Structures, Stabilities, Electronic, and Optical Properties of C-64 Fullerene Isomers, Anions (C-64(2-) and C-64(4-)), Metallofullerene Sc-2@C-64, and Sc2C2@C-64

摘要

The 3465 classical isomers of C-64 fullerene have been investigated by quantum chemical methods PM3, and the most stable isomers have been refined with HCTH/3-21G//SVWN/STO-3G, B3LYP/6-31G(d)//HCTH/3-21G, and B3LYP/6-311G(d)//B3LYP/6-31G(d) level. C-64(D-2:0003) with the lowest e(55) (e(55) = 2), the number of pentagon-pentagon fusions, is predicted to be the most stable isomer and it is followed by the C-64(C-s:0077) and C-64(C-2:0103) isomers within relative energy of 20.0 kcal/mol. C-64(D-2:0003) prevails in a wide temperature range according to energy analysis with entropy contribution at B3LYP/6-31G(d) level. The simulated IR spectra and electronic spectra help to identify different fullerene isomers. All the hexagons in the isomers with e(55) = 2 display local aromaticity. The relative stabilities of C-64 isomers change with charging in ionic states. Doping also affects the relative stabilities of fullerene isomers as demonstrated by Sc-2@C-64(D-2:0003) and Sc-2@C-64(C-s:0077). The bonding of Sc atoms with C-64 elongates the C-C bond of two adjacent pentagons and enhances the local aromaticity of the fullerene cages. Charging, doping, and derativization can be utilized to isolate C-64 isomers through differentiating the electronic and steric effects. (c) 2008 Wiley Periodicals, Inc.