In this paper, we report the design of numerous CnF3- (n = 1-9) models. By means of B3LYP density functional method, we carried out geometry optimization and calculation on the vibrational frequency. After comparison of structure stability, we found that the structures of ground-state (G-S) isomers of odd-n CnF3- (i.e., n = 3, 5, 7 and 9) are with the three fluorine atoms located at one end of the linear Cn chain. The G-S isomers of C2F3-, C4F3-, and C8F3- are with two fluorine atoms bonded to an end carbon of the Cn chain, and one fluorine atom bonded to the adjacent carbon atom. In other words, the two carbon atoms involved in bonding to the fluorine atoms are sp2 hybridized and the Cn chain is not linear. In the case of C6F3-, the G-S isomer is planar cyclic in structure, with each of the three carbon atoms at one side of the hexagonal C6 ring bonded to a fluorine atom. The Cn chain of G-S CnF3- (n = 3-9; C6F3- being the exception) isomers are polyacetylene-like. It is found that the odd-n G-S CnF3- (n = 1-9) are more stable than the adjacent even-n ones. The finding is in accord with the relative intensities of CnF3-observed in mass spectrometric studies. We provide explanations for such trend of even/odd alternation based on concepts of the geometrical structure, bonding character, atomic charges, vertical electron detachment energy, and incremental binding energy.
Scopus Subject Areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Binary cluster anions
- Density functional theory study
- Fluorine-doped anionic carbon clusters