Characterization of nonsegregated C₁₇Si₃ heterofullerenic isomers using density functional theory method

Abstract

Geometry, stability, and electronic properties of nine C 17 Si 3 heterofullerenic isomers (C 17 Si 3 ‐1 to C 17 Si 3 ‐9) are investigated at M062X/6–311++G**, B3LYP/AUG‐cc‐pVTZ, B3LYP/6–311++G**, B3LYP/6–311 + G*, and B3PW91/6–311++G** levels of theory. Vibrational frequency calculations show that all designed isomers are true minima. Exploring the nanocage structures shows the contraction of C=C double bonds to compensate for the longer carbon–silicon bonds. Energy, frequency, geometry, charge, polarity, aromaticity, Δ E LUMO–HOMO , and heat of atomization of these heterofullerenes seem strongly dependent on the topology of the incorporated silicon heteroatoms. While Si substitution increases the conductivity of C 17 Si 3 ‐3, and C 17 Si 3 ‐7 by decreasing their Δ E LUMO–HOMO , Si doping enhances the kinetic stability of C 17 Si 3 ‐1 against electronic excitations via increasing its Δ E LUMO–HOMO and makes them optically active by increasing their hyperpolarizability. The molecular electrostatic potential (MEP) maps indicate that the negative potential sites are on carbon atoms whereas the positive potential sites are around the silicon atoms. High charge transfer on the surfaces of C 17 Si 3 ‐2 to C 17 Si 3 ‐9 heterofullerenes provokes further investigations on their possible application for hydrogen storage. The nucleus‐independent chemical shift (NICS) values show that C 17 Si 3 ‐1 with three silicon atoms in the equatorial position is the most aromatic isomer.