Compound HF@C60

HF@fullerene-C₆₀

Compound data: CIF

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

Compound HF@5 (257 mg, 0.243 mmol) and N-phenylmaleimide (168 mg, 0.971 mmol) were placed inside a Schlenk flask fitted with a straight condenser under nitrogen atmosphere. Distilled 1-chloronaphthalene (15 ml) was added and the solution was degassed. The reaction mixture was refluxed under nitrogen atmosphere for 28 hours then allowed to cool down to room temperature. The solution was purified by flash column chromatography (eluent: toluene) the fraction containing the spots running close to the solvent front (eluent: toluene) were collected and concentrated to afford a solution of HF@C₆₀ in 1-chloronaphthalene. The solvent was evaporated to dryness by vacuum distillation (80 °C, 0.1 mmHg) and the resulting solid washed three times with diethyl ether to afford crude HF@C₆₀ as a black solid (30% filling factor, 153 mg, 86%). Sublimation of HF@C₆₀: crude HF@C₆₀ (20 mg) was placed inside a straight glass tube (0.5in OD, 12 in long). The tube was connected to the sublimation apparatus depicted below that was then evacuated to 10^-5 Torr. The furnace was heated from room temperature to 550 °C with a ramp rate of 10 °C/min. The furnace temperature was kept at 550 °C until the deposition on the cold part of the tube stopped. The system was allowed to cool down to room temperature and the apparatus was then isolated from the vacuum pump. The apparatus was then brought back to ambient pressure by carefully opening the side vent. The sublimation tube was removed, the section containing the sublimate was cut and the material was collected to afford sublimed HF@C₆₀ (15 mg, sublimation yield 75%). It is interesting that when HF@C₆₀ with 30% filling factor is partially sublimed we so no difference in the HF@C₆₀ : C₆₀ ratio between the sublimed and unsublimed material. ¹³C NMR: (100 MHz, odcb-d₄, δ): 142.95 (HF@C₆₀), 142.91 (C₆₀) ppm. MS-APCI: m/z (relative intensity, ion): 739.9 (70%, [M]⁺, HF@C₆₀), 719.9 (100%, [M]⁺, empty C₆₀).

HF@C₆₀ (100% filled): sublimed 30% filled HF@C₆₀ (15 mg) was dissolved in dry, oxygen free toluene (8 ml). The solution was injected (injection volume: 2 ml) onto two 250 x 25 mm Buckyprep® Cosmosil HPLC columns in series (eluent: toluene, eluent flow: 10 ml/min, detection: 326 nm). All the fractions containing HF@C₆₀ were collected and concentrated to afford a solution of 77% filled HF@C₆₀. This solution was further purified as above and the fractions containing only HF@C₆₀ were collected and evaporated to afford quantitatively filled HF@C₆₀ (5.05 mg). Empty C₆₀ was not detected by HPLC, ¹³C NMR or MS. ¹H NMR (400 MHz, toluene-d₈, δ): -2.68 (d, J = 505.5 Hz) ppm. ¹³C NMR: (100 MHz, toluene-d₈, δ): 142.85 ppm. ¹⁹F NMR: (376 MHz, toluene-d₈, δ): -219.94 (d, J = 505.7 Hz) ppm. {¹H}¹⁹F NMR: (376 MHz, toluene-d₈, δ): -219.94 (s) ppm. IR. (Solid sample deposited from CS₂ solution onto the diamond of a Nicolet 380 FTIR instrument with Smart orbit ATR). ν_max 1429, 1182, 576 cm^-1. For comparison C₆₀ ν_max 1428, 1182, 576 cm^-1 UV: (toluene) λ_max (ε): 336.2 nm (62000). C₆₀ λ_max (ε): 335.7 nm (75000). UV: (hexane, 3 fold diluted saturated solution) λ_max (A): 257.4 nm (0.41) 329.8 nm (0.11). C₆₀ λ_max (A): 257.7 nm (0.71), 329.5 nm (0.23) HRMS-APCI (m/z): [M]⁺ calcd for C₆₀HF, 740.006; found, 740.007. Experimental for X-ray structure determination of HF@C₆₀: metallic dark orange plate-shaped crystals of HF@C₆₀ were obtained from carbon disulfide by slow evaporation. A suitable crystal (0.20×0.05×0.02) was selected and mounted on a MITIGEN holder in perfluoroether oil on a Rigaku AFC12 FRE-VHF diffractometer. The crystal was kept at T = 100(2) K during data collection. Data were measured using profile data from scans of 1.0^° per frame for 20.0 s using MoK_a radiation (Rotating Anode, 45.0 kV, 55.0 mA). The total number of runs and images was based on the strategy calculation from the program CrystalClear (Rigaku). The actually achieved resolution was Q = 28.699. Cell parameters were retrieved using the CrysAlisPro (Agilent) software and refined using CrysAlisPro (Agilent) on 7838 reflections, 22 of the observed reflections. Data reduction was performed using the CrysAlisPro (Agilent) software, which corrects for Lorentz polarisation. The final completeness is 99.80 out to 28.699 in Q. The absorption coefficient (m) of this material is 0.302 and the minimum and maximum transmissions are 0.32187 and 1.00000. Using Olex2 (Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. and Puschmann, H. Olex2: A complete structure solution, refinement and analysis program. J. Appl. Cryst. 42, 339-341(2009)), the structure was solved in the space group P2₁/n (# 14) using Direct Methods with the ShelXS (Sheldrick, G.M. A short history of ShelX. Acta Cryst. A64, 339-341 (2008)) structure solution program and refined by Least Squares using ShelXL (Sheldrick, G.M. Crystal structure refinement with SHELXL. Acta Cryst. C71, 3–8 (2015)). All non-hydrogen atoms were refined anisotropically. The crystal was refined as a pseudo-merohedral twin [monoclinic with beta close to 90, - 1 0 0, 0 -1 0 0 0 1, BASF=0.3634(15)). The Shelx rigid body restraint, RIGU, was applied to all atoms with default esds. The H atoms associated with the HF are included in the formula, but not the crystallographic model. As part of the data collection, the unit cell was identified as orthorhombic and mmm symmetry was used for the subsequent data collection strategy. At the structure solution stage the true symmetry was found to be monoclinic 2/m and as a result there are a number of missing reflections. There is a single molecule in the asymmetric unit, which is represented by the reported sum formula. In other words: Z is 4 and Z' is 1. The structure has been deposited at the Cambridge Crystallographic Database: CCDC 1453465.

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Compound HF@C60

HF@fullerene-C₆₀

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