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Computational studies of less common fullerene‐related species
Author(s) -
Lee ShyiLong,
Sun MeiLing,
Slanina Zdeněk
Publication year - 1996
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(1996)60:7<1567::aid-qua38>3.0.co;2-y
Subject(s) - fullerene , buckminsterfullerene , ring (chemistry) , symmetry (geometry) , chemistry , ground state , ab initio , computational chemistry , carbon fibers , molecular physics , chemical physics , atomic physics , crystallography , physics , materials science , geometry , mathematics , organic chemistry , composite number , composite material
The contribution reports results of ongoing computations of various cage structures differing from the well‐known buckminsterfullerene in the number of carbon atoms (C 80 ) in their coordination or in the types of rings involved (C 59 ). The computations have supplied a complete description of the seven isolated‐pentagon‐rule (IPR) isomers of C 80 (i.e., a system not yet observed) at the semiempirical AM1 and SAM1 levels; their energetics was also evaluated at ab initio Hartree‐Fock level in small basis sets. The ground‐state structure of the system possesses a D 5d symmetry, but at supposed synthetic conditions a structure of D 2 symmetry is the most populated, i.e. temperature represents an important factor in the stability relationships. One of the IPR isomers exhibits an I h topological symmetry, but it undergoes a Jahn‐Teller distortion and its symmetry is actually reduced to D 2 . The C 59 serves as an example of odd‐numbered carbon clusters, and new rules are reported for the pentagon/hexagon pattern in the odd clusters, yielding a variable number of the pentagons. Moreover, other rings are considered and the computed ground state of the system in fact contains an eight‐membered ring (while the next lowest species exhibits a nine‐membered ring). Their relative stabilities are not very sensitive to temperature. Altogether 19 isomers of C 59 are treated at the AM1 level. In contrast to even‐numbered fullerenes, with odd fullerenes the cages cannot be built from three‐coordinated carbon atoms only. Hence, we have to allow for two‐ or even four‐coordinated atoms. For example, if we consider one two‐coordinated carbon atom (and the rest three‐coordinated) the number of pentagons drops to 10. If we allow for just one four‐coordinated atom, the number of pentagons changes to 14. Let the number of two‐coordinated carbon atoms be p, and the number of four‐coordinated q . If we still allow only for pentagons and hexagons, it holds for the number of pentagons n 5 = ‐2 p + 2 q + 12. © 1996 John Wiley & Sons, Inc.