Ab initio Study of the Interactions between CO2 and N-Containing Organic Heterocycles

The interactions between carbon dioxide and organic heterocyclic molecules containing nitrogen are studied by using high-accuracy ab initio methods. Various adsorption positions are examined for pyridine. The preferred configuration is an in-plane configuration. An electron donor-electron acceptor (EDA) mechanism between the carbon of CO2 and the nitrogen of the heterocycle and weak hydrogen bonds stabilize the complex, with important contributions from dispersion and induction forces. Quantitative results of the binding energy Of CO2 to pyridine (C5H5N), pyrimidine, pyridazine, and pyrazine (C4H4N2), triazine (C3H3N3), imidozole (C3H4N2), tetrozole (CH2N4) purine (C5H4N4) imidozopyridine (C6H5N3), adenine (C5H5N5), and imidozopyridamine (C6H6N4) for the in-plane configuration ore presented. For purine, three different binding sites ore examined. An approximate coupled-cluster model including single and double excitations with a perturbative estimation of triple excitations (CCSDM) is used for benchmark calculations. The CCSD(T) basis-set limit is approximated from explicitly correlated second-order Moller-Plesset (MP2-F12) calculations in the aug-cc-pVTZ basis in conjunction with contributions from single, double, and triple excitations calculated at the CCSD(T)16-311 + + G** level of theory. Extrapolations to the MP2 basis-set limit coincide with the MP2-F12 calculations. The results are interpreted in terms of electrostatic potential maps and electron density redistribution plots. The effectiveness of density functional theory with the empirical dispersion correction of Grimme (DFT-D) is also examined.