A theoretical thermodynamic investigation of cascade reactions in dinuclear octa-azacryptates involving carbon dioxide.

This paper investigates the thermodynamics of gas-phase CO(2) cascade uptake-reactions in the form of carbonate or monomethylcarbonate anions in the host cavity of various dinuclear octa-azacryptates of m-CH(2)C(6)H(4)CH(2) and 2,5-furano-spaced hosts, L (1) and L (2) cryptands, using density functional theory (DFT). The cascade process involves two stages, namely the formation of dinuclear cryptate complexes, and the subsequent formation of either μ-carbonato cryptate complexes or μ-monomethylcarbonato cryptates. The geometric and electronic structures were also investigated to determine the parameters that affect the stability of the complexes. Natural bond orbital (NBO) analysis was used to investigate the interactions between the trapped anion and its host. Ion selectivity was studied in terms of the formation of dinuclear cryptate complexes, while the basicity and nucleophilicity of cryptands towards Lewis acids was also studied, and good agreement was found vis-à-vis available experimental data.