Nitrogen-Rich Tetrazolo[1,5-b]pyridazine: Promising Building Block for Advanced Energetic Materials

Article abstract of DOI:10.1021/jacs.0c00161

Two metal-free explosives, tetrazolo[1,5-b]pyridazine-containing molecules [6-azido-8-nitrotetrazolo[1,5-b]pyridazine-7-amine (3at) and 8-nitrotetrazolo[1,5-b]pyridazine-6,7-diamine (6)], were obtained via straightforward two-step synthetic routes from commercially available reagents. Compound 3at displays an excellent detonation performance (D_v = 8746 m s^-1 and P = 31.5 GPa) that is superior to commercial primary explosives such as lead azide and diazodinitrophenol (DDNP). Compound 6 has superior thermal stability, remarkable insensitivity, and good detonation performance, strongly suggesting it as an acceptable secondary explosive. The initiating ability of compound 3at has been tested by detonating 500 mg of RDX with a surprisingly low minimum primary charge of 40 mg. The extraordinary initiating power surpasses conventional primary explosives, such as commercial DDNP (70 mg) and reported 6-nitro-7-azido-pyrazol[3,4-d][1,2,3]triazine-2-oxide (ICM-103) (60 mg). The outstanding detonation power of 3at contributes to its future prospects as a promising green primary explosive. In addition, the environmentally benign methodology for the synthesis of 3at effectively shortens the time from laboratory-scale research to practical applications.

Full text of DOI:10.1021/jacs.0c00161

Subscriber access provided by Hong Kong University of Science and Technology Library
Article
Nitrogen-Rich Tetrazolo[1,5-b]pyridazine: Promising
Building Block for Advanced Energetic Materials
Wei Huang, Yongxing Tang, Gregory H Imler, Damon A. Parrish, and Jean'ne M. Shreeve
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.0c00161 • Publication Date (Web): 31 Jan 2020
Downloaded from pubs.acs.org on February 1, 2020
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a service to the research community to expedite the dissemination
of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in
full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully
peer reviewed, but should not be considered the official version of record. They are citable by the
Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore,
the “Just Accepted” Web site may not include all articles that will be published in the journal. After
a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web
site and published as an ASAP article. Note that technical editing may introduce minor changes
to the manuscript text and/or graphics which could affect content, and all legal disclaimers and
ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or
consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W.,
Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 8
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
Nitrogen-Rich Tetrazolo[1,5-b]pyridazine: Promising Building Block for
Advanced Energetic Materials
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
†
‡,†,
§
§
,‡
Wei Huang, Yongxing Tang, * Gregory H. Imler, Damon A. Parrish and Jean’ne M. Shreeve*
†
‡
Dr. W. Huang, Dr. Y. Tang, Nanjing University of Science and Technology, Nanjing, 210094 (China)
Dr. Y. Tang, Prof. J. M. Shreeve, Department of Chemistry, University of Idaho, Moscow, Idaho, 83844-2343 USA. Fax: (+1) 208-
8
85-5173 E-mail: jshreeve@uidaho.edu
§
Dr. G. H. Imler, Dr. D. A. Parrish, Naval Research Laboratory, 4555 Overlook Avenue, Washington, D.C. 20375 USA
KEYWORDS: Energetic Materials, Nitrogen-rich Compounds, Minimum Primary Charge, Explosive, Pyridazine
ABSTRACT: Two metal-free explosives: tetrazolo[1,5-b]pyridazine-containing molecules, [6-azido-8-nitrotetrazolo[1,5-
b]pyridazine-7-amine (3at) and 8-nitrotetrazolo[1,5-b]pyridazine-6,7-diamine (6)] were obtained via straightforward two-
step synthetic routes from commercially available reagents. Compound 3at displays excellent detonation performance (Dv
-1
=
8746 m s and P = 31.5 GPa), which is superior to commercial primary explosives such as lead azide and diazodinitrophenol
(
DDNP). Compound 6 has superior thermal stability, remarkable insensitivity and good detonation performance, strongly
suggesting it as an acceptable secondary explosive. The initiating ability of compound 3at has been tested by detonating
00 mg RDX with a surprisingly low minimum primary charge (MPC) of 40 mg. The extraordinary initiating power surpasses
5
conventional primary explosives, such as commercial DDNP (70 mg) and reported 6-nitro-7-azido-pyrazol[3,4-
d][1,2,3]triazine-2-oxide (ICM-103) (60 mg). The outstanding detonation power of 3at contributes to its future prospects as
a promising green primary explosive. In addition, the environmentally benign methodology for the synthesis of 3at
effectively shortens the time from laboratory-scale research to practical application.
based on nitrogen-rich heterocycles has been reported as
insensitive powerful energetic materials. The fused
INTRODUCTION
8
To satisfy the growing demand for military and civilian
applications, research concerning high-energy density
materials has attracted tremendous attention in the past
decades. Mercury fulminate (MF), lead azide (LA) and lead
styphnate (LS) have dominated the field of primary
pyridazine-based group tetrazolo[1,5-b]pyridazine has
been examined mainly as an active group in the synthesis
of anti-inflammatory drugs. It is noteworthy that the
9
exceptionally high nitrogen content and high thermal
stability could also give rise to materials with applications
in energetic fields. However, tetrazolo[1,5-b]pyridazine has
1
explosives for a very long time. Because of the problems of
1
0
long-term environmental contamination, health effects,
and hazards from extreme sensitivities, it is essential to
rarely been investigated as an energetic building block.
Now novel energetic compounds were prepared based
on tetrazolo[1,5-b]pyridazine by modifying the structure
with different nitrogen-rich groups (nitro, amino, and
azido). The two target molecules, 6-azido-8-
nitrotetrazolo[1,5-b]pyridazine-7-amine (3at) and 8-
nitrotetrazolo[1,5-b]pyridazine-6,7-diamine (6), were
synthesized via facile and straightforward routes in high
yields starting from commercially available 3,6-
dichloropyridazin-4-amineIt is well known that practical
applications of a large number of organic explosives are
2
find green and efficient alternatives. Considering the
safety of operation and transportation, sensitivity to
external stimuli is also a very important factor. Promising
alternative materials should have properties such as:
powerful
energetic
performance,
straightforward
synthesis, good thermal stability, appropriate sensitivity,
3
and high density, and be environmentally benign.
Energetic organic materials are among the most
promising replacements for LA and LS as green energetic
4
11
materials since they overcome the disadvantage of
hindered due to multistep and low yield synthetic routes.
environmental hazards, while concomitantly providing
high energetic performance. Usually, in the initiation of
Low-cost syntheses and easy scalability make 3at and 6
valuable in real-world applications. The detonation
performance, thermal stability and moderate sensitivity of
these novel materials surpass the performance of some of
the conventional explosives, suggesting great potential for
practical application.
5
an energetic material, the breaking of covalent bonds (C–
N, N–N or N–O) results in the rapid release of energy
6
leading to detonation. As a result, designing materials
based on nitrogen-rich heterocycles is an efficient strategy
7
for the generation of novel energetic materials. In recent
years, a very large number of novel energetic materials
RESULTS AND DISCUSSION
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 2 of 8
respectively. The bond lengths in the six-membered ring
Å). The bond angle of N9-N10-C14 is 129.8 which is much
larger than any other angles in the six-membered ring. In
addition, an intermolecular hydrogen bond N(6)-
H(6A)···O(1) is present which aids in stabilizing the
molecule.
SYNTHESIS
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
o
Compound 1 was nitrated with a mixture of 100% nitric
acid and sulfuric acid to prepare 2. Treatment of 2 with
sodium azide in acetone/water resulted in the formation of
3
at (Scheme 1). Instead of a mixture of three tautomers
[diazide (3aa), azide-tetrazole (3at) and ditetrazole (3tt)],
the NMR spectra and single crystal X-ray diffraction
analysis support the sole existence of the azido-tetrazole
form of 3at. This phenomenon has been reported for a
similar compound, 3,6-diazidopyridazine, where azido to
tetrazolo tautomerism is possible but it is found mainly in
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
12
the tetrazole form.
Scheme 1. Synthesis of 3at.
Cl
Cl
N3
N3
N
N
N
N
H2SO4/HNO3
N
N
NO2
NaN3
NO2
NH2
N
N
NO2
NH2
N
NO2
NH2
N
N
N
N
N
N
N
NH2
NH2
N
Cl
Cl
N3
3at
N
N
1
2
3aa
3tt

The synthetic route to 6 is shown in Scheme 2. Reaction
of 2 with hydrazine monohydrate in ethanol gives the
hydrazine-substituted compound 4, which was treated
with sodium nitrite in dilute HCl to yield the tetrazole-
fused diazine compound 5. Treatment of 5 with aqueous
ammonia led to the formation of 6, which was confirmed
by single crystal X-ray diffraction analysis. In addition, four
Figure 1. (a) Molecular structure of 3at; (b) Packing diagram
of 3at.
1
,2,3-triazole N-oxide derivatives from 4 have also been
prepared (Supporting Information). The related synthetic
strategy has laid the groundwork for further preparative
modification of pyridazine fused energetic materials.
Scheme 2. Synthesis of 6.
Figure 2. (a) Molecular structure of 6; (b) Packing diagram of
H2N
N
N
N
Cl
N
NH
N2H4•H2O
EtOH
NaNO2
HCl
N
NO2
NH2
N
NO2
NH2
6
.
NO2
NH2
NO2
NH2
NH3•H2O
N
N
N
N
N
N
N
N
Physical and Detonation Properties
Cl
2
Cl
5
NH2
Cl
4
6
Both 3at and 6 are nitrogen-rich compounds, which
makes them good candidates as energetic materials.
Therefore, their physical and energetic properties were
Crystal Structures
Suitable crystals of 3at were obtained by evaporation of
an acetone solution. It crystallizes in the monoclinic space
group P2 /n with four formula moieties in the unit cell and
1
a crystal density of 1.834 g cm at 296 K. The molecular
structure is given in Figure 1a. The molecule is planar with
both of the torsion angles of O(2)-N(3)-C(4)-C(5) and C(5)-
C(7)-N(8)-N(9) at -179.9(2) . As expected, the atoms (N8,
N9 and N10) of the azido group are linear. The angle N(9)-
N(8)-C(7) is 112.1(2) . The intramolecular hydrogen
bonding of N(6)-H(6A)…O(1) and intermolecular
hydrogen bonding of N(6)-H(6B)…N(14) (symmetry code:
x-1, y, z) form a three-dimensional network. Along the a
axis, the layers are stacked by π-π interactions and
separated by distances of 2.673 Å and 3.037 Å, respectively.
investigated.
The
thermal
stability,
detonation
performance, and mechanical sensitivities are given in
Table 1. The thermal decomposition of 3at and 6 occur at
-3
o
onset temperatures of 163 and 290 C, respectively. These
values, especially for 6, meet most military and civilian
requirements. The drastic change in the thermal behavior
from 3at and 6 is a result of the replacement of the
thermally sensitive azido group by a thermally stable
amino group.
o
o
#
Due to the presence of a large number of N-N or C-N
bonds, 3at and 6 have relatively high nitrogen content (3at:
3.66% and 6: 57.90%). As a result, they have high positive
6
-
1
-1
heats of formation (3at: 811.2 kJ mol , 3.65 kJ g and 6: 446.5
-1
-1
kJ mol , 2.28 kJ g ). This result is consistent with reports
that the azido group increases the heat of formation by
about +364 kJ mol . The densities of 3at and 6 were
found to be 1.82 g cm and 1.80 g cm , respectively, by
using a gas pycnometer at room temperature.
Compound 6 also crystallizes in the monoclinic space
-1 10a
group P2
1
/n with four formula moieties in the unit cell with
-3
-3
a DMSO molecule of crystallization. As shown in Figure 2,
range from 1.308 Å (N9-C7) to 1.491 Å (C7-C5). The shortest
bond length in the five-membered ring is N11-N12 (1.295 all
the atoms in 6 are coplanar. The torsion angles for O(2)-
N(3)-C(4)-C(14) and N(6)-C(5)-C(7)-N(8) are -1.2 and 1.1,
Detonation performances of 3at and 6 were calculated
13
by EXPLO5 software. The values of detonation velocities
) and pressures (P) are given in Table 1. Compound 3at
(D
v
ACS Paragon Plus Environment

Page 3 of 8
Journal of the American Chemical Society
Table 1. Physical and detonation properties of 3at and 6 in comparison with LA, DDNP and TATB.
1
2
3
4
5
6
7
8
9
a)
ρ b)
[g cm-3]
c)
νD d)
[m s-1]
P e)
[Gpa]
IS f)
[J]
FS g)
[N]
T
[
d
f
∆ H
Compounds
at
-1
-1
°C]
[kJ mol /kJ g ]
3
163
290
315
1.82
1.80
4.80
1.72
1.93
811.2/3.65
8746
8434
5920
6900
8179
31.5
27.7
33.8
24.7
30.5
5
>40
2.5-4
1
120
6
446.5/2.28
450.1/1.55
321.0/1.53
>360
0.1-1
24.7
>360
LAh)
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
DDNPi)
TATBj)
157
350
-139.7/-0.54
50
a)
o
b)
Thermal decomposition temperature (onset) under nitrogen gas (DSC, 5 C/min); Measured densities - gas pycnometer
c)
d)
e)
at room temperature; Calculated heat of formation; Calculated detonation velocity; Calculated detonation pressure;
f)
g)
h)
i)
j)
Impact sensitivity; Friction sensitivity; Ref 3b; Ref 14; Ref 15.
= 8746 m s-1
v
has an excellent detonation performance (D
and P = 31.5 GPa), which is superior to commercial primary
-
1
3b
explosives, LA (D
v
= 5920 m s and P = 33.8 GPa) and
-1
14
DDNP (D = 6900 m s and P = 24.7 GPa). The sensitivities
v
toward impact and friction were also determined.
Compound 3at has better safety and reliability than LA and
DDNP with impact (IS) and friction sensitivities (FS) of 5 J
and 120 N, respectively. The relatively lower friction
sensitivity should reduce the likelihood of accidents
caused by slight amounts of friction. The moderate
sensitivities nearly guarantee the possibility of the safety of
production, handling and transportation, and retain
competitive detonation performance at the same time. The
good balance of detonation performance and sensitivity,
plus the environmentally benign syntheses, contribute to
the practical application of 3at as a promising primary
explosive. It is a green and powerful alternative to the toxic
and sensitive LA.
Figure 3. ESP-mapped molecular vdW surface of (a) 3at
and (b) 6. Surface local minima and maxima of ESP are
represented as blue and red spheres, respectively. Only the
strong positive ESPs are labeled.
To gain additional insight in the relationship between
sensitivity and structure, the Hirshfeld surface plots and
two dimensional finger print spectra of 3at and 6 in the
crystal structures were investigated and are shown in
Figure 4. Both of the Hirshfeld surfaces of 3at and 6 have
nearly planar structures. The red dots appear in the side
faces of the plates instead of the front faces, suggesting that
the intermolecular interactions take place mainly through
the external atoms (H, N and O) encompassing the
molecules. From the relative contribution of the contacts,
the major interactions are N…N (28.0%), N…O (26.7%) and
N…H (21.6%) for 3at, and N…H (36.0%), O…H (24.4%) and
H…H (7.5%) for 6. To sum up, the hydrogen-bridge contact
is 24.2% (3at) and 67.9% (6), respectively. The remarkably
abundant hydrogen bonds (67.9%) give rise to the low
sensitivity of 6.
Compound 6 not only has a very good detonation
-1
performance (D
possesses remarkably low sensitivities with IS > 40 J and FS
360 N which are comparable to the traditional insensitive
explosive, 2,4,6-triamino-1,3,5-trinitrobenzene (TATB) (IS
v
= 8434 m s and P = 27.7 GPa), it also
>
1
4
=
50 J and FS > 360 N). In addition, it has a desirable high
o
thermal stability at Td = 290 C. The combined
performance and properties of 6 suggest its potential as a
secondary explosive for practical use.
The calculated electrostatic potentials (ESP) mapped
vdW surfaces of 3at and 6 are shown in Figure 3. In
energetic compounds, the impact sensitivities of the
molecules are closely related to their surface ESPs.
Extensive areas with larger and stronger positive potentials
Initiating Efficiency
The ability to initiate secondary explosives is one of the
most important parameters for a primary explosive. To test
the feasibility of 3at as a primary explosive, an initiation
capability test was performed by using it to detonate 500
mg of secondary explosive (RDX) against a 5 mm lead block
1
6
usually result in increased impact sensitivities.
Compounds 3at and 6 have similar electronegative areas
blue region). However, 3at exhibits a notably larger
(
(
(
Figure 5a). To determine the minimum primary charge
MPC), a certain amount of 3at was filled over 500 mg RDX
electropositive area than 6. Compound 3at has
anomalously strong positive potentials over its left portion,
reflecting the depletion of electronic charge caused by the
azido group. Therefore, compound 3at is more sensitive
than compound 6, which is in accordance with the
experimental results.
and pressed with a static pressure of 40 MPa. The
apparatus was fired by an electric igniter. As is seen in
Figure 5b,
ACS Paragon Plus Environment

Journal of the American Chemical Society
In conclusion, two nitrogen-rich molecules (3at and 6)
Page 4 of 8
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
based on tetrazolo[1,5-b]pyridazine were prepared from
commercially available reagents by using straightforward
synthetic methodology. The detonation performance and
sensitivities toward mechanical stimuli were thoroughly
examined. The prediction models, including ESP mapped
surface, Hirshfeld surface and related fingerprint plot
analysis, were all examined to investigate the relationship
between their structures and sensitivities. Compound 3at
displays a superior detonation performance (Dv = 8746 m
-
1
s
and P = 31.5 GPa) compared to commercial primary
explosives. Furthermore, in the detonation test, compound
at can detonate 500 mg RDX successfully with an ultralow
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
3
MPC of 40 mg, surpassing the commercial primary
explosives (MPC: 70 mg for DDNP, and 60 mg for ICM-103).
The outstanding detonation power and environmentally
benign methodology for the synthesis of 3at contribute to
its future prospects as an efficient green primary explosive.
Compound 6 could possibly be a secondary explosive
owing to its high thermal stability (Td = 290 C),
remarkable insensitivity (IS > 40 J and FS > 360 N) and
good calculated detonation performance (Dv = 8434 m s
and P = 27.7 GPa). The discoveries have led to a strategy for
design of lead-free environmentally friendly primary
explosives, and also introduce fresh perspectives and a new
design of organic explosive with super detonation
performances.
Figure 4. The 2D fingerprint plots and Hirshfeld surfaces
(inside) in crystal stacking for 3at (a) and 6 (b); the pie graphs
for 3at (c) and 6 (d) show the percentage contributions of the
individual atomic contacts to the Hirshfeld surface.
reducing the charge amount of 3at from 80 mg to 40 mg
has only a slight influence on the diameters of the blasted
holes which stay constant around 1.1 cm. Therefore, under
a given charge of secondary explosive, the size of the
blasted hole is independent of the charge of the primary
explosive as long as it can initiate the process successfully.
The test results demonstrate that 3at is a super igniting
explosive with the MPC of 40 mg, which is superior to that
o
-1
2
14
of the reported ICM-103 (60 mg) and DDNP (70 mg).
Thus, 3at is shown to have an extraordinary initiating
ability and to demonstrate great promise for real
applications. After many tests, 3at has been demonstrated
to be used in detonator with electric ignitor.
ASSOCIATED CONTENT
EXPERIMENTAL DETAILS
Caution! The compounds in this work are potentially
energetic materials that could explode under certain
conditions (e.g., impact, friction or electric discharge),
especially the azido compound 3at. Appropriate safety
precautions, such as the use of safety shields in a fume
hood and personal protection equipment (safety glasses,
face shields, ear plugs, as well as gloves) should be taken at
all times when handling these materials.
General methods
All reagents were purchased from AKSci or Alfa Aesar in
analytical grade and were used as supplied. The H, and C
spectra were recorded on a 300 MHz (Bruker AVANCE
1
13
3
00) nuclear magnetic resonance spectrometer. Chemical
1
13
shifts for H and C NMR spectra are given with respect to
external (CH Si. [D ]DMSO was used as a locking solvent
)
3 4
6
unless otherwise stated. IR spectra were recorded using
KBr pellets with a FT-IR spectrometer (Thermo Nicolet
AVATAR 370). Density was determined at room
temperature by employing a Micromeritics AccuPyc II 1340
gas pycnometer. Decomposition (onset) temperatures
were recorded using a dry nitrogen gas purge and a heating
rate of 5 C min on a differential scanning calorimeter
(DSC, TA Instruments Q2000). Elemental analyses (C, H,
N) were performed with a Vario Micro cube Elementar
Analyser. Impact and friction sensitivity measurements
were made using a standard BAM Fall hammer and a BAM
friction tester.
Figure 5. (a) Illustration of initiation capability test of 3at; (b)
Lead plates that were blasted out of the hole by using different
amount of 3at as primary explosive and 500 mg RDX as
secondary explosive.
In consideration of the good explosive performances of
o
-1
3
at and 6, the tetrazolo[1,5-b]pyridazine moiety appears to
be an effective building block to construct highly energetic
materials. With this experience, more powerful and
insensitive energetics could be developed in future
research.
CONCLUSION
Computational Methods
ACS Paragon Plus Environment

Page 5 of 8
Journal of the American Chemical Society
o
1
The gas phase enthalpies of formation were calculated
based on isodesmic reactions. The enthalpy of reaction is
obtained by combining the MP2/6-311++G** energy
difference for the reactions, the scaled zero point energies
4: Orange solid. Td (onset): 229 C. H NMR (d
6
-DMSO):
1
2
3
4
5
6
7
8
9
13
9.20 (s, 1H), 8.43 (s, 2H), 4.90 (s, 2H) ppm. C NMR (d
DMSO): δ 148.5, 141.0, 140.4, 116.5 ppm. IR (KBr): ν = 3434,
3339, 3104, 1638, 1577, 1490, 1436, 1317, 1271, 1175, 1076, 969,
4 5 6 2
881, 729, 720, 661 cm . C H ClN O (204.57): Calcd: C 23.48,
6
-
-1
(
ZPE), values of thermal correction (HT), and other
thermal factors. The solid-state heats of formation were
calculated with Trouton’s rule according to equation (1) (T
represents either the melting point or the decomposition
temperature when no melting occurs prior to
H 2.46, N 41.08 %. Found: C 23.52, H 2.55, N 41.68 %.
Synthesis of 5·H
2
O
Compound 4 (0.56 g, 2.74 mmol) was dissolved in dilute
HCl solution (12%, 12 mL), and a solution of sodium nitrite
1
7
decomposition).
o
(
0.22 g, 3.16 mmol) in water (2 mL) was added at 0 C. The
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1 1

Hsub 188 / Jmol K T
o
reaction mixture was stirred at 0 C for 0.5 h. The
precipitate was collected by filtration and washed with ice
water (15 mL) and dried in air (0.48 g, yield: 75%).
(1)
Crystal Structure Analysis
A clear brown block crystal (3at) of dimensions 0.063 ×
o
o
1
5
6
·H
-DMSO): 9.67 (s, 1H), 9.32 (s, 1H) ppm. C NMR (d
DMSO): δ 147.0, 141.4, 140.2, 115.9 ppm. IR (KBr): ν = 3404,
182, 1636, 1576, 1542, 1519, 1450, 1352, 1318, 1282, 1203, 1161,
2 m
O: White solid. T : 71 C. Td (onset): 196 C. H NMR
3
0.041 × 0.033 mm and a clear colorless block crystal
1
3
(
d
6
-
3
(6·DMSO) of dimensions 0.196 × 0.090 × 0.040 mm was
mounted on a MiteGen MicroMesh using a small amount
of Cargille immersion oil. Data were collected on a Bruker
three-circle platform diffractometer equipped with a
SMART APEX II CCD detector. The crystals were irradiated
3
-1
1
C
097, 1062, 998, 982, 798, 773, 751, 727, 710, 685, 669 cm .
ClN (233.57): Calcd: C 20.57, H 1.73, N 41.98 %.
4
H
4
7 3
O
Found: C 20.58, H 1.81, N 42.46 %.
using graphite monochromated MoK
0.71073 Å). Data were collected at room temperature (20
C).
Data collection was performed and the unit cell was

radiation (λ =
Synthesis of 6
°
Compound 5·H O (0.46 g, 2.0 mmol) was suspended in
2
acetonitrile (15 mL), and aqueous ammonia (28%, 2.0 g)
1
8
was added. The autoclave (30 mL) was sealed and the
initially refined using APEX3 [v2015.5-2]. Data reduction
o
1
9
reaction mixture was heated to 95 C and stirred for 10 h.
was performed using SAINT [v8.34A] and XPREP
20
After cooling, water (20 mL) was added and the reaction
mixture was stirred for 0.5 h. The precipitate was collected
by filtration, washed with water (20 mL), acetonitrile (10
mL), diethyl ether (10 mL) and dried in air (0.31 g, yield:
78%).
[v2014/2].
Corrections were applied for Lorentz,
polarization, and absorption effects using SADABS
21
[v2014/2]. The structures were solved and refined with the
22
aid of the program SHELXL-2014/7. The full-matrix least-
2
squares refinement on F included atomic coordinates and
o
1
anisotropic thermal parameters for all non-H atoms.
Hydrogen atoms were located from the difference
electron-density maps and added using a riding model.
6: Yellow solid. T
d (onset) 6
: 290 C. H NMR (d -DMSO): 7.38
1
3
(br) ppm. C NMR (d -DMSO): δ 155.9, 145.6, 140.3, 109.9
6
ppm. IR (KBr): ν = 3349, 3219, 1686, 1634, 1574, 1548, 1429,
1
7
397, 1359, 1277, 1252, 1191, 1113, 1019, 9999, 953, 937, 818, 772,
Synthesis of 3at
-1
41, 644 cm . C
4 4 8 2
H N O (196.13): Calcd: C 24.50, H 2.06, N
Compound 2 was synthesized from commercially
5
7.13 %. Found: C 24.82, H 2.13, N 57.90 %.
23
available reagent 1 according to the literature. Compound
2 (0.84 g, 4.0 mmol) was dissolved in a mixture of water (5
mL) and acetone (5 mL), then sodium azide (0.80 g, 12.31
mmol) was added. The reaction mixture was stirred for 12
h at room temperature. The precipitate was collected by
filtration, washed with water and dried in air (0.71 g, yield:
80%).
AUTHOR INFORMATION
Corresponding Authors
*
*
E-mail: jshreeve@uidaho.edu (J.M.S.)
E-mail: yongxing@uidaho.edu (Y.T.)
o
1
3
at: Brown solid. Td (onset): 163 C. H NMR (d
6
-DMSO):
-DMSO): δ 149.1,
39.7, 138.1, 115.3 ppm. IR (KBr): ν = 3395, 3165, 2159, 1635,
1525, 1339, 1280, 1191, 1107, 1010, 988, 932, 775, 763, 724, 707,
1
3
9.44 (s, 1H), 9.01 (s, 1H) ppm. C NMR (d
6
SUPPORTING INFORMATION
1
Synthesis of 1,2,3-trizole N-oxide derivatives from 4, crystal
structures and analysis of the obtained compounds are
given in the Supporting Information. This material is
available free of charge via the Internet at
http://pubs.acs.org.
-1
4 2 10 2
648 cm . C H N O (222.13): Calcd: C 21.63, H 0.69, N 63.06
%. Found: C 21.55, H 0.72, N 63.66 %.
Synthesis of 4
Hydrazine monohydrate (0.60 g, 12 mmol) in ethanol (5
ACKNOWLEDGMENT
Financial support of the Office of Naval Research (N00014-16-
mL) was added slowly to a solution of compound 2 (0.84 g,
o
4
.0 mmol) in ethanol (20 mL) at 5 C. The reaction mixture
1
1
-2089), and the Defense Threat Reduction Agency (HDTRA
-15-1-0028) is gratefully acknowledged. This work was
was stirred for 2 h and the precipitate was collected by
filtration, washed with ethanol (10 mL) and dried in air
supported by the National Natural Science Foundation of
China (No. 21905135), Province the Natural Science
Foundation of Jiangsu Province (BK20190458) and the
(
0.72 g, yield: 88%).
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 6 of 8
Fundamental Research Funds for the Central Universities
(No.30919011270).
Nedel'ko, V. V. Synthesis, Thermal Stability, Heats of Formation,
and Explosive Properties of Cyano-substituted Di-, Tri-, and
Tetraazidopyridines. Russ. Chem. Bull. 2009, 58, 2097-2102.
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
9. (a) Jose Lapponi, M.; Carestia, A.; Ines Landoni, V.;
REFERENCES
Rivadeneyra, L.; Etulain, J.; Negrotto, S.; Gabriel Pozner, R.;
Schattner, M. Regulation of Neutrophil Extracellular Trap
Formation by Anti-Inflammatory Drugs. J. Pharmacol. Exp. Ther.
1. (a) Wang, Q.; Han, J.; Zhang, Y.; Yan, Z.; Velasco, E.; Yang, L.;
Wang, B.; Zang, S. Fabrication of Copper Azide Film through
Metal-Organic Framework for Micro-Initiator Applications. ACS
Appl. Mater. Inter. 2019, 11, 8081-8088; (b) Fronabarger, J. W.;
Williams, M. D.; Sanborn, W. B.; Bragg, J. G.; Parrish, D. A.;
Bichay, M. DBX-1-A Lead Free Replacement for Lead Azide.
Propellants Explos. Pyrotech. 2011, 36, 541-550.
2
013, 345, 430-437; (b) Hafez, H. N.; Abbas, H. A. S.; El-Gazzar, A.
R. B. A. Synthesis and Evaluation of Analgesic, Anti-Inflammatory
and Ulcerogenic Activities of Some Triazolo- and 2-Pyrazolyl-
pyrido [2,3-d]pyrimidines. Acta Pharmaceut. 2008, 58, 359-378.
1
0. Chen, S.; Liu, Y.; Feng, Y.; Yang, X.; Zhang, Q., 5,6-Fused
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
2. Deng, M.; Feng, Y.; Zhang, W.; Qi, X.; Zhang, Q. A Green
Bicyclic Tetrazolo-Pyridazine Energetic Materials. Chem.
Commun. 2020, DOI: 10.1039/C9CC08782F.
Metal-Free Fused-Ring Initiating Substance. Nat. Commun. 2019,
10, 1339(1-8).
1
1. (a) Chen, D.; Yang, H.; Yi, Z.; Xiong, H.; Zhang, L.; Zhu, S.;
Cheng, G. An Environmentally Friendly Primary
Explosive with High Heat of Formation. Angew. Chem., Int. Ed.
018, 57, 2081-2084; (b) Kumar, D.; Tang, Y.; He, C.; Imler, G. H.;
3
. (a) Xu, J.; Sun, C.; Zhang, M.; Liu, B.; Li, X.; Lu, J.; Wang, S.;
8 26 4
C N H :
Zheng, F.; Guo, G. Coordination Polymerization of Metal Azides
and Powerful Nitrogen-Rich Ligand toward Primary Explosives
with Excellent Energetic Performances. Chem. Mater. 2017, 29,
2
Parrish, D. A.; Shreeve, J. M. Multipurpose Energetic Materials by
Shuffling Nitro Groups on a 3,3 ′-Bipyrazole Moiety. Chem. Eur.
J. 2018, 24, 17220-17224.
9
725-9733; (b) Fischer, D.; Klapötke, T. M.; Stierstorfer, J.
Potassium 1,1 '-dinitramino-5,5 '-bistetrazolate: Primary
A
Explosive with Fast Detonation and High Initiation Power.
Angew. Chem., Int. Ed. 2014, 53 , 8172-8175. (c) Li, Y.; Qi, C.; Li, S.;
Zhang, H.; Sun, C.; Yu, Y.; Pang, S. 1,1 ′-Azobis-1,2,3-triazole: A
1
2. (a) Abdou, W. M.; Ganoub, N. A.; Sabry, E. Synthesis and
Quantitative Structure-Activity Relationship Study of Substituted
Imidazophosphor Ester Based Tetrazolo[1,5-b]pyridazines as
Antinociceptive/Anti-Inflammatory Agents. Beilstein J. Org.
Chem. 2013, 9, 1730-1736; (b) Kategaonkar, A. H.; Sapkal, S. B.;
Madje, B. R.; Shingate, B. B.; Shingare, M. S. Synthesis of New 4-
High-Nitrogen Compound with Stable
Photochromism. J. Am. Chem. Soc. 2010, 132, 12172-12173.
. Huynh, M. H. V.; Hiskey, M. A.; Meyer, T. J.; Wetzler, M.
N
8
Structure and
4
Green Primaries: Environmentally Friendly Energetic Complexes.
Proc. Natl. Acad. Sci. USA 2006, 103, 5409-5412.
(
4,5-Diphenyl-1H-imidazol-2-yl)tetrazolo[1,5-a]quinolines from
Tetrazolo[1,5-a]quinolines. Chem. Heterocycl. Compds. 2010, 46,
5. (a) Reichel, M.; Dosch, D.; Klapötke, T. M.; Karaghiosoff, K.
Correlation between Structure and Energetic Properties of Three
Nitroaromatic Compounds: Bis(2,4-dinitrophenyl) Ether,
Bis(2,4,6-trinitrophenyl) Ether, and Bis(2,4,6-trinitrophenyl)
Thioether. J. Am. Chem. Soc. 2019, 141, 19911-19916. (b) Liu, Y.;
Zhao, G.; Tang, Y.; Zhang, J.; Hu, L.; Imler, G. H.; Parrish, D. A.;
Shreeve, J. M. Multipurpose [1,2,4]triazolo[4,3-b][1,2,4,5]
tetrazine-based Energetic Materials. J. Mater. Chem. A 2019, 7,
754-758.
13. Sućeska M. EXPLO5 6.01; Brodarski Institute: Zagreb,
Croatia, 2013.
4. Fu, W.; Zhao, B.; Zhang, M.; Li, C.; Gao, H.; Zhang, J.; Zhou,
1
Z. 3,4-Dinitro-1-(1H-tetrazol-5-yl)-1H-pyrazol-5-amine (HANTP)
and Its Salts: Primary and Secondary Explosives. J. Mater. Chem.
A 2017, 5, 5044-5054.
1
5. Boddu, V. M.; Viswanath, D. S.; Ghosh, T. K.; Damavarapu,
7
875-7884.; (c) Klapötke, T. M.; Stiasny, B.; Stierstorfer, J.; Winter,
C. H. Energetic Organic Peroxides Synthesis and
Characterization of 1,4-Dimethyl-2,3,5,6-
tetraoxabicyclo[2.2.1]heptanes. Chem. Eur. Org. J., 2015, 21, 6237-
242; (d) Klapötke, T. M.; Sabaté, C. M. Bistetrazoles: Nitrogen-
R., 2,4,6-Triamino-1,3,5-trinitrobenzene (TATB) and TATB-based
Formulations-a Review. J. Hazard. Mater. 2010, 181, 1-8.
16. (a) Baxter, A. F.; Martin, I.; Christe, K. O.; Haige, R.
Formamidinium Nitroformate: An Insensitive RDX Alternative. J.
Am. Chem. Soc. 2018, 140, 15089-15098. (b) Murray, J. S.; Concha,
M. C.; Politzer, P. Links between Surface Electrostatic Potentials
of Energetic Molecules, Impact Sensitivities and C–NO /N–NO
2 2
Bond Dissociation Energies. Mol. Phys. 2009, 107, 89-97.
17. Westwell, M. S.; Searle, M. S.; Wales, D. J.; Williams, D. H.
Empirical Correlations between Thermodynamic Properties and
Intermolecular Forces. J. Am. Chem. Soc. 1995, 117, 5013-5015.
-
6
Rich, High-Performing, Insensitive Energetic Compounds. Chem.
Mater. 2008, 20, 3629-3637.
6. Huynh, M. H. V.; Hiskey, M. A.; Chavez, D. E.; Naud, D. L.;
Gilardi, R. D. Synthesis, Characterization, and Energetic
Properties of Diazido Heteroaromatic High-Nitrogen C−N
Compound. J. Am. Chem. Soc. 2005, 127, 12537-12543.
7. (a) Herve, G.; Roussel, C.; Graindorge, H. Selective
1
8. Bruker, APEX3 v2015.5-2. Bruker AXS Inc., Madison,
Wisconsin, USA, 2015.
9. Bruker, SAINT v8.34A. Bruker AXS Inc., Madison,
Wisconsin, USA, 2013.
0. Bruker, XPREP v2014/2. Bruker AXS Inc., Madison,
Wisconsin, USA, 2014.
1. Bruker, SADABS v2014/5, Bruker AXS Inc., Madison,
Wisconsin, USA, 2014.
2. Sheldrick, G. M., SHELXL-2014/7. University of Göttingen,
Germany, 2014.
3. Chmovzh, T.; Knyazeva. E.; Popov, V.; Rakitin, O. 4,7-
Preparation of 3,4,5-Trinitro-1H-pyrazole: A Stable All-Carbon-
Nitrated Arene. Angew. Chem., Int. Ed. 2010, 49, 3177-3181; (b) Yin,
P.; Zhang, J.; He, C.; Parrish, D. A.; Shreeve, J. M. Polynitro-
substituted Pyrazoles and Triazoles as Potential Energetic
Materials and Oxidizers. J. Mater. Chem. A 2014, 2, 3200-3208.
1
2
8
. (a) Dalinger, I. L.; Suponitsky, K. Y.; Shkineva, T. K.; Lempert,
2
D. B.; Sheremetev, A. B. Bipyrazole Bearing Ten Nitro Groups - a
Novel Highly Dense Oxidizer for Forward-Looking Rocket
Propulsions. J. Mater. Chem. A 2018, 6, 14780-14786; (b) Tang, Y.;
Dharavath, S.; Imler, G. H.; Parrish, D. A.; Shreeve, J. M.
Nitramino- and Dinitromethyl-substituted 1,2,4-Triazole
Derivatives as High-Performance Energetic Materials. Chem. Eur.
J. 2017, 23, 9185-9191; (c) Mikhailov, Y. M.; Chapyshev, S. V.;
2
2
Dichloro[1,2,5]oxadiazolo[3,4-d]pyridazine 1-oxide. Molbank
2018, 2018, 982(1-3).
ACS Paragon Plus Environment

Page 7 of 8
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
Table of Contents
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 8 of 8
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
ACS Paragon Plus Environment