Article pubs.acs.org/crystal
Incorporation of the Similarly Sized Molecules, Diiodine and Carbon Disulfide, into Cocrystals Formed with the Fullerenes, C60 or C70 Kamran B. Ghiassi, Faye L. Bowles, Susanne Y. Chen, Marilyn M. Olmstead,* and Alan L. Balch* Department of Chemistry, University of California, Davis, California 95616, United States S Supporting Information *
ABSTRACT: 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.
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at low temperature.11 In order to form crystals of C70·3CS2 and 2(C70)·3CS2 that were suitable for single-crystal X-ray diffraction, we found that it was important to have diiodine present in the carbon disulfide solution of C70. However, diiodine was not incorporated into these crystals. Diiodine and carbon disulfide have similar sizes. The volume of a diiodine molecule is 85.1 Å3, whereas the volume of a carbon disulfide molecule is 82.9 Å3.12 Additionally, the two molecules have similar van der Waals lengths: 6.62 Å for diiodine and 6.70 Å for carbon disulfide. Consequently, we expected that these two molecules could substitute for one another. The possibility of incorporation of diiodine into fullerene crystals is intriguing because of the suggestion of conductivity or even superconductivity in such crystals.13 Nevertheless, transmission microscopy,14 X-ray powder diffraction,15 and Raman spectroscopy16 have not fully characterized the structure of this sort of material. Some prior studies were available. Diiodine cocrystallizes with C60 and toluene to produce black crystals of C60·I2·MeC6H5.12 It has been reported that diiodine can substitute for carbon disulfide in crystals of 2C60·3CS2, but crystallographic data on this issue have not been published.12 Here, we report studies of the cocrystallization of C60 or C70 in the presence of diiodine and/or carbon disulfide and explore the formation of mixed cocrystals of carbon disulfide/diiodine with fullerenes.
INTRODUCTION Solvated crystals of fullerenes are frequently produced from solutions of fullerenes in organic solvents. However, these materials frequently have presented properties that have posed problems for full structural understanding. It is likely that the first report of crystallization of C60 involved the solvate C60· 4(C6H6).1,2 The structure of this solid is complicated by significant disorder at room temperature and the occurrence of a phase change that occurs upon cooling.2−5 Crystallization of C60 from solutions containing n-pentane produces needleshaped crystals of C60·n-C5H12 with a ten-sided morphology and pseudo-ten-fold symmetry in the diffraction pattern.6 Twinning and disorder appear to contribute to the unusual diffraction pattern found for these crystals. As a consequence of these issues, solvates have rarely been useful in determining the structures of higher fullerenes and endohedral fullerenes.7 Fullerenes are usually quite soluble in carbon disulfide, which has been used to extract them from the raw soot obtained in the electric arc synthesis of fullerenes.8 The volatility of carbon disulfide allows it to be easily removed from the extract. Evaporation of a carbon disulfide solution containing purified C60 yields the solvate 2C60·3CS2 as brown crystals.9 At room temperature, these crystals are disordered, but they undergo a reversible phase change when cooled. At 90 K, the monoclinic phase contains two C60 molecules and three carbon disulfide molecules in the asymmetric unit.10 All of these molecules are ordered. Recently, we reported that crystals of carbon disulfide solvates of the higher fullerenes C70 and D5h-C90 can be obtained and that the fullerene components of these solvates, D5h(1)-C90·CS2, C70·3CS2, and 2(C70)·3CS2, are well-ordered © 2014 American Chemical Society
Received: June 4, 2014 Revised: August 10, 2014 Published: August 20, 2014 5131
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Table 1. Crystal Data for C70 and C60 Cocrystals C70·I2 chemical formula formula weight color, habit crystal system space group T (deg K) a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z dcalc (g cm−3) μ (mm−1) F(000) crystal size (mm) reflections collected, Rint data/parameters/restraints Rint R1 [I > 2σ(I)]a wR2 (all data)b largest dif. peak and hole (e Å−3) chemical formula formula weight color, habit crystal system space group T (deg K) a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z dcalc (g cm−3) μ (mm−1) F(000) crystal size (mm) reflections collected, Rint data/parameters/restraints Rint R1 [I > 2σ(I)]a wR2 (all data)b largest dif. peak and hole (e Å−3) a
C70·0.85I2·0.15CS2
C70I2 C70.15I1.70S0.30 1094.50 1067.85 black block black block monoclinic monoclinic P21/n P21/n 90(2) 90(2) 11.0613(7) 11.0939(12) 21.9269(13) 21.932(2) 14.0907(9) 14.0954(16) 90 90 90.065(3) 90.106(2) 90 90 3417.6(4) 3429.6(7) 4 4 2.127 2.068 1.904 1.645 2104 2063 0.231 × 0.148 × 0.138 0.110 × 0.100 × 0.100 80 452 44 922 10 438/650/0 10 378/666/0 0.0270 0.0228 0.0175 0.0184 0.0453 0.0476 0.421 and −0.398 0.383 and −0.594 D5h-C70·3CS2c 2(D5h-C70)·3CS2c 2C60·2.46CS2·0.54I2 C73S6 1069.09 black block triclinic P1̅ 90(2) 10.1998(4) 14.2540(6) 14.3062(6) 86.279(3) 73.297(2) 89.643(3) 1987.82(14) 2 1.786 0.441 1068 0.93 × 0.87 × 0.39 23264 6886/712/0 0.055 0.0815 0.2471 0.651 and −0.811
C143S6 1909.79 black block monoclinic P21/c 90(2) 19.2587(11) 19.5039(11) 19.8293(11) 90 106.076(4) 90 7157.0(7) 4 1.772 0.335 3816 0.35 × 0.15 × 0.11 81796 16 375/1342/0 0.050 0.1055 0.2604 1.938 and −1.322
C122.46I1.08S4.92 1765.98 black block orthorhombic P212121 90(2) 9.8819(4) 24.9614(9) 25.3649(9) 90 90 90 6256.7(4) 4 1.875 0.793 3484 0.52 × 0.30 × 0.15 61982 19 127/1201/10 0.0265 0.0412 0.1037 1.58 and −1.01
C70·0.68I2·0.32CS2 C70.32I1.36S0.64 1038.06 black block orthorhombic Fddd 90(2) 28.316(5) 28.318(5) 34.196(6) 90 90 90 27 421(8) 32 2.012 1.365 16141 0.301 × 0.237 × 0.169 121 736 12 489/682/0 0.0328 0.0288 0.0615 0.502 and −0.381 2C60·3CS2d C123S6 1669.59 dark brown lath monoclinic P21/n 90(2) 9.8722(12) 25.466(3) 24.671(3) 90 90.047(3) 90 6202.5(7) 4 1.788 0.297 3336 0.065 × 0.13 × 0.36 60760 14 233/1162/0 0.115 0.0579 0.1224 0.46 and −0.46
For data with I > 2σ(I), R1 = ∑||Fo| − |Fc||/∑|Fo|. bFor all data, wR2 = (∑[w(Fo2 − Fc2)2]/∑[w(Fo2)2])1/2 cData from ref 11. dData from ref 10.
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RESULTS The Molecular and Supramolecular Structure of C70·I2. Black blocks of C70·I2 were obtained by diffusion of a solution of diiodine in diethyl ether into a toluene solution of C70. Additionally, these crystals could be grown from a variety of solvent mixtures, including diiodine in diethyl ether layered over C70 dissolved in toluene, chlorobenzene, or 1,2dichlorobenzene; diiodine in cyclohexane layered over C70 dissolved in 1,2-dichlorobenzene; or diiodine in toluene layered
over C70 dissolved in toluene or benzene. Crystal data for this monoclinic crystal along with the other crystals considered here are given in Table 1. The asymmetric unit consists of a fully ordered molecule of C70 and a molecule of diiodine, both in general positions. Figure 1 shows a drawing of the fullerene and three of the surrounding diiodine molecules that make the closest contact with the carbon cage. The I1−I2 distance is 2.6837(2) Å. For comparison, the I−I distance in crystalline diiodine at 110 K is 5132
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Figure 1. Structure of C70·I2 showing the fullerene and the adjacent diiodine molecules that make close contact with thermal contours at 50%. These close contacts are I1B···C2, 3.104(2); I2C···C26, 3.068(3); and I2A···C35, 3.675(2) Å. Close contact with a neighboring C70 molecule occurs at C64 and C66.
2.715(6) Å.17 Figure 2 shows the molecular packing within the crystal. As this drawing indicates, six diiodine molecules
Figure 3. A portion of the packing in C70·I2 that shows the end-on and side-on interactions between I2 and D5h-C70. The positions of closest approach of two fullerenes are depicted with dashed lines. The distances involved are C64···C66′, 3.109(3) Å; C53···C5″, 3.275(3) Å; and C32···C6″, 3.704(4). Symmetry codes: ′ = −x, 1 − y, 1 − z; ′′ = 0.5 + x, 0.5 − y, 0.5 + z.
2(C70)·3CS2 were obtained by diffusion of a cyclohexane solution of diiodine into a carbon disulfide solution of C70. Monoclinic crystals of C70·0.85I2·0.15CS2 are isostructural with those of C70·I2. Thus, crystals of C70·0.85I2·0.15CS2 contain carbon disulfide molecules that substitute for some of the diiodine molecules in C70·I2, with the two components occupying a common site. The I1−I2 distance is 2.6890 (5) Å. The C−S distances are 1.341(14) and 1.506(14) Å. These C−S distances are somewhat shorter than the C−S distances in C70· 3CS2, which range from 1.538(6) to 1.552(8) Å, and in 2(C70)· 3CS2, where they range from 1.537(9) to 1.568(9) Å. This apparent shortening probably results from the disorder and the superposition of the diiodine and carbon disulfide molecules. Figure 4 shows a drawing of the C70 molecule in C70·0.85I2· 0.15CS2 that includes the three positions where the carbon disulfide molecules make close contact with the cage. Figure 5 shows the molecular packing in C70·0.85I2·0.15CS2. Only the positions of the carbon disulfide molecules are shown in this drawing. However, it would be unusual to have more than a single carbon disulfide adjacent to any given fullerene due to the low population of carbon disulfide molecules in the actual solid. It does not appear that additional carbon disulfide can be substituted for diiodine in these crystals. We have examined a second crystal of this material that was obtained from an independent preparation. Refinement of the structure lead to the same composition: C70·0.85I2·0.15CS2. The Arrangement of Molecules within C70·0.68I2· 0.32CS2. Diffusion of a cyclohexane solution of diiodine into a carbon disulfide solution of C70 produces black blocks of C70· 0.68I2·0.32CS2, which crystallize in the Fddd space group as the sole product. Alternatively, black blocks of C70·0.68I2·0.32CS2 can be produced along with crystals of the monoclinic phase
Figure 2. Molecular packing in C70·I2 looking at the ab plane and down the c axis. Diiodine molecules are violet; C70 molecules are cream.
surround each C70 molecule, but only three of these diiodine molecules closely approach the cage. Additionally, two C70 molecules make very close sideways contact, and two make somewhat longer contacts to neighboring cages, as shown in Figure 3. Hirshfeld surfaces for this and the other new cocrystals reported here are available in the Supporting Information, Figures SI-1−SI-3.18 The Supramolecular Architecture of C70 ·0.85I 2 · 0.15CS2. A crystal of C70·0.85I2·0.15CS2 was obtained by diffusion of a carbon disulfide solution of C70 into a benzene solution of diiodine. In contrast, two other solvent systems produced two other carbon disulfide solvates that were free of diiodine. As reported previously, black crystals of C70·3CS2 were obtained from mixing an ethanol solution of diiodine with a carbon disulfide solution of C70. Similarly, black crystals of 5133
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presence of overlapping diiodine and carbon disulfide molecules. Figure 6 shows a C70 molecule with the two flanking diiodine molecules. These diiodine molecules make the closest approach
Figure 6. Close contacts between C70 and diiodine or carbon disulfide in C70·0.68I2·0.32CS2. The close intermolecular contacts are I2···C24, 3.193(3) Å; I1···C34, 3.187(3) Å; S2A···C24, 3.107(10) Å; and S1··· C34, 3.070(7) Å.
Figure 4. Structure of C70·0.85I2·0.15CS2 showing the fullerene and the adjacent positions for the carbon disulfide molecules that make close contact with thermal contours at 50%. These close contacts are S2C···C2, 3.000(8); S1B···C26, 3.137(9); and S1A···C35, 3.760(8) Å.
to the fullerene. The arrangement shown in Figure 6 produces chains that propagate through the crystal along the c axis. Figure 7 shows the packing within C70·0.68I2·0.32CS2. In this drawing, the positions of the carbon disulfide molecules have been omitted.
Figure 5. Molecular packing in C70·0.85I2·0.15CS2 looking at the ab plane and down the c axis. This view shows the positions of the CS2 molecules and omits the more prevalent diiodine molecules. Carbon disulfide molecules are gold and gray; C70 molecules are cream.
Figure 7. Molecular packing in C70·0.68I2·0.32CS2 looking at the bc plane and down the a axis. This view shows the positions of the diiodine molecules and omits the carbon disulfide molecules. Chains of alternating diiodine and C70 molecules run along the c axis. Diiodine molecules are violet; C70 molecules are cream.
when toluene solutions of diiodine and a carbon disulfide solution of C70 are allowed to diffuse together. The asymmetric unit of C70·0.68I2·0.32CS2 consists of an ordered molecule of C70 and two sites occupied by diiodine and carbon disulfide molecules. These sites consist of two locations for iodine atoms with occupancies of 0.6831(14) and 0.6814(14), two positions for sulfur atoms with occupancies of 0.3169(14) and 0.3186(14), and two locations for carbon atoms with occupancies of 0.1585(7) and 0.1593(7). Complete diiodine and carbon disulfide molecules are generated at both sites by inversion through centers of symmetry. The I1−I1A distance is 2.6724(14) Å, and the I2−I2A distance is 2.6856(15) Å. For the carbon disulfide molecules, the S1− C71 distance is 1.541(6) Å, whereas the S2−C72 distance is 1.514(6) Å. As noted above for C70·0.85I2·0.15CS2, the apparent shortening of these C−S distances is caused by the
We have examined a second crystal from an independent preparation and found that it had a similar composition: C70· 0.71I2·0.29CS2. We have not been able to find binary cocrystals of the two hypothetical compositions, C70·2I2 or C70·2CS2. Diiodine Incorporation in 2C60·3CS2. Despite numerous attempts, we have not been able to form a simple cocrystal of C60 and diiodine that would be an analogue of C70·I2. However, diiodine can cocrystallize with C60 in the presence of carbon disulfide to form black crystals of 2C60·2.46CS2·0.54I2. These crystals were obtained by evaporation of a carbon disulfide solution that was saturated with both C60 and diiodine and allowed to evaporate. As the data in Table 1 show, crystals of 2C60·2.46CS2·0.54I2 are not isostructural with those of 2C60·3CS2, whose structure 5134
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was reported earlier.10 However, the two structures are quite similar. Figure 8 shows the packing in 2C60·2.46CS2·0.54I2. The
occupied, this contact can be avoided if only one of the two neighboring sites is occupied by diiodine, with carbon disulfide occupying the other position.
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DISCUSSION Despite the similarity in sizes of diiodine and carbon disulfide, the binary cocrystals of these with C70 (C70·I2, C70·3CS2, and 2(C70)·3CS2) differ in stoichiometry and supramolecular structure. We have obtained three new ternary cocrystals that contain diiodine, carbon disulfide, and a fullerene: C70·0.85I2· 0.15CS2, C70·0.68I2·0.32CS2, and 2C60·2.46CS2·0.54I2. These three cocrystals all involve situations where molecules of carbon disulfide and diiodine occupy common sites with fractional occupancy. The similarity in sizes of these two molecules facilitates this sort of substitution. The fullerene components in all four new cocrystals are fully ordered at 90 K. Crystals of C70·I2 and C70·0.85I2·0.15CS2 are isostructural with fractional substitution of carbon disulfide for diiodine occurring in the latter. The structure of 2C60·2.46CS2·0.54I2 is closely related to that of 2C60·3CS2, but the former is orthorhombic, space group P212121, whereas the latter is monoclinic, P21/n. Two of the three carbon disulfide positions in 2C60·3CS2 underwent fractional replacement by diiodine. C70·0.68I2·0.32CS2 has a unique structure that is not related to any of the other compounds reported here or to the carbon disulfide solvates of C70: D5h-C70·3CS2 and 2(D5h-C70)·3CS2. Although we have not conducted extensive phase studies, the formation of the various binary and ternary fullerene compounds, along with the near congruence of positions of diiodine and carbon disulfide molecules in these structures, suggests that diiodine and carbon disulfide can form solid solutions with fullerenes. On the other hand, continuous substitution of diiodine for carbon disulfide is not possible without a phase change. Because the four structures reported here have twin components with twin parameters near 50:50, they have all likely undergone ordering transitions at low temperature. In the case of 2C60·2.46CS2·0.54I2, for example, below 144 K a phase change from orthorhombic (P21nb) to a lower symmetry orthorhombic (P212121) form occurs. In our hands, C70, but not C60, forms a stoichiometric cocrystal with diiodine. In fact, stability constant measurements had found earlier that C60 does not form a stable complex with diiodine in different organic solvents at room temperature.19 It is tempting to suppose that C70 may have a somewhat greater preference for diiodine due to shape compatibility. In fact, a nearly parallel alignment of the diiodine axis with the 5-fold axis of C70 is present in all three of these structures.
Figure 8. Molecular packing in 2C60·2.46CS2·0.54I2 looking at the bc plane and down the a axis. The two different fullerenes are colored pale blue and cream. In order to distinguish the two sites where carbon disulfide and diiodine are present, the iodine atoms are violet in one site and pink in the other, whereas the sulfur atoms are yellow−orange in one and orange−red in the other.
asymmetric unit contains two ordered C60 molecules, one site containing a fully occupied carbon disulfide molecule, and two sites that are shared by carbon disulfide and diiodine. For comparison, Figure 9 shows the molecular arrangements in
Figure 9. Molecular packing in 2C60·3CS2 looking at the bc plane and down the a axis. The two different fullerenes are colored pale blue and cream. Note that two carbon disulfide molecules lie in the bc plane whereas the third molecule of carbon disulfide is oriented nearly perpendicular to that plane.
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CONCLUSIONS Although the sizes of diiodine and carbon disulfide are similar, this similarity does not produce cocrystals with analogous compositions. Diiodine forms only a binary cocrystal, C70·I2, with C70; no binary cocrystal forms with C60. In contrast, carbon disulfide forms binary cocrystals with either C60 or C70: 2C60·3CS2, C70·3CS2, and 2(C70)·3CS2. The presence of diiodine facilitates the growth of crystals of the latter two without being incorporated into these crystals at any detectable level.11 However, the similarity of sizes and shapes of diiodine and carbon disulfide does allow substitution of one for another in some cases. Thus, carbon disulfide can replace ∼15% of the diiodine in C70·I2 to form C70·0.85I2·0.15CS2. Crystallization of
2C60·3CS2. Notice that two of the carbon disulfide molecules in 2C60·3CS2 lie in the bc plane, whereas the third carbon disulfide molecule lies nearly perpendicular to that plane. The two carbon disulfide sites in the bc plane are the positions where diiodine can replace carbon disulfide to form the ternary cocrystal, 2C60·2.46CS2·0.54I2, as seen in Figure 8. No replacement of the third carbon disulfide molecule by diiodine occurs. Also, notice the close contact of the two diiodine molecules, which can be seen where the violet and pink spheres contact. The distance for this I···I contact is 3.0234(13) Å. Because the site for the diiodine molecule is only partially 5135
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C60 in the presence of diiodine and carbon disulfide produces crystals of 2C60·2.46CS2·0.54I2. These crystals are not isostructural with 2C60·3CS2, but they have a very closely related structure in which diiodine molecules replace two of the three different types of carbon disulfide molecules. Finally, crystallization of C70 in the presence of diiodine and carbon disulfide produces a new crystalline material, C70·0.68I2· 0.32CS2. In all of these mixed cocrystals, the diiodine and carbon disulfide molecules share common sites and common orientations.
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EXPERIMENTAL SECTION
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ASSOCIATED CONTENT
Article
REFERENCES
(1) Krätschmer, W.; Lamb, L. D.; Fostiropoulos, K.; Huffman, D. R. Nature 1990, 347, 354. (2) Olmstead, M. M.; Balch, A. L.; Lee, H. M. Acta Crystallogr. 2012, B68, 66. (3) Meidine, M. F.; Hitchcock, P. B.; Kroto, H. W.; Taylor, R.; Walton, D. R. M. J. Chem. Soc., Chem. Commun. 1992, 1534. (4) Balch, A. L.; Lee, J. W.; Noll, B. C.; Olmstead, M. M. J. Chem. Soc., Chem. Commun. 1993, 56. (5) Bürgi, H. B.; Restori, R.; Schwarzenbach, D.; Balch, A. L.; Lee, J. W.; Noll, B. C.; Olmstead, M. M. Chem. Mater. 1994, 6, 1325. (6) Fleming, R. M.; Kortan, A. R.; Hessen, B.; Siegrist, T.; Thiel, F. A.; Marsh, P.; Haddon, R. C.; Tycko, R.; Dabbagh, G.; Kaplan, M. L.; Mujsce, A. M. Phys. Rev. B: Condens. Matter Mater. Phys. 1991, 44, 888. (7) For an exception, see Stevenson, S.; Lee, H. M.; Olmstead, M. M.; Kozikowski, C.; Stevenson, P.; Balch, A. L. Chem.Eur. J. 2002, 8, 4528. (8) Ruoff, R. S.; Tse, D. S.; Malhotra, R.; Lorents, D. C. J. Phys. Chem. 1993, 97, 3379. (9) Boeyens, J. C. A.; Ramm, M.; Zobel, D.; Luger, P. S.-Afr. Tydskr. Chem. 1997, 50, 28. (10) Olmstead, M. M.; Jiang, F.; Balch, A. L. Chem. Commun. 2000, 483. (11) Bowles, F. L.; Mercado, B. Q.; Ghiassi, K. B.; Chen, S. Y.; Olmstead, M. M.; Yang, H.; Liu, Z.; Balch, A. L. Cryst. Growth Des. 2013, 13, 4591. (12) Morosin, B.; Newcomer, P. P.; Baughman, R. J.; Venturini, E. L.; Loy, D.; Schirber, J. E. Phys. C 1991, 185, 21. (13) Kobayashi, M.; Akahama, Y.; Kawamura, H.; Shinohara, H.; Sato, H.; Saito, Y. Mater. Sci. Eng., B 1993, 19, 100. (14) Haruta, M.; Kurata, H.; Isoda, S. Fullerenes, Nanotubes, Carbon Nanostruct. 2008, 16, 454. (15) Kobayashi, M.; Akahama, Y.; Kawamura, H.; Shinohara, H.; Sato, H.; Saito, Y. Solid State Commun. 1992, 81, 93. (16) Huong, P. V. Solid State Commun. 1993, 88, 23. (17) van Bolhuis, F.; Koster, P. B.; Migchelsen, T. Acta Crystallogr. 1967, 23, 90. (18) Spackman, M. A.; Jayatilaka, D. CrystEngComm 2009, 11, 19. (19) Beck, M. T.; Mándi, G.; Kéki, S. Russ. Chem. Bull. 1996, 45, 2024. (20) SAINT; Bruker AXS Inc.: Madison, WI. (21) Sheldrick, G. M. SADABS, SHELXS-2014, SHELXL-2014; University of Göttingen: Göttingen, Germany.
Materials. C70 and C60 were purchased from SES research with 99% purity. No further purification was performed. Carbon disulfide, diiodine, ethanol, and cyclohexane were used as received. Crystal Growth. C70·I2. A filtered aliquot from the solution containing 0.394 mmol of diiodine dissolved in diethyl ether was layered over a filtered aliquot of 0.170 mmol of C70 dissolved in toluene. C70·0.85I2·0.15CS2. A filtered aliquot from the solution containing 0.255 mmol of C70 dissolved in carbon disulfide was layered over a filtered aliquot of 0.394 mmol of diiodine dissolved in benzene. C70·0.68I2·0.32CS2. A filtered aliquot from the solution containing 0.394 mmol of diiodine dissolved in cyclohexane was layered over a filtered aliquot of 0.255 mmol of C70 dissolved in carbon disulfide. 2C60·2.46CS2·0.54I2. Black blocks resulted from the layering of a saturated solution of diiodine in carbon disulfide over a saturated solution of C60 in carbon disulfide. Crystal Structure Determinations. The crystals were removed from the glass tubes in which they were grown together with a small amount of mother liquor and immediately coated with hydrocarbon oil on a microscope slide. A suitable crystal of each compound was mounted on a glass fiber or polymer loop with silicone grease and placed in the cold stream of a Bruker SMART 1000 or SMART Apex II CCD with graphite monochromated Mo Kα radiation (λ = 0.71073) at 90(2) K. All data sets were reduced with the use of Bruker SAINT,20 and a multiscan absorption correction was applied with the use of SADABS.21 Refinement was carried out with SHELXL-2014.21 Crystal data are given in Table 1. The crystal containing C60 was refined as an inversion twin. The crystals containing C70 were refined as pseudomerohedral twins. Further details of the refinements are contained in the Supporting Information.
S Supporting Information *
Figures showing the Hirshfeld surfaces for C70·I2,, C70·0.68I2· 0.32CS2, and 2C60·2.46CS2·0.54I2; X-ray crystallographic files in CIF format for C70·I2, C70·0.85I2·0.15CS2, C70·0.68I2·0.32CS2, and 2C60·2.46CS2·0.54I2. This material is available free of charge via the Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
Corresponding Authors
*(M.M.O.) E-mail:
[email protected]. *(A.L.B.) E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS We thank the U.S. National Science Foundation (grant CHE1305125 to A.L.B. and M.M.O.) for support and Joseph Wescott and Prof. Feilong Jiang for experimental assistance. 5136
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