Synthesis, structure, and antimicrobial activity of N,6-diaryl-4-methyl-2-oxo-1,2,3,6-tetrahydropyrimidine-5-carboxamides

Article abstract of DOI:10.1134/S1070363216110062

Reactions of acetoacetic acid N-arylamides with aromatic aldehydes and urea led to the formation of N,6-diaryl-4-methyl-2-oxo-1,2,3,6-tetrahydropyrimidine-5-carboxamides. Structure and antimicrobial activity of the compounds obtained were examined.

Full text of DOI:10.1134/S1070363216110062

ISSN 1070-3632, Russian Journal of General Chemistry, 2016, Vol. 86, No. 11, pp. 2437–2441. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © V.L. Gein, T.M. Zamaraeva, A.Yu. Fedotov, A.V. Balandina, M.V. Dmitriev, 2016, published in Zhurnal Obshchei Khimii, 2016,
Vol. 86, No. 11, pp. 1794–1798.
Synthesis, Structure, and Antimicrobial Activity
of N,6-Diaryl-4-methyl-2-oxo-1,2,3,6-tetrahydropyrimidine-
5-carboxamides
V. L. Geina*, T. M. Zamaraevaa, A. Yu. Fedotova, A. V. Balandinaa, and M. V. Dmitrievb
a Perm State Pharmaceutical Academy, Ministry of Healthcare of the Russian Federation,
ul. Polevaya 2, Perm, 614990 Russia
*e-mail: geinvl48@mail.ru
b Perm State National Research University, Perm, Russia
Received May 12, 2016
Abstract—Reactions of acetoacetic acid N-arylamides with aromatic aldehydes and urea led to the formation
of N,6-diaryl-4-methyl-2-oxo-1,2,3,6-tetrahydropyrimidine-5-carboxamides. Structure and antimicrobial activity
of the compounds obtained were examined.
Keywords: Biginelli reaction, acetoacetic acid N-arylamides, aromatic aldehydes, urea, antimicrobial activity
DOI: 10.1134/S1070363216110062
Most of the methods for preparation of pyrimidine
derivatives are based on the known Biginelli reaction
discovered in 1893 year for the synthesis of pyrimidi-
nones by reacting aromatic aldehyde, urea and ethyl
acetoacetate [1–4]. A great interest of the synthetic
chemists to the Biginelli condensation made it possible
to extend the scope of substrates [5–7]. Use of keto-
amides as β-dicarbonyl compounds allowed obtaining
pyrimidine 5-carbamoyl derivatives possessing high
antihypertensive [8], antitumor [9], tuberculocidal
[10], and antimycobacterial [11–13] activity.
compounds were obtained by reacting acetoacetic acid
N-arylamides with aromatic aldehydes and urea using
the procedure described in [14].
The reactions proceeded in the solvent-free condi-
tions at 120–150°C for 5–7 min (Scheme 1). Yields of
the target compounds were 62–84%.
Compounds 1–11 were colorless crystalline
substances soluble in DMF, DMSO, soluble at heating
in acetic acid and ethanol, insoluble in water.
In the IR spectra of compounds 1–11 there were
absorption bands due to stretching vibrations of CON
(1676–1688 cm–1) and C=O groups (1704–1720 cm–1),
as well as N–H (3168–3432 cm–1) and C=C bonds
(1600–1620 cm–1).
Here we report on the synthesis of previously
unknown N,6-diaryl-4-methyl-2-oxo-1,2,3,6-tetrahydro-
pyrimidine-5-carboxamides 1–11 and the investigation
of their structure and antimicrobial activity. The target
Scheme 1.
R1
O
R1
O
O
O
O
N
H
NH
+
+
R2
H
H2N
NH2
N
R2
N
O
H
H
R1 = H (1–3), CH3 (4–7), CH3O (8, 9, 10), Cl (11); R2 = 3-FC6Н4 (1), 2-NO2C6Н4 (2), 4-C6H5C6Н4 (3), 4-NO2C6Н4 (4),
2-ClC6Н4 (5, 9), 3-FC6Н4 (6, 10), 2,5-(CH3O)2C6H3 (7), 4-HO-3-C2H5OC6H3 (8), 4-CH3OC6Н4 (11).
2437

2438
GEIN et al.
Fig. 1. General view of the molecule of 9 in the crystal.
1
The H NMR spectra of carboxamides 1–11 con-
tained the signals of 4-CH3 (1.84–2.15 ppm), H6 (5.05–
5.87 ppm) and H1 (6.77–7.80 ppm, J1,6 = 1.8–1.9 Hz),
amide NH (8.68–9.60 ppm) and 3-NH (7.98–
8.79 ppm) protons, as well as the signals of aromatic
protons and of substituents at the aromatic ring.
–y, –z + 1]. Acetic acid molecule are also stabilized by
intermolecular hydrogen bonding. The hydrogen bond
parameters are listed in Table 1.
A plausible mechanism of the reaction is shown in
Scheme 2. Probably, in the first step urea reacted with
aromatic aldehyde to form aminocarbinol which
further suffered dehydration. In the second step the
reaction of acetoacetic acid N-arylamide with N-benzyl-
ideneurea afforded linear ureide, which underwent
cyclization to form desired N,6-diaryl-4-methyl-2-oxo-
1,2,3,6-tetrahydropyrimidine-5-carboxamide.
To determine the spatial structure of compound 9 in
the crystal, single crystals were grown by a slow
evaporation of acetic acid solution that were studied by
X-ray diffraction method. Compound 9 crystallizes in
a triclinic centrosymmetric space group P-1 as a 1 : 1
solvate with acetic acid (Fig. 1). Tetrahydropyrimidine
ring has a distorted boat conformation. The fragment
N3C2C3C4 is planar within 0.01 Å; the C1 and N2 atoms
are out-of-plane by 0.274 and 0.395 Å, respectively.
The chlorophenyl moiety is located in a pseudo-axial
position. The fragment C3C11O2N1C12 of arylcarbamoyl
group, which is planar within 0.02 Å, is turned with
respect to methoxyphenyl and dihydropyrimidine rings:
the torsion angles C11N1C12C17 and C2С3C11O2 are
equal to –15.9(4)° and 16.5(4)°. In the crystal mole-
cules of 9 form centrosymmetric dimer associates due
to intermolecular hydrogen bond N3–H3···O3 [–x + 3,
Antimicrobial activity of the compounds obtained
against bacteria St. aureus, E.coli, C. albicans was
determined by serial dilutions of test compound
solution in meat-peptone broth and Sabouraud liquid
medium. Bacterial load on 1 mL of culture liquid was
250 000 microbial cells. Control and experimental
samples were incubated in a heating cabinet at 36–37°C
for 18–20 h. Growth of bacterial cultures or inhibition
due to the bacteriostatic action of the test compounds
was registered. Minimum inhibitory concentrations
(MIC, μg/mL), which inhibits the growth of bacterial
Table 1. Hydrogen bonds parameters in molecule of 9
D–H···A
N2–H2···O1S
d(D–H), Å
d(H···A), Å
d(D···A), Å
DHA, deg
164(2)
0.82(2)
2.19(2)
2.981(3)
N3–H3···O3 [−x + 3, −y, −z + 1]
O2S–H2S···O3
0.80(2)
0.89(4)
2.08(2)
1.78(4)
2.875(2)
2.657(3)
176(2)
172(3)
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SYNTHESIS, STRUCTURE, AND ANTIMICROBIAL ACTIVITY
2439
Scheme 2.
NH2
NH2
O
H
OH NH2
H
NH2
+
O
R2
R2
O
N
H
O
R2
R1
N
O
R1
O
O
R1
O
O
N
H
N
N
NH
NH2
O
H
H
R2
N
H
R2
N
O
H
cultures, are shown in Table 2. According to the data
obtained, compounds 1–11 showed weak antimicrobial
activity.
4-Methyl-N-phenyl-6-(3-fluorophenyl)-2-oxo-
1,2,3,6-tetrahydropyrimidine-5-carboxamide (1). A
mixture of 0.01 mol of acetoacetanilide, 0.01 mol of
3-fluorobenzaldehyde, and 0.01 mol of urea was
heated at 120–150°C for 5–7 min until gas evolution
completed and the reaction mixture solidified. After
cooling, the solid was treated with ethanol; the pre-
cipitate was filtered off and recrystallized from
ethanol. Yield 2.73 g (84%), mp 248–250°C (C2H5OH).
IR spectrum, ν, cm–1: 1610 (C=C), 1688 (CON), 1720
EXPERIMENTAL
IR spectra were recorded on a Specord M-80 spec-
1
trometer from mulls in mineral oil. H NMR spectra
were registered on a Bruker 500 spectrometer
(500.13 MHz), internal reference TMS. Elemental
analysis was performed on a Perkin Elmer 2400
instrument. Melting points were determined on a M-
565 apparatus.
1
(CO), 3215, 3320, 3410 (NH). Н NMR spectrum
(DMSO-d6), δ, ppm: 1.96 s (3Н, 4-СН3), 5.28 d (1Н,
СН, J1,6 = 1.8 Hz), 7.20–7.58 m (9H, C6H5, FC6H4),
7.52 d (1Н, 1-NH, J1,6 = 1.8 Hz), 7.98 br.s (1Н, 3-NH),
X-Ray diffraction study was performed on a
Xcalibur Ruby diffractometer equipped with CCD
detector by standard method (MoKα-radiation,
ω-scanning) [15]. The extinction was empirically
accounted for using SCALE3 ABSPACK algorithm
[15]. The structure was solved by the direct method
and refined by full-matrix anisotropic approximation
for all non-hydrogen atoms. Hydrogen atoms of NH
and OH groups were localized from difference electron
density synthesis and refined independently in
isotropic approximation. The other hydrogen atoms
were refined using a rider model in isotropic
approximation with dependent thermal parameters. All
calculations were made using SHELXL [16] and
OLEX2 [17] programs.
Table 2. Antimicrobial activity of compounds 1–11
MIC, μm/mL
Compound
Сandida
albicans
St. aureus
E. coli
1
500
1000
250
500
1000
250
500
2
500
3
250
4
500
500
500
5
500
1000
1000
1000
1000
1000
250
1000
1000
1000
1000
1000
500
6
500
The crystals of 9 were triclinic, C19H18ClN3O3·
C2H4O2, space group P-1; unit cell parameters at
295(2) K: a 7.4500(17)°, b 8.8713(16)°, c 17.040(3) Å,
α 83.915(15), β 85.167(17), γ 72.842(19)°, V 1068.3(4)
Å3, dcalc 1.3432 g cm–3, µ 0.216 mm–1, Z 2. The final
refinement parameters: R1 0.0621, wR2 0.1365 [for
3449 reflections with I > 2σ(I)], R1 0.0948, wR2 0.1592
(for all 4963 independent reflections), S 1.059. The
results obtained were deposited in the Cambridge
Crystallographicl Data Center (CCDC 1476230).
7
500
8
1000
1000
250
9
10
11
Dioxidine
250
62.5–1000
500
3.9–62.5
500
–
Chloramine B
Fluconazole
500
–
250
–
–
8–32
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 11 2016

2440
GEIN et al.
8.76 s (1Н, NH, amide). Found, %: С 66.33, 66.57; Н
4.88, 5.05; N 12.82, 13.05. C18H16FN3O2. Calculated,
%: С 66.45; Н 4.96; N 12.92.
(6). Yield 2.57 g (76%), mp 217–219°С (C2H5OH). IR
spectrum, ν, cm–1: 1620 (C=C), 1676 (CON), 1712
(CO), 3210, 3240, 3416 (NH). Н NMR spectrum
1
(DMSO-d6), δ, ppm: 1.90 s (3Н, 4-СН3), 2.10 s (3Н,
СН3C6H4), 5.35 d (1Н, СН, J1,6 = 1.9 Hz), 6.96–7.35
Compounds 2–11 were prepared similarly.
4-Methyl-N-phenyl-6-(2-nitrophenyl)-2-oxo-1,2,3,6-
tetrahydropyrimidine-5-carboxamide (2). Yield 2.85 g
(81%), mp 234–236°С (C2H5OH). IR spectrum, ν,
cm–1: 1612 (C=C), 1680 (CON), 1716 (CO), 3200,
m (8H, СН3C6H4, FC6H4), 7.51 d (1Н, 1-NH, J1,6
=
1.9 Hz), 8.64 br.s (1Н, 3-NH), 8.92 s (1Н, NH, amide).
Found, %: С 67.13, 67.36; Н 5.26, 5.42; N 12.27,
12.51. C19H18FN3O2. Calculated, %: С 67.25; Н 5.35;
N 12.38.
1
3360, 3420 (NH). Н NMR spectrum (DMSO-d6), δ,
ppm: 1.99 с (3Н, 4-СН3), 5.87 d (1Н, СН, J1,6
=
4-Methyl-N-2-methylphenyl-6-(2,5-dimethoxy-
phenyl)-2-oxo-1,2,3,6-tetrahydropyrimidine-5-car-
boxamide (7). Yield 2.36 g (62%), mp 202–204°С
(C2H5OH). Н NMR spectrum (DMSO-d6), δ, ppm:
1.91 s (3Н, 4-СН3), 2.12 s (3Н, СН3C6H4), 3.65 s and
1.9 Hz), 7.15–7.42 m (9H, C6H5, NO2C6H4), 7.49 d
(1Н, 1-NH, J1,6 = 1.9 Hz), 8.79 br.s (1Н, 3-NH), 8.92 s
(1Н, NH, amide). Found, %: С 61.25, 61.48; Н 4.49,
4.66; N 15.78, 16.03. C18H16N4O4. Calculated, %: С
61.36; Н 4.58; N 15.90.
1
3.68 s [6Н, (СН3O)2C6H3], 5.56 d (1Н, СН, J1,6
=
4-Methyl-N-phenyl-6-(biphenyl-4-yl)-2-oxo-1,2,3,6-
tetrahydropyrimidine-5-carboxamide (3). Yield
2.37 g (62%), mp 254–256°С (C2H5OH). 1Н NMR spec-
trum (DMSO-d6), δ, ppm: 2.11 s (3Н, 4-СН3), 5.49 d
(1Н, СН, J1,6 = 1.9 Hz), 7.05–7.78 m (14H, C6H5,
С6Н5C6H4), 7.80 d (1Н, 1-NH, J1,6 = 1.9 Hz), 8.76 br.s
(1Н, 3-NH), 9.60 s (1Н, NH, amide). Found, %: С
75.07, 75.30; Н 5.44, 5.61; N 10.85, 11.09. C24H21N3O2.
Calculated, %: С 75.18; Н 5.52; N 10.96.
1.9 Hz), 6.66–7.08 m [7H, СН3C6H4, (СН3O)2C6H3],
6.77 d (1Н, 1-NH, J1,6 = 1.9 Hz), 8.53 br.s (1Н, 3-NH),
8.68 s (1Н, NH, amide). Found, %: С 66.01, 66.24; Н
6.00, 6.17; N 10.90, 11.15. C21H23N3O4. Calculated,
%: С 66.13; Н 6.08; N 11.02.
4-Methyl-N-2-methoxyphenyl-6-(4-hydroxy-3-
ethoxyphenyl)-2-oxo-1,2,3,6-tetrahydropyrimidine-
5-carboxamide (8). Yield 2.74 g (69%), mp 220–222°С
(C2H5OH). IR spectrum, ν, cm–1: 1600 (C=C), 1680
(CON), 1710 (CO), 3150 (OH), 3176, 3392, 3424
4-Methyl-N-2-methylphenyl-6-(4-nitrophenyl)-2-
oxo-1,2,3,6-tetrahydropyrimidine-5-carboxamide (4).
Yield 2.38 g (65%), mp 233–235°С (C2H5OH). IR
spectrum, ν, cm–1: 1610 (C=C), 1688 (CON), 1720
1
(NH). Н NMR spectrum (DMSO-d6), δ, ppm: 1.28 t
(3Н, СН3CH2O J = 6.0 Hz), 2.14 s (3Н, 4-СН3), 3.61 s
(3Н, СН3OC6H4), 3.89 q (2Н, СН3CH2O, J = 6.0 Hz),
5.05 d (1Н, СН, J1,6 = 1.8 Hz), 6.70–7.84 m (7H,
1
(CO), 3200, 3336, 3416 (NH). Н NMR spectrum
(DMSO-d6), δ, ppm: 1.90 s (3Н, 4-СН3), 2.10 s (3Н,
СН3C6H4), 5.44 d (1Н, СН, J1,6 = 1.9 Hz), 6.86–8.20
СН3OC6H4, HO-C2H5OC6H3), 7.37 d (1Н, 1-NH, J1,6
=
1.8 Hz), 7.98 br.s (1Н, 3-NH), 8.68 s (1Н, NH, amide),
8.81 s (1Н, OH). Found, %: С 63.36, 63.60; Н 5.75,
5.93; N 10.46, 10.70. C21H23N3O5. Calculated, %: С
63.47; Н 5.83; N 10.57.
m (8H, СН3C6H4, NO2C6H4), 7.02 d (1Н, 1-NH, J1,6
=
1.9 Hz), 8.75 br.s (1Н, 3-NH), 8.99 s (1Н, NH, amide).
Found, %: С 62.19, 62.41; Н 4.87, 5.04; N 15.16,
15.41. C19H18N4O4. Calculated, %: С 62.29; Н 4.95; N
15.29.
4-Methyl-N-2-methoxyphenyl-6-(2-chlorophenyl)-
2-oxo-1,2,3,6-tetrahydropyrimidine-5-carboxamide
(9). Yield 2.60 g (70%), mp 236–238°С (C2H5OH). IR
spectrum, ν, cm–1: 1620 (C=C), 1688 (CON), 1720 (CO),
4-Methyl-N-2-methylphenyl-6-(2-chlorophenyl)-
2-oxo-1,2,3,6-tetrahydropyrimidine-5-carboxamide
(5). Yield 2.27 g (64%), mp 226–228°С (C2H5OH). 1Н
NMR spectrum (DMSO-d6), δ, ppm: 1.84 s (3Н, 4-
1
3208, 3416, 3432 (NH). Н NMR spectrum (DMSO-
d6), δ, ppm: 2.19 s (3Н, 4-СН3), 3.64 s (3Н, СН3OC6H4),
5.60 d (1Н, СН, J1,6 = 1.8 Hz), 6.62–7.34 m (8H,
СН3OC6H4, ClC6H4), 7.78 d (1Н, 1-NH, J1,6 = 1.8 Hz),
7.85 br.s (1Н, 3-NH), 8.82 s (1Н, NH, amide). Found,
%: С 61.26, 61.50; Н 4.81, 4.98; N 11.17, 11.42.
C19H18ClN3O3. Calculated, %: С 61.38; Н 4.88; N 11.30.
СН3), 2.08 s (3Н, СН3C6H4), 5.70 d (1Н, СН, J1,6
=
1.8 Hz), 6.98–7.29 m (8H, СН3C6H4, ClC6H4), 7.37 d
(1Н, 1-NH, J1,6 = 1.8 Hz), 8.60 br.s (1Н, 3-NH), 8.87 s
(1Н, NH, amide). Found, %: С 64.03, 64.27; Н 5.02,
5.19; N 11.68, 11.93. C19H18ClN3O2. Calculated, %: С
64.14; Н 5.10; N 11.81.
4-Methyl-N-2-methoxyphenyl-6-(3-fluorophenyl)-
2-oxo-1,2,3,6-tetrahydropyrimidine-5-carboxamide
(10). Yield 2.63 g (74%), mp 196–198°С (C2H5OH).
4-Methyl-N-2-methylphenyl-6-(3-fluorophenyl)-
2-oxo-1,2,3,6-tetrahydropyrimidine-5-carboxamide
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 86 No. 11 2016

SYNTHESIS, STRUCTURE, AND ANTIMICROBIAL ACTIVITY
RC2008v077n12ABEH003894
2441
IR spectrum, ν, cm–1: 1608 (C=C), 1680 (CON), 1712
1
(CO), 3168, 3232, 3416 (NH). Н NMR spectrum
(DMSO-d6), δ, ppm: 2.15 s (3Н, 4-СН3), 3.67 s (3Н,
СН3OC6H4), 5.28 d (1Н, СН, J1,6 = 1.9 Hz), 6.84–7.74
6. Wan, J.-P. and Liu, Y., Synthesis, 2010, p. 3943. doi
10.1055/s-0030-1258290
7. Kappe, C.O., Multicomponent Reactions, 2005, p. 95.
doi 10.1002/3527605118.ch4
m (8H, СН3OC6H4, FC6H4), 7.70 d (1Н, 1-NH, J1,6
=
8. Marvaniya, H.M., Parikh, P.K., and Sen, D.J., J. Appl.
Pharm. Sci., 2011, vol. 1, no. 5, p. 109.
9. Kumar, B.R.P., Sankar, G., Baig, R.B.N., and
Chandrashekaran, S., Eur. J. Med. Chem., 2009, vol. 44,
p. 4192. doi 10.1016/j.ejmech.2009.05.014
1.9 Hz), 8.32 br.s (1Н, 3-NH), 8.76 s (1Н, NH, amide).
Found, %: С 64.11, 64.34; Н 5.02, 5.18; N 11.70,
11.95. C19H18FN3O3. Calculated, %: С 64.22; Н 5.11;
N 11.82.
4-Methyl-N-2-chlorophenyl-6-(4-methoxyphenyl)-
2-oxo-1,2,3,6-tetrahydropyrimidine-5-carboxamide
(11). Yield 2.49 g (67%), mp 213–215°С (C2H5OH).
IR spectrum, ν, cm–1: 1600 (C=C), 1688 (CON), 1704
(CO), 3168, 3250, 3400 (NH). Н NMR spectrum
(DMSO-d6), δ, ppm: 2.13 s (3Н, 4-СН3), 3.67 s (3Н,
СН3OC6H4), 5.24 d (1Н, СН, J1,6 = 1.8 Hz), 6.77–7.40
10. Yadlapalli, R.K., Chourasia, O.P., Vemuri, K.,
Sritharan, M., and Perali, R.S., Bioorg. Med. Chem.
Lett., 2012, vol. 22, p. 2708. doi 10.1016/
j.bmcl.2012.02.101
11. Zalavadiya, P.D., Ghetiya, R.M., Dodiya, B.L.,
Vekariya, P.B., and Joshi, H.S., J. Heterocycl. Chem.,
2013, vol. 50, p. 973. doi 10.1002/jhet.728
1
m (8H, СН3OC6H4, ClC6H4), 7.47 d (1Н, 1-NH, J1,6
=
12. Gein, V.L., Fedotov, A.Y., Zamaraeva, T.M., Bobyle-
va, A.A., Kasimova, N.N., and Odegova, T.F., Pharm.
Chem. J., 2013, vol. 46, no. 12, p. 720. doi 10.1007/
s11094-013-0877-6
1.8 Hz), 8.67 br.s (1Н, 3-NH), 8.77 s (1Н, NH, amide).
Found, %: С 61.27, 61.51; Н 4.80, 4.97; N 11.19,
11.43. C19H18ClN3O3. Calculated, %: С 61.38; Н 4.88;
N 11.30.
13. Zamaraeva, T.M., Odegova, T.F., Fedotov, A.Yu.,
Tomilov, M.V., Gein, V.L., and Slepukhin, P.A., Russ.
J. Gen. Chem., 2014, vol. 84, no. 10, p. 1950. doi
10.1134/S1070363214100168.
REFERENCES
14. Gein, V.L., Zamaraeva, T.M., Kurbatova, A.A., and
Vakhrin, M.I., Chem. Heterocycl. Compd., 2010,
vol. 46, no. 7, p. 856. doi 10.1007/s10593-010-0594-y
1. Sweet, F.S. and Fissekis, J.D., J. Am. Chem. Soc., 1973,
vol. 95, no. 26, p. 8741. doi 10.1021/ja00807a040
2. Kappe, C.O., J. Org. Chem., 1997, vol. 62, no. 21,
p. 7201. doi 10.1021/jo971010u
15. CrysAlisPro,
Agilent
Technologies,
Version
1.171.37.33 (release 27-03-2014 CrysAlis171 .NET).
3. Kappe, C.O., Heterocycles, 1997, vol. 45, no. 10,
p. 1967. doi 10.3987/COM-97-7931
16. Sheldrick, G.M., Acta Crystallogr. (C), 2015, vol. 71,
p. 3. doi 10.1107/S2053229614024218
4. Kappe, C.O., Eur. J. Med. Chem., 2000, vol. 35,
p. 1043. doi 10.1016/S0223-5234(00)01189-2
5. Vdovina, S.V. and Mamedov, V.A., Russ. Chem. Rev.,
17. Dolomanov, O.V., Bourhis, L.J., Gildea, R.J., Ho-
ward, J.A.K., and Puschmann, H., J. Appl. Crystallogr.,
2009, vol. 42, p. 339. doi 10.1107/S0021889808042726
2008,
vol.
77,
p.
1017.
doi
10.1070/
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