Stereochemical patterns in bromofullerenes C60Br2 to C60Br12

The stabilities of different isomers of C₆₀Br_n have been calculated for n = 2 to 12. A general stereochemical pattern which emerges is the tendency to form strings created by the edge sharing of C₆Br₂ hexagonal faces. Stable structures are formed if these strings form loops, thereby eliminating string ends, which may involve the creation of C₆Br₃ hexagonal faces. A particularly stable structure is formed at C₆₀Br₆ in which the loop forms a C₁₀Br₆ fragment with a pentagonal pyramidal arrangement of six bromine atoms. Two isomers of C₆₀Br₁₂ are also particularly stable. One isomer contains two of these Br₆ pentagonal pyramids on opposite sides of the molecule, and the other isomer contains a single large loop wrapped around the middle of the molecule.