Predicting the lowest energy isomers of C{sub 60}H{sub 36} and C{sub 70}H{sub 36}

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:141505

Book, L D; Scuseria, G E ^[1]

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1. Rice Univ., Houston, TX (United States)

Examination by mass spectroscopy of products of the hydrogenation of C{sub 60} and C{sub 70} indicates that the most abundant molecules formed are C{sub 60}H{sub 36} and C{sub 70}H{sub 36}. The extremely large number of possible isomers of these molecules makes systematic calculations to determine their thermodynamically most stable structures impossible. Here the authors use the the molecular mechanics program MM3 to establish the relative energies of isomers that could be especially stable due to extensive pi conjugation or low strain. Many isomers with 36 hydrogens attached to different sets of carbons on the fullerenes C{sub 60} and C{sub 70} were studied. Once the structures of the low energy isomers were narrowed down to a select few, the authors performed higher level calculations using the minimum-basis Hartree-Fock self-consistent-field (SCF) method. Results indicate that the lowest energy isomer of C{sub 60}H{sub 36} is the one in which the molecule`s 12 double bonds are moved as far apart as possible. In the case of C{sub 70}H{sub 36}, the lowest energy isomer appears to be the one in which the hydrogens are concentrated in the caps of the C{sub 70} structure, while the double bonds in the center form a surface that resembles a graphitic tube.

• OSTI ID: 141505
• Report Number(s): CONF-930304--
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
66 PHYSICS
ENERGY DEPENDENCE
FULLERENES
HARTREE-FOCK METHOD
ISOMERS
MOLECULAR MODELS
MOLECULAR STRUCTURE
PROBABILISTIC ESTIMATION
SELF-CONSISTENT FIELD