Abstract
Here we show that substituting the ten protons in the dianion of a
bispentalene derivative
(C18H102-) by six
Si2+ dications produces a minimum energy structure
with two planar tetracoordinate carbons (ptC). In
Si6C18, the ptCs are embedded in the
terminal C5 pentagonal rings and participate in a
three-center, two-electron (3c-2e) Si-ptC-Si σ-bond. Our exploration of
the potential energy surface identifies a triphenylene derivative as the
putative global minimum. But robustness to Born-Oppenheimer molecular
dynamics (BOMD) simulations at 900 and 1500 K supports bispentalene
derivative kinetic stability. Chemical bonding analysis reveals ten
delocalized π-bonds, which, according to Hückel’s 4n+2 π-electron rule,
would classify it as an aromatic system. Magnetically induced current
density analysis reveals the presence of intense local paratropic
currents and a weakly global diatropic current, the latter agreeing with
the possible global aromatic character of this specie.