MOLECULAR AND ELECTRONIC-STRUCTURES OF SOME TRIMERS OF POLYHEDRAL CARBON CLUSTERS

Geometries and electronic structures of four crimped linear carbon clu sters were modeled by the MNDO/PM3 method. Three of these clusters (C- 180 clusters) are trimers of I-h-C-60 fullerene, which differ from eac h other by the mode of linkage of the monomers. The fourth cluster (C- 172 pseudo-trimer) consists of two C-58 fragments of C-60 fullerene In ked to each other through the C-56 cluster. The optimum geometric para meters, heats of formation, and ionization potentials were calculated for the above-mentioned systems as well as for the corresponding C-120 and C-116 dimers. The possibility of extrapolation of the data on dim ers and trimers to linear oligomers of the C-60 and C-56 clusters with a larger number of repeating fragments is discussed. The character of linkages of monomers was analyzed for the two trimers under considera tion, which have the most complex mode of binding of the C-60 fulleren e molecule and its fragments, using the C60H20 and C72H24 molecules (w hose carbon skeletons model the structures of these linkages) as examp les.