Alkali metal trifluoroacetates for the nucleophilic trifluoromethylation of fullerenes

Article abstract of DOI:10.1016/j.jfluchem.2019.109344

Fullerene C₆₀ readily reacts with potassium and cesium trifluoroacetates yielding C₆₀(CF₃)^–M⁺ salts, and subsequent acid hydrolysis gives ortho-C₆₀(CF₃)H. The reaction rate and the probability of the alternative reaction pathways strongly depend on the particular metal cation. Thus, the reactivity increases in the order Li < Na < K≈Cs, in correlation with the decreasing thermal stability. Furthermore, the sodium and, especially, lithium salts tend to effect CF₂- rather than CF₃-functionalization of the fullerene, in good accordance with the hard/soft acids and bases theory. The nucleophilic trifluoromethylation is found to be applicable to other pristine fullerenes like C₇₀ as well as to fullerene derivatives like p⁷mp-C₇₀(CF₃)₁₀. It enables selective preparation of low trifluoromethylated fullerenes via regioselective consecutive trifluoromethylation under accurately controlled solution-phase conditions.

Full text of DOI:10.1016/j.jfluchem.2019.109344

Accepted Manuscript
Title: Alkali metal trifluoroacetates for the nucleophilic
trifluoromethylation of fullerenes
Authors: Viktor P. Bogdanov, Veronika A. Dmitrieva, Vitaliy
A. Ioutsi, Nikita M. Belov, Alexey A. Goryunkov
PII:
DOI:
Article Number:
S0022-1139(19)30097-1
https://doi.org/10.1016/j.jfluchem.2019.109344
109344
Reference:
FLUOR 109344
To appear in:
FLUOR
Received date:
Revised date:
Accepted date:
21 March 2019
5 July 2019
6 July 2019
Please cite this article as: Bogdanov VP, Dmitrieva VA, Ioutsi VA, Belov
NM, Goryunkov AA, Alkali metal trifluoroacetates for the nucleophilic
trifluoromethylation of fullerenes, Journal of Fluorine Chemistry (2019),
https://doi.org/10.1016/j.jfluchem.2019.109344
This is a PDF file of an unedited manuscript that has been accepted for publication.
As a service to our customers we are providing this early version of the manuscript.
The manuscript will undergo copyediting, typesetting, and review of the resulting proof
before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that
apply to the journal pertain.

Alkali metal trifluoroacetates for the nucleophilic
trifluoromethylation of fullerenes
1
,2
1
1,2
Viktor P. Bogdanov , Veronika A. Dmitrieva , Vitaliy A. Ioutsi ,
Nikita M. Belov , Alexey A. Goryunkov1
1
1
Department of Chemistry, Lomonosov Moscow State University, bld. 3, 1 Leninskiye Gory,
1
19991, Moscow, Russia
2
Endocrinology Research Centre, 12 Dm.Ul'yanova str., 117036, Moscow, Russia
Graphical Abstract
Highlights:

Facile and rapid method for nucleophilic fullerene trifluoromethylation by thermolysis of
trifluoroacetates was developed.
ortho-C60(CF )H was obtained with 30% yield and unambiguously characterized.
Reactivities of CF CO M are increased within the row of Li<Na<K≈Cs in agreement


3
3
2
with the thermal stability drop.
–


CF
3
addition mode for K/Cs salts switches over to :CF addition for Na/Li salts in good
2
accordance with HSAB theory.
Proposed synthetic route can be adopted for trifluoromethylation of electron-deficient
fullerenes and related compounds.
Abstract
1

Fullerene C60 readily reacts with potassium and cesium trifluoroacetates yielding C60(CF
3
)–M+
salts, and subsequent acid hydrolysis gives ortho-C60(CF )H. The reaction rate and the
3
probability of the alternative reaction pathways strongly depend on the particular metal cation.
Thus, the reactivity increases in the order Li<Na<K≈Cs, in correlation with the decreasing
thermal stability. Furthermore, the sodium and, especially, lithium salts tend to effect CF
2
- rather
than CF -functionalization of the fullerene, in good accordance with the hard/soft acids and
3
bases theory. The nucleophilic trifluoromethylation is found to be applicable to other pristine
7
fullerenes like C70 as well as to fullerene derivatives like p mp-C70(CF
3
)10. It enables selective
preparation of low trifluoromethylated fullerenes via regioselective consecutive
trifluoromethylation under accurately controlled solution-phase conditions.
1
. Introduction
In the past decade, the most common methods for fullerene trifluoromethylation were based on
the thermolysis of CF I or silver trifluoroacetate [1–3]. Typically, radical trifluoromethylation of
3
fullerenes yields a complex mixture of products with broad compositional and isomeric
distribution, but normally only a few compounds are available in isolable amounts. To
selectively obtain particular trifluoromethylated products, one needs a specifically tailored
synthetic approach, but so far such approaches are known only for two derivatives of C60, para-
C
60(CF
3
)
2
[4] and S
6
-C60(CF
3
)12 [5].
Surprisingly, nucleophilic trifluoromethylation of fullerenes or their derivatives has not
been yet reported. Moreover, while silver trifluoroacetate is extensively used in fullerene
trifluoromethylation, the reaction of fullerenes with alkali metal trifluoroacetates has not yet
been investigated, even though several related successful reactions have been reported. Thus, C60
and C70 are known to undergo nucleophilic trichloromethylation under gentle heating with alkali
metal trichloroacetates, and the thermally labile C60/70(CCl
) under refluxing at 80–110 °C [6,7]. Analogously, refluxing of alkali metal
chlorodifluoroacetates at 160–180 °C with fullerenes in ortho-dichlorobenzene in the presence of
8-crown-6 as a phase transfer catalyst [8,9] (inspired by the analogous treatment of alkenes in
diglyme or triglyme [10,11]) yields C60/70(CF ) derivatives, though this reaction is presently
believed to be [2+1]-cycloaddition of the pre-formed :CF carbenes, since no C60/70(CF
Cl)–
intermediates have been detected. Also to be mentioned is the treatment of C -C60Cl with
Li to give C )H upon the subsequent protonation [12].
Thermolysis of the alkali metal halodifluoroacetates is known to proceed via
3
)– anionic intermediates can give
C
60/70(CCl
2
1
2
2
2
s
6
C
2
F
5
s
-C60(C
F
2 5
–
–
decarboxylation, leaving CF
2
X anions. In some cases, X is then abstracted to give :CF
2
carbenes [11,13–15]. Recently, a CF –
intermediate was isolated and spectroscopically
3
2

+
–
characterized as a [K(18-crown-6)] CF complex that is stable at –78 °C but is prone to a slow
3
α-defluorination at –35 °C, also to give :CF , as a side process to deprotonation of the THF
2
–
medium [16]. CF
3
generation by means of thermolysis can be employed for the nucleophilic
trifluoromethylation of aryl halides, aldehydes, ketones, diaryldisulfides, as well as for gem-
difluorocyclopropanation of alkenes via further decomposition of CF –
to :CF [17–22]. In
3
2
particular, aryl halides and carbonyl compounds undergo nucleophilic trifluoromethylation in
reaction with alkali metal trifluoroacetates [19,20,23]. The reaction is typically carried out in
dipolar aprotic solvents in the presence of copper(I) iodide as a catalyst and stabilizer under
several hours of refluxing.
In this work, we report the first nucleophilic trifluoromethylation of the pristine fullerenes
7
C
60 and C70 and of the exohedral derivative p mp-C70(CF
3
)10 with alkali metal trifluoroacetates in
–
solution. In contrast to most of the other substrates, fullerenes rapidly attach a CF
3
anion
without a need for stabilizers or activators. The present approach afforded selective preparation
and the first comprehensive characterization of ortho-C60(CF )H (Fig. 1). Previously, preparation
of C60(CF )H and the related C60(CF Br)H and C60(CF Cl)H was reported in some early works
24,25], but treatment of C60 with di(trifluoroacetyl) peroxide or perfluoroalkyl halides under the
radical functionalization conditions and subsequently with Bu SnH gave only moderate yields of
the target product, and no spectroscopic data for C60(CF )H has ever been reported, except for
3
3
2
2
[
3
3
the mass spectra [26,27]. We have also obtained two major isomeric compounds of C70(CF )H
3
7
and four isomers of C70(CF
3
)
11H obtained from p mp-C70(CF
3
10
) .
2
. Results and discussion
Lithium, sodium, potassium, and cesium trifluoroacetates were prepared by treatment of
the respective carbonates with CF COOH followed by freeze-drying. Their composition was
verified by means of the ATR–IR spectroscopy (see Fig S1 in ESI). Intense symmetric and
3
–
1
asymmetric stretching bands of the carboxylate group (1670–1653, 1472–1425 cm ), C–F
–
1
stretching bands (1200–1110 cm ), carboxylate scissoring bands and C–C stretching bands
–
1
(
860–720 cm ) were in a good agreement with the reference data [28–30]. The CF COOLi
3
–1
sample also demonstrated a broad absorption band at 3200–3600 cm due to the absorbed water,
a sign of higher hygroscopicity compared to the other trifluoroacetates.
The decomposition temperatures of the solid CF COOM salts are known to show a
3
decreasing trend from 250 °C for Li to 210 °C (Na), 150 °C (K), and 154 °C (Cs) [31], i.e., their
lability increases with the size of the alkali metal cation. Cesium salts usually being better
3

soluble in organic solvents, we started from a systematic study of the reaction of C60 with cesium
trifluoroacetate. The conditions of the series of experiments with CF COOCs are listed in Table
. Ortho-dichlorobenzene, benzonitrile (PhCN) and oDCB:PhCN 8:2 v/v mixtures were used as
3
1
solvents due to a combination of high boiling point (ca 180 °C) with relatively high fullerene
solubility (ca 25 mg of C60 per ml in oDCB and 0.4 mg/ml in PhCN at 25 °C) [32]. Rapid color
change of the reaction mixture from purple (pristine fullerene) to black (dark green on dilution),
–
which is known to indicate the formation of the anionic monoadducts C60R [33,34], occurred
within 2 min of refluxing. Attribution of the color change to C60(CF
)– is further supported by
3
the UV/Vis/NIR spectrum of the reaction media (Fig. 2b) with its broad bands at 620 and 930
–
nm that are characteristic of the C60R anions [35,36] while being absent from the spectrum of
pristine fullerene (Fig. 2a). Upon acidic workup, the mixture turns brown, and the said broad
bands vanish. Instead, the final spectrum features a small peak at 430 nm (Fig. 2c) typical of
various ortho-C60
R
2
adducts [36–40]. HPLC analysis of the acidified mixture (Fig. 3a) reveals
unreacted C60 (t
R
=7.6 min) together with some weaker retained major reaction product (t = 6.9
R
min).
The HPLC-purified reaction product was identified by means of high-resolution mass
spectrometry (Fig S3 in ESI) as C60(CF )H, a compound that, as of yet, remained without
spectroscopic and structural characterization. The UV/Vis absorption data of C60(CF )H (Fig S2
in ESI) strongly resemble those for the ortho-C60(CCl )H and other ortho-C60 compounds
6,38], and the H, C, and H– C HMBC NMR spectra further provide a clear and unequivocal
3
3
3
R
2
1
13
1
13
[
1
19
support of the ortho-addition pattern (Figs. 2 and S4, S5). The H and F NMR spectra feature
singlets at 6.88 ppm and –72.32 ppm, respectively, confirming the presence of only a single type
1
3
of both hydrogen and fluorine atoms. In the proton-decoupled C NMR spectrum we observed
2
2
5 resonances of sp -C atoms (130 – 155 ppm; theory predicts 30 signals for C
s
-symmetric
ortho-C60XY, some likely being overlapped) and three quartets at 54.7 (JCF = 2.20 Hz), 67.7 (JCF
3
=
29.71 Hz), and 127.8 ppm (JCF = 280.60 Hz) due to the sp -C atoms. The magnitude of the JCF
3
coupling constants dictates assignment of the sp -C resonances to the C–C–CF
3
, C–CF
3
, and CF
3
1
13
carbon atoms, respectively, thus suggesting, in further agreement with the H– C HMBC data,
adjacent location of the H and CF
3
addends. Finally, the DFT calculations reveal that the ortho-
protonation of C60(CF
3
)– is favored by both the thermodynamic and kinetic factors. Firstly, this is
the ortho-position along the [6,6]-bond that shows the largest effective negative charge;
secondly, protonation at the ortho-position is 28 kJ mol–1 more favorable than at the para-
position and even more so than the rest of the alternatives.
The optimal synthetic conditions with respect to the solvent composition, amount of the
substrate, reaction atmosphere, and reaction time were achieved in the experiments nos. 8 and 9
4

of Table 1. It was found, that the 8:2 v/v mixture of oDCB:PhCN likely provides the optimally
balanced solubility of both C60 and CF COOCs and that the reaction time needs to be limited to
–10 min, possibly in order to obtain the maximum amount of the labile C60(CF
)– intermediate.
3
6
3
The inertness of the reaction atmosphere turns out to crucially affect the yield of the
product and the selectivity. Thus, the HPLC analyses of the ambient atmosphere reaction
revealed several by-products with high retention times (t
R
= 15–18 min) typical of double-caged
+
fullerene dimers [41,42]. Instead of the molecular ions C60(CF
spectra of C60(CF
originated from the [C60(CF
can be oxidated with the molecular oxygen to the respective neutral radical species and further
recombine into [C60(CF )] , similarly to the formation of the (C60CH Ph) and (C60H) dimers
upon electrochemical oxidation of C60(CH Ph) and C60H , respectively. [43,44].
3
)H that prevail in the mass-
3
)H, LC-APPI-MS analysis revealed the fragment C60(CF
3
)+ ions which likely
)– intermediates
3
)] precursor. One can hypothesize that the C60(CF
2
3
3
2
2
2
2
–
–
2
The above-optimized reaction conditions were used in a comparative reactivity study of all
four alkali metal trifluoroacetates (Table 2 and Fig 3a). HPLC monitoring of the reaction mixture
reveals that reactivity increases in the order Li<Na<K≈Cs, which correlates with the order of
thermal stability of the trifluoroacetates [31]. While potassium and cesium trifluoroacetates
rapidly decompose at 180 °C and selectively yield C60(CF
trifluoroacetate thermolyzes considerably slower and gives both C60(CF
Finally, lithium salt decomposes even slower to produce C60(CF ).
3
)H via C60(CF
3
)–, sodium
3
)H and C60(CF
2
).
2
Initially, it was necessary to find out, whether any less substantial synthetic conditions
would make any significant difference. Firstly, we tested different phase transfer catalysts
+
+
(
PTC), namely 15-crown-5 and 12-crown-4, that are complementary to the Na and Li ions,
respectively (Table 2). It turned out that 18-crown-6 is still advantageous due to stronger binding
to the respective cations [45,46], the yield of C60(CF )H being slightly reduced when using with
2-crown-4 and 15-crown-5. However, no qualitative differences have been observed (see the
HPLC traces for CF COONa and CF COOLi with varied crown ethers in the Fig S7 of the ESI).
3
1
3
3
Likewise, additional experiments with trace amounts of water intended to simulate
hygroscopicity of the trifluoroacetates did not reveal any qualitative effect on the composition of
the products. One can only find a need to increase the reaction time and the excess of the
trifluoroacetate in order to compensate for the possible rapid protonation of the intermediate
CF –
anion.
3
5

Turning to the principal effect of the alkali metal cation as revealed by the data of Table 2,
there is a switch of reaction pathways when going from the larger Cs and K to the smaller Na
+
+
–
and Li cations. While with the K and Cs cations the lifetime of the CF
3
anion is long enough
to react with C60 (see Fig 3b), with Na and, especially, with Li there is a much increased rate of
decomposition toward the singlet :CF carbene (MCF →:CF +MF) and, accordingly, C60(CF
becomes the major product. Those differences are in line with the concept of hard/soft acids and
bases (HSAB theory) [47,48]. Indeed, CF Li is known to readily decompose, apparently to :CF
even when formed at low temperature in the presence of a suitable electrophile, but the other
metal cations are capable of stabilizing the CF –
anion. For example, CF MgI is stable enough to
+
+
2
3
2
2
)
3
2
,
3
3
react with various electrophiles at low temperature [49], copper(I) iodide can be used to stabilize
–
the CF
3
anion for the purpose of decarboxylative nucleophilic trifluoromethylation of aryl
halides and carbonyl compounds [19,50]. One can expect the Gibbs energy of α-defluorination
of CF M to correlate with the lattice energy of MF that equal –1045, –924, –822, and –737 kJ
3
–1
mol for M=Li, Na, K, and Cs, respectively [51], so that the decomposition to the :CF
2
carbene
becomes the principal pathway in the lithium trifluoroacetate case.
The nucleophilic trifluoromethylation route looks perfectly applicable not only to the
pristine fullerenes but also to their derivatives. We further tested our synthetic methodology with
7
the pristine C70 and with its exohedral derivative p mp-C70(CF
3
)10 [52]. The HPLC-APPI-MS
data revealed the formation of at least two isomers of C70(CF
11H (Fig. 4, S8 and S9). Comparison of the UV/Vis data for the major C70(CF
isomers (t =10.8 and 11.9 min, see Fig S9) against the previously characterized C70(CCl
isomers [6] makes possible to identify them as the C - and C
pole of the C70 cage, namely 7,22-C70(CF )H and 8,25-C70(CF
according to IUPAC recommendation [53]). While 7,22-C70(CF
two equivalent stereoisomers, 8,25-C70(CF )H allows for the two possible isomers depending on
the position of each of the addends. In view of higher reactivity of the atoms in the polar
pentagon of C70 toward nucleophilic addition [6,54], we expect that it is the CF group that is
attached at the respective position 25. A comprehensive study of the isomers of C70(CF )H and
11H will be a subject of our further publications.
3
)H and at least of four isomers of
C
70(CF
3
)
3
)H
)H
R
3
1
s
-symmetric ortho-adducts at the
)H (locant indexes are given
)H should be a mixture of the
3
3
3
3
3
3
C
70(CF )
3
3
. Conclusion
Nucleophilic trifluoromethylation of the fullerene compounds can be readily carried out by
means of thermolysis of the potassium and cesium trifluoroacetates. Rapid conversion of the C60
fullerene into C60(CF
3
)– and, upon subsequent protonation, into ortho-C60(CF
)H demonstrates
3
high efficiency of our approach. Moreover, it can be easily transferred onto other fullerene
6

substrates, including the already functionalized compounds, as is illustrated by
7
trifluoromethylation of C70 and p mp-C70(CF
3
)10. Importantly, our method requires milder
solution-phase conditions than the common high temperature trifluoromethylation and thus can
be executed in a selective and directed manner. We, therefore, believe that the nucleophilic
trifluoroacetate pathway can be developed into a methodology for large-scale synthesis of many
less-accessible isomers of the trifluoromethylated fullerenes including the compounds of
potential interest as electron acceptors in the molecular electronics [55,56], and/or as the
fluorescent materials [57].
4
. Experimental
4
.1. Reagents and solvents
All reagents and solvents were used as received unless otherwise noted. Fullerenes C60
(
99.8%) and C70 (99.5%) were purchased from “Fullerene centre”. CF
3
COOH (99+%, Sigma
I (P&M-Invest, 98%), 18-crown-6 (99%, Acros Organics), 15-crown-5 (98%,
CO (M = Li, Na, K, Cs; 98%, Reachim,
Russia), ortho-dichlorobenzene (99%, abcr), benzonitrile (99%, Sigma-Aldrich), and toluene
99.8%, Khimmed, Russia). Prior to usage toluene was distilled at atmospheric pressure while
Aldrich), CF
3
Sigma-Aldrich), 14-crown-4 (98%, Sigma-Aldrich), M
2
3
(
oDCB and benzonitrile were distilled at 20 mbar vacuum (68 °C and 80 °C boiling points
respectively).
4
.2. HPLC
HPLC analyses were performed using Agilent 1100 instrument equipped with a diode-
array detector (DAD) and a temperature controlled Cosmosil Buckyprep analytical column (4.6
mm I.D. × 25 cm, Nacalai Tesque Inc.). HPLC separation was carried out on an Cosmosil
Buckyprep semi-preparative column (10 mm I.D. × 25 cm, Nacalai Tesque Inc.) using Waters
1
500 chromatographic system equipped with an isocratic pump and a dual wavelength UV/Vis
–
1
detector. Toluene was used as an eluent at flow rates of 1.0 and 4.6 ml min , HPLC traces were
registered at 290 and 360 nm simultaneously.
4
.3. MS and LC-MS
LC-APPI-MS data were acquired using the above mentioned HPLC instrument with
Agilent 6410 triple quadrupole mass spectrometer in positive mode. APPI HRMS spectra in
positive ion mode were acquired for toluene solutions using AB Sciex TripleTOF 5600+
instrument equipped with a PhotoSpray ion source.
7

4
.4. UV/Vis/NIR spectroscopy
UV/Vis spectra of C60(CF )H in toluene solution were obtained using the abovementioned
3
HPLC DAD detector in the 290–900 nm range with 2 nm resolution. UV/Vis/NIR spectra were
obtained in 200–1100 nm wavelength range using Avantes-2048 waveguide spectrometer
equipped with a linear CCD detector (300 gr/mm grating, 50 m slit, 2.4 nm resolution) and an
AvaLight-DHc light source. The studied samples were loaded into the 1 cm × 0.4 cm quartz cells
(Quartz SUPRASIL, Hellma Analytics).
4
.5. NMR spectroscopy
1
19
13
The H, F, and C and 2D NMR spectra of C60(CF
using a Bruker Avance-III spectrometer operating at 600.3, 564.7 and 150.9 MHz respectively;
tetramethylsilane (Me Si,  0.00 ppm) and hexafluorobenzene (C ,  162.9 ppm) were
applied as an internal standard.
3
)H were recorded in a chloroform-d
4
H
6
F
6
F
4
.6. IR spectroscopy
IR spectra of alkali metal trifluoroacetates were registered within the wavenumber range of
–
1
–1
5
00–4000 cm (resolution of 2 cm ) using FTIR IRAffinity-1 spectrometer (Shimadzu, Japan)
and MIRacle ATR (Pike Technologies) equipped with a diamond/ZnSe crystal plate.
4
.7. Quantum chemical calculations
DFT calculations of the relative energies of C60(CF
3
)H isomers and C60(CF
)– anion were
3
performed with the use of PRIRODA package [58]. The PBE exchange-correlation functional
59] and the built-in TZ2P-quality basis set were used.
[
4
.8. Alkali metal trifluoroacetates preparation
Anhydrous trifluoroacetic acid (1.7 mL, 22 mmol, 10% excess) was added to water
solution (50 mL) of alkali metal carbonate (10 mmol of Li
2
CO
3
, Na
2
CO
3
, K
2
CO
3
, or Cs
2
CO ) at
3
room temperature and stirred for 30 min. Then the solvent was removed using rotary evaporator
at 60° at 40 mbar. Obtained solid samples were further freeze-dried at room temperature and 0.2
mbar (Christ Alpha 1-2 LD plus freeze dryer) for 12 hours. White-colored products were
obtained with quantitative yields and identified as respective alkaline-metal trifluoroacetates
using IR data in good accordance with early reported data [28–30].
4
.9. Syntheses of C60(CF
3
)H
Finely grounded sample of C60 fullerene (40 mg, 0.056 mmol) was dissolved in ortho-
dichlorobenzene/benzonitrile mixture (8:2 v/v, 20 mL) and placed into the three-neck flask
mounted into magnetic stirrer equipped with a heater. Then 20 l phase transfer catalyst (either
8

1
8-crown-6, 15-crown-5 or 12-crown-4) and ca 15-fold molar excess of CF COOM (0.84 mmol)
3
were added and the mixture sparged with Ar for 15 minutes while stirring before heating up.
Within 2 minutes upon reaching the boiling point, the reaction mixture containing K or Cs salts
turned black (dark green at dilution). After reaching the boiling point the mixture was refluxed
for 6 min for K and Cs, 20 min for Na, 1 hour for Li and then allowed to cool down to the room
temperature and quenched with 0.5 mL of CF COOH. The obtained product was filtered through
3
a silica gel column to remove inorganic residue and subjected further purification. The brown
product was isolated by HPLC with 30% isolated yield (ca 50% HPLC yield) for the synthesis
with CF
.10. Preparation of p mp-C70(CF
Trifluoromethylated fullerene p mp-C70(CF
3
COOCs.
7
4
)
3 10
7
3
)
10 was synthesized from C70 and CF I using
3
7
two-stage ampoule approach according to work [60]. Individual p mp-C70(CF
3
)10 (99+%) was
isolated by means of HPLC separation (Cosmosil Buckyprep, 10 mm I.D. × 25 cm, toluene as an
eluent ), MALDI MS, NMR, and UV/Vis data of obtained sample were found to be in good
accordance with literature data [60].
7
4
.10. Hydrotrifluoromethylation of C70 and p mp-C70(CF
)
3 10
Fine grounded sample of the fullerene substrate (20 mg, 0.023 mmol for C70, 6 mg, 0.004
mmol for C70(CF 10,) was dissolved in ortho-dichlorobenzene/benzonitrile mixture (8:2 v/v, 20
mL for C70, 6 ml for C70(CF 10) and placed into the three-neck flask mounted into magnetic
stirrer equipped with heater. Then 20 l of 18-crown-6 and ca 15-fold molar excess of
CF COOCs (85 mg, 0.345 mmol for C70, 15 mg, 0.06 mmol for C70(CF 10) were added and the
3
)
3
)
3
3
)
mixture sparged with Ar for 15 minutes while stirring before heating up. Within 2 minutes upon
reaching the boiling point, the reaction mixture turned dark green. After reaching the boiling
point, the mixture was refluxed for 6 minutes and then allowed to cool down to the room
temperature and quenched with 0.5 mL of CF
3
COOH. The obtained mixture was filtered through
a silica gel column to remove inorganic residue and subjected to LC-APPI-MS analysis.
4
.11. Compound data
Lithium trifluoroacetate: a white solid, 1.6 g, 67% yield. IR (ATR, υ/cm ) 1663, 1472, 1198,
141, 859, 802, 729.
Sodium trifluoroacetate: a white solid, 1.8 g, 66% yield. IR (ATR, υ/cm ): 1717, 1669, 1448,
182, 1140, 840, 801, 725.
Potassium trifluoroacetate: a white solid, 2.2 g, 72% yield. IR (ATR, υ/cm ): 1709, 1653, 1436,
172, 1133, 837, 805, 722.
–
1
1
–
1
1
–1
1
9

–
1
Cesium trifluoroacetate: a white solid, 4.2 g, 84% yield. IR (ATR, υ/cm ): 1689, 1665, 1425,
1
1
417, 1199, 1158, 1108, 828, 799, 719.
-trifluoromethyl-1,9-dihydro[C60-I ]fullerene: a brown solid, 30% isolated yield (52 % HPLC
h
yield, 92% HPLC yield based on converted C60). HPLC (Cosmosil Buckyprep 4.6 mm ID × 25
cm, toluene, 1 ml/min) t 7.0 min. UV/vis (toluene, λmax / nm): 326, 432, 694. HRMS (APPI,
positive ion mode), m/z calculated for [C61
MHz, CDCl , 25°C, TMS): 6.88 (1H, s, HCcage). F NMR (564.7 MHz, CDCl
162.90): –72.32 (3F, s, F
Hz, HCcage), 67.73 (q, 2JCF = 28.7 Hz, F
R
+
1
F H] : 790.0025, found: 790.0029. H NMR (600.3
3
1
9
3
3
, 25°C, C
, 25°C, TMS): 54.66 (q, 3JCF = 2.2
CCcage), 127.82 (q, 1JCF = 280.6 Hz, F
C), {135.77,
37.94, 139.96, 140.78, 141.10, 141.85, 142.22, 142.25, 142.31, 142.76, 142.86, 143.25, 144.35,
6
F
6
,  =
F
1
3
–
3
C). C NMR (150.9 MHz, CDCl
3
3
3
1
1
1
44.78, 145.25, 145.45, 145.73, 146.23, 146.33, 146.42, 146.51, 146.63, 146.75, 147.02,
2
50.79} (total 25 signals, sp -Ccage).
C
70(CF
3
)H (isomer I, 7,22-adduct): (Cosmosil Buckyprep 4.6 mm ID× 25 cm, toluene, 1 ml/min)
t
R
10.8 min. UV/vis (toluene, λmax / nm): 363, 400, 443, 690. APPI MS (positive ion mode), m/z
+
911 (98) [M+H]+
+
(
rel. int.): 840 (8) [M-CF
)H (isomer II), 25-trifluoromethyl-8,25-dihydro[C70-D5h]fullerene: (Cosmosil Buckyprep
.6 mm ID × 25 cm, toluene, 1 ml/min) t 11.9 min. UV/vis (toluene, λmax / nm): 340, 395, 465,
3
H] , 910 (100) [M]+
,
,
[M] (second isotopomer).
C
70(CF
3
4
6
R
+
+
70. APPI MS (positive ion mode), m/z (rel. int.): 840 (8) [M-CF H] , 910 (90) [M] , 911 (100)
3
M+H]+
[M] (second isotopomer).
+
[
,
C
70(CF
3
)
11H (I) (Cosmosil Buckyprep 4.6 mm ID× 25 cm, toluene/hexane 8:2 v/v, 1 ml/min) t
R
3
.2 min. UV/vis (toluene, λmax / nm): 480 (absorption edge). APPI MS (positive ion mode), m/z
+
+
(
rel. int.): 1530 (12) [M-CF
3
H] , 1600 (100) [M] .
C
70(CF
3
)
11H (II) (Cosmosil Buckyprep 4.6 mm ID× 25 cm, toluene/hexane 8:2 v/v, 1 ml/min) t
R
3
.5 min. UV/vis (toluene, λmax / nm): 395, 480, 500. APPI MS (positive ion mode), m/z (rel.
+
+
int.): 1530 (8) [M-CF H] , 1600 (100) [M] .
3
C
70(CF
3
)11H (III) (Cosmosil Buckyprep 4.6 mm ID× 25 cm, toluene/hexane 8:2 v/v, 1 ml/min) t
R
3
1
.8 min. UV/vis (toluene, λmax / nm): 380, 500. APPI MS (positive ion mode), m/z (rel. int.):
+
+
530 (4) [M-CF H] , 1600 (100) [M] .
3
Acknowledgments
The authors are indebted to Dr I.N. Ioffe (Lomonosov Moscow State University) for fruitful
discussions and helpful suggestion. This work was supported by the Russian Foundation for
Basic Research (project № 18-33-01192). This work was supported in part by M.V.Lomonosov
Moscow State University Program of Development and project “Chemical thermodynamics” (№
1
0

АААА-А16-116061750195-2). The research is carried out using the equipment of the shared
research facilities of HPC computing resources at Lomonosov Moscow State University
Appendix A. Supplementary data
Supplementary material related to this article can be found, in the online version, at doi:
https://doi.org/XXX.
References
[
1] O.V. Boltalina, A.A. Popov, I.V. Kuvychko, N.B. Shustova, S.H. Strauss,
Perfluoroalkylfullerenes, Chem. Rev. 115 (2015) 1051–1105. doi:10.1021/cr5002595.
2] E.I. Dorozhkin, D.V. Ignat’eva, N.B. Tamm, A.A. Goryunkov, P.A. Khavrel, I.N. Ioffe,
A.A. Popov, I.V. Kuvychko, A.V. Streletskiy, V.Y. Markov, J. Spandl, S.H. Strauss, O.V.
Boltalina, Synthesis, Characterization, and Theoretical Study of Stable Isomers of
[
C
70(CF
3
)
n
(n = 2, 4, 6, 8, 10), Chem. Eur. J. 12 (2006) 3876–3889.
doi:10.1002/chem.200501346.
[
3] E.I. Dorozhkin, A.A. Goryunkov, I.N. Ioffe, S.M. Avdoshenko, V.Y. Markov, N.B.
Tamm, D.V. Ignat’eva, L.N. Sidorov, S.I. Troyanov, Synthesis, structure, and theoretical
study of lower trifluoromethyl derivatives of [60]fullerene, Eur. J. Org. Chem. 60 (2007)
5
082–5094. doi:10.1002/ejoc.200700487.
[
[
[
4] I.V. Kuvychko, J.B. Whitaker, B.W. Larson, R.S. Raguindin, K.J. Suhr, S.H. Strauss,
O.V. Boltalina, Pressure effect on heterogeneous trifluoromethylation of fullerenes and its
application, J. Fluorine Chem. 132 (2011) 679–685. doi:10.1016/j.jfluchem.2011.03.008.
5] S.I. Troyanov, A. Dimitrov, E. Kemnitz, Selective Synthesis of a Trifluoromethylated
Fullerene and the Crystal Structure of C60(CF
974. doi:10.1002/anie.200503964.
3
)12, Angew. Chem. Int. Ed. 45 (2006) 1971–
1
6] M.G. Apenova, V.A. Akhmetov, N.M. Belov, A.A. Goryunkov, I.N. Ioffe, N.S. Lukonina,
V.Y. Markov, L.N. Sidorov, Alkali-metal trichloroacetates for dichloromethylenation of
fullerenes: Nucleophilic addition-substitution route, Chem. Asian J. 9 (2014) 915–923.
doi:10.1002/asia.201301413.
[
[
7] M. Tsuda, T. Ishida, T. Nogami, S. Kurono, M. Ohashi, C61Cl
characterization of dichlorocarbene adducts of C60, Tetrahedron Lett. 34 (1993) 6911–
912. doi:10.1016/S0040-4039(00)91828-8.
8] A.S. Pimenova, A.A. Kozlov, A.A. Goryunkov, V.Y. Markov, P.A. Khavrel, S.M.
Avdoshenko, V.A. Vorobiev, I.N. Ioffe, S.G. Sakharov, S.I. Troyanov, L.N. Sidorov,
2
. Synthesis and
6
Preparation and structures of [6,6]-open difluoromethylene[60]fullerenes: C60(CF
, Dalt. Trans. 60 (2007) 5322–5328. doi:10.1039/b708167g.
2
) and
C
2 2
60(CF )
[
9] N.A. Samoylova, N.M. Belov, V.A. Brotsman, I.N. Ioffe, N.S. Lukonina, V.Y. Markov,
A. Ruff, A.V. Rybalchenko, P. Schuler, O.O. Semivrazhskaya, B. Speiser, S.I. Troyanov,
T.V. Magdesieva, A.A. Goryunkov, [6,6]-Open and [6,6]-Closed Isomers of C70(CF
Synthesis, Electrochemical and Quantum Chemical Investigation, Chem. Eur. J. 19 (2013)
7969–17979. doi:10.1002/chem.201302946.
2
):
1
[
[
[
10] D.L.S. Brahms, W.P. Dailey, Fluorinated Carbenes, Chem. Rev. 96 (1996) 1585–1632.
doi:10.1021/cr941141k.
11] M. Fedoryński, Syntheses of gem -Dihalocyclopropanes and Their Use in Organic
Synthesis, Chem. Rev. 103 (2003) 1099–1132. doi:10.1021/cr0100087.
12] I.V. Kuvychko, N.B. Shustova, S.M. Avdoshenko, A.A. Popov, S.H. Strauss, O.V.
Boltalina, In search of fullerene-based superacids: Synthesis, X-ray structure, and DFT
study of C60(C
13] J.-A. Ma, D. Cahard, Strategies for nucleophilic, electrophilic, and radical
trifluoromethylations, J. Fluorine Chem. 128 (2007) 975–996.
doi:10.1016/j.jfluchem.2007.04.026.
2
F
5
)
5
H, Chem. Eur. J. 17 (2011) 8799–8802. doi:10.1002/chem.201101328.
[
1
1

[
14] C. Alonso, E. Martínez De Marigorta, G. Rubiales, F. Palacios, Carbon
trifluoromethylation reactions of hydrocarbon derivatives and heteroarenes, Chem. Rev.
1
15 (2015) 1847–1935. doi:10.1021/cr500368h.
[
[
15] D.E. Yerien, S. Barata-Vallejo, A. Postigo, Difluoromethylation Reactions of Organic
Compounds, Chem. Eur. J. 23 (2017) 14676–14701. doi:10.1002/chem.201702311.
16] G.K.S. Prakash, F. Wang, Z. Zhang, R. Haiges, M. Rahm, K.O. Christe, T. Mathew, G.A.
Olah, Long-Lived Trifluoromethanide Anion: A Key Intermediate in Nucleophilic
Trifluoromethylations, Angew. Chem. Int. Ed. 53 (2014) 11575–11578.
doi:10.1002/anie.201406505.
[
[
[
[
17] K. Matsui, E. Tobita, M. Ando, K. Kondo, A convenient trifluoromethylation of aromatic
halides with sodium trifluoroacetate, Chem. Lett. 10 (1981) 1719–1720.
doi:10.1246/cl.1981.1719.
18] G.E. Carr, R.D. Chambers, T.F. Holmes, D.G. Parker, Sodium perfluoroalkane
carboxylates as sources of perfluoroalkyl groups, J. Chem. Soc., Perkin Trans. 1. (1988)
9
21–926. doi:10.1039/p19880000921.
19] Y. Chang, C. Cai, Trifluoromethylation of carbonyl compounds with sodium
trifluoroacetate, J. Fluorine Chem. 126 (2005) 937–940.
doi:10.1016/j.jfluchem.2005.04.012.
20] Y. Chang, C. Cai, Sodium trifluoroacetate: an efficient precursor for the
trifluoromethylation of aldehydes, Tetrahedron Lett. 46 (2005) 3161–3164.
doi:10.1016/j.tetlet.2005.03.072.
[
[
21] Y. Chang, C. Cai, Sodium Trifluoroacetate: an Efficient Difluorocarbene Precursor for
Alkenes, Chem. Lett. 34 (2005) 1440–1441. doi:10.1246/cl.2005.1440.
22] K. Oshiro, Y. Morimoto, H. Amii, Sodium bromodifluoroacetate: A difluorocarbene
source for the synthesis of gem-difluorocyclopropanes, Synthesis 99 (2010) 2080–2084.
doi:10.1055/s-0029-1218754.
[
[
23] G. Li, C. Zhang, C. Song, Y. Ma, Progress in copper-catalyzed trifluoromethylation,
Beilstein J. Org. Chem. 14 (2018) 155–181. doi:10.3762/bjoc.14.11.
24] M. Yoshida, A. Morishima, Y. Morinaga, M. Iyoda, Reactions of fullerols and fullerene
dimer containing perfluoroalkyl groups with tributyltin hydride, Tetrahedron Lett. 35
(1994) 9045–9046. doi:10.1016/0040-4039(94)88423-4.
[
25] M. Yoshida, D. Suzuki, M. Iyoda, Convenient Synthesis of 1-Fluoroalkyl-2-
hydro[60]fullerene Using Fluoroalkyl Halide with Tributyltin Hydride under Radical
Conditions, Chem. Lett. 25 (1996) 1097–1098. doi:10.1246/cl.1996.1097.
[
[
26] O.V. Boltalina, A.Y. Lukonin, J.M. Street, R. Taylor, C60
2000) 1601–1602. doi:10.1039/b004467i.
27] A.D. Darwish, A.K. Abdul-Sada, A.G. Avent, Y. Lyakhovetsky, E.A. Shilova, R. Taylor,
Unusual addition patterns in trifluoromethylation of [60]fullerene, Org. Biomol. Chem. 1
F exists!, Chem. Commun.
2
(
(2003) 3102–3110. doi:10.1039/b305741k.
[
[
28] M.J. Baillie, D.H. Brown, K.C. Moss, D.W.A. Sharp, Anhydrous metal trifluoroacetates,
J. Chem. Soc. A Inorganic, Phys. Theor. (1968) 3110–3114. doi:10.1039/j19680003110.
29] A. Regis, J. Corset, IR study of solutions of lithium trifluoroacetate in non-aqueous
solvents. Structure of ion pairs and triple ions, Chem. Phys. Lett. 32 (1975) 462–465.
doi:10.1016/0009-2614(75)85215-8.
[
30] W.
Klemperer,
G.C.
Pimentel,
Hydrogen
Bonding
in
Sodium
Trifluoroacetate‐ Trifluoroacetic Acid Compounds, J. Chem. Phys. 22 (1954) 1399–1402.
doi:10.1063/1.1740405.
[
[
31] R. Dallenbach, P. Tissot, Properties of molten alkali metal trifluoracetates, J. Therm.
Anal. 20 (1981) 409–417. doi:10.1007/BF01912890.
32] K.N. Semenov, N.A. Charykov, V.A. Keskinov, A.K. Piartman, A.A. Blokhin, A.A.
Kopyrin, Solubility of Light Fullerenes in Organic Solvents, J. Chem. Eng. Data 55
(2010) 13–36. doi:10.1021/je900296s.
1
2

[
33] Y. Murata, K. Motoyama, K. Komatsu, T.S.M. Wan, Synthesis, properties, and reactions
of a stable carbanion derived from alkynyldihydrofullerene: 1-octynyl-C60 carbanion,
Tetrahedron 52 (1996) 5077–5090. doi:10.1016/0040-4020(96)00115-9.
[
[
34] J. Cousseau, E. Allard, S. Chopin, Functionalization of [60]fullerene through the anionic
route, C. R. Chim. 9 (2006) 1051–1057. doi:10.1016/j.crci.2005.11.007.
35] S. Fukuzumi, T. Suenobu, T. Hirasaka, R. Arakawa, K.M. Kadish, Formation of C60
Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and S 2
N
Reactions, J. Am. Chem. Soc. 120 (1998) 9220–9227. doi:10.1021/ja9815430.
2
-
[
36] W.W. Yang, Z.J. Li, X. Gao, Reaction of C60 with organic halides revisited in DMF:
Proton transfer from water to RC60- and unexpected formation of
1
,2-Dihydro[60]fullerenes, J. Org. Chem. 75 (2010) 4086–4094. doi:10.1021/jo100430a.
[
[
37] C.C. Henderson, P.A. Cahill, C60 : Synthesis of the Simplest C60 Hydrocarbon
H
2
Derivative, Science 259 (1993) 1885–1887. doi:10.1126/science.259.5103.1885.
38] E. Allard, L. Rivière, J. Delaunay, D. Dubois, J. Cousseau, Chemical generation and
2
-
reactivity of C60 . High-yield and regioselective alkylation of [60, I(h)] fullerene,
Tetrahedron Lett. 40 (1999) 7223–7226. doi:10.1016/S0040-4039(99)01467-7.
[
39] M.S. Meier, J. Kiegiel, Preparation and Characterization of the Fullerene Diols 1,2-
C
60(OH)
2
, 1,2-C70(OH)
2
, and 5,6-C70(OH) , Org. Lett. 3 (2001) 1717–1719.
2
doi:10.1021/ol0159120.
[
[
40] M.S. Meier, R.G. Bergosh, M.E. Gallagher, H.P. Spielmann, Z. Wang, Alkylation of
dihydrofullerenes, J. Org. Chem. 67 (2002) 5946–5952. doi:10.1021/jo020216e.
41] A. Gromov, S. Lebedkin, S. Ballenweg, A.G. Avent, R. Taylor, W. Krätschmer, C120
The first [60]fullerene dimer with cages bis-linked by furanoid bridges, Chem. Commun.
1997) 209–210. doi:10.1039/a606794h.
42] A.A. Goryunkov, I.N. Ioffe, P.A. Khavrel, S.M. Avdoshenko, V.Y. Markov, Z. Mazej,
L.N. Sidorov, S.I. Troyanov, The former “C60 16” is actually a double-caged adduct:
16)(C60), Chem. Commun. (2007) 704–706. doi:10.1039/B615457C.
43] T. Tanaka, K. Komatsu, Synthesis of the singly bonded fullerene dimer C120
O :
2
(
[
[
[
[
[
[
F
(C F
60
H
2
and the
2
−
difullerenylacetylene C122
H
2
, and generation of the all-carbon dianion C122 , J. Chem.
Soc., Perkin Trans. 1. (1999) 1671–1676. doi:10.1039/a902178g.
44] W.-W. Yang, Z.-J. Li, X. Gao, Formation of Singly Bonded PhCH
2
C
60–C60CH Ph Dimers
2
from 1,2-(PhCH
2
)HC60 via Electroreductive C60–H Activation, J. Org. Chem. 76 (2011)
6
067–6074. doi:10.1021/jo2006768.
45] H.P. Hopkins, A.B. Norman, Conductance and infrared studies on acetonitrile solutions
containing crown ethers and alkali metal salts, J. Phys. Chem. 84 (1980) 309–314.
doi:10.1021/j100440a019.
46] B. Swain, Separation and purification of lithium by solvent extraction and supported
liquid membrane, analysis of their mechanism: a review, J. Chem. Technol. Biotechnol.
9
1 (2016) 2549–2562. doi:10.1002/jctb.4976.
47] R.G. Pearson, Hard and soft acids and bases, HSAB, part II: Underlying theories, J.
Chem. Educ. 45 (1968) 643–648. doi:10.1021/ed045p643.
[
[
48] R.G. Pearson, Chemical hardness, Wiley-VCH, 1997.
49] R.N. Haszeldine, Perfluoroalkyl Grignard and Grignard-type reagents. Part IV.
Trifluoromethylmagnesium
doi:10.1039/jr9540001273.
iodide,
J.
Chem.
Soc.
(1954)
1273–1279.
[
50] A. Lishchynskyi, M.A. Novikov, E. Martin, E.C. Escudero-Adán, P. Novák, V. V.
Grushin, Trifluoromethylation of Aryl and Heteroaryl Halides with Fluoroform-Derived
CuCF
3
: Scope, Limitations, and Mechanistic Features, J. Org. Chem. 78 (2013) 11126–
1
1146. doi:10.1021/jo401423h.
[
[
51] R.C. Weast, M.J. Astle, W.H. Beyer, others, CRC handbook of chemistry and physics,
CRC Press Boca Raton, FL, 1988.
52] I.E. Kareev, I.V. Kuvychko, A.A. Popov, S.F. Lebedkin, S.M. Miller, O.P. Anderson,
1
3

S.H. Strauss, O.V. Boltalina, High-Temperature Synthesis of the Surprisingly Stable
10 Isomer with a para7-meta-para Ribbon of Nine C (CF Edge-Sharing
C
1
-C70(CF
3
)
6
)
3 2
Hexagons, Angew. Chem. Int. Ed. 44 (2005) 7984–7987. doi:10.1002/anie.200502419.
[
53] W.H. Powell, F. Cozzi, G.P. Moss, C. Thilgen, R.J.-R. Hwu, A. Yerin, Nomenclature for
the C60-I
h
and C70-D5h(6) fullerenes (IUPAC Recommendations 2002), Pure Appl. Chem.
7
4 (2002) 629–695. doi:10.1351/pac200274040629.
[
[
54] Z. Wang, M.S. Meier, Monoalkylation of C60 and C70 with Zn and Active Alkyl
Bromides, J. Org. Chem. 68 (2003) 3043–3048. doi:10.1021/jo020563o.
55] A.A. Popov, I.E. Kareev, N.B. Shustova, S.F. Lebedkin, S.H. Strauss, O.V. Boltalina, L.
Dunsch, Synthesis, Spectroscopic and Electrochemical Characterization, and DFT Study
of Seventeen C70(CF
21. doi:10.1002/chem.200700970.
56] O.O. Semivrazhskaya, A.V. Rybalchenko, M.P. Kosaya, N.S. Lukonina, O.N. Mazaleva,
I.N. Ioffe, S.I. Troyanov, N.B. Tamm, A.A. Goryunkov, Lower
3
) Derivatives (n =2, 4, 6, 8, 10, 12), Chem. Eur. J. 14 (2008) 107–
n
1
[
trifluoromethyl[70]fullerene derivatives: novel structural data and an survey of electronic
properties, Electrochim. Acta 255 (2017) 472–481. doi:10.1016/j.electacta.2017.09.161.
57] K.P. Castro, Y. Jin, J.J. Rack, S.H. Strauss, O.V. Boltalina, A.A. Popov, Perfluoroalkyl
[
[
[
70]-fullerenes as robust highly-luminescent fluorocarbons, or position of one CF
3
group
matters, J. Phys. Chem. Lett. 4 (2013) 2500–2507. doi:10.1021/jz401068t.
58] D.N. Laikov, Fast evaluation of density functional exchange-correlation terms using the
expansion of the electron density in auxiliary basis sets, Chem. Phys. Lett. 281 (1997)
1
51–156. doi:10.1016/S0009-2614(97)01206-2.
[
[
59] J.P. Perdew, K. Burke, M. Ernzerhof, Generalized Gradient Approximation Made Simple,
Phys. Rev. Lett. 77 (1996) 3865–3868. doi:10.1103/PhysRevLett.77.3865.
60] V.A. Brotsman, V.P. Bogdanov, A.V. Rybalchenko, E.P. Galanicheva, N.M. Belov, V.Y.
Markov, N.S. Lukonina, I.N. Ioffe, S.I. Troyanov, E. Kemnitz, A.A. Goryunkov,
Reductive Hydrogenation of C
s
-C70(CF
3
)
8
and C
1
-C70(CF )10, Chem. Asian J. 11 (2016)
3
1
945–1954. doi:10.1002/asia.201600491.
1
4

Figure captions
Figure 1. Side view of ortho-C60(CF )H
3
Figure 2. UV/Vis/NIR spectra of C60 (a), reaction mixture before (b) and after (c) acidic workup.
13C NMR spectrum (d) of C
60(CF
)H (the residual toluene signals are marked with asterisks, H
1
3
1
9
and F spectra are shown in the left and right insets, respectively).
1
5

Figure 3. (a) HPLC traces (290 nm) of the CF COOM/C60 reaction products (M=Li–Cs) after
3
the acidic workup. (b) The proposed reaction scheme.
Figure 4. (a) LC-APPI-MS (positive mode) traces of the CF COOCs/C70 reaction mixture,
3
(toluene, 1 ml/min; BPC (base peak chromatogram) and selected ion monitoring traces) (b) LC-
APPI-MS traces of the CF
ml/min)
3
COOCs/C70(CF )10 reaction mixture (toluene/hexane 8:2 v/v, 1
3
1
6

Table
Table 1. Trifluoromethylation of fullerene C60 with CF
COOCs. [a]
3
Solvent
Time /
min
C
60(CF )H
3
Exp. No. C60, mg
Atmosphere[b]
[
c]
(v/v)
yield / %
18 (26)
45 (88)
30 (34)
36 (39)
21 (23)
47 (56)
10 (11)
50 (72)
52 (92)
32 (93)
10 (95)
1
2
3
4
5
6
7
8
9
20
5
oDCB
inert
inert
inert
inert
inert
inert
air
20
20
20
20
30
15
15
10
6
PhCN
20
40
40
40
40
40
40
40
40
oDCB:PhCN (8:2)
oDCB:PhCN (8:2)
oDCB:PhCN (8:2)
oDCB:PhCN (8:2)
oDCB:PhCN (8:2)
oDCB:PhCN (8:2)
oDCB:PhCN (8:2)
oDCB:PhCN (8:2)
oDCB:PhCN (8:2)
inert
inert
inert
inert
1
0
1
4
1
2
[
a] Solvent volume 20 mL, CF
for inert atmosphere. [c] The yields are according to the HPLC analysis (see ESI
for details), the values in parentheses are based on the rate of conversion of C60
3
COOCs/C60 molar ratio of 15:1.[b] Argon was used
.
1
7

Table 2. Reaction of C60 with alkali metal trifluoroacetates in the presence of a phase-transfer
catalyst.[
a]
C
60
Yield / %
)H
[
b]
T
/
dec
Salt
t / min
PTC
conversion /
%
°C
C60(CF
3
C
60(CF )
2
1
8CR6
2CR4
8CR6
5CR5
12
7
22
19
60
56
<0.5
<0.1
16
11
35
3
0.5
4
8
<0.3
<0.3
CF
3
COOLi
250
60
20
1
1
1
CF
3
COONa 210
COOK 150
COOCs 154
CF
3
6
6
18CR6
18CR6
CF
3
52
[
a] Reaction conditions: 40 mg C60, 15-fold molar excess of CF COOM and 20 l of phase
3
transfer catalyst [PTC: 18-crown-6 (18CR6), 15-crown-5 (15CR5), or 12-crown-4 (12CR4)]
were dissolved in 20 mL of mixture oDCB:PhCN (8:2 v/v) and refluxed (ca 180 °C) under Ar.
Products were identified using HPLC, UV-Vis, and LC-MS data; C60 conversion rate and
product yield were estimated from the HPLC data (see ESI for details). [b] Onset of
decomposition in the solid state according to the TGA data [31].
1
8