Desensitization of the dinitromethyl group: Molecular/crystalline factors that affect the sensitivities of energetic materials

Article abstract of DOI:10.1039/c8ta09176e

The dinitromethyl group has attracted considerable attention because of its high nitrogen and oxygen content, positive oxygen balance and high energy. Although most dinitromethyl-functionalized compounds suffer from sensitivity to mechanical stimuli, a series of 3-dinitromethanide-1,2,4-triazolone-based energetic salts have now been synthesized and fully characterized. Of these, the ammonium salt is insensitive to impact and friction. X-ray single crystal analysis shows that the ammonium moiety arranges through a close layer-by-layer assembly, which is helpful in decreasing sensitivity. In addition, intramolecular hydrogen-bonding interactions, and intense π-π interactions also are stabilizing factors which impact the sensitivity of the ammonium salt. The enthalpies of formation and energetic properties of the series of salts were determined in order to reach the conclusion that these multiple stabilization factors are effective tools in decreasing the sensitivity of dinitromethyl-based energetic materials.

Full text of DOI:10.1039/c8ta09176e

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Materials Chemistry A
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Desensitization of the dinitromethyl group:
molecular/crystalline factors that affect the
sensitivities of energetic materials†
Cite this: J. Mater. Chem. A, 2018, 6,
2705
2
abc
Jiaheng Zhang, *ab Damon A. Parrishd
Jichuan Zhang,
c
and Jean'ne M. Shreeve
*
The dinitromethyl group has attracted considerable attention because of its high nitrogen and oxygen
content, positive oxygen balance and high energy. Although most dinitromethyl-functionalized
compounds suffer from sensitivity to mechanical stimuli, a series of 3-dinitromethanide-1,2,4-triazolone-
based energetic salts have now been synthesized and fully characterized. Of these, the ammonium salt is
insensitive to impact and friction. X-ray single crystal analysis shows that the ammonium moiety arranges
through a close layer-by-layer assembly, which is helpful in decreasing sensitivity. In addition,
intramolecular hydrogen-bonding interactions, and intense p–p interactions also are stabilizing factors
which impact the sensitivity of the ammonium salt. The enthalpies of formation and energetic properties
of the series of salts were determined in order to reach the conclusion that these multiple stabilization
factors are effective tools in decreasing the sensitivity of dinitromethyl-based energetic materials.
Received 20th September 2018
Accepted 24th October 2018
DOI: 10.1039/c8ta09176e
rsc.li/materials-a
0
0
0
22
3
,3 -dinitro-5,5 -bis-1,2,4-triazole-1,1 -diol and its derivatives
Introduction
2
3,24
and 5-nitro-3-trinitromethyl-1H-1,2,4-triazolate derivatives.
Since Alfred Nobel paved the way to the development of dyna- Since the excellent energetic properties of these materials are
mite, energetic materials have drawn extensive interest and have generally superior to those of RDX and comparable to HMX,
1
been widely used in both military and civilian applications,
they are attractive for development as modern energetic
2,3
such as gas generating agents suitable for airbags, propellants compounds.
4–7
8–13
as fuel for rockets, and explosives for bombs and mines.
Dinitromethyl is a promising energetic group owing to its
For modern energetic compounds, insensitivity and excellent high nitrogen and oxygen content, which oen leads to high
detonation properties are two very important characteristics energy density for dinitromethyl-functionalized compounds
25,26
that are contradictory in nature; hence, achieving a ne balance including an acceptable oxygen balance.
However, most of
between low sensitivity and high energetic performance is the dinitromethyl-based compounds are sensitive to mechan-
27
a huge challenge. However, a few instances exist which combine ical stimulus. For instance, 2-dinitromethyl-5-nitrotetrazole
insensitivity and high energetic performance successfully, such and dihydroxylammonium 3-dinitromethyl-4-nitraminofur-
1
4–19
28
ꢀ
1
as TATB, LLM-116 and LLM-105 (Scheme 1),
inspiring us to azan, detonation velocities and pressures are 9.22 km s ,
ꢀ1
further explore excellent insensitive materials with high energy. 9.65 km s and 38.5 Gpa, 43 Gpa, respectively. At the same
Azole-based energetic materials have aroused enormous time, the impact and friction sensitivities of these two
attention because of the relatively high heats of formation and compounds are 5, 8 J and 80, 64 N, respectively. According to the
friendly environment upon decomposition. Triazole-based standard, these two representatives fall in the extremely
energetic materials, combine heats of formation, energetic sensitive level, which seriously limits their potential applica-
20
29
2
1
properties, and sensitivity in a ne balance, for example, tions. Hence, to make functionalized compounds which are
insensitive to mechanical stimulus, use of such an excellent and
a
State Key Laboratory of Advanced Welding and Joining, Harbin Institute of
Technology, Shenzhen, 518055, China
b
Research Centre of Flexible Printed Electronic Technology, Harbin Institute of
Technology, Shenzhen, 518055, China
c
Department of Chemistry, University of Idaho, Moscow, Idaho 83844-2343, USA.
E-mail: Jshreeve@uidaho.edu
d
Naval Research Laboratory, 4555 Overlook Avenue, Washington, D.C. 20375, USA
†
Electronic supplementary information (ESI) available. CCDC 1853787, 1853790
and 1853948. For ESI and crystallographic data in CIF or other electronic format
see DOI: 10.1039/c8ta09176e
Scheme 1 Several classical high-energy-insensitive compounds.
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attractive energetic moiety is an exciting challenge. Our group
recently proposed enforced layer-by-layer stacking, which can
30
decrease sensitivity effectively. Additionally, intramolecular
hydrogen-bonds also play a signicant role in improving
31,32
33
stability.
In our continuing efforts, enforced layer-by-layer
stacking and intramolecular hydrogen bonding interactions
were combined extensively in the crystals of ammonium
3-dinitromethanide-1,2,4-triazolone (2). A large number of O–H
weak interactions and intense p–p interactions were also found in
the crystals of 2. Overall, these positive factors led to the insen-
sitivity of 2 towards impact and friction, which is remarkably less
sensitive than other 3-dinitromethanide-1,2,4-triazolone-based
compounds.
Results and discussion
Synthesis and single crystal X-ray structures
Compound 1 and its silver salt were prepared according to
33
the procedure described in our earlier work. Compounds 2, 4,
Fig. 2 (a) Single-crystal X-ray structure of 2; (b) edge-to-face p–p
7
–12 were obtained through the reaction of 1 and free bases, stacking of triazolone rings; (c) intermolecular hydrogen bonds and
unit cell view along the c axis.
and aqueous ammonia. Compounds 5 and 6 were obtained
through the reaction of the silver salt of 1 and the chlorides of 5,
and 6, respectively (Fig. 1).
˚
˚
Crystals of 2, 5$H
2
O, and 6 are suitable for single-crystal from 1.86 A to 2.12 A, falling within the normal hydrogen
X-ray diffraction; all of them were crystallized from the bonding range. The distance between the two triazolone centroids
˚
˚
mixture of ethanol and water. Ammonium 3-dinitromethanide- is 3.247 A (Fig. 2b), which is less than 4.0 A, suggesting that two of
ꢀ
1
,2,4-triazolone (2) crystallizes in the triclinic space group P1 the 3-dinitromethanide-1,2,4-triazolone anions are in the range of
(2), with two 3-dinitromethanide-1,2,4-triazolone anions and p–p interactions and the triazolone ring from above is stacked
two ammonium ions in each lattice cell (Z ¼ 2, Fig. 2a). The close to the dinitromethyl group from below. In other words, the
ꢀ
3
density of 2 is 1.86 cm at 150 K which approaches the highest arrangement of anions and cations crystalizes face-to-face. The
densities of any known dinitromethyl-based ammonium salts. layer arrangement of 3-dinitromethanide-1,2,4-triazolone anions
The ammonium ions and the corresponding anions are and ammonium cations is connected through hydrogen bonds
coplanar and form a layer-by-layer stacking structure. In addi- and p–p interactions forming a 3-D net structure (Fig. 2c).
tion, a large number of intramolecular hydrogen bonds form
Monohydrate
guanidinium
3-dinitromethanide-1,2,4-
among the ammonium ions, triazole rings, and dinitromethyl triazolone (5$H O) is a yellow block crystal which crystallizes in
2
groups. The lengths of the hydrogen bonds (O/N/H) range the triclinic space group P 1ꢀ (2), with two 3-dinitromethanide-1,2,4-
triazolone anions, two water molecules, and two guanidinium
ions in each lattice cell (Z ¼ 2) (Fig. 3a). The density of 5$H O is
2
ꢀ
3
1
.754 g cm at 150 K. Similar to 2, the 3-dinitromethanide-1,2,4-
triazolone anion, water molecule, and guanidinium cation are
coplanar, and the crystal also crystallizes in the form of layer-by-
layer stacking. The distance between the two centroids of tri-
˚
azolone is 3.442 A (Fig. 3b), which is also in the range of p–p
interactions, and the 3-dinitromethanide-1,2,4-triazolone anion,
water molecule, and guanidinium cation are extensively con-
nected by hydrogen bonds (Fig. 3c). The lengths of hydrogen
bonds (O/N/H) are in the range of 1.804 to 2.389 A˚ .
Aminoguanidinium 3-dinitromethanide-1,2,4-triazolone (6)
crystallizes in the same space group as 2 (Fig. 4a), with a density
ꢀ
3
of 1.77 g cm
at 150 K. The dinitromethyl and the dia-
minoguanidinium groups are in the same plane due to hydrogen
bonding interactions. The volume of the diaminoguanidinium
cation is larger than the guanidinium and ammonium cations,
leading to the compression of the arrangement space; hence, the
torsion angle between the triazolone and the dinitromethyl
ꢁ
groups is 43.05 , and the 3-D network of the crystal results
Fig. 1 Synthesis route of 3-dinitromethanide-1,2,4-triazolone-based
compounds.
through hydrogen bonding (Fig. 4b).
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intramolecular hydrogen-bonding plays an important role in
improving the stabilities of these salts. The bond dissociation
energy between anions and cations also plays a signicant role
in enhancing their thermal stabilities because the bond disso-
ciation energies in salts are usually higher relative to their
20
precursors.
Sensitivities are crucial in the evaluation of the safety char-
acteristics of energetic materials during manufacturing, appli-
cations, and transportation. The experimental impact and
friction sensitivity values were determined with standard BAM
drop hammer and friction tester techniques. Among these
synthesized 3-dinitromethanide-1,2,4-triazolone-based salts,
the ammonium salt of 3-dinitromethanide-1,2,4-triazolone is
insensitive to impact and friction (Table 1), it shows comparable
sensitivities to TATB and LLM-116, which further highlights its
2
potential applications. The insensitivity of 5$H O to mechanical
stimuli may be the result of the water molecule of crystalliza-
tion. Except for 4, the impact sensitivities of all the remaining
3
3
-dinitromethanide-1,2,4-triazolone salts are between 32 and
5 J. All of these salts are insensitive towards friction (>360 N)
and are remarkably less sensitive than their precursor (22 J,
2
Fig. 3 (a) Single-crystal X-ray structure of 5$H O; (b) layer-by-layer
stacking of 5; (c) unit cell and intermolecular hydrogen bonds of 5.
240 N) on impact and friction to stimuli.
Theoretically, any external mechanical force acting on an
energetic material can lead to a certain deformation to produce
strain and store mechanical energy which results in many
“
hotspots” during this progress. When the temperature of these
hotspots” becomes higher than the decomposition tempera-
“
ture of the material, decomposition or explosion may be acti-
34,35
vated.
molecules or ions are classied into four categories, namely
1) layer assembly; (2) wavelike; (3) crossing; and (4) mixing,
In general, the arrangement of these energetic
31
(
respectively. Among these, the layer assembly is the desirable
arrangement for energetic constituents since the layer assembly
geometries of energetic materials can absorb mechanical
stimuli by converting kinetic energy into layer sliding which
33
results in lower sensitivity.
To gain further information about inter- and intramolecular
effects and comprehensively study their inuence on crystal
packing, as well as sensitivities associated with 2 and other
3-dinitromethanide-1,2,4-triazolone salts, the non-covalent
interaction (NCI) plot was applied to analyze real space struc-
34,35
ture based on electron density.
The calculated results based
Fig. 4 (a) Single-crystal X-ray structure of 6; (b) crystal stacking of 6. on this simple theory indicate that the interlayer p–p interac-
tions are more intense and spread over a larger area in 2
compared to that of 6, which can be easily observed as large green
isosurfaces (Fig. 5). In addition, the shape of hydrogen bonding
Thermal stability and sensitivity
In general, thermal stability is a primary concern since an (HB) in the NCI plot can be characterized by the small, ellipse
unacceptably low decomposition temperature will strictly limit shaped surfaces which, in theory, are large accumulations of
applications of the energetic material. Differential scanning electron density. In contrast to 6, more extensive HB interactions
calorimetric (DSC) measurements were performed on all the were observed in layered 2. Hence, more intensive p–p interac-
ꢁ
ꢀ1
compounds at a scanning rate of 5 C min , and comparison of tions and hydrogen bonding of the layer-by-layer stacking, these
the decomposition results with that of the parent compound positive factors result in 2 being insensitive to impact and
ꢁ
(
T : 127 C, Table 1) shows that all of the salts are more stable friction.
d
thermally. Compound 2 has an onset decomposition tempera-
In addition to the closer layer-by-layer packing, the weak
ꢁ
ture of 166 C, which is consistent with its hydroxylammonium interactions, which primary consist of O–H ‘so’ interactions,
salt. For compounds 4, 5, and 10, decomposition temperatures play a signicant role in the sensitivity of energetic materials. In
ꢁ
36
are 184, 178, and 213 C, respectively (Table 1). Addition to the this study, Hirschfeld surfaces were employed to analyse the
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Table 1 Physical properties of compound 2 and 4–12
a
d
ꢁ
b
ꢀ3
c
ꢀ1
ꢀ1
d
ꢀ1
e
f
g
Comp
T
C
r [g cm
]
ꢀD
f
H [kJ mol /kJ g
]
D [m s
]
P [Gpa]
IS (J)
FS (N)
2
4
5
6
7
8
9
166
184
178
155
150
148
170
213
144
154
360
205
280
178
1.85
1.88
1.74
1.77
1.76
1.74
1.78
1.86
1.84
1.84
1.93
1.81
1.91
1.90
174/0.84
128/0.58
194/0.78
83/0.31
43.9/0.16
170.9/0.46
8.6/0.03
729.2/2.12
118.4/0.32
14.4/0.03
ꢀ154.2/ꢀ0.60
80/0.36
9081
9226
7989
8594
8111
8182
8201
9108
9196
8879
8114
8795
9144
8573
37.0
37.4
24.2
28.9
25.9
26.4
26.2
34.0
33.6
31.9
31.2
34.9
39.2
34.2
>40
26
>40
33
32
32
32
35
34
34
>360
240
>360
>360
>360
>360
>360
>360
>360
>360
>360
120
1
1
1
0
1
2
TATB
RDX
HMX
>40
7.4
7.4
>40
104.8/0.36
96.3/0.56
120
>360
LLM-116
a
b
ꢁ
c
d
Decomposition temperature (onset). Density measured by gas pycnometer (25 C). Heat of formation. Detonation velocity (calculated with
e
f
g
Explo5 v6.01). Detonation pressure (calculated with Explo5 v6.01). Impact sensitivity. Friction sensitivity.
weak interactions of compounds 2, 5, and 6 (Fig. 6 and 7), and suggesting again that there exists powerful p–p interactions in 2
further to examine up to 33 dinitromethyl-functionalized between the two adjacent triazole rings (Fig. 7). Therefore, the
27,28,33,37–42
CIFs
from the Cambridge Structural Database.
closer layer-by-layer package, multi intramolecular hydrogen-
We found that among these 36 dinitromethyl-functionalized bonding interactions, and second highest and relatively
energetic compounds, 2 has the second highest percentage of stronger O–H weak interactions as well as extensive p–p inter-
O–H weak interactions, possessing 59%. Although the percentage actions, all contribute to the insensitivity of 2.
of O–H weak interactions of 2 is slightly lower than that of the
DBDNT (diammonium 3,5-bis(dinitromethyl)-1,2,4-triazolate),
interactions (indicated by the location and size of the red
square frame) in 2 are apparently higher than that of the DBDNT.
Furthermore, from the pie graphs of individual atomic contacts
percentage contributions, it is seen that the percentage of C–N
and N–C weak interactions of 2 is 4.3% which is the highest value
of all the 3-dinitromethanide-1,2,4-triazolone-based compounds,
Density and detonation properties
At ambient temperature, the densities of 2 and 4–12 fall
ꢀ
3
ꢀ3
between 1.73 g cm and 1.90 g cm . The densities of 2, 4, 8, 10
Fig. 5 NIC plots of gradient isosurfaces (s ¼ 0.5 au) for 2 (a) and 6 (b)
unit cells. The geometries of the unit cells were optimized at the
BLYPD3/def2-QZVPP method 32 using ORCA 3.0.33. The surfaces are
colored on a blue-green-red scale indicating strong attractive inter- Fig. 6 (a) Weak interactions of 2; (b) weak interactions of DBDNT; (c)
actions, weak attractive, and strong nonbonded overlap, respectively. the strength distribution statistics of total O–H weak interactions.
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Experimental
Safety precautions
Although we experienced no difficulties in synthesis and char-
acterization of these materials, proper protective procedures
should be followed. All the reactions were carried out in a hood
behind a safety shield and face shield, and leather gloves were
worn at all times. Caution was exercised at all times during the
synthesis, characterization, and handling of any of these
materials.
Fig. 7 Pie graphs of individual atomic contacts percentage contri-
bution to the Hirshfeld surfaces for 2 (a), 5 (b), and 6 (c).
ꢀ
3
Materials and methods
and 12 are equal to or greater than 1.80 g cm , belonging to the
class of high density energetic materials (HEDM). Compounds 2 Commercial analytical grade reagents were used without
ꢀ
3
1
13
and 4 have densities of 1.85 and 1.88 g cm , respectively, which further purication. H and C spectra were recorded on
are only rarely reported for dinitromethyl-based energetic a 300 MHz (Bruker AVANCE 300) nuclear magnetic resonance
ammonium and diaminoguanidinum salts.
Based on the calculated heats of formation, detonation 500 MHz (Bruker AVANCE 500) nuclear magnetic resonance
spectrometer operating at 300.13 and 75.48 MHz, respectively. A
1
5
properties of all the new compounds were determined by spectrometer operating at 50.69 MHz was used to obtain
N
1
3
EXPLO5 (6.01). As shown in Table 1, all the dinitromethyl- spectra for 2. Chemical shis in the 1H and C spectra are
1
5
functionalized energetic salts have excellent detonation reported relative to Me
4 3
Si and N NMR to MeNO . DFT and ab
performance. The detonation velocity and pressure of 2 are initio calculations were carried out using the Gaussian 09
ꢀ
1
43
9
081 m s and 37.0 Gpa, superior to TATB at the same level of program package. The NCIs plots were calculated using
44
45
sensitivity, suggesting its promising applications as a candidate Multiwfn and visualized by VMD program. Hirshfeld
to replace TATB. Compounds 4, 10 and 11 possess higher surfaces and associated 2D ngerprints were generated by
ꢀ
1
46
detonation velocities and pressures (4: D ¼ 9226 m s , P ¼ 37.4 CrystalExplorer 3.1.25. The X-ray intensity data were measured
ꢀ
1
ꢀ1
Gpa; 10: D ¼ 9108 m s , P ¼ 34.0 Gpa; 11: D ¼ 9196 m s , P ¼ on a Bruker Apex 2 CCD system equipped with a graphite
˚
3
3.6 Gpa, respectively) than those of RDX, and detonation monochromator and a Mo-Ka ne focus tube (l ¼ 0.71073 A).
velocities comparable to those of HMX. Moreover, these An Oxford Cobra low-temperature device was used to maintain
compounds exhibit lower sensitivities than RDX and HMX, low temperatures. The melting and decomposition (onset)
indicating that they are the potential candidates for applica- points were obtained on a differential scanning calorimeter
ꢁ
ꢀ1
tions that require such properties.
(TA Instruments Co., model Q10) at the scan rate of 5 C min .
Densities were measured at room temperature using a Micro-
meritics AccuPyc 1330 gas pycnometer. The impact and friction-
sensitivity measurements were conducted by employing a stan-
dard BAM Fallhammer and a BAM friction tester.
Conclusions
In summary, the ammonium salt of dinitromethanide-1,2,4-
triazolone (2) crystallizes with close layer-by-layer stacking,
which plays a positive role in decreasing sensitivity. In addition, X-ray crystallography
intramolecular hydrogen-bonding interactions, second highest
A yellow block crystal of dimensions 0.095 ꢂ 0.063 ꢂ
(possessing 59%) and relatively stronger O–H weak interactions,
3
0
.028 mm for 2, a faint yellow block crystal of dimensions
as well as powerful p–p interactions together result in the
insensitivity of 2 towards mechanical stimuli which makes it
remarkably less sensitive than other 3-dinitromethanide-1,2,4-
triazolone-based compounds. The detonation velocity and
3
0
.44 ꢂ 0.21 ꢂ 0.04 mm for 5 and a yellow needle crystal of
3
dimensions 0.10 ꢂ 0.08 ꢂ 0.02 mm for 6 were used for the
X-ray crystallographic analysis. The X-ray intensity data were
measured on a Bruker Apex 2 CCD system equipped with
ꢀ
1
pressure of 2 are 9081 m s and 37.0 Gpa, respectively –
superior to TATB. This indicates that 2 may be a potential
replacement of TATB. In addition, the detonation performance
a graphite monochromator and a Mo-Ka ne focus tube
˚
(
0.71073 A). An Oxford Cobra low-temperature device was used
to maintain low temperatures. The frames were integrated with
the Bruker SAINT Soware package using a narrow-frame
algorithm and data were corrected for absorption effects
ꢀ
1
of 4, 10 and 11 (4: D ¼ 9226 m s , P ¼ 37.4 Gpa; 10: D ¼
ꢀ1
ꢀ1
9
108 m s , P ¼ 34.0 Gpa; 11: D ¼ 9196 m s , P ¼ 33.6 Gpa,
respectively) are superior to those of RDX and detonation
velocities are comparable to HMX, and are less sensitive to
impact and friction than those of RDX and HMX, suggesting
that these compounds could act as potential candidates with
decreased sensitivity and high performance. Overall, through
utilization of these stable factors, dinitromethyl-based energetic
materials can become insensitive, and these ndings may be
a promising tool to design high energy insensitive materials.
47
using the multiscan method (SADABS). The structures were
48
solved and rened using the Bruker SHELXTL Soware
Package.
Syntheses
General procedure for the preparation of salts 2, 4, 7, 8, 9
and 10. Compound 1 (0.378 g, 2 mmol) was added to ethanol
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(20 mL) with stirring. The free base (2 mmol) of aqueous NMR (DMSO-d6): d 171.4, 156.0, 153.1, 139.4, 124.4 ppm; IR
ammonia (25%), hydrazine hydrate (80%), and the neutral (KBr): ~n 3356, 3139, 1708, 1558, 1499, 1309, 1198, 1004,
ꢀ
1
compounds of 7–10 were added to the ethanol solution, 731 cm ; elemental analysis, calcd (%) for C H N O (273.17):
5
7 9 5
respectively. The reaction mixture was stirred at room temper- C: 21.76; H: 2.55; N: 46.75; found, C: 22.10; H: 2.59; N: 47.75.
ature for 30 min followed by standing for 3 h. The precipitate 4-Amino-1,2,4-triazolium 3-dinitromethanide-1,2,4-triazolone
was collected by ltration and washed with small amounts of (8). Yellow solid (0.84 g, 95%); H NMR (DMSO-d6): d 11.4
1
ethanol (5 ꢂ 2 mL) to give the products aer air drying.
(s, 1H), 11.1 (s, 1H), 9.74 (br, 2H), 8.7 (s, 1H), 6.0 (br, 2H) ppm;
C NMR (DMSO-d6): d 156.0, 144.0, 139.3, 124.3 ppm; IR (KBr):
1
3
General procedure for the preparation of salts 5 and 6. To
a stirring solution of the silver salt of 1 (590 mg, 2.0 mmol) in ~n 3337, 3240, 3124, 1690, 1548, 1483, 1376, 1296, 1222, 1136,
ꢀ1
water (10 mL), were added chlorides of 5 (191 mg, 2 mmol) or 6 1107, 993 cm ; elemental analysis, calcd (%) for C H N O
7 9 5
5
(221 mg, 2 mmol), respectively. Then, the reaction mixture was (273.17): C: 21.98; H: 2.58; N: 46.15; found, C: 22.00; H: 2.52; N:
stirred at room temperature for 30 min followed by standing for 45.95.
3
h. The ltrate was evaporated in vacuo; the solid residue was
3,5-Diamino-1,2,4-triazolium 3-dinitromethanide-1,2,4-triazolone
1
recrystallized from methanol and dried.
General procedure for the preparation of salts 11 and 12. 11.1 (s, 1H), 8.8 (s, 1H), 7.3 (s, 4H) ppm; C NMR (DMSO-d6):
Compound 1 (0.378 g, 2 mmol) was added to the ethanol with d 159.4, 156.7, 140.3, 124.4 ppm; IR (KBr): ~n 3325, 3157, 1700,
(9). Yellow solid (0.84 g, 95%); H NMR (DMSO-d6): d 11.4 (s, 1H),
1
3
ꢀ
1
stirring and the free base (4 mmol) of 11 and 12 were added to 1656, 1611, 1574, 1490, 1385, 1325, 1032, 1009, 937, 728 cm
;
the ethanol solution, respectively. The reaction mixture was elemental analysis, calcd (%) for C H N O (288.18): C: 20.84; H:
5
8 10 5
stirred at room temperature for 30 min followed by standing for 2.80; N: 48.60; found, C: 20.59; H: 2.60; N: 48.35.
3
h. The precipitate was collected by ltration and washed with
3,6,7-Triamino-[1,2,4]triazolo[4,3-b][1,2,4]triazolium 3-dinitro-
methanide-1,2,4-triazolone (10). Yellow solid (0.84 g, 95%); H
1
small amount of ethanol to give the products aer air drying.
Ammonium 3-dinitromethanide-1,2,4-triazolone (2). Yellow NMR (DMSO-d6): d 11.4 (s, 2H), 11.2 (s, 1H), 8.1 (s, 2H), 7.2 (s,
1
13
solid (0.84 g, 95%); H NMR (DMSO-d6): d 11.2 (s, 1H), 11.5 2H), 5.7 (s, 2H) ppm; C NMR (DMSO-d6): d 160.1, 156.0, 147.5,
1
3
(
s, 1H), 7.0–7.3 (t, 4H) ppm; C NMR (DMSO-d6): d 156.2, 139.5, 141.3, 139.5, 124.4 ppm; IR (KBr): ~n 3455, 3354, 3288, 3234,
1
5
1
2
1
24.6 ppm; N NMR (DMSO-d6): d ꢀ21.9, ꢀ112.2, 210.8, 212.9, 3153, 1690, 1653, 1551, 1475, 1410, 1275, 1250, 1140, 1041, 760,
ꢀ1
36.7, 358.3 ppm; IR (KBr): ~n 3064, 1692, 1545, 1481, 1449, 1351, 729 cm ; elemental analysis, calcd (%) for C H N O (345.24):
6
9 13 5
ꢀ1
222, 1215, 1150, 1065, 1036, 955, 802, 760, 739, 548 cm
elemental analysis, calcd (%) for C H N O (206.04): C: 17.48;
H: 2.93; N: 40.77; found, C: 17.29; H: 2.66; N: 40.55.
;
C: 21.00; H: 2.64; N: 53.05; found, C: 20.55; H: 2.60; N: 52.26.
Carbohydrazide 3-dinitromethanide-1,2,4-triazolone (11).
Yellow solid (0.84 g, 95%); H NMR (DMSO-d6): d 11.4 (br, 1H),
3
6 6 5
1
1
3
Hydrazinium 3-dinitromethanide-1,2,4-triazolone (4). Yellow 11.1 (br, 1H), 8.0 (br, 10H) ppm; C NMR (DMSO-d6): d 158.7,
1
solid (0.84 g, 95%); H NMR (DMSO-d6): d 11.4 (s, 1H), 11.1 155.9, 139.4, 124.4 ppm; IR (KBr): ~n 3346, 3113, 1663, 1570,
1
3
ꢀ1
(
1
s, 1H), 9.95 (s, 5H) ppm; C NMR (DMSO-d6): d 155.9, 139.4, 1480, 1460, 1213, 1136, 1068, 978, 798, 761 cm ; elemental
1
5
24.4 ppm; N NMR (DMSO-d6): d ꢀ21.9, ꢀ112.2, ꢀ210.9, analysis, calcd (%) for C
5 15 13 7
H N O (369.26): C: 16.26; H: 4.09; N:
ꢀ
212.8, ꢀ217.0, ꢀ237.4, ꢀ331.6 ppm; IR (KBr): ~n 3343, 3287, 49.31; found, C: 16.11; H: 4.09; N: 49.04.
3
1
(
074, 2992, 2887, 1725, 1628, 1575, 1508, 1250, 1140, 1102,
Dicarbohydrazide 3-dinitromethanide-1,2,4-triazolone (12).
Yellow solid (0.84 g, 95%); H NMR (DMSO-d6): d 11.4 (br, 1H),
ꢀ
1
1
080, 966, 746 cm ; elemental analysis, calcd (%) for C H N O
7 7 5
221.13): C: 16.29; H: 3.19; N: 44.34; found, C: 16.19; H: 3.16; N: 11.1 (br, 1H), 8.0 (br, 10H) ppm; C NMR (DMSO-d6): d 157.3,
3
1
3
1
5
43.89.
155.9, 139.4, 124.4 ppm; N NMR (DMSO-d6): d ꢀ21.9, ꢀ72.2,
Guanidinium 3-dinitromethanide-1,2,4-triazolone (5). Yellow ꢀ112.2, ꢀ237.5, ꢀ297.9 ppm; IR (KBr): ~n 3346, 3112, 1664, 1570,
1
ꢀ1
solid (0.84 g, 95%); H NMR (DMSO-d6): d 11.1 (br, 2H), 7.0 (br, 1479, 1460, 1212, 1136, 1070, 978, 799, 762 cm ; elemental
1
3
6
H) ppm; C NMR (DMSO-d6): d 157.9, 156.5, 140.0, 124.7 ppm; analysis, calcd (%) for C
7 15 13 9
H N O (425.28): C: 19.77; H: 3.56; N:
IR (KBr): ~n 3466, 3414, 3349, 3269, 3206, 1723, 1647, 1494, 1452, 42.82; found, C: 19.69; H: 3.55; N: 42.04.
ꢀ1
1
361, 1219, 1134, 1072, 962 cm ; elemental analysis, calcd (%)
for C H N O (248.16): C: 19.36; H: 3.25; N: 45.15; found, C:
4
8 8 5
Conflicts of interest
19.15; H: 3.13; N: 44.40.
Aminoguanidinum 3-dinitromethanide-1,2,4-triazolone (6). The authors declare no conict of interest
1
Yellow solid (0.84 g, 95%); H NMR (DMSO-d6): d 11.4 (s, 1H),
1
3
1
1.1 (s, 1H), 8.54 (s, 1H), 6.7–7.2 (br, 4H), 4.67 (s, 2H) ppm;
C
Acknowledgements
1
5
NMR (DMSO-d6): d 158.8, 156.0, 139.4, 124.4 ppm; N NMR
DMSO-d6): d ꢀ21.9, ꢀ112.2, ꢀ112.4, ꢀ211.0, ꢀ213.0, ꢀ236.5, The authors acknowledge nancial support from the Office of
(
ꢀ
238.5, ꢀ282.5, 284.4 ppm; IR (KBr): ~n 3426, 3343, 3226, 1740, Naval Research (N00014-16-1-2089), the Defense Threat Reduction
ꢀ1
1
665, 1506, 1448, 1393, 1233, 1138, 1072, 1033, 962 cm
;
Agency (HDTRA 1-15-1-0028), the Shenzhen Science and Tech-
(263.17): C: 18.26; nology Innovation Committee (JCYJ20151013162733704), and the
Thousand Talents Plan (Youth). X-ray single crystal structure
-Amino-1,2,4-triazolium 3-dinitromethanide-1,2,4-triazolone determinations have been deposited with the Cambridge Crystal-
4 9 9 5
elemental analysis, calcd (%) for C H N O
H: 3.45; N: 47.90; found, C: 17.98; H: 3.45; N: 47.28.
3
1
(
7). Yellow solid (0.84 g, 95%); H NMR (DMSO-d6): d 11.4 lographic Data Centre with CCDC numbers (1853787, 1853790,
1
3
(s, 1H), 11.1 (s, 1H), 7.8 (s, 1H), 7.5 (s, 2H), 5.9 (s, 1H) ppm;
C
1853948).†
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7 X. Zhao, S. Li, Y. Wang, Y. Li, F. Zhao and S. Pang, J. Mater.
Chem. A, 2016, 4, 5495–5504.
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