MOLECULAR MECHANICS OF TOROIDAL CARBON MOLECULES

Molecular mechanics calculations were performed for toroidal carbon cages in the form of non-chiral and chiral polyhex structures and for the structures with five-, six- and seven-membered rings which were distributed in such a way that mechanical strain was kept at minimum. The results show that for polyhex toroidal structures the bending of tubule axes looks to be the main contribution to the mechanical strain. When the strain is reduced by turning hexagons to pentagons and seven-membered rings the energy of formation of toroidal C-150 becomes comparable to the values which are found in medium size fullerenes.