Insights into the interactions of CO₂ with amines: a DFT benchmark study

Abstract

The interaction between CO2 and 1,2-diaminoethane was computed using pure and hybrid density functionals. The CAM-B3LYP and wB97X-D functionals using a triple-ζ basis set that includes diffuse and polarization functions are the best functionals for calculating the relative energies of the zwitterion intermediate compared to a coupled-cluster with a single, double and non-iterative triple excitation (CCSD(T)) approach extrapolated to a complete basis set limit. With the two functionals and the triple-ζ basis set, the zwitterion is 1.70 kcal mol(-1) less stable than the reactants, and close to 1.63 kcal mol(-1) computed using the CCSD(T) approach. The inclusion of vibrational and thermal corrections and of entropic effects increases the relative energy of the zwitterion to 14.7 kcal mol(-1). Bending of the CO2 geometry increases its acidity due to a 1.09 eV reduction in the LUMO energy. Calculation of the CO2 interaction energy with a set of amines revealed that the interaction energies show a high correlation with their basicities, with the stronger bases stabilizing the zwitterion. For the most basic amine computed (3,4,6,7,8,9-hexahydro-2H-pyrimido[1,2-a]pyrimidine), the Gibbs free energy of the zwitterion is 15.8 kcal mol(-1) lower than the reactants. Therefore, for this highly basic amine, the zwitterion may have a longer lifetime, in contrast to 2-aminoethanol (MEA), where it is only a transient species.

Tetrel, chalcogen, and CH⋅⋅O hydrogen bonds in complexes pairing carbonyl-containing molecules with 1, 2, and 3 molecules of CO2

“…[5][6][7][8][9][10] CO 2 has also been the subject of numerous computational studies. [11][12][13][14][15][16] Other efforts have added to understanding the interactions of CO 2 with various solutes, especially those containing carbonyl functional groups or aromatic systems and other heteroatoms as nitrogen, sulfur, or halogens in their compositions. [17][18][19][20][21][22][23][24][25][26][27][28] These works have added to our understanding by providing a clear definition of the conformational landscape in systems in which CO 2 acts as both electron acceptor and donor in noncovalent complexes with different solutes and in the presence of a variety of heteroatoms in their compositions, which offer many peculiarities in their structures.…”

MP2 versus density functional theory calculations in CO2‐sequestration reactions with anions: Basis set extrapolation and solvent effects

“…As expected, the base strength, quantified by the GPB, shows a high correlation with the Gibbs free energy for the A − + CO 2 reactions (Figure 1). The more negative Gibbs free energies are found for stronger bases, which can donate electron density more easily [15].…”

“…Recent studies have focused on the interaction mechanism of different chemical absorbents with carbon dioxide using both density functional theory (DFT) and wavefunction-based approaches [15,16]. Carneiro et al studied the reaction between CO 2 and amines using the CAM-B3LYP and ωB97X-D functionals and the MP2 method with the aug-cc-pVTZ basis sets [15]. All energies were subsequently extrapolated to the complete basis set (CBS) limit using Truhlar's procedure [17].…”

“…All energies were subsequently extrapolated to the complete basis set (CBS) limit using Truhlar's procedure [17]. They have shown that the interaction energy and stabilization of the zwitterion intermediate show high correlation with the basicity of the amines [15]. Different kinds of basic species, such as amines [9,16] and benzylchalcogenides [18] were also investigated by theoretical procedures, trying to quantify their capacity to react with CO 2 .…”

Adsorption of Bitumen Model Compounds on Kaolinite in Liquid and Supercritical Carbon Dioxide Solvents: A Study by Periodic Density Functional Theory and Molecular Theory of Solvation

“…The interaction of amines with CO 2 and the relative energies of the zwitterion intermediates in the carbamic acid reaction mechanism have been studied using pure and hybrid density functionals. 34,35 Correlated ab initio molecular dynamics simulations of the acetone−CO 2 complex reveal the Lewis acid and Lewis base behaviors of CO 2 . 36 Density functional theory (DFT) studies of the condensation of supercritical CO 2 on kaolinite agree with microbalance measurements in that CO 2 adsorption is favorable and shows distorted T-shaped clustering.…”