Interactions of carbon dioxide with model organic molecules: A comparative theoretical study

Interaction energies obtained using CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVTZ computations including both ZPE and BSSE corrections range from −2.9 to −14.2 kJ mol−1. While formic acid forms the most stable complex with CO2, formaldehyde yields the least stable complex. Lewis acid–base interaction such as C–N⋯C(CO2), CO⋯C(CO2), which overcomes C–H⋯O blue-shifting hydrogen bond, plays a significant role in stabilizing most complexes. However, the strength of (HCOOH, CO2) is mainly determined by O–H⋯O red-shifting hydrogen bond. The C–H⋯O blue-shifting hydrogen bond is revealed upon complexation of CH3OH, HCHO, HCOOH, CH3COCH3 and HCOOCH3 with CO2. Remarkably, existence of weak hydrogen bonded C–H⋯O interaction is not found in the (CH3OCH3, CO2) and (CH3NH2, CO2) pairs.