Mendeleev Communications Electronic Version, Issue 4, 1999 (pp. 129–170) Intercalation compounds of fluorinated graphite with camphor Vera M. Paasonen* and Albert S. Nazarov Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation. Fax: +7 3832 34 4489; e-mail: albert@che.nsk.su The title compounds of the composition C2.22FHaly·zC10H16O (y = 0.1 and 0.02 for Hal = Cl and Br, respectively) have been prepared and found to be the compounds of stage at z = 0.14.The synthesis methods for intercalation compounds of fluorinated graphite (ICFG) with different organic compounds exhibiting mutual solubility are well known.1,2 These methods are based on the following exchange reactions: where x ª 2. ICFG with ClF3 or BrF3, which were obtained according to procedures described in refs. 3 and 4 were used as the initial CnHalFm. However, there is no publications on the methods providing intercalation of solids from solutions into fluorinated graphite using reactions (1) and (2). Methods based on the intercalation of solids from their solutions are widely used to synthesise intercalated graphite compounds.5,6 Because of this, the development of the intercalation of solids from their solutions into fluorinated graphite is topical.We studied the intercalation of camphor from acetone, ethanol and acetic acid solutions into fluorinated graphite. The solvents are able to form ICFG,1,2 i.e., to penetrate into the interstitial space of fluorinated graphite according to reactions (1) and (2).For this reason, the solutions of camphor as a model substance to be intercalated were examined in this study. The synthesis of ICFG is described below. A weighed portion of CnHalFm (1–2 g) was placed in a Teflon vessel, acetone (20 ml) was added, and the mixture was kept at room temperature for 3 days. The solid phase was filtered off through a glass filter, washed two or three times with 5% camphor solutions in appropriate solvents, and kept in these solutions for 5 days.Next, the solid product was placed onto a filter and washed with the corresponding solvent to remove solid camphor impurities. Finally, the product was dried in a nitrogen flow to a constant mass. The absence of solid camphor in the resulting ICFG was checked by X-ray diffraction analysis. 1H NMR spectra were recorded on a pulse Bruker SXP-4-100 spectrometer at a frequency of 90.01 MHz. IR spectra were recorded on a Specord 75-IR spectrometer. The samples of mass 3–3.5 mg were prepared as pellets with KBr. The composition of the ICFG was studied by elemental analysis for C, F, H and Cl (or Br). X-ray diffraction patterns were recorded on a DRON-3 diffractometer using filtered CuKa radiation (Ni filter).The patterns of samples under a layer of the liquid phase were recorded using a special Teflon cell covered with a Teflon film 5 mm in thickness. The patterns of dried samples were recorded using a quartz cell with applied vacuum grease. 1H NMR spectra of dried ICFG with camphor at 298 K contained a single (within the range 0–25 kHz) rather narrow signal (DH1/2 ª 2.151 kHz), which is characteristic of the intercalated substances.This is the evidence of high mobility of camphor in the interstitial space of fluorinated graphite, which is typical of monomolecular layers of intercalated substances in layered compounds.7,8 X-ray diffraction patterns of dry samples exhibit (i) the retention of stage 1 in the ICFG with camphor, (ii) the transition of stage 1 into stage 2 for the ICFG with acetone, ethanol and acetic acid.The latter case is a common feature of the ICFG formed according to reactions (1) and (2) with volatile intercalants. 1,2 Interlayer distances in fluorinated graphite containing no intercalants (in the initial ICFG with BF3) are 6 Å.9 This allows us to estimate the ‘thickness’ of intercalated monolayers of intercalants in the stage 1 ICFG as di a = Jc – 6 Å and the identity period for stage 2 ICFG as Jc b = Jc + 6 Å.X-ray data (Table 1) suggest that Jc for the stage 1 ICFG synthesised using 5% camphor solutions is ~11.6 Å and does not depend on the nature of solvent, i.e., it is determined by the size and orientation of intercalated camphor molecules.Figure 1 shows the IR spectra of the initial camphor, ICFG with acetone and ICFG obtained using a 5% camphor solution in acetone. The IR spectra of ICFG exhibit bands in the C–F bond absorption region (1100–1200 cm–1), which are characteristic of the initial CnHalFm compounds and ICFG with liquid intercalants obtained from these compounds. The absorption bands characteristic of individual camphor (1020, 1050, 1385, 1410, 1450, 1740, 2840 and 2950 cm–1) are observed in the IR spectrum of ICFG with camphor, similarly to the spectrum of the initial camphor, but the absorption bands corresponding to acetone (530, 1220, 1360, 1420, 1715, 2920 and 3000 cm–1) are absent in this case (while they are observed in ICFG with acetone).The IR spectra of dry ICFG obtained from the solutions CnHalFm + Me2CO ® CxFHaly·z1Me2CO + R1 ® CxFHaly·z2R1 + z1Me2CO, CxFHaly·z2R1 + R2®CxFHaly·z3R2 + z2R1, (1) (2) a di a denotes the calculated data of the ‘thickness’ of intercalated monomolecular layers; Jc b denotes the calculated data of the identity period for the stage 2 ICFG.Initial compound is ICFS with BrF3. Table 1 X-Ray diffraction data for ICFG.a Intercalated compound Under liquid solvent After drying in air Jc = d001/Å di a = Jc – 6/Å Jc/Å (experiment) Jc b = d001 + 6/Å (calculation) Acetone 9.6 3.6 15.4 15.6 Ethanol — — 15.6 — Acetic acid 9.3 3.3 15.6 15.3 5% camphor solution in: Acetone 11.5 5.5 11.5 17.5 Ethanol 11.6 5.6 11.6 17.6 Acetic acid 11.6 5.6 11.6 17.6 a ICFG were prepared using a 5% camphor solution in ethanol (experiment nos. 1 and 2) or a 5% camphor solution in acetone (experiment nos. 3 and 4). Table 2 Composition of ICFG with camphor after drying in air.a Experiment Elemental analysis, found (calculated) (%) Calculated (%) Empirical formula C F Br Cm Cc R 1 64.56 (62.85) 27.89 (28.27) 2.00 (2.64) 39.12 25.44 32.27 C2.22FBr002·0.144R 2 64.22 (63.21) 28.13 (27.63) 2.30 (2.58) 39.42 24.80 31.46 C2.22FBr002·0.140R 3 61.49 (63.25) 26.82 (27.56) 2.40 (2.56) 37.62 23.87 30.29 C2.22FBr002·0.141R 4 61.47 (63.33) 26.62 (28.43) 2.10 (2.57) 37.32 24.15 30.64 C2.22FBr002·0.143RMendeleev Communications Electronic Version, Issue 4, 1999 (pp. 129–170) of camphor in ethanol and acetic acid are similar to the above spectra. These data allow us to assume that the solvents are absent from dry ICFG with camphor.Based on this assumption and on the elemental analysis data (Table 2), the empirical formulae of dry ICFG with camphor (R) were calculated. In the absence of solvents in these ICFG, the total carbon (C) content of the ICFG described as CxFHaly·zC10H16O is evidently determined by the carbon of the matrix (Cm) and the carbon of camphor (Cc), or C = Cm + Cc. Cm was calculated using the atomic ratio of carbon to fluorine (Cm/F) in ICFG formed in reactions (1) and (2).It is known10 that this ratio is close to 2.22 when CnBrFm is used. Cc was calculated as the difference C – Cm. This allowed us to calculate the empirical formulae of the obtained ICFG with camphor. The data in Table 2 are the evidence of good reproducibility of the syntheses and show that the calculated camphor content of the dry ICFG is practically independent of the nature of solvent.This confirms the assumption that the solvents are absent from dry ICFG, which was based on the IR-spectral data. Table 2 shows that the empirical formula of dry ICFG obtained according to reactions (1) and (2) using CnBrFm and 5% camphor solutions in acetone, ethanol and acetic acid is close to C2.22FBr0.02·zC10H16O, where z ~ 0.14.Similar experiments and calculations showed that the composition of dry ICFG with camphor obtained using CnClFm is close to C2.23FCl0.1·zC10H16O, where z ~ 0.14. Thus, reactions (1) and (2) can be used to synthesise ICFG with solids. The decomposition of stage 1 ICFG in air, which was described in ref. 10 is not a common feature of ICFG.The stage 1 ICFG stable in air can be prepared when solids are intercalated from their solutions by reactions (1) and (2). Of course, the kinetic stability of these compounds is implied. References 1 N. F. Yudanov, A. S. Nazarov and I. I. Yakovlev, Tezisy dokladov VI Vsesoyuznogo simpoziuma po khimii neorganicheskikh ftoridov (Proceedings of VI All-Union Symposium on Chemistry of Inorganic Fluorides), Novosibirsk, 1981, p. 94 (in Russian). 2 V. G. Makotchenko, A. S. Nazarov, G. C. Yur’ev and I. I. Yakovlev, Zh. Neorg. Khim., 1991, 36, 1950 (Russ. J. Inorg. Chem., 1991, 36, 1110). 3 A. S. Nazarov, V. G. Makotchenko and I. I. Yakovlev, Zh. Neorg. Khim., 1978, 23, 1680 (Russ. J. Inorg. Chem., 1978, 23, 925). 4 Y. I. Nikonorov and L.L. Gornostaev, Izv. Sib. Otd. Akad. Nauk SSSR, Ser. Khim. Nauk, 1978, 9, 55 (in Russian). 5 E. Stumpp, Mater. Sci. Eng., 1977, 31, 53. 6 R. Vangelisti and A. Herold, Mater. Sci. Eng., 1977, 31, 67. 7 A. M. Panich, A. M. Danilenko, S. P. Gabuda and I. I. Yakovlev, Zh. Strukt. Khim., 1988, 29 (2), 55 [J. Struct. Chem. (Engl. Transl.), 1988, 29, 211]. 8 A. M. Panich and N. F. Yudanov, Zh. Strukt. Khim., 1991, 32 (2), 79 [J. Struct. Chem. (Engl. Transl.), 1991, 32, 220]. 9 N. F. Yudanov and L. T. Chernyavski, Zh. Strukt. Khim., 1988, 29 (3), 78 [J. Struct. Chem. (Engl. Transl.), 1988, 29, 412]. 10 N. F. Yudanov and L. T. Chernyavski, Zh. Strukt. Khim., 1987, 28 (4), 86 [J. Struct. Chem. (Engl. Transl.), 1987, 28, 534]. 400 1000 2000 3000 n/cm–1 Absorption Figure 1 IR spectra of (1) camphor and (2)–(4) ICFG: (2) CnBrFm, (3) ICFG with a 5% camphor solution in acetone and (4) ICFG with acetone. 1 2 3 4 Received: 2nd April 1998; Com. 98/1285 (8/02790K)