Reaction of fullerene C60 with 2-azido-4,6-diphenylpyrimidine

Article abstract of DOI:10.1023/B:RUCB.0000011875.65588.6f

The first representative of the pyrimidine-substituted [60]fullereno[1,2-b] aziridines was synthesized by the reaction of fullerene C₆₀ with 2-azido-4,6-diphenylpyrimidine. 2-(Azahomo[60]fullereno)-4,6-diphenylpyrimidine was found to be formed as a by-product. The electrochemical properties of the adducts were studied.

Full text of DOI:10.1023/B:RUCB.0000011875.65588.6f

Russian Chemical Bulletin, International Edition, Vol. 52, No. 10, pp. 2171—2174, October, 2003
2171
Reaction of fullerene С60 with 2ꢀazidoꢀ4,6ꢀdiphenylpyrimidine
a
a
а
b
I. P. Romanova,a G. G. Yusupova, D. G. Yakhvarov, О. А. Larionova, N. N. Mochul´skaya,
ꢀ
L. P. Sidorova,b V. N. Charushin,c V. V. Zverev,a and O. G. Sinyashina
aA. E. Arbuzov Institute of Organic and Physical Chemistry,
Kazan Research Center of the Russian Academy of Sciences,
8 ul. Akad. Arbuzova, 420088 Kazan, Russian Federation.
Fax: +7 (843 2) 75 2253. Eꢀmail: romanova@iopc.kcn.ru
bUral State Industrial University,
19 ul. Mira, 620002 Ekaterinburg, Russian Federation.
Fax: +7 (343 2) 74 0458. Eꢀmail: 7708@mail.ur.ru
cInstitute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences,
20 ul. S. Kovalevskoi, 620219 Ekaterinburg, Russian Federation.
Fax: +7 (343 2) 74 1189. Еꢀmail: charushin@prm.uran.ru
The first representative of the pyrimidineꢀsubstituted [60]fullereno[1,2ꢀb]aziridines was
synthesized by the reaction of fullerene C60 with 2ꢀazidoꢀ4,6ꢀdiphenylpyrimidine. 2ꢀ(Azaꢀ
homo[60]fullereno)ꢀ4,6ꢀdiphenylpyrimidine was found to be formed as a byꢀproduct. The
electrochemical properties of the adducts were studied.
Key words: [60]fullerene, 2ꢀazidopyrimidines, [60]fullereno[1,2ꢀb]aziridine, azaꢀ
homo[60]fullerene, electrochemistry.
Researchers are interested in reactions of fullerenes
with 2ꢀazidopyrimidines for several reasons.1 First, these
reactions make it possible to fix pharmacophobic pyrimiꢀ
dine fragments on the fullerene framework. Second, they
afford adducts with different structures of the fullerene
sphere and exocyclic organic fragment. Finally, covalent
bonding in one molecule of the fullerene sphere and elecꢀ
tronꢀwithdrawing pyrimidine fragment increases the elecꢀ
tron affinity (EA) of the sphere compared to the EA of
nonꢀmodified fullerene С60. For example, the reactions
of С60 with 2ꢀazidopyrimidine and 2ꢀazidoꢀ5ꢀnitroꢀ
pyrimidine afforded nitropyrimidineꢀsubstituted azaꢀ
homofullerene and previously unknown [60]fullereꢀ
no[1´,2´:4,5]imidazo[1,2ꢀb]pyrimidines.1 According to
the data of cyclic voltammetry, all these adducts exhibit
the stronger electronꢀacceptor properties than nonꢀmodiꢀ
fied fullerene. However, no formation of [60]fulleꢀ
reno[1,2ꢀb]aziridines, which are traditional for the reacꢀ
tions of fullerenes with organic azides,2 was found in these
reactions. The adduct of this structure, along with the
formation of a new representative of pyrimidineꢀsubstiꢀ
tuted azahomofullerenes, was obtained in the reaction of
С60 with 2ꢀazidopyrimidine with two phenyl substituents
in positions 4 and 6 of the ring. This work is devoted to
the study of this reaction, isolation of the adducts, and
establishment of their structures and electronꢀwithdrawꢀ
ing capability.
As known, azidopyrimidines can exist in solutions as
two tautomers: azidic and tetrazolic.3 The tetrazole—azide
equilibrium depends on the structure and position of subꢀ
stituents in the pyrimidine cycle and the temperature and
polarity of the solvent. According to the IR and 13С,
1Н NMR spectra, 2ꢀazidoꢀ4,6ꢀdiphenylpyrimidine (1) in
the solid state and in solution exists only as the azidic
tautomer. The IR spectrum of the solid sample of this
compound in the KBr pellet contains three intense bands
at 2153, 2125, and 2109 cm–1 characteristic of the N3
azido group. They are retained in the IR spectrum of
compound 1 in chloroform. The 13С and 1Н NMR specꢀ
tra of compound 1 exhibit signals of only one isomer.
The reactions of С60 with azide 1 were carried out in
oꢀdichlorobenzene (oꢀDCB). The reactants in a ratio of
1 : 1 were first stirred at 100 °C. According to the TLC
data, even after 40 h of heating, unreacted azide 1 reꢀ
mained in the reaction mixture. The separation of the
components of the reaction mixture by column chromaꢀ
tography using toluene as the eluent gave fractions conꢀ
taining unreacted fullerene (70% of the starting amount
of fullerene) and several fractions of the adduct. The adꢀ
ducts were not separated because of a small amount of the
last fractions.
The temperature of the reaction of С60 with azide 1
was increased to 180 °C. According to the TLC data,
compound 1 has completely reacted for 4 h of heating.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2056—2059, October, 2003.
1066ꢀ5285/03/5210ꢀ2171 $25.00 © 2003 Plenum Publishing Corporation

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Russ.Chem.Bull., Int.Ed., Vol. 52, No. 10, October, 2003
Romanova et al.
time, the spectrum of adduct 3 in a longꢀwave region
exhibited a narrow band with λmax 420 nm and two broad
lowꢀintense bands with λmax 490 and 664 nm, respecꢀ
tively. In the UV spectrum of adduct 2, the narrow band
at 420—430 nm and the band with λmax 660 nm were
absent, whereas the broad band appeared at 520 nm. This
shape of the UV spectra indicates1,2 that adduct 2 is
azahomo[60]fullerene (adduct at the 5,6ꢀopen bond of
С60), while adduct 3 has the [60]fullereno[1,2ꢀb]aziridine
structure (adduct at the 6,6ꢀclosed bond of С60). The low
yield of adduct 2 did not allow us to obtain a good
13С NMR spectrum for this compound. Such a spectrum
was obtained for adduct 3.
In the proton decoupled 13С NMR spectrum of adꢀ
duct 3, the fullerene sphere was characterized by 14 sigꢀ
nals with δ 140—145 and one signal with δ 83.37. As
known,1,2 this region contains signals of the sp2ꢀhybridꢀ
ized carbon atoms of the fullerene sphere. The number of
signals in the 13С NMR spectrum of adduct 3 in this
region and their relative intensities (three signals with
intensity of 2 С, nine signals with intensity of 4 С, and
two signals with 8 С intensity) correspond to the С2ν symꢀ
metry of the molecule. Theoretically,4 16 lines (3 with
2 C intensity and 13 with 4 C intensity) should correꢀ
spond to this type of symmetry in the 13С NMR spectrum
of monoorganofullerenes. In the spectrum of adduct 3,
two lines with 4 C intensity each are probably overlapped.
In the 13С NMR spectrum of adduct 3, the positions
of signals of the carbon atoms of the pyrimidine cycle and
phenyl radicals did not substantially differ from those of
signals of the same carbon atoms in the spectrum of the
starting azide 1. This indicates that the phenyl residues
are equivalent and the nitrogen atoms of the pyrimidine
cycle are not involved in ring closure on the fullerene
surface. In other words, the data of the 13С NMR specꢀ
trum in combination with the UV spectroscopic data inꢀ
dicate that adduct 3 is [60]fullereno[1,2ꢀb]aziridinoꢀ
pyrimidine rather than [60]fullereno[1´,2´:4,5]imidꢀ
azo[1,2ꢀb]pyrimidine, whose formation has previously
been observed in the reactions of fullerene with 2ꢀazidoꢀ
pyrimidine and 2ꢀazidoꢀ5ꢀnitropyrimidine.1
As already mentioned above, the electrochemical reꢀ
duction of fullerenoimidazolines and nitropyrimidineꢀ
substituted azahomofullerene occurred more easily than
the reduction of nonꢀmodified fullerene.1 Therefore, it
was of interest to study the electronꢀacceptor capability of
pyrimidineꢀsubstituted fullerenoaziridine 3 and azahomoꢀ
fullerene 2 and to estimate the influence of the fullerene
sphere structure on the electrochemical reduction of the
adducts with the same organic fragments. For this purꢀ
pose, we studied the electrochemical behavior of adducts
2 and 3 by cyclic voltammetry (CV). The results obtained
were compared to the CV data for nonꢀmodified fullerene
and starting azide 1 and to the electron affinity values
calculated by the РМ3 method.
Reaction conditions: 180 °C, oꢀDCB, 4 h.
Column chromatography on silica gel using a toluꢀ
ene—petroleum ether (4 : 1) mixture as the eluent reꢀ
sulted in the separation of unreacted fullerene (15% of the
starting amount of fullerene), a fraction containing
monoadducts 2 and 3, and several fractions of mixtures of
polyadduct isomers. Cycloadducts 2 and 3 were isolated
in the individual state, as followed from the TLC data, by
the repeated column chromatography of the second fracꢀ
tion. The resulting yield of each adduct was 6 and 12%,
respectively, of the starting amount of fullerene. The comꢀ
positions of adducts 2 and 3 were established by elemental
analysis. According to the results of this method, adducts
2 and 3 are monoadducts, i.e., in each case, one azide
molecule added to the fullerene framework accompanied
by the elimination of the nitrogen molecule. The IR
spectra of adducts 2 and 3 did not contain bands at
2100—2200 cm–1 corresponding to the azido group but
contained intense bands at 526 cm–1 characteristic of all
types of monoorgano[60]fullerenes. The pyrimidine and
phenyl fragments of molecules of adducts 2 and 3 in the
IR spectra were characterized by the same set of bands at
the same wavelengths.
1
The Н NMR spectra of adducts 2 and 3 were also
identical and did not substantially differ from the specꢀ
trum of the starting azide 1. Thus, the combination of the
1
elemental analysis and IR and Н NMR spectroscopic
data indicates that monoadducts 2 and 3 differ only by the
structure of the fullerene sphere.
An information on the fullerene sphere structure of
monoorganofullerenes can be obtained from the UV and
13С NMR spectra. The UV spectra of adducts 2 and 3 in
the wavelength region of 200—400 nm contained two
bands, whose λmax did not substantially differ. At the same

Reaction of C60 with 2ꢀazidoꢀ4,6ꢀdiphenylpyrimidine Russ.Chem.Bull., Int.Ed., Vol. 52, No. 10, October, 2003
Table 1. Potentials (Epred/V) and currents (Ipred/µA) at peaks in
2173
the reduction of the pyrimidine fragment is accompanied
by the protonation of the anionic center. The further
reduction of adduct 3 forms the tetraanion.
the CV curves of fullerene C60 and compounds 1—3
Comꢀ
pound
E1
(Ip )
E 2
E3
(Ip
E 4
(Ip )
Finally, the reduction of adduct 2 also forms the
tetraanion. However, the potential of the second reducꢀ
tion peak is somewhat unusual. Relatively to the second
peaks in the CV curves of С60 and adduct 3, this peak in
the CV curve of adduct 2 is considerably shifted toward
the more cathodic region. This peak corresponds, most
likely, to the simultaneous reduction of the fullerene and
pyrimidine fragments of the molecule of adduct 2, and
the shift values indicate the partial conjugation of the
fullerene sphere of azahomofullerene with the aromatic
fragments of the molecules.
1
2
3
4
(Ip
)
)
С60
1
–0.83
(4.2)
–1.24
(3.8)
–1.70
(3.9)
–1.86
(11.8)
–1.88
(1.4)
–2.16
(4.6)
2
–1.00
(1.5)
–0.96
(3.4)
–1.44
(2.0)
–1.28
(2.1)
–2.35
(1.3)
–2.34
(3.2)
3
–1.87
(4.9)
Under the studied conditions, four reversible oneꢀelecꢀ
tron reduction peaks, whose potentials are presented in
Table 1, are detected in the CV curve of the starting С60.
Azidopyrimidine 1 was reduced irreversibly. The single
reduction peak was observed in the potential interval in
which the second peak of nonꢀmodified fullerene was
detected (Table 1). It is known that pyrimidines5 with
electronꢀwithdrawing substituents at the С(2) atom are
capable of accepting one electron during electrochemical
reduction to form the radical monoanion. This is accomꢀ
panied by the С(4)=N(3) bond opening followed by the
protonation of the anionic center. It is most likely that
this process occurs during the electrochemical reduction
of azide 1, because we have previously6 shown that the
azido group is not reduced in the potential interval from 0
to –2.5 V under the conditions studied. It is noteworthy
that the reduction of azide 1 is more difficult than the
Thus, the use of 2ꢀazidopyrimidine with the donating
phenyl substituents in positions 4 and 6 of the pyrimidine
cycle in the reaction with С60 results in the formation of
two types of adducts with different structures of the
fullerene sphere: azahomofullerene and previously unꢀ
known pyridineꢀsubstituted fullereno[1,2ꢀb]aziridine. Acꢀ
cording to the calculation, the heats of formation of
compounds 2 and 3 are close and equal to 911.5 and
914.5 kcal mol–1, respectively. The energies of the highꢀ
est occupied orbitals are –9.208 eV for adduct 2 and
–9.213 eV for adduct 3, and the energies of the lowest
unoccupied orbitals coincide being –2.814 eV. The fronꢀ
tier orbitals of adducts 2 and 3 are predominantly localꢀ
ized on the fullerene shell. Note that the energies of the
frontier orbitals of fullerene С60 calculated by the РМ3
method are –9.208 and –2.887 eV. The dipole moments
of adducts 2 (3.33 D) and 3 (3.95 D) do not either differ
substantially. However, adducts 2 and 3 differ by the
charges on the nitrogen atom of the aziridine cycle, being
equal to 0.160 and 0.141 a.u., respectively, which indiꢀ
cates the more efficient conjugation and additional stabiꢀ
lization of the open structure 2.
reduction of nonsubstituted 2ꢀazidopyrimidine1 (E1 red
=
p
–1.81 V), which is probably related to the presence of the
donating phenyl substituents in the pyrimidine cycle.
The cyclic voltammograms of adducts 2 and 3 exhibꢀ
ited four reversible reduction peaks. In both cases, the
first peaks corresponded to the reduction of the fullerene
spheres to form radical anions. Note that the withdrawing
of the first electron by adduct 3 is by 40 mV easier than the
reduction of adduct 2, despite the isostructural character
of azahomofullerenes and starting fullerene. Compared to
nonꢀmodified С60, both adducts 2 and 3 were reduced in
the region of more cathodic potentials, which is characꢀ
teristic of the most fullerene monoadducts and agrees
with the donor character of the substituents in the pyrimiꢀ
dine cycle. The calculation showed that the electron afꢀ
finity of adduct 2 did not substantially differ from that of
adduct 3, being 2.58 eV, which is lower than the electron
affinity of nonꢀmodified fullerene (2.65 eV). The second
peak in the CV curve of adduct 3 also corresponds to the
transfer of one electron to the fullerene fragment to form
the dianion. The current value of the third reduction peak
of adduct 3 indicates that the fullerene sphere and pyrimiꢀ
dine fragment are simultaneously reduced. The sphere of
adduct 3 reversibly withdraws the third electron, whereas
Experimental
IR spectra were obtained on a Вruker IFSꢀ113V FTIR specꢀ
1
trometer in KBr pellets and CHCl3 solutions. Н NMR spectra
were recorded on a Bruker WMꢀ250 instrument (250.13 MHz)
in CDCl3 using Ме4Si as the internal standard. 13С NMR
spectra were obtained on a Вruker MSLꢀ400 instrument at
ν 100.62 MHz. The δ values were calculated relatively to Ме4Si.
0
UV spectra were recorded on a Specord UVꢀVIS instrument. In
the CV studies, a stationary disk glassyꢀcarbon electrode with a
working surface area of 3.14 mm2 was used as the working elecꢀ
trode. Voltammograms (CV curves) were recorded using a
PIꢀ50ꢀ1 potentiostat with a PRꢀ8 programmer, and the electroꢀ
chemical cell was connected according to the threeꢀelectrode
scheme. CV curves were detected on a twoꢀcoordinate recorder
with a linear potential scan rate of 50 mV s–1. CV curves were
obtained in an oꢀDCB : MeCN (3 : 1) mixture vs. Bu4NBF4
(0.1 M). An Ag/0.01 М AgNO3 system in MeCN served as the
reference electrode. A Pt wire was used as the auxiliary elecꢀ

2174
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 10, October, 2003
Romanova et al.
trode. Measurements were carried out in a cell, whose temꢀ
perature was maintained at 25 °C, in an argon atmosphere.
The concentration of С60 and azide 1 in solutions was
1Н NMR, δ: 7.55—7.58 (m, 6 Н, 2 Ph); 8.02 (s, 1 H, H(5)); 8.29
(dd, 4 Н, 2 Ph, 3JН,Н = 6.5 Hz, 4JН,Н = 2.5 Hz).
2ꢀ{[60]Fullereno[1,2ꢀb]aziridino}ꢀ4,6ꢀdiphenylpyrimidine
(3). Found (%): С, 94.22; Н, 0.67; N, 4.30. С76Н11N3. Calcuꢀ
lated (%): С, 94.51; Н, 1.14; N, 4.35. IR (KBr), ν/cm–1: 1584,
1570, 1524, 1429, 1340, 763, 688 (Ph, pyrimidine cycle);
526 (fullerene fragment). UV (CH2Cl2), λmax/nm: 256, 325,
420 (narrow), 490, 664. 1Н NMR, δ: 7.53—7.56 (m, 6 Н, 2 Ph);
2•10–3 mol L–1, and that of the adducts was 1•10–3 mol L–1
.
The electronic structures, heats of formation, and electron afꢀ
finities of compounds 2 and 3 were studied by the РМ3 method
using the GAMESS program.7 The energies of the lowest unocꢀ
cupied orbital (ε *) and experimental electron affinity of nonꢀ
1
modified fullerene С60 (2.65 eV) were used for the theoretical
estimation of the electron affinities (EA) of adducts 2 and 3:
EA(adduct) = EA(C60) – ε*1(adduct) + ε*1(C60). Anhydrous
oꢀDCB and MeCN were obtained by distillation over Р2О5.
[60]Fullerene was synthesized at the G. A. Razuvaev Institute of
Organometallic Chemistry of the Russian Academy of Sciences
(Nizhnii Novgorod).8 2ꢀHydrazinoꢀ4,6ꢀdiphenylpyrimidine was
synthesized according to a previously described procedure.9
2ꢀAzidoꢀ4,6ꢀdiphenylpyrimidine (1). A solution of NaNO2
(0.9 g, 13.0 mmol) in water (7 mL) was added by portions to a
suspension of 2ꢀhydrazinoꢀ4,6ꢀdiphenylpyrimidine (2.9 g,
11.4 mmol) in 18% hydrochloric acid (14 mL) cooled to 0 °C in
such a way that the temperature of the reaction mixture did not
exceed 0—3 °C. After 1 h, a precipitate formed was filtered off,
washed with water, and recrystallized from aqueous EtOH. The
yield of compound 1 was 2.3 g (74%), m.p. 150—151 °C.
Found (%): С, 70.40; Н, 4.12; N, 25.60. С16Н11N5. Calcuꢀ
lated (%): С, 70.32; Н, 4.06; N, 25.63. IR (KBr), ν/cm–1: 2153,
2125, 2109 (N3); 1569, 1526, 1441, 1338, 764, 688 (Ph, pyrimiꢀ
dine cycle). IR (CHCl3), ν/cm–1: 2154, 2133, 2115 (N3);
1574, 1529, 1443, 1345 (Ph, pyrimidine cycle). UV (CH2Cl2),
7.94 (s, 1 H, H(5)); 8.22 (dd, 4 Н, 2 Ph, 3JН,Н = 6.3 Hz, 4JН,Н
=
2.8 Hz). 13С NMR, δ: 108.72 (C(5)); 126.91, 128.47, 130.07,
136.77 (Ph); 163.99 (C(2)); 166.53 (C(4), С(6)); С60N2: 83.37,
143.04, 144.35, 145.00 (2 С), 140.34, 141.25, 142.49, 142.60,
144.08, 144.71, 144.98, 145.21, 145.41 (4 С), 143.34,
145.34 (8 C).
This work was financially supported by the Russian
Foundation for Basic Research (Project Nos. 02ꢀ03ꢀ32932
and 03ꢀ03ꢀ06091) and the Ministry of Science, Inꢀ
dustry, and Technologies of the Russian Federation
(MKꢀ749.2003.03, NSh 1985.2003.03; 1766.2003.03).
References
1. I. P. Romanova, V. V. Kalinin, A. A. Nafikova, D. G.
Yakhvarov, V. V. Zverev, V. I. Kovalenko, G. L. Rusinov,
P. V. Plekhanov, V. N. Charushin, and O. G. Sinyashin, Izv.
Akad. Nauk, Ser. Khim., 2003, 163 [Russ. Chem. Bull., Int.
Ed., 2003, 52, 173].
2. U. Reuther and A. Hirsch, Carbon, 2000, 38, 1539.
3. M. Tisler, Synthesis, 1973, 123.
4. V. I. Kovalenko, in sb. statei "Struktura i dinamika
molekulyarnykh sistem", ch. 2 [Collection of Articles "Structure
and Dynamics of Molecular Systems," Part 2], Izdꢀvo MarGTU,
IoshkarꢀOla, 1997, 91 (in Russian).
5. D. L. Smith and P. J. Elving, J. Am. Chem. Soc., 1962, 84, 2741.
6. O. G. Sinyashin, I. P. Romanova, G. G. Yusupova, A. A.
Nafikova, V. I. Kovalenko, N. M. Azancheev, V. V. Yanilkin,
and Y. G. Budnikova, Mendeleev Commun., 2000, 61.
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M. S. Gordon, J. J. Jensen, S. Koseki, N. Matsunaga,
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Montgomery, J. Comput. Chem., 1993, 14, 1347.
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Kaverin, Tez. dokl. VIII Mezhdunar. konf. [Proc. VIII Intern.
Conf.] ICHMS´2003 "Hydrogen Materials Science and Chemisꢀ
try of Carbon Nanomaterials" (Sudak—Crimea—Ukraine,
14—20 September, 2003), Kiev, 2003, 486.
λ
max/nm: 257, 317. 1Н NMR, δ: 7.48—7.55 (m, 6 Н, 2 Ph, тꢀH,
рꢀH, C6H5); 7.87 (s, 1 H, Н(5)); 8.17 (dd, 4 Н, 2 Ph, 2 оꢀH,
4
3JН,Н = 6.9 Hz, JН,Н = 2.9 Hz). 13С NMR, δ: 108.41 (d, C(5),
1
1JC,H = 165.1 Hz); 127.50 (ddd, oꢀC (Ph), JC,H = 161.6 Hz,
3JC,H = 8.0 Hz, 4JC,H = 7.0 Hz); 129.12 (dd, mꢀC (Ph), 1JC,H
160.9 Hz, JC,H = 7.0 Hz); 131.50 (dt, pꢀC (Ph), JC,H
161.6 Hz, 3JC,H = 7.0 Hz); 136.42 (m, Ci(Ph)); 162.77 (s, C(2));
166.99 (s, C(4), С(6)).
=
=
2
1
Reaction of С60 with azide 1. Azide 1 (43 mg, 0.16 mmol) was
added to a solution of С60 (95 mg, 0.132 mmol) in anhydrous
oꢀDCB (25 mL), and the mixture was heated with stirring for 4 h
at 180 °C. The solvent was evaporated in vacuo, and a residue
was chromatographed on a column with silica gel. Using a toluꢀ
ene—petroleum ether (4 : 1) mixture as the eluent, С60 (14 mg,
15%) and fractions containing monoꢀ and polyadducts were
isolated. Compound 2 (8 mg, 6%) (Rf = 0.67, a toluene—petroꢀ
leum ether (4 : 3) mixture as the eluent) and compound 3 (15 mg,
12%) (Rf = 0.42) were isolated by double chromatography of the
fraction containing the monoadducts.
2ꢀ(Azahomo[60]fullereno)ꢀ4,6ꢀdiphenylpyrimidine (20).
Found (%): С, 94.38; Н, 0.77; N, 4.31. С76Н11N3. Calcuꢀ
lated (%): С, 94.51; Н, 1.14; N, 4.35. IR (KBr), ν/cm–1: 1584,
1570, 1524, 1430, 1341, 763, 689 (Ph, pyrimidine cycle); 526
(fullerene cycle). UV (CH2Cl2), λmax/nm: 258, 327, 443, 520.
9. V. A. Chuiguk and T. I. Glukhova, Ukr. Khim. Zh. [Ukr.
Chem. J.], 1980, 835 (in Russian).
Received June 30, 2003