The Calculated Structure and Energetics of (CO2)2@C84

Calculations are presented for the encapsulation of two CO2 molecules in the most common C84 fullerenes, producing (CO2)2@D2(22)-C84 and (CO2)2@D2d(23)-C84. The calculations are performed at the DFT M06-2X/6-31+G* level with the BSSE correction. The encapsulation energy for (CO2)2@D2(22)-C84 and (CO2)2@D2d(23)-C84 is calculated as −4.9 and −5.6 kcal/mol, respectively. The encapsulation of two CO2 molecules is attractive, though the energy gain is, owing to a steric hindrance, smaller than previously found for the encapsulation of one CO2. The IR vibrational spectra are presented, too.