Incorporation of the Similarly Sized Molecules, Diiodine and Carbon Disulfide, into Cocrystals Formed with the Fullerenes, C₆₀ or C₇₀

Cocrystallization of diiodine and carbon disulfide with the two common fullerenes, C₆₀ and C₇₀, has been examined. The binary cocrystal, C₇₀·I₂, readily formed when a solution of diiodine in diethyl ether was layered over C₇₀ dissolved in toluene, chlorobenzene, or 1,2-dichlorobenzene, but no binary cocrystal of diiodine and C₆₀ could be obtained despite persistent efforts. The ternary cocrystal, C₇₀·0.85I₂·0.15CS₂, which was grown from a carbon disulfide solution of C₇₀ and a benzene solution of diiodine, is isostructural with C₇₀·I₂ but has 15% of the diiodine sites replaced with carbon disulfide. In contrast, C₇₀·0.68I₂·0.32CS₂, which was obtained from diffusion of a cyclohexane solution of diiodine into a carbon disulfide solution of C₇₀, is a unique ternary cocrystal that is not related to any binary cocrystal of C₇₀ with diiodine or carbon disulfide. Crystals of 2C₆₀·2.46CS₂·0.54I₂ were obtained from a saturated carbon disulfide solution of diiodine and C₆₀. Black crystals of 2C₆₀·2.46CS₂·0.54I₂ form in a different space group from those of the solvate 2C₆₀·3CS₂ but have a very similar structure. Remarkably, diiodine molecules fractionally replace carbon disulfide in only two of the three independent sites within this crystal.