Synthesis and Electrochemical Properties of 2-(4-R1-Phenyl)-6-(4-R2-phenyl)-4-phenyl-3,4-dihydro1,2,4,5-tetrazin-1(2H)-yls

Article abstract of DOI:10.1134/S1070363220030044

Abstract: A new methodology for creating electroactive components for organic batteries,based on the construction of a molecular platform including stable3,4-dihydro-1,2,4,5-tetrazin-1(2H)-ylradicals was described. A series of2-(4-R¹-phenyl)-6-(4-R²-phenyl)-4-phenyl-3,4-dihydro-1,2,4,5-tetrazin-1(2H)-yls with substituents of various nature wasobtained. It was shown that the substituents R¹ inthe aromatic ring at position 2 of the tetrazinyl fragment influence the valueof the oxidation potential in the radical, but do not influence the value of thereduction potentials, while the substituent R² of thearomatic ring at position 6 influence the values of the reduction potentials andpractically do not influence oxidation potential values. Based on the obtainedelectrochemical data, a correlation structure–potential value was revealed forthe cathodic and anodic process, with the help of which triarylsubstituted3,4-dihydro-1,2,4,5-tetrazin-1(2H)-ylradicals with high values of the electrochemical gap were obtained.

Full text of DOI:10.1134/S1070363220030044

ISSN 1070-3632, Russian Journal of General Chemistry, 2020, Vol. 90, No. 3, pp. 341–351. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Zhurnal Obshchei Khimii, 2020, Vol. 90, No. 3, pp. 353–364.
Synthesis and Electrochemical Properties
of 2-(4-R1-Phenyl)-6-(4-R2-phenyl)-4-phenyl-3,4-dihydro-
1,2,4,5-tetrazin-1(2H)-yls
S. G. Kostryukova,*, A. V. Balandinaa, A. Sh. Kozlova, E. V. Kraynova, M. K. Pryanichnikovaa,
O. Yu. Chernyaevaa, A. A. Akhmatovaa, and Yu. I. Lukshinaa
a National Research Ogarev Mordovia State University, Saransk, 430005 Russia
*e-mail: kostryukov_sg@mail.ru
Received September 17, 2019; revised September 17, 2019; accepted September 20, 2019
Abstract—Anew methodology for creating electroactive components for organic batteries, based on the construc-
tion of a molecular platform including stable 3,4-dihydro-1,2,4,5-tetrazin-1(2H)-yl radicals was described.Aseries
of 2-(4-R1-phenyl)-6-(4-R2-phenyl)-4-phenyl-3,4-dihydro-1,2,4,5-tetrazin-1(2H)-yls with substituents of various
nature was obtained. It was shown that the substituents R1 in the aromatic ring at position 2 of the tetrazinyl frag-
ment influence the value of the oxidation potential in the radical, but do not influence the value of the reduction
potentials, while the substituent R2 of the aromatic ring at position 6 influence the values of the reduction potentials
and practically do not influence oxidation potential values. Based on the obtained electrochemical data, a correlation
structure–potential value was revealed for the cathodic and anodic process, with the help of which triarylsubstituted
3,4-dihydro-1,2,4,5-tetrazin-1(2H)-yl radicals with high values of the electrochemical gap were obtained.
Keywords: 3,4-dihydro-1,2,4,5-tetrazin-1(2H)-yl radicals, cyclic voltammetry, electron-donating substituent,
electron-withdrawing substituent, electrode potential, electrochemical gap
DOI: 10.1134/S1070363220030044
Tetrazinyl radicals (verdazyls), the preparation of
which has been first reported in 1964 [1], are related to
“electron amphoteric” [2], i.e., capable of both oxidizing
and reducing, thus forming stable cations and anions
(Scheme 1).
Currently, the main lines of research for verdazyl
radicals are the study of their magnetic properties [6–10]
and complexation ability [11–15]. At the same time, the
redox properties of radicals of this type were studied
much less. For example, the electrochemical behavior
of the triphenylverdazyl radical in DMF in the presence
of carboxylic acids has been studied in [16]. Authors
[17] have studied the redox properties of some verdazyl
radicals by cyclic voltammetry method. A correlation
between the distribution of electron spins and redox
properties was found. It was shown that the boundary
orbitals along which oxidation and reduction processes
Verdazyls are the only family of neutral radicals whose
stability competes with the stability of known nitroxyl
radicals [3]. Versatile properties of verdazyl radicals that
make them suitable for use in organic radical batteries
[4] are the lack of a tendency to dimerization, as well as
air and water resistance [5].
Scheme 1.
5
4
N
N
N
N
N
N
N
N
ꢀeꢀ
+eꢀ
+eꢀ
ꢀeꢀ
3
C
6
C
C
C
C
C
1
N
2
N
Nꢁ
ꢀ N
341

342
KOSTRYUKOV et al.
Scheme 2.
(1) CH2O, KHSO4,
5
5
N
4
N
4
N
DMFꢀH2O, 20ꢀ40oC
NH
(2) NaOH, O2, 20oC
3
6
R2
R2
3
N
N
N
N
1
2
2
1
R1
1aꢀ1q
R1
2aꢀ2q
R1 = R2 = H (a); R1 = H, R2 = Me (b); R1 = H, R2 = OMe (c); R1 = H, R2 = NMe (d); R1 = H, R2 = NO (e);
2
2
R1 = H, R2ꢀ ꢀꢀɋ1ꢀꢁf); R1 = Me, R2 = H (g); R1 = OMe, R2 = H (h); R1 = NMe , R2 = H (i); R1 = NO ,
2
2
R2 = H (j); R1 = CN, R2 = H (k); R1 = CN, R2ꢀ ꢀɆɟꢀꢁl); R1 = CN, R2ꢀ ꢀɈɆɟꢀꢁm); R1 = CN, R2 = NMe (n);
2
2
R1 = Me, R2 = CN (o); R1ꢀ ꢀɈ0Hꢂꢀ5 = CN (p); R1 = NMe , R2 = CN (q).
2
occur are localized in different parts of the molecule: the
largest contribution to the oxidation process is made by
the HOMO of the nitrogen atom in position 2, and the
largest contribution to the reduction process is made
by the LUMO of the carbon atom in position 6. The
symmetric all-organic non-aqueous redox flow battery
was studied using 3-phenyl-1,5-di-p-tolylverdazyl as a
charge storage material, which can be reversibly oxidized
and reduced through the one-electron processes [18].
The possibility of using verdazyl radicals as materials
for storing electricity has also been mentioned in the
review [19]. The synthesis of 6-oxo-verdazyl radical
polymers with tunable electrochemical properties has
been described in [20], which confirms the possibility
of their use for functional redox thin films production.
substituted triaryl-verdazyl radicals with high values
of the electrochemical gap were obtained. The cyclic
voltametry (CVA) method was used as an express method
for estimating the values of the electrochemical gap of
the obtained verdazyl radicals.
Triaryl-verdazyl radicals 1a–1q bearing various para-
substituted benzene fragments at positions 2 and 6 of the
3,4-dihydro-1,2,4,5-tetrazine ring were the objects of
our study. The radicals 1a–1q were obtained according
to the classical scheme starting from the corresponding
formazans 2a–2q (Scheme 2).
Compounds 2a–2q were synthesized by the reaction
of phenylhydrazones 3a–3f of substituted benzaldehydes
4a–4f with aryldiazonium salts 5a–5f derived from para-
substituted anilines 6a–6f. The target verdazyls 1a–1q
were produced by condensation of formazans 2a–2q with
formaldehyde in the presence of KHSO4 (Scheme 3).
However, in the case of substituted formazans 2b–2q,
cyclization is more difficult; therefore, the reactions were
carried out at 40°С. The intermediate leucobases were
oxidized with air to radicals 1a–1q. It should be noted
that in the presence of substituents, the last oxidation step
required a longer time.
The unique structure of tetrazinyl radicals allows one
to finely control the redox properties by varying the nature
of the substituents at the nitrogen (position 2) and carbon
atom (position 6) of the 3,4-dihydro-1,2,4,5-tetrazine
fragment. Herein, we reported the synthesis of verdazyl
radicals with substituents of various nature located at
the para positions of benzene rings. It was shown that
the substituents at position 6 of the 3,4-dihydro-1,2,4,5-
tetrazine fragment strongly influence the values of the
reduction potentials and practically do not influence the
values of the oxidation potential, while the substituents
at position 2 strongly influence the value of the oxidation
potential, but do not influence the value of the reduction
potentials. Based on the obtained electrochemical data,
a structure–potential correlation was revealed for the
cathodic and anodic process, with the help of which
This method of producing verdazyl radicals is widely
used, although with some restrictions. For example, in
the presence of strong electron-withdrawing substituents
in the aromatic ring of benzaldehyde, the yields of
formazans are usually low [17]. Using the synthesis of
1,5-diphenyl-3-arylverdazyls as an example, it has been
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SYNTHESIS AND ELECTROCHEMICAL PROPERTIES
343
Scheme 3.
Ph
NH
O
N
R1
PhNHNH2
1
N
N2
5
NH
4N
Ph
R2
4aꢀ4f
R2
DMF, Py
0ꢀ25oC
3aꢀ3f
3
NH2
+N2
Clꢀ
NaNO2
HCl
R2
R1
5aꢀ5f
R1
6aꢀ6f
2aꢀ2q
R1, R2 = H (a), Me (b), MeO (c), NMe (d), NO (e), CN (f).
2
2
shown that the yields of formazans increase when the
DMF–pyridine system is used as a solvent [21].
radicals 1a–1q were characterized using IR, UV, ESR
spectroscopy and mass spectrometry methods. In general,
all 2,6-diaryl-4-phenyl-3,4-dihydro-1,2,4,5-tetrazin-
1 (2H)-yls 1a–1q are finely crystalline substances of green
or brown color. In the IR spectra of these compounds
there is a vibration band in the region of ~1150–
1160 cm– 1 , which characterizes the verdazyl radicals. For
benzene solutions of radicals 1a–1q, typical time-stable
ESR spectra are recorded, containing 9 wide lines with
an intensity ratio of 1 : 4 : 10 : 16 : 19 : 16 : 10 : 4 : 1,
due to the interaction of an unpaired electron with four
Hydrazones 3a–3f were obtained in 60–90% yield by
condensation of aldehydes 4a–4f with phenylhydrazine
according to the known methods; their physico-chemical
constants correspond to the literature data.
Structure of formazans 2a–2q was confirmed by IR,
1Н, 13С NMR spectroscopy, and mass spectrometry data.
Thus, in the IR spectra there are absorption characteristic
bands of the C=N (1600–1590 cm–1), N–H (3400–
3300 cm–1) and N=N (1500–1480 cm–1) bonds. Verdazyl
Table 1. Electrochemical characteristics of 2-(4-R1-phenyl)-6-(4-R2-phenyl)-4-phenyl-3,4-dihydro-1,2,4,5-tetrazin-1(2Н)-yls
1a–1q
Comp.
no.
Comp.
no.
R1
R2
Eox, V
Ered, V Egap, V
R1
R2
Eox, V
Ered, V
Egap, V
1a
1b
1c
1d
1e
1f
1j
1k
1l
H
H
H
Me
OMe
NMe2
NO2
CN
H
0.31
0.24
0.20
0.16
0.41
0.38
0.29
0.26
0.24
–0.81
–0.81
–0.85
–0.86
–0.65
–0.67
–0.82
–0.87
–0.88
1.12
1.01
1.05
1.02
1.06
1.05
1.11
1.13
1.12
NO2
CN
H
H
0.32
0.34
0.23
0.20
0.17
0.33
0.36
0.38
–0.64
–0.65
–0.70
–0.67
–0.67
–0.86
–0.87
–0.88
0.96
0.99
0.93
0.87
0.84
1.19
1.23
1.24
H
CN
Me
1m
1n
1o
1p
1q
H
CN
OMe
NMe2
CN
H
CN
H
Me
1g
1h
1i
Me
OMe
NMe2
OMe
NMe2
CN
H
CN
H
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KOSTRYUKOV et al.
5.6 Hz
Magnetic field, Gs
ȿ, eV
Fig. 1. ESR spectrum of verdazyl 1e.
Fig. 2. Cyclic voltammograms of compounds 1a, 1l and 1q.
spectrally equivalent nitrogen atoms of tetrazine ring.
Figure 1 shows the ESR spectrum of verdazyl 1d.
The substituent at position 6 of the aromatic ring has
a stronger effect on the reduction process and much less
on the oxidation process. Thus, the oxidation potential
(Eox) is slightly shifted to the cathode region in the case
of compounds with electron-withdrawing groups 1i (NO2)
and 1k (CN), and in the case of compounds with donor
substituents (Me, OMe, NMe2) to the anode region. At
the same time, a rather strong effect on the reduction
potential (Ered) is observed. Thus, electron-withdrawing
nitro and cyano groups shift the Ered value to the cathode
region by 0.17 V for compounds 1k (NO2) and 1k (CN)
as compared to verdazyl 1a. Donor substituents slightly
influence the reduction potential, shifting the Ered value
to the anode region: by 0.02 (1g, Me), 0.05 (1h, OMe)
and 0.07 V (1i, NMe2) in comparison to verdazyl 1a.
The electrochemical properties of radicals 1a–1q were
studied by cyclic voltammetry method in an acetonitrile
solution using Bu4NBF4 as supporting electrolyte. A
glassy carbon electrode was used as the working electrode,
platinum was the counter electrode, and the standard silver
chloride electrode was used as the reference electrode.
Almost all radicals, with the exception of the nitro
derivative 1d, exhibit completely reversible oxidation
and reduction processes. The oxidation potentials of
verdazyls 1a–1q are in the range from 0.17 to 0.41 V
(Ag/AgCl/KCl). The reduction of these radicals occurs
at negative potentials from –0.64 to –0.88 V (Ag/AgCl/
KCl). Table 1 shows the electrochemical characteristics
of compounds 1a–1q.
In general, for verdazyl radicals 1b–1k, the magnitude
of the electrochemical gap (Egap = |Еox – Еred|) does not
change much in comparison to radical 1a.
As can be seen from the obtained data, the nature of
the substituent in the para-position of 2-aryl fragment
has a stronger effect on the oxidation process and much
less on the reduction process. Thus, donor substituents
facilitate the oxidation process by shifting Eox value to the
cathode region [by 0.07 V for verdazyl 1b (Me), 0.11 V
for 1c (OMe), 0.15 V 1d (NMe2) in comparison to radical
1a]. The methyl radical does not influence the reduction
process; methoxy and dimethylamino groups slightly
shift Ered value to the anode region by 0.04 and 0.05 V,
respectively, in comparison with verdazyl 1a. Electron-
withdrawing substituents facilitate the reduction process
by shifting Ered value to the cathode region [by 0.16 V
for verdazyl 1e (NO2) and 0.14 V for verdazyl 1f (CN)
in comparison to radical 1a].
With the simultaneous presence of donor (at position
2) and acceptor (at position 6) substituents (verdazyl
radicals 1o–1q), a more significant increase in the value
of the electrochemical gap is observed. This is due to the
fact that the electron-donating groups in position 2 shift
the Eox value to the cathode region, and the electron-
withdrawing CN group in position 6 shifts the Eox value
to the anode region, thereby increasing the difference
between the peak values of oxidation and reduction
potentials.
With the reverse distribution of substituents (verdazyl
1l–1n), a narrowing of the electrochemical gap is
observed, since the acceptor nitrile group at position 6
shifts the Eox value to the anode region, and the donor
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SYNTHESIS AND ELECTROCHEMICAL PROPERTIES
345
groups shift the Eox value to the cathode region, thereby
reducing the difference between the peak values of
oxidation and reduction potentials.
phenylhydrazine hydrochloride and 2.46 g of anhydrous
sodium acetate in 70 mL of water a solution of 0.02 mol
of aldehyde 4a–4f in 25 mL of dioxane was added
with stirring in small portions. Upon completion of
the addition, the reaction mixture was stirred at room
temperature for ~20–60 min. The precipitate was filtered
off and washed on the filter with water, then dried in air.
The desired products were purified by recrystallization.
Melting points and spectral characteristics coincided with
published data.
Figure 2 shows the CV curves of some verdazyl
radicals that best demonstrate the changes in the
electrochemical behavior of compounds 1a, 1n, and 1q
due to the substituents effect.
The magnitude of the electrochemical gap influences
the capacity of a battery based on neutral radicals [22];
therefore, the use of radicals in organic batteries having
a significant difference between the electrochemical
potentials of oxidation and reduction can significantly
increase the capacity of an energy storage device.
1-Benzylidene-2-phenylhydrazone (3a). Yield
4.19 g (72.6%), mp 155–156°C (ethanol).
1-(4-Methylbenzylidene)-2-phenylhydrazone (3b).
Yield 4.35 g (68.9%), mp 113–114°C (ethanol).
EXPERIMENTAL
1-(4-Methoxybenzylidene)-2-phenylhydrazone
(3c). Yield 4.42 g (65.2%), mp 119–120°C (ethanol).
The solvents were dried and distilled before use. All
reagents (Sigma Aldrich, Merck) were used without
further purification.
1-(4-Dimethylaminobenzylidene)-2-phenyl-
hydrazone (3d). Yield 3.90 g (54.3%), mp 147–148°C
(ethanol).
1Н and С NMR spectra were recorded on a JNM-
13
ECX400 Jeol spectrometer (400.1 and 100.6 MHz,
respectively) from CDCl3 solutions. IR spectra were
registered from KBr pellets on an InfraLUM FT-02
Fourier spectrometer. Elemental analysis was performed
on a Vario MICRO CHNS analyzer. Analytical TLC
conditions: Silufol UV-245, eluents—benzene, methylene
chloride–ethyl acetate (2 : 1), display by iodine. For
column chromatography, silica gel L40/100μ was
used; the eluent was benzene. The melting points were
determined in sealed glass capillaries using an MP-50
melting point analyzer (Mettler Toledo, Switzerland).
Mass spectra (EI, 70 eV) were registered on a KONIK
RBK-HRGC 5000B-MSQ12 spectrometer (Spain) in the
positive ionization mode. Visible electron spectra were
recorded on a Shimadzu UV-2600 spectrophotometer.
ESR spectra were recorded using an ESP 70–03XD/2
ESR spectrometer. Electrochemical data were taken
by cyclic voltametry in an acetonitrile solution (0.1 M
n-Bu4NBF4) using a Gamry potentiostat (Canada) in a
5 mL electrochemical cell. A glassy carbon electrode,
S2 = 0.125 cm2, was used as the working electrode. The
electrode was carefully polished and washed before
measurements. The counter electrode was platinum,
the reference electrode was the standard silver chloride
electrode (E0 = 0.33 V in CH3CN vs Fc/Fc+).All solutions
were completely deaerated by purging with argon through
them.
1-(4-Nitrobenzylidene)-2-phenylhydrazone (3e).
Yield 5.43 g (75.1%), mp 158–159°C (ethanol).
1-(4-Cyanobenzylidene)-2-phenylhydrazone (3f).
Yield 4.72 g (71.2%), mp 177–178°C (ethanol).
General procedure for the synthesis of formazans
2a–2q. A solution of 0.01 mol of phenylhydrazone
3a–3f in a mixture of 5 mL of pyridine and 10 mL of
DMF was cooled to –10–5°С. Aryldiazonium salt 5a–5f
was prepared separately: to 0.011 mol of aniline 6a–6f
a solution of 0.011 mol of NaNO2 in 3 mL of H2O was
added, then 3.5 mL of concentrated hydrochloric acid
was added, maintaining the temperature in the range of
0–5°С. The resulting suspension of the corresponding
arenediazonium salt 5a–5f was added in small portions
to the solution of phenylhydrazone 3a–3f, preventing
the temperature from rising above 5°С. In this case, the
reaction mixture acquired dark cherry color. The reaction
mixture was kept for 3 h at a temperature of ~ 5°C and
then for 12 h at room temperature, then diluted with
20 mL of water. Formazan was extracted with CH2Cl2
(3×20 mL). The combined organic extracts were washed
with water (3×10 mL), then passed through a layer of
neutral Al2O3 and the solvent was removed in vacuum.
The resulting product was triturated with methanol.
1,3,5-Triphenylformazan (2a). Yield 1.97 g (65.6%),
mp 148–150°C (methanol). IR spectrum, ν, cm–1: 752.3 m,
1018.3 s, 1234.5 s, 1493.1 s (N=N), 1511.9 s (N=N),
General procedure for the synthesis of phenyl-
hydrazones 3a–3f. To a solution of 4.34 g (0.03 mol) of
1
1597.2 s (C=N), 3353.2 w (N–H). Н NMR spectrum,
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KOSTRYUKOV et al.
δ, ppm: 7.60–7.25 m (9H), 7.73 d. d (4H, J = 8.0,
1.2 Hz), 8.15 d. t (2H, J= 8.0, 1.4 Hz), 15.38 s (1H, NH).
13C NMR spectrum, δС, ppm: 119.3, 122.7, 126.4, 128.1,
128.4, 129.0, 129.5, 129.6, 130.0, 130.4, 138.0, 141.7,
148.5. UV spectrum (CH2Cl2), λmax, nm (ε, M cm–1): 270
(17250), 300 (22000), 488 (14250). Mass spectrum, m/z
(Irel, %): 300 (30) [M]+, 285 (25), 272 (33), 246 (34), 194
(100), 167 (40), 103 (40), 63 (50). Found, %: C 76.16;
H 5.54; N 18.36. C19H16N4. Calculated, %: С 75.98; Н
5.37; N 18.65.
7.58–7.68 m (4H), 7.65 t. t (1Н, J = 7.7, 1.4 Hz), 15.45 s
(1Н NH). 13C NMR spectrum, δC, ppm: 40.31 [(СH3)2N],
113.8, 114.5, 122.2, 124.7, 126.2, 129.2, 129.2, 131.7,
145.4, 151.4, 153.1, 155.1. UV spectrum (CH2Cl2), λmax
,
nm (ε, M cm–1): 276 (20200), 405 (17000), 530 (21500).
Mass spectrum, m/z (Irel, %): 343 (10) [M]+, 327 (20),
251 (35), 239 (55), 93 (100). Found, %: С 73.52; Н 6.20;
N 20.51. C21H21N5. Calculated, %: С 73.44; Н 6.16; N
20.39.
3-(4-Nitrophenyl)-1,5-diphenylformazan (2e). Yield
1.52 g (44.0%), mp 207–209°С (methanol). IR spectrum,
ν, cm–1: 740.3 m, 1242.5 s, 1350.7 (NO2), 1493.1 s (N=N),
1527.1 (NO2), 1561.9 s (N=N), 1597.2 s (C=N), 3353.2 w
(N–H). 1H NMR spectrum, δ, ppm: 7.58–7.27 m (10H),
7.77 d (2Н, J = 8.0 Hz), 8.41 d (2Н, J = 9.0 Hz), 15.80 s
(1H). 13C NMR spectrum, δС, ppm: 113.6, 120.6, 122.8,
124.6, 127.5, 128.4, 129.8, 140.7, 144.4, 148.5, 152.3,
154.9. UV spectrum (CH2Cl2), λmax, nm (ε, M cm–1): 266
(20200), 419 (17000), 490 (20900). Mass spectrum, m/z
(Irel, %): 345 (56) [M]+, 328 (46), 299 (66), 241 (100), 105
(62). Found, %: С 65.96; Н 4.41; N 20.21. C19H15N5O2.
Calculated, %: С 66.08; Н 4.38; N 20.28.
3-(p-Tolyl)-1,5-diphenylformazan (2b). Yield 1.51 g
(48.3%), mp 156–157°C (methanol). IR spectrum, ν, cm–1:
812.3 m, 1015.3 s, 1226.5 s, 1493.1 s (N=N), 1509.4 s
1
(N=N), 1598.2 s (C=N), 3353.2 w (N–H). H NMR
spectrum, δ, ppm: 2.22 s (3Н, CH3), 7.20–7.30 m (4H),
7.34 t. t (1Н, J = 7.6, 1.2 Hz), 7.42 d. d. d (2Н, J = 8.1,
7.6, 1.5 Hz), 7.51–7.68 m (5H), 7.62 d. d (2Н, J = 8.0,
1.7 Hz), 15.36 s (1Н NH). 13C NMR spectrum, δС, ppm:
21.3, 114.5, 122.2, 124.7, 125.5, 129.2, 129.4, 131.7,
139.7, 145.4, 153.1, 154. 5. UV spectrum (CH2Cl2), λmax
,
nm (ε, M cm–1): 279 (18600), 306 (25500), 498 (17000).
Mass spectrum, m/z (Irel, %): 314 (14) [M]+, 299 (25), 286
(23), 222 (49), 209 (100), 63 (50). Found, %: С 76.36;
Н 5.74; N 17.96. C20H18N4. Calculated, %: С 76.41; Н
5.77; N 17.82.
3-(4-Cyanophenyl)-1,5-diphenylformazan (2f).
Yield 1.30 g (41.0%), mp 177–178°С (methanol). IR
spectrum, ν, cm–1: 741.3 m, 1243.5 s, 1473.1 s (N=N),
1512.4 s (N=N), 1598.2 s (C=N), 2255.1 (CN), 3359.2 w
(N–H). 1H NMR spectrum, δ, ppm: 7.58–7.27 m (10H),
7.65 d (2Н, J = 8.0 Hz), 8.37 d (2Н, J = 9.0 Hz), 15.78 s
(1Н, NH). 13C NMR spectrum, δС, ppm: 113.1, 118.6
(CN), 119.6, 120.8, 121.6, 123.4, 126.5, 127.8, 139.7,
3-(4-Methoxyphenyl)-1,5-diphenylformazan (2c).
Yield 1.48 g (45.0%), mp 172–173°С (methanol). IR
spectrum, ν, cm–1: 1172.3 s, 1226.0 s, 1250.2, 1358.7,
1487.1 s (N=N), 1512.4 s (N=N), 1597.3 s (C=N),
3354.2 w (N–H). 1H NMR spectrum, δ, ppm: 3.85 s (3Н,
CH3O), 7.58–7.27 m (6H), 7.76 d (4Н, J= 8.0 Hz), 8.02 d
(2Н, J = 9.0 Hz), 8.31 d (2Н, J = 9.0 Hz), 15.45 s (1Н
141.4, 145.5, 148.3, 150.9. UV spectrum (CH2Cl2), λmax
,
nm (ε, M cm–1): 272 (30200), 338 (27000), 488 (21000).
Mass spectrum, m/z (Irel, %): 325 (28) [M]+, 297 (31), 271
(22), 219 (100), 192 (40), 105 (40). Found, %: С 73.96;
Н 4.61; N 21.41. C20H15N5. Calculated, %: С 73.83; Н
4.65; N 21.52.
13
NH). C NMR spectrum, δС, ppm: 55.8, 113.6, 120.4,
123.1, 124.8, 127.0, 128.3, 129.2, 129.9, 131.8, 145.4,
148.2, 154.1, 160.3. UV spectrum (CH2Cl2), λmax, nm (ε,
M cm–1): 279 (20700), 308 (27400), 522 (15900). Mass
spectrum, m/z (Irel, %): 330 (10) [M]+, 315 (37), 238 (40),
226 (58), 224 (55), 93 (100), 65 (30). Found, %: С 72.36;
Н 5.51; N 17.01. C20H18N4O. Calculated, %: С 72.71;
Н 5.49; N 16.96.
1-(p-Tolyl)-3,5-diphenylformazan (2g). Yield 1.69 g
(54.1%), mp 153–154°C (methanol). IR spectrum, ν,
cm–1:815.3m, 1017.3s, 1228.5s, 1494.1s(N=N), 1510.4s
1
(N=N), 1599.2 s (C=N), 3352.2 w (N–H). H NMR
3-[4-(Dimethylamino)phenyl]-1,5-diphenyl-
formazan (2d). Yield 1.48 g (43.0%), mp 207–209°С
(methanol). IR spectrum, ν, cm–1: 739.4 s, 1172.3 s,
1226.0 s, 1250.2, 1358.7, 1487.1 s (N=N), 1512.4 s
(N=N), 1597.3 s (C=N), 2987.5 m, 3354.2 w (N–H). 1H
NMR spectrum, δ, ppm: 2.81 s [6Н, (СH3)2N], 6.60 d. d
(2Н, J = 8.2, 1.1 Hz), 7.26 d. t (2Н, J = 8.1, 1.2 Hz),
7.31–7.46 m (3H), 7.54 d. d. d (2Н, J = 8.1, 1.4, 1.3 Hz),
spectrum, δ, ppm: 2.15 s (3Н, CH3), 7.11 d. d (2Н, J =
8.0, 1.6 Hz), 7.22–7.30 m (3H), 7.34 t. t (1H, J = 7.6,
1.2 Hz), 7.43–7.57 m (4H), 7.63 d. d (2H, J = 8.1,
1.5 Hz), 8.26 d. t (2H, J = 8.5, 1.4 Hz), 15.33 s (1H). 13C
NMR spectrum, δС, ppm: 21.2 (СН3), 114.5, 122.3, 124.7,
125.4, 128.9, 129.2, 131.7, 132.4, 145.4, 149.5, 154.1. UV
spectrum (CH2Cl2), λmax, nm (ε, M cm–1): 275 (16600),
310 (26700), 496 (16800). Mass spectrum, m/z (Irel, %):
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314 (7), 286 (24), 207 (30), 195 (55), 105 (100). Found,
%: С 76.25; H 5.84; N 17.91. C20H18N4. Calculated, %:
С 76.41; H 5.77; N 17.82.
1-(4-Cyanophenyl)-3,5-diphenylformazan (2k).
Yield 1.79 g (55.0%), mp 173–175°С (methanol). IR
spectrum, ν, cm–1: 741.3 m, 1243.9 s, 1473.1 s (N=N),
1511.9 s (N=N), 1597.2 s (C=N), 2253.1 (CN), 3359.2 w.
1H NMR spectrum, δ, ppm: 7.65–7.30 m (10H), 8.09 d. d
(2H, J= 8.0, 1.5 Hz), 8.27 d. d (2H, J= 9.0, 1.5 Hz), 15.40 s
(1H, NH). 13C NMR spectrum, δС, ppm: 106.3, 113.9,
118.4 (CN), 123.0, 124.1, 125.4, 127.3, 128.5, 129.1,
131.9, 136.2, 146.2, 150.3, 155.1. UV spectrum (CH2Cl2),
λmax, nm (ε, M cm–1): 273 (33400), 340 (26000), 489
(21500). Mass spectrum, m/z (Irel, %): 325 (22) [M]+, 310
(30), 297 (43), 271 (30), 220 (61), 194 (100), 167 (40),
130 (50). Found, %: С 73.91; H 4.68; N 21.47. C20H15N5.
Calculated, %: С 73.83; H 4.65; N 21.52.
1-(4-Methoxyphenyl)-3,5-diphenylformazan (2h).
Yield 1.33 g (40.1%), mp 119–120°С (methanol). IR
spectrum, ν, cm–1: 1176.3 s, 1229.0 s, 1255.2, 1348.7,
1485.9 s (N=N), 1511.4 s (N=N), 1598.4 s (C=N),
3355.1 w (N–H). 1H NMR spectrum, δ, ppm: 3.82 s (3Н,
СН3О), 7.60–7.15 m (10H), 7.92 d (2H, J= 9.0 Hz), 8.15 d
(2H, J = 8.0 Hz), 15.40 s (1H, NH). 13C NMR spectrum,
δС, ppm: 55.7 (СН3О), 113.6, 115.1, 122.1, 125.0, 128.0,
128.8, 129.6, 131.8, 135.4, 140.4, 144.2, 153.1, 160.6. UV
spectrum (CH2Cl2), λmax, nm (ε, M m–1): 280 (20200),
310 (25100), 520 (14700). Mass spectrum, m/z (Irel, %):
330 (10) [M]+, 303 (25), 276 (20), 195 (55), 122 (100),
104 (51), 93 (70). Found, %: С 72.36; H 5.51; N 17.01.
C20H18N4O. Calculated, %: С 72.71; H 5.49; N 16.96.
1-(4-Cyanophenyl)-3-(p-tolyl)-5-phenylformazan
(2l). Yield 1.46 g (43.0%), mp 152–153°С (methanol).
IR spectrum, ν, cm–1: 743.5 m, 1244.5 s, 1463.8 s (N=N),
1510.4 s (N=N), 1599.0 s (C=N), 2235.1 (CN), 2967.5,
3359.2 w (NH). 1H NMR spectrum, δ, ppm: 2.22 s (3H,
CH3), 7.24 d. d (2H, J = 7.9, 1.2 Hz), 7.30–7.45 m (3H),
7.59–7.69 m (6H), 8.20 d. d (2H, J= 8.3, 1.6 Hz), 15.66 s
(1H, NH). 13C NMR spectrum, δС, ppm: 21.3 (CH3),
106.3, 114.5, 118.5 (CN), 123.1, 124.7, 125.5, 129.2,
129.3, 131.7, 133.4, 139.7, 145.4, 150.5, 155.05. UV
spectrum (CH2Cl2), λmax, nm (ε, M cm–1): 276 (14300),
428 (12500), 498 (16800). Mass spectrum, m/z (Irel, %):
325 (24), 297 (43), 220 (63), 194 (100), 130 (50), 91
(67). Found, %: С 74.43; H 5.07; N 20.57. C21H17N5.
Calculated, %: С 74.32; H 5.05; N 20.63.
1-(4-Dimethylaminophenyl)-3,5-diphenylformazan
(2i). Yield 1.51 g (44.0%), mp 147–149°С (methanol).
IR spectrum, ν, cm–1: 740.4 s, 1171.5 s, 1225.8 s, 1251.6,
1359.2, 1481.7 s (N=N), 1509.4 s (N=N), 1596.9 s (C=N),
2986.5 cр, 3355.2 w (N–H). 1H NMR spectrum, δ, ppm:
2.90 s [6H, (CH3)2N], 7.05 d. d (2H, J = 8.2, 2.0 Hz),
7.19–7.29 m (3H), 7.34 t. t (1H, J = 7.6, 1.2 Hz), 7.42
d. d (2H, J = 8.2, 1.5 Hz), 7.52 d. d . d (2H, J = 8.5, 7.6,
1.3 Hz), 7.63 d. d . d (2H, J = 8.1, 7.6, 1.5 Hz), 8.25 d. t
(2H, J = 8.5, 1.4 Hz), 15.40 s (1H, NH). 13C NMR
spectrum, δС, ppm: 40.4 [(CH3)2N], 111.6, 114.5, 124.7,
125.4, 125.5, 128.9, 127.7, 129.2, 131.7, 145.4, 150.5,
153.0, 155.1. UV spectrum (CH2Cl2), λmax, nm (ε,
M cm–1): 278 (17900), 420 (20400), 520 (19800). Mass
spectrum, m/z (Irel, %): 343 (9), 328 (59), 315 (37), 195
(94), 135 (100). Found, %: С 73.48; H 6.20; N 20.31.
C21H21N5. Calculated, %: С 73.44; H 6.16; N 20.39.
1-(4-Cyanophenyl)-3-(4-methoxyphenyl)-5-phenyl-
formazan (2m). Yield 1.53 g (43.1%), mp 142–144°С
(methanol). IR spectrum, ν, cm–1: 742.3 m, 1223.5 s,
1244.5 cр, 1470.1 s (N=N), 1510.4 s (N=N), 1598.2 s
1
(C=N), 2255.1 (CN), 2996.1 m, 3359.2 w (N–H). H
NMR spectrum, δ, ppm: 3.80 s (3H, CH3O). 7.05 d. d
(2H, J = 8.5, 1.2 Hz), 7.30–7.45 m (3H), 7.56 d. d (2H,
J=8.3, 1.8 Hz), 7.59–7.69 m (4H), 8.20 d. d (2H, J= 8.5,
1.6 Hz), 14.66 s (1H, NH). 13C NMR spectrum, δС, ppm:
55.5 (CH3O), 106.4, 114.0, 114.8, 118.6 (СN), 123.1,
124.7, 127.0, 129.3, 131.2, 133.5, 145.3, 150.4, 155.1,
160.2. UV spectrum (CH2Cl2), λmax, nm (ε, Mcm–1): 272
(12900), 420 (10500), 492 (15800). Mass spectrum, m/z
(Irel, %): 355 (12) [M]+, 340 (38), 327 (35), 250 (45), 238
(37), 226 (68), 118 (90), 93 (100). Found, %: С 70.88;
H 4.89; N 19.65. C21H17N5O. Calculated, %: С 70.97;
H 4.82; N 19.71.
1-(4-Nitrophenyl)-3,5-diphenylformazan (2j). Yield
1.86 g (54.0%), mp 197–198°С (methanol). IR spectrum,
ν, cm–1: 739.9 m, 1241.5 s, 1352.7 (NO2), 1492.1 s (N=N),
1526.7 (NO2), 1562.1 s (N=N), 1598.7 s (C=N), 3358.2 w
(N–H). 1H NMR spectrum, δ, ppm: 7.58–7.27 m (10H),
7.79 d (2H, J = 8.0 Hz), 8.33 d (2H, J = 9.0 Hz), 15.40 s
(1H, NH). 13C NMR spectrum, δС, ppm: 113.9. 122.4,
123.6, 124.7, 126.8, 127.9, 128.8, 130.1, 135.7, 144.2,
148.2, 153.3, 155.8. UV spectrum (CH2Cl2), λmax, nm
(ε, M cm–1): 266 ( 20800), 424 ( 17100), 490 ( 20200).
Mass spectrum, m/z (Irel, %): 345 (10) [M]+, 317 (12), 299
(14), 224 (19), 195 (100), 123 (12). Found, %: С 65.96;
H 4.41; N 20.21. C19H15N5O2. Calculated, %: С 66.08;
H 4.38; N 20.28.
1-(4-Cyanophenyl)-3-(4-dimethylaminophenyl)-
5-phenylformazan (2n). Yield 1.80 g (49.0%), mp
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KOSTRYUKOV et al.
151–152°С (methanol). IR spectrum, ν, cm–1: 741.2 m,
1220.1 s, 1240.8 cр, 1469.2 s (N=N), 1508.4 s (N=N),
1596.9 s (C=N), 2254.1 (CN), 2995.8 s, 3355.2 w (N–H).
1H NMR spectrum, δ, ppm: 2.82 s [6H, (CH3)2N],
6.61 d. d (2H, J = 8.2, 1.1 Hz), 7.35 t. t (1H, J = 7.6,
1.3 Hz), 7.42 d. t (2H, J= 8.0, 1.3 Hz), 7.59–7.70 m (6H),
8.19 d. d (2H, J=8.3, 1.6 Hz), 14.66 s (1H, NH). 13C NMR
spectrum, δС, ppm: 40.3 [(CH3)2N], 106.4, 113.8, 114.5,
118.6 (СN), 123.0, 124.7, 126.2, 129.2, 131.7, 133.4,
(71). Found, %: С 70.88; H, 4.89; N 19.65. C21H17N5O.
Calculated, %: С 70.97; H 4.82; N 19.71.
1-(4-Dimethylaminophenyl)-3-(4-cyanophenyl)-
5-phenylformazan (2q). Yield 1.18 (32.1%), mp
144–145°С (methanol). IR spectrum, ν, cm–1: 745.2 m,
1224.1 s, 1242.1 cр, 1470.1 s (N=N), 1510.2 s (N=N),
1598.1 s (C=N), 2255.3 (CN), 2996.1 s, 3353.8 w (N–H).
1H NMR spectrum, δ, ppm: 2.90 s [6H, (CH3)2N],
7.05 d. d (2H, J = 8.2, 1.5 Hz), 7.30–7.47 m (5H),
7.64 d. d. d (2H, J = 8.1, 7.6, 1.4 Hz), 7.84 d. d (2H, J =
8.6, 1.7 Hz), 8.00 d. d (2H, J = 8.6, 1.7 Hz), 14.87 s (1H,
NH). 13C NMR spectrum, δС, ppm: 40.7 [(CH3)2N), 111.6,
112.2, 114.5, 118.5 (СN), 124.7, 125.5, 127.1, 129.2,
131.7, 132.3, 145.4, 150.5, 153.3, 159.5. UV spectrum
(CH2Cl2), λmax, nm (ε, M cm–1): 280 ( 15900), 440
(14500), 510 ( 19800). Mass spectrum, m/z (Irel, %): 368
(8) [M]+, 353 (23), 340 (33), 234 (52), 220 (75), 134 (100),
93 (76). Found, %: С 71.69; H 5.44; N 22.79. C22H20N6.
Calculated, %: С 71.72; H 5.47; N 22.81.
145.4, 150.5, 151.4, 155.1. UV spectrum (CH2Cl2), λmax
,
nm (ε, M cm–1): 277 (14700), 436 (14500), 505 (20800).
Mass spectrum, m/z (Irel, %): 368 (11) [M]+, 353 (65), 340
(39), 261 (65), 238 (60), 118 (90), 93 (100). Found, %:
С 71.78; H 5.49; N 22.75. C22H20N6. Calculated, %: С
71.72; H 5.47; N 22.81.
1-(p-Tolyl)-3-(4-cyanophenyl)-5-phenylformazan
(2o). Yield 1.46 g (43.0%), mp 152–153°С (methanol).
IR spectrum, ν, cm–1: 747.5 m, 1249.5 s, 1468.1 s (N=N),
1515.1 s (N=N), 1598.8 s (C=N), 2237.0 (CN), 2969.5,
3358.2 w (NH). 1H NMR spectrum, δ, ppm: 2.15 s (3H,
CH3), 7.12 d. d (2H, J = 8.0, 1.6, 0.5 Hz), 7.35 t. t (1H,
J = 7.6, 1.3 Hz), 7.39–7.51 m (4H), 7.64 d. d. d (2H,
J = 8.1, 7.6, 1.5 Hz), 7.87 d. d (2H, J = 8.6, 1.5 Hz),
8.01 d. d (2H, J = 8.3, 1.6 Hz), 15.60 s (1H, NH). 13C
NMR spectrum, δС, ppm: 21.2 (CH3), 112.2, 114.5, 118.4
(CN), 122.2, 124.7, 127.1, 128.9, 129.2, 131.7, 132.0,
General procedure for synthesis of verdazyls
1a–1q. A mixture of 0.001 mol of formazan 2a–2q,
50 mL of DMF, 1.36 g (0.01 mol) of KHSO4, and 1.5 g
of paraform was stirred for 24 h at room temperature,
then the reaction mixture was filtered. Under stirring,
12 mL of a 37% formalin solution and 10 mL of 2 N
NaOH solution were successively added dropwise to the
filtrate with stirring. Stirring was continued, depending
on the starting formazan, from 0.5 h to 24 h with constant
air purging, after which the reaction mixture was diluted
with 100 mL of water. The product was extracted with
C6H6 (3×50 mL). The combined organic extracts were
washed with water (3 × 50 mL), then dried with anhydrous
MgSO4 and filtered through a pad of silica gel. The
solvent was removed in vacuum. The resulting product
was crystallized from methanol.
132.4, 145.4, 150.5, 155.0. UV spectrum (CH2Cl2), λmax
,
nm (ε, M cm–1): 275 (15300), 426 (13500), 496 (15900).
Mass spectrum, m/z (Irel, %): 325 (24), 297 (43), 220
(63), 194 (100), 130 (50), 91 (67). Found, %: С 74.39;
H 5.01; N 20.59. C21H17N5. Calculated, %: С 74.32; H
5.05; N 20.63.
1-(4-Methoxyphenyl)-3-(4-cyanophenyl)-5-phenyl-
formazan (2р). Yield 1.10 g (31.0%), mp 135–137°С
(methanol). IR spectrum, ν, cm–1: 742.0 m, 1222.9 s,
1243.8 cр, 1468.1 s (N=N), 1509.5 s (N=N), 1597.8 s
2,4,6-Triphenyl-3,4-dihydro-1,2,4,5-tetrazin-
1(2H)-yl (1a). The duration of oxidation by air is 0.5 h.
Yield 0.173 g (55.2%), mp 139–140°С (methanol). IR
spectrum, ν, cm–1: 752.5 s, 1145.6 m, 1207.3 m, 1265.1 m,
1323.0 m, 1488.9 s, 1585.3 s. UV spectrum (CH2Cl2),
1
(C=N), 2250.9 (CN), 2996.1 m, 3359.2 w (N–H). H
NMR spectrum, δ, ppm: 3.82 s (3H, CH3O), 6.99 d. d (2H,
J = 8.3, 2.4 Hz), 7.35 т. т (1H, J = 7.6, 1.3 Hz), 7.42 d. t
(2H, J= 8.1, 1.3 Hz), 7.59–7.69 m (4H), 7.85 d. d (2H, J=
8.6, 1.7 Hz), 8.00 d. d (2H, J = 8.6, 1.7 Hz), 14.65 s (1H,
λ
max, nm (ε, M cm–1): 273 (62300), 405 (7500), 716
(3600). Mass spectrum, m/z (Irel %): 313 [M]+ (32), 299
(15), 286 (16), 209 (60), 104 (100). Found %: С 76.92;
H, 5.51; N 17.74. C20H17N4. Calculated, %: С 76.65; H,
5.47; N 17.88.
13
NH). C NMR spectrum, δС, ppm: 55.2, 112.2, 114.5,
114.6, 118.5, 124.7, 125.5, 127.1, 129.2, 131.7, 132.2,
145.4, 150.5, 154.9, 159.8. UV spectrum (CH2Cl2), λmax
,
nm (ε, M cm–1): 273 (12900), 424 (10500), 490 (15800).
Mass spectrum, m/z (Irel, %): 355 (10) [M]+, 340 (22),
327 (25), 234 (49), 220 (56), 129 (55), 121 (100), 93
2,4-Diphenyl-6-(p-tolyl)-3,4-dihydro-1,2,4,5-
tetrazin-1(2Н)-yl (1b). The duration of oxidation by air
is 2 h. Yield 0.17 g (52.0%), mp 111–112°С (methanol).
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IR spectrum, ν, cm–1: 780.1 s, 820.1 m, 1146.2 m,
1208.7 m, 1260.3 m, 1385.1 m, 1490.1 s, 1586.0 s,
2967.1 s. UV spectrum (CH2Cl2), λmax, nm (ε, M cm–1):
245 (12300), 284 (19500), 325 (9500), 395 (6500), 720
(3900). Mass spectrum, m/z (Irel, %): 327 (30) [M]+, 301
(80), 254 (44), 223 (52), 133 (49), 120 (100). Found, %:
С 77.09; H 5.81; N 17.09. C21H19N4. Calculated, %: С
77.04; H 5.85; N 17.11.
338 (17) [M]+, 324 (80), 312 (86), 286 (35), 237 (74),
146 (48), 131 (85), 106 (100). Found %: С 74.48; H 4.73;
N 20.59. C21H15N5. Calculated, %: С 74.54; H 4.77; N
20.70.
2-(p-Tolyl)-4,6-diphenyl-3,4-dihydro-1,2,4,5-
tetrazin-1(2Н)-yl (1g). The duration of oxidation by air
is 5 h. Yield 0,104 g (32.0%), mp 138–139°С (methanol).
IR spectrum, ν, cm–1: 746.1 s, 1143.2 s, 1205.7 m,
1387.1 m, 1494.1 s, 1590.0 s. UV spectrum (CH2Cl2),
λmax, nm (ε, M cm–1): 246 (9900), 280 (22500), 320
(12400), 398 (7400), 721 (3400). Mass spectrum, m/z
(Irel, %): 327 (17) [M]+, 301 (85), 251 (60), 224 (65), 120
(74), 106 (100). Found, %: С 77.08; H 5.91; N 17.16.
C21H19N4. Calculated, %: С 77.04; H 5.85; N 17.11.
2,4-Diphenyl-6-(4-methoxyphenyl)-3,4-dihydro-
1,2,4,5-tetrazin-1(2Н)-yl (1c). The duration of oxidation
by air is 3 h. Yield 0.197 g (50.2%), mp 71–72°С
(methanol). IR spectrum, ν, cm–1: 825.5 c, 1105.6 cр,
1207.7 m, 1233.6 m, 1399.5 s, 1488.8 s, 1589.1 s. UV
spectrum (CH2Cl2), λmax, nm (ε, M cm–1): 280 (28400),
319 (10500), 388 (7300), 730 (3200). Mass spectrum,
m/z (Irel, %): 343 (15) [M]+, 317 (100), 315 (50), 301
(60), 267 (50), 242 (70), 151 (44), 136 (90). Found, %:
С 73.51; H 5.51; N 16.29. C21H19N4O. Calculated, %: С
73.45; H 5.58; N 16.32.
2-(4-Methoxyphenyl)-4,6-diphenyl-3,4-dihydro-
1,2,4,5-tetrazin-1(2Н)-yl (1h). The duration of oxidation
by air is 3 h. Yield 0.197 g (50.2%), mp 71–72°С
(methanol). IR spectrum, ν, cm–1: 880.5 m, 1120.7 m,
1249.6 s, 1506.8 s, 1609.1 m, 1708.1 m. UV spectrum
(CH2Cl2), λmax, nm (ε, M cm–1): 280 (28400), 319
(10500), 388 (7300), 730 (3200). Mass spectrum, m/z (Irel,
%): 343 (15) [M]+, 317 (100), 315 (50), 301 (60), 267
(50), 242 (70), 151 (44), 136 (90). Found, %: С 73.51;
H 5.51; N 16.29. C21H19N4O. Calculated, %: С 73.45;
H 5.58; N 16.32.
2,4-Diphenyl-6-(4-dimethylaminophenyl)-3,4-
dihydro-1,2,4,5-tetrazin-1(2Н)-yl (1d). The duration
of oxidation by air is 5 h. Yield 0.135 g (38.0%), mp
124–125°С (methanol). IR spectrum, ν, cm–1: 765.9 s,
800.1 m, 1126.2 m, 1212.7 m, 1270.9 m, 1390.1 m,
1491.9 s, 1592.1 s, 2969.1 s. UV spectrum (CH2Cl2), λmax
,
nm (ε, M cm–1): 290 (29400), 325 (11500), 405 (7300),
740 (4200). Mass spectrum, m/z (Irel, %): 356 (23) [M]+,
342 (47), 330 (80), 315 (44), 254 (78), 239 (60), 149
(100), 106 (83). Found, %: С 74.11; H 6.31; N 19.59.
C22H22N5. Calculated, %: С 74.13; H 6.22; N 19.65.
2-(4-Dimethylaminophenyl)-4,6-diphenyl-3,4-
dihydro-1,2,4,5-tetrazin-1(2Н)-yl (1i). The duration
of oxidation by air is 3 h. Yield 0.181 g (51.1%), mp
95–96°С (methanol). IR spectrum, ν, cm–1: 770.9 s,
812.1 m, 1131.2 m, 1227.0 m, 1280.2 m, 1395.2 m,
2,4-Diphenyl-6-(4-nitrophenyl)-3,4-dihydro-
1,2,4,5-tetrazin-1(2Н)-yl (1e). The duration of oxidation
by air is 10 h. Yield 0.147 g (41.1%), mp 120–122°С
(methanol). IR spectrum, ν, cm–1: 740.5 s, 1152.3 m,
1208.9 m, 1349.7 s (NO2), 1495.1 s, 1532.1 s (NO2),
1589.9 s. UV spectrum (CH2Cl2), λmax, nm (ε, M cm–1):
293 (45300), 350 (14500), 738 (8400). Mass spectrum,
m/z (Irel, %): 358 (21) [M]+, 334 (100), 308 (48), 275
(59), 261 (80), 257 (82), 151 (60), 106 (100). Found, %:
С 67.11; H 4.53; N 19.49. C20H16N5O2. Calculated, %:
С 67.03; H 4.50; N 19.54.
1495.9 s, 1595.1 s, 2970.1 s. UV spectrum (CH2Cl2), λmax
,
nm (ε, M cm–1): 288 (28400), 320 (10600), 400 (6300),
736 (3200). Mass spectrum, m/z (Irel, %): 356 (11) [M]+,
342 (36), 330 (80), 255 (65), 164 (50), 149 (65), 106
(100). Found, %: С 74.21; H 6.21; N 19.59. C21H19N4O.
Calculated, %: С 74.13; H 6.22; N 19.65.
2-(4-Nitrophenyl)-4,6-диphenyl-3,4-dihydro-
1,2,4,5-tetrazin-1(2Н)-yl (1j). The duration of oxidation
by air is 10 h. Yield 0.147 g (41.1%), mp 120–122°С
(methanol). IR spectrum, ν, cm–1: 755.5 s, 1161.3 m,
1210.8 m, 1350.7 s (NO2), 1490.1 s, 1536.1 s (NO2),
1591.0 s UV spectrum (CH2Cl2), λmax, nm (ε, M cm–1):
290 (35300), 340 (12500), 735 (7400). Mass spectrum,
m/z (Irel, %): 358 (21) [M]+, 334 (100), 275 (56), 261
(83), 257 (85), 151 (62), 106 (100). Found, %: С 67.11;
H 4.53; N 19.49. C20H16N5O2. Calculated, %: С 67.03;
H 4.50; N 19.54.
2,4-Diphenyl-6-(4-cyanophenyl)-3,4-dihydro-
1,2,4,5-tetrazin-1(2Н)-yl (1f). The duration of oxidation
by air is 10 h. Yield 0.121 g (36.0%), mp 117–119°С
(methanol). IR spectrum, ν, cm–1: 740.5 m, 1152.3 m,
1208.9 m, 1495.1 s, 1589.9 s, 2241.0 m (CN). UV
spectrum (CH2Cl2), λmax, nm (ε, M cm–1): 287 (34300),
334 (12500), 740 (9400). Mass spectrum, m/z (Irel, %):
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KOSTRYUKOV et al.
2-(4-Cyanophenyl)-4,6-diphenyl-3,4-dihydro-
862.7 s, 1196.3 m, 1224.2 m, 1495.4 s, 1599.0 s, 2246.1 m
(CN). UV spectrum (CH2Cl2), λmax, nm (ε, M cm–1): 285
(42400), 335 (12500), 398 (7300), 750 (4000). Mass
spectrum, m/z (Irel, %): 352 (18) [M]+, 328 (70), 326
(100), 324 (65), 249 (50), 228 (65), 121 (70), 106 (74),
79 (63). Found, %: С 74.88; H 5.13; N 19.79. C22H18N5.
Calculated, %: С 74.98; H 5.15; N 19.87.
1,2,4,5-tetrazin-1(2Н)-yl (1k). The duration of oxidation
by air is 10 h. Yield 0.122 g (36.0%), mp 103–104°С
(methanol). IR spectrum, ν, cm–1: 745.6 m, 1160.3 m,
1211.9 m, 1489.1 s, 1592.1 s, 2245.0 m (CN). UV
spectrum (CH2Cl2), λmax, nm (ε, M cm–1): 290 (29300),
344 (10500), 756 (7300). Mass spectrum, m/z (Irel, %):
338 (17) [M]+, 312 (90), 286 (35), 286 (35), 237 (80),
146 (48), 131 (85), 106 (100). Found, %: С 74.48; H
4.73; N 20.59. C21H15N5. Calculated, %: С 74.54; H
4.77; N 20.70.
2-(4-Methoxyphenyl)-6-(4-cyanophenyl)-4-phenyl-
3,4-dihydro-1,2,4,5-tetrazin-1(2Н)-yl (1p). The
duration of oxidation by air is 24 h. Yield 0.141 g (41.0%),
mp 91–93°С (methanol). IR spectrum, ν, cm–1: 825.5 s,
1155.1 s, 1207.5 m, 1234.1 m, 1400.5 m, 1488.6 s,
1591.6 s, 2223.1 (CN). UV spectrum (CH2Cl2), λmax, nm
(ε, M cm–1): 286 (37500), 330 (12500), 390 (7500), 730
(4200). Mass spectrum, m/z (Irel, %): 368 (14) [M]+, 342
(78), 326 (51), 300 (38), 236 (69), 151 (49), 131 (100),
121 (84), 106 (89). Found, %: С 71.77; H 4.98; N 19.08.
C22H18N5O. Calculated, %: С 71.72; H 4.92; N 19.01.
2-(4-Cyanophenyl)-6-(p-tolyl)-4-phenyl-3,4-
dihydro-1,2,4,5-tetrazin-1(2Н)-yl (1l). The duration
of oxidation by air is 24 h. Yield 0.117 (33.2%), mp
125–126°С (methanol). IR spectrum, ν, cm–1: 740.6 m,
856.1 s, 1165.3 m, 1219.2 m, 1490.4 s, 1596.0 s, 2245.6 m
(CN). UV spectrum (CH2Cl2), λmax, nm (ε, M cm–1): 292
(29800), 346 (11800), 760 (6300). Mass spectrum, m/z
(Irel, %): 352 (17) [M]+, 326 (100), 300 (32), 276 (45), 237
(73), 223 (47), 133 (60), 122 (90). Found, %: С 74.88;
H 5.13; N 19.79. C22H18N5. Calculated, %: С 74.98; H
5.15; N 19.87.
2-(4-Dimethylaminophenyl)-6-(4-cyanophenyl)-4-
phenyl-3,4-dihydro-1,2,4,5-tetrazin-1(2Н)-yl (1q). The
duration of oxidation by air is 24 h. Yield 0.171 g (45.0%),
mp 101–102°С (methanol). IR spectrum, ν, cm–1: 817.2 s,
1066 s, 1145.6 m, 1200.9 m, 1496.9 s, 1590.8 s, 2245.1 m
(CN), 2989.6 m. UV spectrum (CH2Cl2), λmax, nm (ε, M
cm–1): 290 (35500), 335 (14500), 400 (8500), 735 (3600).
Mass spectrum, m/z (Irel, %): 381 (15) [M]+, 367 (40), 355
(100), 326 (54), 277 (49), 255 (74), 236 (67), 149 (65),
106 (69). Found, %: С 72.35; H, 5.58; N 22.09. C23H21N6.
Calculated, %: С 72.42; H 5.55; N 22.03.
2-(4-Cyanophenyl)-6-(4-methoxyphenyl)-4-
phenyl-3,4-dihydro-1,2,4,5-tetrazin-1(2Н)-yl (1m).
The duration of oxidation by air is 24 h. Yield 0.1915 g
(52.1%), mp 83–84°С (methanol). IR spectrum, ν, cm–1:
820.2 s, 1157.6 s, 1205.2 m, 1494.0 s, 1587.8 s, 2241.1 m
(CN). UV spectrum (CH2Cl2), λmax, nm (ε, M cm–1):
282 (48400), 330 (11500), 393 (8300), 742 (4000). Mass
spectrum, m/z (Irel, %): 368 (14) [M]+, 344 (60), 342 (85),
340 (76), 326 (54), 237 (74), 146 (63), 133 (86), 131
(100), 106 (75). Found, %: С 71.81; H, 4.88; N 19.09.
C22H18N5O. Calculated, %: С 71.72; H 4.92; N 19.01.
FUNDING
This work was financially supported by the Russian
Foundation for Basic Research (project no. 18-43-130002).
2-(4-Cyanophenyl)-6-(4-dimethylaminophenyl)-4-
phenyl-3,4-dihydro-1,2,4,5-tetrazin-1(2Н)-yl (1n). The
duration of oxidation by air is 24 h. Yield 0.126 g (33.1%),
mp 122–123°С (methanol). IR spectrum, ν, cm–1: 820.2 s,
1076 s, 1157.6 m, 1205.2 m, 1494.0 s, 1587.8 s, 2241.1
m (CN), 2982.6 m. UV spectrum (CH2Cl2), λmax, nm (ε,
M cm–1): 293 (38400), 356 (14500), 420 (9200), 761
(4400). Mass spectrum, m/z (Irel, %): 381 (14) [M]+, 355
(90), 262 (50), 254 (81), 237 (68), 149 (84), 133 (76), 106
(106). Found, %: С 72.35; H 5.58; N 22.09. C23H21N6.
Calculated, %: С 72.42; H 5.55; N 22.03.
CONFLICT OF INTEREST
No conflict of interest was declared by the authors.
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