Hydrogenation of [60]Fullerene with Lithium in Aliphatic Amines

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Letters to the Editor / Carbon 42 (2004) 667–691 675 Hydrogenation of [60]fullerene with lithium in aliphatic amines Jun-Ping Zhang, Nai-Xing Wang *, Yun-Xu Yang, An-Guang Yu Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 100101 Beijing, China Received 4 July 2003; accepted 19 December 2003

Keywords: A. Fullerene; C. Mass spectroscopy

Subsequent to the discovery by Kratschmer€ et al. [1] The toluene solution was dried over Na2SO4, and sol- of a method for the macroscopic synthesis of C60,a vent was evaporated under reduced pressure to give 51 flurry of activity directed at establishing a preliminary mg of a light-yellow solid. The crude product was picture of fullerene chemistry soon followed. In par- purified by column chromatography. 1H NMR (400 ticular, the hydrogenation of the [60]fullerene and MHz, o-C6D4Cl2): d 2.60-4.20 (a broad band), 3.10, [70]fullerene is of special interest. Many routes for 3.40. FT-IR v (KBr, cm1): 2913, 2847, 1605, 1492, hydrogenating fullerene were established including 1453, 1260, 1097, 1024, 803, 697. MS m=z (matrix- Birch reduction [2], hydroboration [3], hydrozirconation assisted laser desorption/ionization time-of-flight þ [4], solid phase hydrogenation [5], transfer hydrogena- (MALDI-TOF)): 755.3 (C60H35). tion [6], electrochemical reduction [7], dissolving metals In the MALDI-TOF mass spectrum of the crude þ reduction [8] as well as chemical reduction with diimides product the C60H35 ion [12] (m=z ¼ 755:5) was detected [9], hydrogen radical induced hydrogenation [10] and indicating the main product is C60H36. Simultaneously, photoinduced electron transfer [11]. because of the sensitivity of C60H36 to light and oxygen þ C60H36, first synthesized by the method of the Birch [8], small satellite peaks (C60H36O , m=z ¼ 771:5) were reduction, was loaded with 4.8 wt.% hydrogen indicat- observed. The electron deficiency of C60 and nucleo- ing [60]fullerene might be as a potential hydrogen stor- philicity of aliphatic amines resulted in the formation age material. If a 100% conversion of C60H36 were of a trace of amine adducts [13] (C60H35(HNCH2- þ achieved, 18 mols of H2 gas would be liberated from CH2NH) , m=z ¼ 813:6). Attempt to purify the hydro- each mole of fullerene hydride. genated product using TLC following other procedures However, the Birch reduction requires a long period [2] was frustrated because the Rf value is zero. Then of waiting for the ammonia to evaporate. This makes other developers, such as toluene, chloroform, n-hexane this experiment inconvenient. or a mixture of them, were tried with the same results. Herein, we report the reduction of C60 by lithium in By trying to purify the hydrogenated product many ethylenediamine, 1,3-propanediamine, 1,2-propanedi- times, we found C60H36 can be purified perfectly by amine, n-propylamine and 2,20-diaminodiethylamine. using mixture of silica gel (0.10–0.15 mm) and ion ex- tert-Butanol was used as proton source. The results of change resin (003 · 7, styrene-DVB, 0.3–0.4 mm) as the reducing reactions depended on the solubility of C60 packing material (The volume ratio of silica gel and ion and lithium in aliphatic amines. exchange resin is 4:1.) and toluene as eluent. 1 To a solution of 50 mg (0.07 mmol) C60 in 50 ml of The H NMR spectrum of the reduced product in ethylenediamine were added 1.64 g (21 mmol) of tert- [D4]-o-dichlorobenzene showed a broad group of signals butanol and 0.15 g (0.21 mmol) of lithium. The mixture between d ¼ 2:60 and 4.40 with two distinct maxima at was stirred vigorously under a N2 atmosphere. The dark d ¼ 3:10 and 3.40 [2,6]. The unusually broad shape is solution soon turned to white and then blue. However probably caused by the presence of several isomers of the blue color disappeared quickly owing to the decay of C60H36 [2,8]. the solvated electrons. When the solution turned to The IR spectrum exhibited bands at 2913, 2847, 2824, white, the reaction was complete. The resulting solution 1605, 1492 cm1, strongly suggesting the presence of C– was then poured into 100 ml of ice water. The mixture H and C@C bonds in the reduced product. The presence was extracted with toluene, and then washed with brine. of bands at 697, 1024, 1097, 1260, 1453 cm1 would indicate the spherical fullerene structure is still present but considerably distorted. The spectrum is somewhat * Corresponding author. Tel.: +86-10-64856872; fax: +86-10- similar to the one published previously by Attalla and 64879375. co-workers, which was found to be consistent with D3d E-mail address: [email protected] (N.-X. Wang). symmetry [10,14].

676 Letters to the Editor / Carbon 42 (2004) 667–691

Comparing with the reduction in ethylenediamine, References adducts of amine with C60 increased a little bit in 1,3- propanediamine, 1,2-propanediamine and n-propyl- [1] Kratshmer€ W, Lamb LD, Fostiropoulous K, Huﬀman DR. Solid C.sub.60: a new form of carbon. Nature 1990;347: amine because of longer dissolving time of C60 and 354–8. longer reaction time. For example, completely dissolving [2] Haufer RE, Conceicao J, Chibante LPF, Chai Y, Byrne NE,

50 mg of C60 in 1,3-propanediamine, 1,2-propanedi- Flanagan S, et al. Eﬃcient production of C60 (buckminsterfuller- amine and n-propylamine need 2.5, 4.5 and 6.0 h, ene), C60H36, and the solvated buckide ion. J Phys Chem respectively. In these solutions, the reactions need 0.33, 1990;94:8634–6. 0.50 and 3.0 h when lithium was added, respectively. [3] Henderson CC, Cahill PA. C60H2: synthesis of the simplest C60 hydrocarbon derivative. Science 1993;259:1885–7. To search for a perfect solvent for this reduction [4] Ballenwey S, Gleiter R, Kratshmer€ W. Hydrogenation of buck- 0 reaction, 2,2 -diaminodiethylamine was tried and a good minsterfullerene C60 via hydrozirconation: a new way to organo- result was obtained, MS showed that the peak’s inten- fullerenes. Tetrahedron Lett 1993;34:3737–40. sity of amine adducts (C60H35(HNCH2CH2NCH2CH2- [5] Jin C, Hettich R, Compton R, Joyce D, Blencoe J, Burch T. þ Direct solid-phase hydrogenation of fullerenes. J Phys Chem NH2) , m=z ¼ 856:0 (2.92%)) was very weak because of 1994;98:4215–7. short reaction time. However, when we tried to reduce [6] Ruchardt€ C, Gerst M, Ebenhoch J, Beckkaus HD, Campbell the amine adducts into hydrides by prolonging the EE, Tellgmann R, et al. Transfer hydrogenation and deuteration

reaction time to 12 h in Li-amine-tert-butanol system, of buckminsterfullerene C60 by 9,10-dihydroanthracene and 0 0 the expected results were not obtained, we found that 9,9 ,10,10 [D4]dihydroanthracene. Angew Chem Int Ed Engl the peak’s intensity of amine adducts in mass spectrum 1993;32:584–6. [7] Cliﬀel DE, Bard AJ. Electrochemical studies of the protonation of increased (m=z ¼ 856:1 (9.31%)). This showed that the C60 and C602. J Phys Chem 1994;98:8140–3. amine adducts could not be hydrogenized into fullerene [8] Darwish AD, Abdul-Sada AK, Langley J, Kroto HW, Taylor R, hydrides in the reduction system by prolonging the Walton DRM. Polyhydrogenation of [60]- and [70]-fullerenes. reaction time. J Chem Soc Perkin Trans 1995;2:2359–65. [9] Avent AG, Darwish AD, Heimbach DK, Kroto HW, Meidine In summary, a simple, rapid synthesis for C60H36 was MF, Parsons JP, et al. Formation of hydrides of fullerene-C and developed by treating [60]fullerene with lithium in ali- 60 fullerene-C70. J Chem Soc Perkin Trans 1994;2:15–22. phatic amines under mild conditions, which replaced [10] Attalla MI, Vassallo AM, Tattam BN, Hanna JV. Preparation of and eliminated liquid ammonia with its troublesome hydrogen radical induced hydrogenation. J Phys Chem 1993;97: handling in the classic Birch reductions. In the reduction 6329–31. system 2,20-diaminodiethylamine is the best solvent for [11] Fukuzumi S, Suenobu T, Kawamura S, Shida A, Mikami K. Selective two-electron reduction of C60 by 10-methyl-9,10-dihy- preparing C60H36. Now we have done preliminary re- droacridine via photoinduced electron transfer. J Chem Soc Chem search work on the decomposition of C60H36 [15]. To Commun 1997:291–2. explore the new ways of decomposing fullerene hy- [12] Rogner I, Birkett P, Campbell EEB. Hydrogenated and chlori- drides, which might be as the resource of hydrogen, will nated fullerenes detected by ‘‘cooled’’ modiﬁed matrix-assisted be the challenge for our future work. laser desorption and ionisation mass spectroscopy (MALDI-MS). Int J Mass Spectrum Ion Process 1996;156:103–8. [13] Kampe KD, Egger N, Vogel M. Diamino and tetraamino

derivatives of buckminsterfullerene C60. Angew Chem Int Ed Acknowledgements Engl 1993;32:1174–6. [14] Hall LE, Mckenzie DR, Attalla MI, Vassallo AM, Davis RL, We thank the National 863 Program (no. Dunlop JB, et al. The structure of hydrogenated fullerene (C60H36). J Phys Chem 1993;97:5741–4. 2003AA323030) and the National Natural Science [15] Wang NX, Wang L, Liu W, Ou YX, Li WJ. Some thermal

Foundation of China (no. 50272069) for ﬁnancial sup- decomposition reactions of C60H36. Tetrahedron Lett 2001;42: port. 7911–3.