Theoretical study on σ- and π-hole carboncarbon bonding interactions: implications in CFC chemistry

In this manuscript the ability of CO₂ and several CFCs to establish noncovalent carboncarbon interactions (termed as noncovalent carboncarbon bonding) with atmospheric gases CO, ethene and ethyne has been studied at the RI-MP2/def2-TZVPD level of theory. We have used several CFCs (CFCl₃, CF₃Cl, CF₂Cl₂ and CH₃F) and the CO₂ molecule as σ- and π-hole carbon bond donors (electron poor carbon atoms). As electron rich moieties we have used CO, ethene and ethyne (electron rich carbon atom bearing molecules). We have also used Bader's theory of "atoms in molecules" to further analyse and characterize the noncovalent interactions described herein. Finally, we have analyzed possible cooperativity effects between the noncovalent carboncarbon bonding and hydrogen bonding interactions in the case of ethyne.