Unstable in air cubic co-crystals of C60·12CCl2Br2 and C60·12CBr2(CH3)2 were grown in saturated solutions.
Cubic co-crystals transform into the stable hexagonal co-crystals C60·2CCl2Br2 or C60·2CBr2(CH3)2.
V/Z for cubic and hexagonal co-crystals depend exclusively on the vdW volumes of the constituents.