showed that the [F H6232]5+ has maximum amounts of interaction, strain and formation energies. Moreover, there is a good agreement between the theoretical and experimental stability constants.
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