Interaction Energies of CO2·Amine Complexes: Effects of Amine Substituents

Electronic Interactions in Iminophosphorane Superbase Complexes with Carbon Dioxide

Iminophosphoranes or phosphazenes are an important class of compounds with increasing use in synthetic organic chemistry as neutral organic superbases exhibiting low nucleophilicity. Their electronic structure and therefore their properties strongly depend on substitution, but there have been very few theoretical studies devoted to this topic, and more specifically to the formation of electron donor-acceptor complexes of iminophosphoranes with electrophiles. In this work, we have investigated the interaction with carbon dioxide at different ab initio levels. Carbon dioxide usually behaves as a Lewis acid and the reaction with iminiphosphoranes has been described as a nonconventional aza-Wittig process leading to isocyanates. The reaction can be conducted in supercritical CO₂ conditions (carbon dioxide acts as both solvent and reactant), which is a promising strategy in the context of green chemistry. Our calculations have been carried out at the CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVTZ level for model systems and at the M06-2X/6-611+G(d,p) level for a larger species used in experiments. The electronic interactions and the interaction energies are analyzed and discussed in detail using the natural bond orbital method. Proton affinities and gas-phase basicities are provided as well.

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

The interactions between CO₂ and aliphatic (primary, secondary and tertiary) and aromatic amines were computed using pure and hybrid density functionals.

Observation of guanidine–carbon dioxide complexation in solution and its role in the reaction of carbon dioxide and propargylamines

The first observation of guanidine–CO₂ ‘activation’ complexes in solution and their implications on the catalytic activity of guanidines are reported.