Abstracts Book - IMRC 2018

• SF4-O009
EFFECT OF CARBON REPLACEMENT BY B - IN MONOCYCLIC AND
POLYCYCLIC AROMATIC HYDROCARBONS
William Tiznado 1
1 Universidad Andrés Bello, Chemistry, Chile.
The viability of global minimum aromatic systems, structurally analog to
monocyclic and polycyclic aromatic hydrocarbons, but obtained after successive
replacements of a C atom by its isoelectronic LiB fragment, was explored by ab
initio computations. The global minimum of the designed systems was identified
after a nearly exhaustive exploration of the potential energy surface, using
different algorithms and based on cellular automaton and genetic
algorithms. Interestingly, the most stable structures in the majority of the
studied cases preserved the structure of their hydrocarbon analogs.
Additionally, the Li counterions first occupied the axial positions, with a
maximum of two Li + by a ring (forming an inverted sandwich). Then, lithiums
were placed in equatorial positions bridging B-B bonds. The C-C, C-B bonds were
found to be 2c-2e covalent bond in nature, whereas the B-Li-B (equatorial) was
found to be a covalent multicenter 3c-2e s bond, as reflected in adaptive natural
density partitioning (AdNDP) analyses. Furthermore, an AdNDP analysis
recovered the same number of delocalized π-orbitals as their organic analogs,
with these systems preserving their aromatic character, and thus justifying the
proclivity to sandwich inverted form (with the adequate number of lithium). The
aromatic character of these species was confirmed by the analysis of both the
ring currents and the induced magnetic fields. Finally, the hydrogen-trapping
capability of the design systems was theoretically evaluated. Calculations
showed that each axial Li traps 3H 2 molecules, turning them into interesting
models to explore suitable materials, for example, those based on
functionalized graphene.
Keywords: Boron-carbon clusters, aromaticity, aromatic hydrocarbon
Presenting authors email: wtiznado@unab.cl