Computational Comparison of the Water-Dimer Encapsulations into D2(22)-C84 and D2d(23)-C84

Abstract

The water dimer encapsulations into D2(22)-C84 and D2d(23)-C84 fullerenes are evaluated. The encapsulation energy is computed at the M06-2X/6-31++G** level and it is found that the energy gain upon encapsulation into the D2(22)-C84 and D2d(23)-C84 cages is −17.37 and −15.48 kcal/mol, respectively. Encapsulation equilibrium constants are computed using partitions functions based on the M06-2X/6-31++G** molecular data. The yield for (H2O)2@D2(22)-C84 is higher than for (H2O)2@D2d(23)-C84, however, the yield ratio decreases with increasing temperature and for high temperatures is close to 2:1. The M06-2X/6-31++G** computed rotational constants are presented for a possible use in detection of the water-dimer endohedrals by rotational spectroscopy in laboratory or interstellar space.