CO₂@C₈₄: DFT Calculations of Structure and Energetics

Encapsulations of carbon dioxide into (Formula presented.) (22)- (Formula presented.) and (Formula presented.) (23)- (Formula presented.) fullerenes are evaluated. The encapsulation energy is computed with the DFT M06-2X/6-31+ (Formula presented.) approach corrected for the basis set superposition error evaluated by the counterpoise method. The resulting encapsulation energy for (Formula presented.) @ (Formula presented.) (22)- (Formula presented.) and (Formula presented.) @ (Formula presented.) (23)- (Formula presented.) amounts to substantial values of −14.5 and −13.9 kcal/mol, respectively. The energy gain is slightly larger than for CO@ (Formula presented.), already synthesized with a high-temperature and high-pressure treatment—so that a similar preparation of (Formula presented.) could be possible. The calculated rotational constants and IR vibrational spectra are presented for possible use in detection. The stability of (Formula presented.) (Formula presented.) is also briefly discussed.