Waves of Halogen–Halogen Bond Formation in the Cocrystallization of Hexabromobenzene and 1,2,4,5-Tetrabromobenzene with C₇₀

The
single crystal X-ray structures of three well-ordered cocrystals
of C70 with brominated benzenes are examined. The crystals
are those of C70·C6Br6·C7H8, C70·C6Br6·C6H6, and C70·2­(1,2,4,5-tetrabromobenzene)·CS2. While all three structures exhibit extensive van der Waals
interactions, the presence of a wavelike C–Br---Br structural
motif is a distinctive part of the cocrystal assembly. In these three
crystal structures, it is observed that the Br---Br interactions are
a cross between type I and II halogen–halogen bonds. In our
hands, this structural motif does not occur in structures with C60.