Theoretical Investigation into the Structural, Thermochemical, and Electronic Properties of the Decathio[10]circulene

For the first time, a theoretical study has been performed on the prototypical decathio[10]circulene (C20S10) species, which is an analogue of the novel octathio[8]circulene “Sulflower” molecule (C16S8). Examinations of the singlet and triplet states of C20S10 were made at the B3LYP/6-311G(d) level. Local minima of C 2 and C s symmetry were found for the lowest singlet and triplet states, respectively. The stability of C20S10 was assessed by calculating the ΔH°f of C16S8 and C20S10 and the ΔH o for their decomposition into C2S units. Frontier molecular orbital plots show that structural adjacent steric factors along with the twist and strain orientations of C20S10 do not disturb the aromatic π-delocalizing effects. In fact, C20S10 maintains the same p z HOMO character as C16S8. These similarities are further verified by density-of-states characterization. Calculated infrared spectra of C16S8 and C20S10 show broad similarities. Molecular electrostatic potential results reveal that eight of the peripheral sulfur atoms are the most electronegative atoms in the molecule, while the interior ten-membered ring exhibits virtually no electronegativity.