STRUCTURES AND STABILITIES OF HYDROFULLERENES - COMPLETION OF A TETRAHEDRAL FUSED QUADRUPLE CROWN STRUCTURE AND A DOUBLE CROWN STRUCTURE ATC60H36

The calculation of the stabilities of different isomers of C60Hn has b een extended from n = 24 to n = 36. The stepwise addition of pairs of hydrogen atoms to C60H24, which contains a C18H18 crown as the dominan t structural feature, forms a fused double crown structure at C60H32 a nd a fused quadruple crown structure of tetrahedral T symmetry at C60H 36. Another isomer of C60H36, consisting of two independent crowns, is slightly more stable than the fused quadruple crown structure. Furthe r hydrogenation is relatively unfavourable. The centres of the crowns contain C6 rings in which the bonding is unusually delocalised.