Electronic Structures and Geometries of C₆₀ Anions via Density Functional Calculations

Abstract

The geometries and electronic structures of C60 and its mono- through hexaanions, all of which have been prepared in macroscopic quantities, are calculated using modern density functional techniques. Clear assignments of the electronic states, symmetries, and Jahn−Teller distorted geometries of the ions, which are difficult to determine experimentally, are obtained. The results are compared with available experimental data, and the agreement is excellent. Our calculations predict the geometries and electronic structures which have not yet been measured. Comparison with previous theoretical work indicates that density functional theory is the method of choice for the fullerene anions.

Discrete Fulleride Anions and Fullerenium Cations

“…It is a natural consequence of electronic structure and was anticipated in early molecular orbital calculations 1 which place a low-lying unoccupied t 1u level about 2 eV above the h u HOMO: [2][3][4] Early in the gas-phase investigations of fullerenes, the electron affinity of C 60 was measured and found to be high (2.69 eV). [5][6][7] When the macroscopic era of C 60 chemistry began in 1990, this property was soon found to translate into the solution phase. 8 In a rather remarkable cyclic voltammogram (see Figure 1), the reversible stepwise addition of up to six electrons was soon demonstrated electrochemically.…”

“…The most remarkable of these are the superconducting phases, A 3 C 60 (A ) alkali metal cation). 11 The extended properties of these systems have been extensively reviewed elsewhere [12][13][14][15] but are part of this review when connections can be made to the discrete C 60 n-ions. Another early development was the discovery of a unique fulleride phase which displays ferromagnetism: [TDAE]- [C 60 ] (TDAE ) tetrakis(dimethylamino)ethane).…”

“…Another early development was the discovery of a unique fulleride phase which displays ferromagnetism: [TDAE]- [C 60 ] (TDAE ) tetrakis(dimethylamino)ethane). 16 Solid-state superconductivity and ferromagnetism in [60]-fulleride materials arises from cooperative interactions between electrons on adjacent buckyballs. The ball-to-ball contact is relatively meager, but tangential contact at near van der Waals separation is sufficient to develop the appropriate electronic band structures.…”

“…20 An unanticipated property of discrete C 60 n-fullerides is their propensity to disobey Hund's rule. For example, the 3-fold degeneracy of the t 1u LUMO leads to the expectation of a spin quartet ground state for C 60 3-:…”

Distribution of field-induced charges in C60 fullerite

“…An analysis of the results of quantum mechanical calculations both semiempirical and ab initio [14][15][16] shows that the approximation (2) is rather accurate for several electrons or holes. The higher-order terms can violate the independence of the charge-profile shape on the concentration of injected charges.…”