Carbo-Cages: A Computational Study

Inspired by their geometrical perfection,
intrinsic beauty, and
particular properties of polyhedranes, a series of carbo-cages is
proposed in silico via density functional theory computations. The
insertion of alkynyl units into the C–C bonds of polyhedranes
results in a drastic lowering of the structural strain. The induced
magnetic field shows a significant delocalization around the three-membered
rings. For larger rings, the response is paratropic or close to zero,
suggesting a nonaromatic behavior. In the carbo-counterparts, the
values of the magnetic response are shifted with respect to their
parent compounds, but the aromatic/nonaromatic character remains unaltered.
Finally, Born–Oppenheimer molecular dynamics simulations at
900 K do not show any drastic structural changes up to 10 ps. In the
particular case of a carbo-prismane, no structural change is perceived
until 2400 K. Therefore, although carbo-cages have enthalpies of formation
1 order of magnitude higher than those of their parent compounds,
their future preparation and isolation should not be discarded, because
the systems are kinetically stable, explaining why the similar systems
like carbo-cubane have already been synthesized.