4-(1-Amino-5-aminotetrazolyl)methyleneimino-3-methylfuroxan and its derivatives: Synthesis, characterization, and energetic properties

Article abstract of DOI:10.1002/ejic.201301363

The condensation reaction of 4-formyl-3-methylfuroxan with 1,5-diaminotetrazole led to 4-(1-amino-5-aminotetrazolyl)methyleneimino-3- methylfuroxan (1) in high yield. Its structure was confirmed by an X-ray diffraction study. 4-(1-Amino-5-nitriminotetrazolyl)methyleneimino-3- methylfuroxan (2) was obtained through the nitration of 1 with 100 % HNO ₃. The nitrogen-rich salts of 2 with bases such as 1-amino-1,2,3-triazole (3), 4-amino-1,2,4-triazole (4), and 3-amino-1,2,4- triazole (5) were synthesized and characterized by IR, Raman, and NMR spectroscopy and elemental analysis. In addition, the structures of 2, 4, and 5 were further confirmed by single-crystal X-ray diffraction analyses. Compound 5 decomposes at 183 °C, whereas 3 and 4 are less stable and decompose at 139 and 164 °C, respectively. The heats of formation, detonation parameters, and impact sensitivity of 1-5 were investigated by theoretical and experimental methods. The synthesis of 4-(1-amino-5-aminotetrazolyl)methyleneimino-3- methylfuroxan from 3-methyl-4-formylfuroxan and 1,5-diaminotetrazole yields a thermally stable energetic compound. Its nitroiminotetrazole derivative exhibits high positive heats of formation and good detonation performance. Three nitrogen-rich energetic salts combine moderate thermal stabilities with acceptable sensitivities. Copyright

Full text of DOI:10.1002/ejic.201301363

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DOI:10.1002/ejic.201301363
4-(1-Amino-5-aminotetrazolyl)methyleneimino-3-
methylfuroxan and Its Derivatives: Synthesis,
Characterization, and Energetic Properties
Yongxing Tang,[a] Hongwei Yang,[a] Jianhua Shen,[a] Bo Wu,[a]
Xuehai Ju,[a] Chunxu Lu,[a] and Guangbin Cheng*[a]
Keywords: Energetic materials / Nitrogen heterocycles / Structure elucidation / Density functional calculations
The condensation reaction of 4-formyl-3-methylfuroxan with
1,5-diaminotetrazole led to 4-(1-amino-5-aminotetrazolyl)-
methyleneimino-3-methylfuroxan (1) in high yield. Its struc-
ture was confirmed by an X-ray diffraction study. 4-(1-
by IR, Raman, and NMR spectroscopy and elemental analy-
sis. In addition, the structures of 2, 4, and 5 were further con-
firmed by single-crystal X-ray diffraction analyses. Com-
pound 5 decomposes at 183 °C, whereas 3 and 4 are less
Amino-5-nitriminotetrazolyl)methyleneimino-3-methylfur- stable and decompose at 139 and 164 °C, respectively. The
oxan (2) was obtained through the nitration of 1 with 100%
HNO3. The nitrogen-rich salts of 2 with bases such as 1-
heats of formation, detonation parameters, and impact sensi-
tivity of 1–5 were investigated by theoretical and experimen-
amino-1,2,3-triazole (3), 4-amino-1,2,4-triazole (4), and 3- tal methods.
amino-1,2,4-triazole (5) were synthesized and characterized
be used as a valuable substrate in the preparation of high-
Introduction
energy-density materials. However, DAT, like most other
tetrazole derivatives, is oxygen deficient. To find practical
use as a high explosive, the introduction of oxidizing groups
to DAT is required.
The development of new high-energy-density materials
(HEDM) continues to focus on the synthesis of the high-
nitrogen compounds. High-nitrogen materials are increas-
ingly being tested as green replacements for traditional ex-
plosives, which are toxic and carcinogenic.[1] Many high-
nitrogen heterocycles such as furazan,[2] 1,2,3,4-tetrazine,[3]
tetrazole,[4] and triazole[5] have exceptionally high heats of
formation and are highly endothermic in nature. Recently,
many types of energetic compounds containing different
energetic moieties have been investigated and synthesized.[6]
The synthesis of tetrazoles as energetic materials and in-
termediates to energetic materials has been in focus for the
last two decades. Most of the energy derives from positive
heats of formation rather than from oxidation of a carbon
backbone. 1,5-Diaminotetrazole (DAT),[7] as a simple
tetrazole derivative, exhibits a relatively high thermal sta-
bility owing to the electron-donating side groups. In ad-
dition, DAT has a high heat of formation; therefore, it can
Furoxan (1,2,5-oxadiazole 2-oxide) is a highly energetic
heterocycle of the isoxazole family and a N-oxide derivative
of furazan. As such, the introduction of a furoxan ring to
organic compounds has been proved to increase crystal
density and improve explosive performance compared to
that for nitro groups.[8] Firstly, the aromatic nature of the
furoxan moiety makes the molecule thermally stable. Sec-
ondly, the planarity of the ring helps to increase the crystal
density owing to the dense packing of molecules. Thirdly,
furoxan, which has a “latent” nitro group within one side
of its ring, is an effective structural unit that itself is an
explosive group. By introducing a furoxan ring into high-
energy-density molecules, the density can be increased by
ca. 0.06–0.08gcm–3, and the detonation velocity can also
be increased by ca. 300ms–1.[9]
Considering these factors, the combination of the two
different energetic units (tetrazole and furoxan) into one
molecule is expected to produce good energetic materials
with excellent properties such as good thermal stability and
low sensitivity. In this paper, we describe the synthesis of 4-
(1-amino-5-aminotetrazolyl)methyleneimino-3-methylfur-
oxan (1) from 3-methyl-4-formylfuroxan[10] and 1,5-di-
aminotetrazole.[11] The nitration of 1 with 100% nitric acid
[a] School of Chemical Engineering, Nanjing University of Science
and Technology,
Xiaolingwei 200, Nanjing, Jiangsu, China
E-mail: gcheng@mail.njust.edu.cn
http://www.njust.edu.cn/
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201301363.
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resulted in a nitroiminotetrazole derivative 4-(1-amino-5- man spectroscopy and elemental analysis. The structures of
nitriminotetrazolyl)methyleneimino-3-methylfuroxan (2), 1, 2, 4, and 5 were further confirmed by single-crystal X-
which exhibits good detonation performance because it ray diffraction.
combines the strongly oxidizing nitroimino group, a fur-
oxan ring, and the energetic nitrogen-rich backbone in one
Single-Crystal X-ray Analysis
molecule. Furthermore, three energetic salts were obtained.
These compounds were fully characterized by IR spec-
Single crystals of 1, 4, and 5 were obtained by slow evap-
oration of solutions of 1, 4, and 5 in MeOH/H2O, and sin-
gle crystals of 2 were obtained by recrystallization from
water. Their ORTEP and packing diagrams are shown in
Figures 1–4, and the crystallographic data are summarized
in Table 1. The bond lengths and angles are also listed in
the Supporting Information (Tables S1–S16).
1
troscopy, Raman spectroscopy, elemental analysis, H and
13C NMR spectroscopy, and single-crystal structure analy-
ses. Their densities, heats of formation, thermal behavior,
and detonation parameters were further investigated by ex-
perimental and theoretical methods.
Results and Discussion
Synthesis
As shown in Scheme 1, 4-(1-amino-5-aminotetrazolyl)-
methyleneimino-3-methylfuroxan (1) was prepared in a high
yield of 75% by the condensation reaction of 4-formyl-3-
methylfuroxan with 1,5-diaminotetrazole in water at 75 °C.
An initial attempt to synthesize 4-(1-amino-5-nitrimino-
tetrazolyl)methyleneimino-3-methylfuroxan (2) by nitration
of 1 with a mixture of excess 95% nitric acid and 98% sulf-
uric acid was unsuccessful. However, compound 2 was ob-
tained in 41% yield by the nitration of 1 with 100% nitric
acid (Scheme 1). Compound 2 is neither hygroscopic nor
sensitive towards light and air. The formation of the nitro-
gen-rich salts was accomplished in a straightforward man-
ner by acid–base reactions between 2 and energetic bases in
aqueous solutions. The structures of the resulting com-
1
pounds are supported by H and 13C NMR, IR, and Ra-
Figure 1. (a) Thermal ellipsoid plot (50%) and labeling scheme for
1. Hydrogen atoms are included but are unlabeled for clarity. (b)
Ball-and-stick packing diagram of 1 viewed down the b and c axes.
Dashed lines indicate strong hydrogen bonds.
Compound 1 crystallizes with a calculated density of
1.546 gcm–3 in the space group P21/c with four formula
units in the unit cell. The ring geometries of the tetrazole
and furoxan rings are in good agreement with those pre-
viously reported.[12] The N6–C2 and C1–N1 bond lengths
are 1.277 and 1.330 Å, respectively. The dihedral angle be-
tween the two planes is 5.936°. The molecular unit is de-
picted in Figure 1 (a). The hydrogen bonds build up a dense
3D network as shown in Figure 1 (b). The 3D network con-
sists of condensed “rhombic prisms” built by the molecules
Scheme 1. Synthesis of 4-(1-amino-5-aminotetrazolyl)methyl-
eneimino-3-methylfuroxan (1), 4-(1-amino-5-nitriminotetrazolyl)-
methyleneimino-3-methylfuroxan (2), and salts (3–5).
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Figure 2. (a) Thermal ellipsoid plot (50%) and labeling scheme for
2. Hydrogen atoms are included but are unlabeled for clarity. (b)
Ball-and-stick packing diagram of 2 viewed down the a and c axes.
Dashed lines indicate strong hydrogen bonds.
Figure 4. (a) Thermal ellipsoid plot (50%) and labeling scheme for
5. Hydrogen atoms are included but are unlabeled for clarity. (b)
Ball-and-stick packing diagram of 5 viewed down the b axis.
Dashed lines indicate strong hydrogen bonds.
of 1. The oxygen atom (O2) of the N-oxide group is in-
volved in the formation of a weak intermolecular hydrogen
bond with the NH fragment [H···O is 0.8600 Å, N···O
2.892(3) Å, N–H···O angle 143°].
Compound 2 crystallizes in the space group P21/c with
four formula units in the unit cell and a density of
1.712 gcm–3, which is significantly higher than that of 1.
This result nicely confirms the concept of increased density
by the introduction of NO2 groups.[13] The unit cell of 2 is
depicted in Figure 2 (a). Correspondingly, the bonds C1–
N1 (1.271 Å) and C2–N6 (1.321 Å) are shortened compared
to the values of 1.363(2) and 1.356(2) Å for 1. The tetrazole
ring is slightly distorted, and the dihedral angle between the
two planes is 7.62(1)°. From Figure 2 (b), it can be clearly
seen that intermolecular hydrogen bonds are formed in the
compound, and the extensive hydrogen-bonding interac-
tions contribute to an increase in density. Analysis of the
crystal packing of 2 shows that the 3D network is Z-shaped.
Compounds 4 and 5 crystallize in the space group P21/c
with four formula units in the unit cell. The structure of 5
shows only a slightly higher density (1.681 gcm–3) than that
Figure 3. (a) Thermal ellipsoid plot (50%) and labeling scheme for
4. Hydrogen atoms are included but are unlabeled for clarity. (b)
Ball-and-stick packing diagram of 4 viewed down the a axis.
Dashed lines indicate strong hydrogen bonds.
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Table 1. Crystallographic data for 1, 2, 4, and 5.
1
2
4
5
Formula
C5H6N8O2
210.18
291
monoclinic
P21/c
6.2287(11)
8.0735(12)
17.9653(17)
90
C5H5N9O4
255.18
291
monoclinic
P21/c
6.268(4)
16.508(9)
9.862(5)
90
C7H9N13O4
339.27
173
monoclinic
P21/c
7.7870(19)
17.917(4)
10.411(2)
90
C7H9N13O4
339.27
173
monoclinic
P21/c
12.589(3)
5.3365(10)
20.130(4)
90
FW [gmol–1]
Temperature [K]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
γ [°]
91.840(3)
90
903.0(2)
4
104.01(6)
90
990.0(9)
4
111.121(2)
90
1355.0(5)
4
97.582(2)
90
1340.5(4)
4
Cell volume [Å3]
Z
ρcalcd. [gcm–3]
Absorption correction
θ range for data collection[°]
Refinement method
Goodness-of-fit on F2
R1, wR2 [IϾ2σ(I)]
R1, wR2 (all data)
1.546
1.712
1.663
multiscan
1.681
3.27–25.99
2.56–22.97
2.27–26.00
2.44–23.72
full-matrix least squares on F2
1.034
1.038
1.043
1.027
0.0571, 0.1325
0.0698, 0.1412
0.0492, 0.1320
0.0523, 0.1368
0.332 and –0.301
0.0481, 0.1226
0.0818, 0.1515
0.420 and –0.506
0.0450, 0.1043
0.0662, 0.1154
0.214 and –0.269
Largest diff. peak and hole [eÅ–3] 0.207 and –0.239
of 4 (1.663 gcm–3). The structure of the anion is similar to
In all of the 13C NMR spectra, the shifts corresponding
that of the corresponding acid 2. The C2–N6 bond lengths to the cations and anions in this study are in good agree-
(1.353 and 1.362 Å, respectively) in 4 and 5 are both longer ment with previously recorded shifts for the relevant cations
than that of 2, which may be attributed to the protonation and anions.[14] In the 13C NMR spectra of the salts 3–5, the
of the tetrazole ring. In the structure of 4, a hydrogen atom resonance of the carbon atom of the tetrazole ring is ob-
occupies two positions at N11 (0.77) and N5 (0.23). Further served at lower field (δ = ca. 153.5 ppm) than that of 2
details are provided in the Supporting Information.
(δ = 152.3 ppm) as a consequence of the deshielding effect
produced by the delocalization of the negative charge.
NMR Spectroscopy
Thermal Behavior and Sensitivities
Compounds 1–5 in [D6]DMSO were analyzed by 1H and
1
13C NMR spectroscopy (Figures S1–S10). In the H NMR
The thermal stabilities of the above compounds were de-
spectra, the C–H proton resonances are observed as sharp termined by differential scanning calorimetric (DSC) mea-
signals at δ = 9.08 (1), 9.31 (2), 9.30 (3), 9.26 (4), and surements at 5 °Cmin–1 (Figures S11–S15). The decomposi-
9.25 ppm (5). In addition, the methyl proton signals are tion temperatures are given as peak maximum temperatures
found at δ = 2.35–2.44 ppm. The highly acidic N–H proton (Table 2). The highest decomposition temperature (205 °C)
resonance is found as a broad resonance at δ = 11.65 ppm was observed for 1, and the lowest decomposition tempera-
for 2. The N–H proton resonance of the triazole cation of ture (139 °C) was obtained for the salt 3. The DSC curve
3 is found at δ = 7.92 ppm, whereas that of the triazole of 3 shows an endothermic event with a heat variation start-
cation of 4 is found at δ = 9.43 ppm. The 3-amino-1,2,4- ing at 133 °C, followed by two exothermic events (Td = 139
triazole cation of 5 shows signals at δ = 8.31 (CH) and and 154 °C). The endothermic event at 133 °C is character-
8.04 ppm (NH+).
istic of a melting process. Nitriminotetrazole 2 showed an
Table 2. Properties of 1–5 compared with those of TNT and RDX.
1
2
3
4
5
TNT
RDX
1.816
ρ[a] [gcm–3]
Q[b] [Jg–1]
D[c] [ms–1]
P[d] [GPa]
1.546
4894
6980
19.65
544.40
200
205
0.180
7.6
1.712
6441
8060
27.94
742.99
140
146
0.050
5.8
1.663[j]
5784
7690
25.01
995.05
133
139
0.500
20
1.663
5508
7600
24.41
901.26
150
164
0.750
32
1.681
5090
7510
23.98
759.41
179
183
0.600
24
1.65
4271
6881
19.50
–295.00
80
8977
35.17
92.60
–
ΔfHm [kJmol–1]
[e]
[f]
Tm [°C]
[g]
Tdec [°C]
295[17]
–
205[16]
0.1–0.2[17]
7.5[17]
ESD[h] [J]
IS[i] [J]
15[17]
[a] Density from X-ray diffraction. [b] Heat of explosion. [c] Calculated detonation velocity. [d] Calculated detonation pressure. [e]
Calculated molar enthalpy of formation. [f] Melting point (onset). [g] Temperature of decomposition (peak of maximum). [h] Electrostatic
discharge sensitivity. [i] Impact sensitivity. [j] Calculated with the same density as that of 4.
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exothermic decomposition in the temperature range 135– as 1-amino-1,2,3-triazole (3), 4-amino-1,2,4-triazole (4),
155 °C with a peak maximum at 146 °C. In comparison and 3-amino-1,2,4-triazole (5) were investigated and char-
with the decomposition temperature of 2, those of both the acterized by IR, Raman, and NMR spectroscopy and ele-
triazole salts 4 and 5 were higher. Therefore, these studies mental analysis. Furthermore, the structural characteristics
show that salts 4 and 5 presented here have higher thermal for 2, 4, and 5 were further confirmed by single-crystal X-
stabilities than that of 2, which is probably attributable to ray diffraction analyses. Compound 5 has high thermal sta-
the extensive hydrogen bonding, as observed in the crystal bility with a decomposition temperature of 183 °C, whereas
structures, and the higher electron density within the tetraz- 3 and 4 are less stable and decompose at 139 and 164 °C,
ole ring. Salt 4 undergoes a three-step decomposition, and respectively. The heats of formation of 1–5 were predicted
the exothermic peaks are presented at 164, 169, and 174 °C, at the CSB-4M level of theory. All of the compounds have
respectively.
highly endothermic heats of formation; 5 has the highest
Impact-sensitivity measurements were performed by heat of formation (995.1 kJmol–1) of 1–5.
using the standard BAM method.[15] Additionally, all com-
pounds were tested for sensitivity toward electrical dis-
Experimental Section
charge by using an ESD JGY-50 III electric spark tester.
The data are shown in Table 2. The sensitivity of parent
compound 1 (7.6 J) is similar to that of RDX (7.5 J). The
nitration product 2 is more sensitive (5.8 J) than RDX;
however, the impact sensitivities for salts 3–5 of 20–32 J are
Caution! Although none of the compounds described herein exploded
or detonated in the course of this research, these materials should be
handled with extreme care by using the best safety practices.
Laboratories and personnel should be properly grounded, and safety
much higher than that of RDX. As can be seen from equipment such as Kevlar gloves, leather coats, face shields, and ear
plugs are strongly recommended.
Table 2, similar trends are observed in the electrostatic dis-
charge sensitivity results. Although 2 is sensitive (50 mJ) to
electrostatic discharge, 3 (500 mJ), 4 (750 mJ), and 5
(600 mJ) are significantly less sensitive.
General Methods: All chemical reagents and solvents (analytical
grade) were used as supplied unless otherwise stated. H and 13C
1
NMR spectra were measured with a Bruker Avance III 500 MHz
Digital NMR Spectrometer operating at 500 and 126 MHz, respec-
tively. FTIR spectra were recorded with a BOMEM MB Series
154S FTIR spectrometer. Raman spectra were measured with a
RamTracer®-200 instrument. Mass spectra were recorded with an
ultrafleXtreme MALDI-TOF/MS instrument with an electron im-
Heats of Formation and Detonation Parameters
To investigate the energetic properties of these new com-
pounds, the gas-phase enthalpies of formation of the above pact (EI) ion source. Elemental analyses were performed with a
Vario EL III instrument. TG and DSC studies were performed at
a heating rate of 5 °Cmin–1 in closed Al containers with a nitrogen
flow of 30 mLmin–1 with an STD-Q600 instrument. The electro-
static sensitivity test was performed with an ESD JGY-50 III elec-
tric spark tester. The impact-sensitivity tests were performed with
an HGZ-1 drop hammer. Test specimens were kept between two
hardened anvils, and a 2.0 or 5.0 kg drop weight was allowed to
fall freely from different heights. Twenty-five tests were conducted
for each compound.
compounds were calculated by using the Gaussian 03 suite
of programs.[18] The lattice energy of the ionic salts were
predicted by using the formula suggested by Jenkins et
al.[19] The results are listed in Table 2. The resulting heats
of formation of these compounds vary between 544.4 (1)
and 995.1 kJmol–1 (3). The predicted heats of explosion of
1–5 vary between the low value for the nitrogen-rich com-
pound 1 (4894 Jg–1) to the high value for nitramine com-
pound 2 (6441 Jg–1).
The P and D values in Table 2 indicate that no com-
pound can reach the detonation performance of RDX
(8977 ms–1, 35.17 GPa); however, 2 (8060 ms–1, 27.94 GPa)
exhibits superior detonation performance than that of TNT
X-ray Crystallography: The X-ray diffraction measurements for 1
and 2 were performed with a Rigaku RAXIS-RAPID imaging-
plate diffractometer at 291 K by using graphite-monochromated
Mo-Kα radiation (λ = 0.71075 Å). The data were collected by the
ω-scan technique. The data for 4 and 5 were collected with a Bruker
(6881 ms–1, 19.50 GPa). The corresponding parameters of three-circle platform diffractometer equipped with a SMART
APEX II CCD detector. A Kryo-Flex low-temperature device was
used to keep the crystals at a constant 173 K during the data collec-
tion. The data collection and the initial unit cell refinement was
performed by using APEX2 (v2010.3-0).[20] Data Reduction was
performed by using SAINT (v7.68A)[21] and XPREP (v2008/2).[22]
Corrections were applied for Lorentz, polarization, and absorption
effects by using SADABS (v2008/1).[23] The structure was solved
and refined with the aid of the programs in the SHELXTL-plus
(v2008/4)[24] system of programs. The full-matrix least-squares re-
finement on F2 included atomic coordinates and anisotropic ther-
mal parameters for all non-H atoms. The H atoms were included
in a riding model. The structure was solved by direct methods with
SHELXS-97 and expanded by using the Fourier technique. The
non-hydrogen atoms were refined anisotropically. The hydrogen
atoms were located and refined. Please see the CIF files. Relevant
salts 3, 4, and 5 are better than that of TNT, whereas the
result of 1 (6980 ms–1, 19.65 GPa) is similar to that of TNT.
Conclusions
The parent compound 1 was prepared in 75% yield
through the condensation reaction of 4-formyl-3-methyl-
furoxan with 1,5-diaminotetrazole. It was fully charac-
terized, and its structure was confirmed by single-crystal X-
ray diffraction. The new nitramine derivative 4-(1-amino-5-
nitriminotetrazolyl)methyleneimino-3-methylfuroxan
(2)
was prepared by nitration of 1 with 100% nitric acid. In
comparison with 1, it shows a lower decomposition point
(146 vs. 205 °C). The nitrogen-rich salts of 2 with bases such data are given in Tables S1–S16.
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Theoretical Study: Computations were performed by using the
P = 1.558 ρ2Φ
(3)
(4)
(5)
Gaussian03 suite of programs. The elementary geometric optimiza-
tion and the frequency analysis were performed at the level of the
Becke three parameter, Lee–Yan–Parr (B3LYP) functional[25] with
the 6-311+G** basis set.[26] All of the optimized structures were
characterized to be local energy minima on the potential surface
without any imaginary frequencies.
D = 1.01Φ1/2(1 + 1.30ρ0)
Φ = 0.4889N(MQ)1/2
D is the predicted detonation velocity (kms–1), P is the detonation
pressure (GPa), and ρ is the compound density (cm3 mol–1). Φ, N,
M and Q are characteristic parameters of an explosive; Q is the
chemical energy of detonation (kJg–1). The crystal densities and
the calculated heats of formation were used to compute the D and
P values.
Starting Materials: 4-Formyl-3-methylfuroxan,[10] 1,5-diamino-
tetrazole,[11] 1-amino-1,2,3-triazole,[30] 4-amino-1,2,4-triazole,[31]
and 3-amino-1,2,4-triazole[32] were synthesized according to litera-
ture procedures.
The predictions of heats of formation (HOF) used the hybrid DFT-
B3LYP methods with the 6-311+G** basis set through designed
isodesmic reactions. The isodesmic reaction processes, that is, the
number of each kind of formal bond is conserved, were used with
the application of the bond separation reaction (BSR) rules. The
molecule was broken down into a set of two heavy-atom molecules
containing the same component bonds. The isodesmic reactions
used to derive the HOF of the title compounds are shown in
Scheme 2. The change of enthalpy for the reactions at 298 K can
be expressed as Equation (1).
4-(1-Amino-5-aminotetrazolyl)methyleneimino-3-methylfuroxan (1):
A suspension of DAT (1.0 g, 10 mmol) in water (10 mL) was added
to a solution of 3-methyl-4-furaxancarbaldehyde (1.28 g, 10 mmol)
in water (10 mL). Two drops of concentrated HCl were then added,
and the mixture was heated at 75 °C for 1 h and then cooled. The
precipitate was collected by filtration and washed with ice water,
yield 1.58 g (75%), white powder. 1H NMR (500 MHz, [D6]-
DMSO): δ = 9.08 (s, 1 H), 7.45 (s, 2 H), 2.44 (s, 3 H) ppm. 13C
NMR (126 MHz, [D6]DMSO): δ = 152.5, 152.3, 142.5, 111.2,
8.7 ppm. IR: ν = 3395 (vw), 3086 (w), 3020 (vw), 2921 (vw), 1660
˜
(m), 1599 (vs), 1464 (s), 1443 (s), 1354 (m), 1308 (v), 1265 (v), 1173
(v), 1094 (m), 1046 (s), 989 (m), 971 (m), 880 (v), 832 (s), 777 (m),
725 (m), 680 (m) cm–1. Raman: ν = 1616, 1590, 1440, 1356, 1308,
˜
1268, 1178, 1104, 1040, 990, 970, 876, 828, 772, 718, 614 cm–1. MS
(EI): m/z (%) = 210 (18) [M]+, 142 (100), 125 (67) [M – CH3N5]+.
C5H6N8O2 (210.06): calcd. C 28.58, H 2.88, N 53.32; found C
28.56, H 2.86, N 53.33. Electrostatic discharge sensitivity (ESD):
180 mJ. Impact friction: 7.6 J.
4-(1-Amino-5-nitriminotetrazolyl)methyleneimino-3-methylfuroxan
(2): At 0 °C, solid 1 (1.0 g, 4.76 mmol) was added in small portions
to 100% HNO3 (10 mL). The reaction mixture was stirred at 0 °C
for 8 h. The solution was poured into ice water (50 mL) and then
extracted with diethyl ether (25 mLϫ4). The combined organic
phase was dried with anhydrous MgSO4 and filtered. Compound
Scheme 2. Isodesmic and tautomeric reactions to compute the
HOF.
1
ΔH298 = ΣΔfHP – ΣΔfHR
(1) 2 was obtained by slow evaporation, yield 0.5 g (41%). H NMR
(500 MHz, [D6]DMSO): δ = 11.65 (br), 9.31 (s, 1 H), 2.37 (s, 3 H)
ppm. 13C NMR (126 MHz, [D6]DMSO): δ = 152.3, 150.7, 145.0,
ΔfHR and ΔfHP are the HOF of the reactants and products at 298
K, respectively, and ΔH298 can be calculated from the following
expression, see Equation (2).
111.1, 8.5 ppm. IR: ν = 3020 (vw), 1627 (m), 1599 (m), 1569 (m),
˜
1505 (s), 1474 (m), 1418 (vw), 1298 (w), 1274 (w), 1236 (vs), 1204
(s), 1121 (s), 1047 (m), 990 (m), 956 (s), 874 (m), 822 (m), 736 (m),
679 (m), 611 (m) cm–1. Raman: ν = 1624, 1614, 1570, 1510, 1418,
˜
ΔH298 = ΔE298 + Δ(PV) = ΔE0 + ΔZPE + ΔHT + ΔnRT
(2)
1332, 1236, 1204, 1182, 1124, 1022, 990, 872, 756, 610, 466 cm–1.
C5H9N9O4 (255.05): calcd. C 23.54, H 1.98, N 49.40; found C
23.58, H 1.99, N 49.36. ESD: 50 mJ. Impact friction: 5.8 J.
ΔE0 is the change in total energy between the products and the
reactants at 0 K; ΔZPE is the difference between the zero-point
energies (ZPE) of the products and the reactants at 0 K; ΔHT is
General Procedure for Synthesis of Salts 3–5: A solution of 1-
the thermal correction from 0 to 298 K. The Δ(PV) value in Equa- amino-1,2,3-triazole (0.084 g, 1 mmol), 4-amino-1,2,4-triazole
tion [(2)] is the PV work term. It equals ΔnRT for the reactions of
an ideal gas. For the isodesmic reactions, Δn = 0, so Δ(PV) = 0.
On the left side of Equation [(1)], apart from target compound, all
the others are called reference compounds. The HOF of reference
compounds are available either from experiments[27–29] or from the
high-level computing such as CBS-4M.
(0.084 g, 1 mmol) and 3-amino-1,2,4-triazole (0.084 g, 1 mmol) in
H2O (5 mL) was added dropwise to a suspension of 2 (0.255 g,
1 mmol) in H2O (5 mL) under stirring. The mixture was stirred at
room temperature for 2 h. The precipitate was then removed by
filtration and washed with a small amount of ice water. The filtrate
was dried to afford the crude product. Salts 3, 4, and 5 were then
recrystallized from methanol.
The detonation velocity (D) and detonation pressure (P) were
evaluated by the empirical Kamlet–Jacobs (K–J) equations as
shown in Equations (3), (4), (5).
3: 0.32 g of white solid was obtained (yield 94%). 1H NMR
(500 MHz, [D6]DMSO): δ = 9.30 (s, 1 H), 7.92 (s, 1 H), 7.68 (s, 1
Eur. J. Inorg. Chem. 2014, 1231–1238
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H), 2.36 (s, 3 H) ppm. 13C NMR (126 MHz, [D6]DMSO): δ =
[4]
a) M. Göbel, K. Karaghiosoff, T. M. Klapötke, D. G. Piercey,
J. Stierstorfer, J. Am. Chem. Soc. 2010, 132, 17216–17226; b)
N. Fischer, D. Izsak, T. M. Klapötke, J. Stierstorfer, Chem. Eur.
J. 2013, 19, 8948–8957; c) Y.-H. Joo, J. M. Shreeve, Angew.
Chem. 2009, 121, 572; Angew. Chem. Int. Ed. 2009, 48, 564–
567.
a) A. A. Dippold, T. M. Klapötke, J. Am. Chem. Soc. 2013,
135, 9931–9938; b) T. M. Klapötke, C. M. Sabate, Eur. J. Inorg.
Chem. 2008, 5350–5366; c) A. A. Dippold, T. M. Klapötke,
F. A. Martin, S. Wiedbrauk, Eur. J. Inorg. Chem. 2012, 2429–
2443.
a) H. F. Huang, Z. M. Zhou, L. X. Liang, J. H. Song, K.
Wang, D. Cao, W. W. Sun, C. M. Bian, M. Xue, Chem. Asian
J. 2012, 7, 707–714; b) L. X. Liang, H. F. Huang, K. Wang,
C. M. Bian, J. H. Song, L. M. Ling, F. Q. Zhao, Z. M. Zhou,
J. Mater. Chem. 2012, 22, 21954–21964.
a) T. M. Klapötke, F. A. Martin, J. Stierstorfer, Chem. Eur. J.
2012, 18, 1487–1501; b) J. C. Galvez-Ruiz, G. Holl, K. Kar-
aghiosoff, T. M. Klapötke, K. Lohnwitz, P. Mayer, H. Noth,
K. Polborn, C. J. Rohbogner, M. Suter, J. J. Weigand, Inorg.
Chem. 2005, 44, 4237–4253; c) Y.-H. Joo, B. Twamley, S. Garg,
J. M. Shreeve, Angew. Chem. 2008, 120, 6332–6335; d) Y.-H.
Joo, B. Twamley, J. M. Shreeve, Chem. Eur. J. 2009, 15, 9097–
9104; e) F. Li, X. M. Cong, Z. M. Du, C. L. He, L. S. Zhao,
L. Q. Meng, New J. Chem. 2012, 36, 1953–1956; f) Y. X. Tang,
H. W. Yang, J. H. Shen, B. Wu, X. H. Ju, C. X. Lu, G. B.
Cheng, Angew. Chem. Int. Ed. 2013, 52, 4875–4877.
a) V. P. Sinditskii, A. V. Burzhava, A. B. Sheremetev, N. S.
Aleksandrova, Propellants Explos. Pyrotech. 2010, 37, 575–580;
b) I. N. Zyuzin, K. Y. Suponitsky, A. B. Sheremetev, J. Hetero-
cycl. Chem. 2012, 49, 561–565; c) E. G. Francois, D. E. Chavez,
M. M. Sandstrom, Propellants Explos. Pyrotech. 2010, 35, 529–
534; d) L. X. Wang, X. L. Tuo, C. H. Yi, H. T. Zou, J. Xu,
W. L. Xu, J. Mol. Graphics Modell. 2009, 28, 81–87.
a) J. P. Agrawal, High energy materials, Propellants, Explosives
and Pyrotechnics, Wiley-VCH, Weinheim, Germany, 2010, p.
100–102; b) C. Zhang, THEOCHEM 2006, 765, 77–83.
R. Fruttero, B. Ferrarotti, A. Serafino, A. D. Stilo, A. Gosco,
J. Heterocycl. Chem. 1989, 26, 1345–1347.
152.3, 151.5, 144.7, 131.6, 123.6, 111.2, 8.5 ppm. IR: ν = 3267 (vw),
˜
3150 (w), 1626 (s), 1606 (m), 1525 (w), 1469 (m), 1433 (m) 1385
(w), 1301 (s), 1279 (vs), 1257 (vs), 1227 (vs), 1173 (m), 1131 (m),
1080 (m), 1007 (m), 968 (w), 868 (m), 820 (w), 787 (s), 758 (s), 689
(m), 612 (s) cm–1. Raman: ν = 1606, 1522, 1438, 1384, 1304, 1184,
˜
[5]
[6]
[7]
1128, 1084, 1004 cm–1. C7H9N13O4 (339.09): calcd. C 24.78, H 2.67,
N 53.68; found C 24.72, H 2.69, N 53.66. ESD: 500 mJ. Impact
friction: 20 J.
4: 0.30 g of white solid was obtained (yield 88%). 1H NMR
(500 MHz, [D6]DMSO): δ = 9.43 (s, 2 H), 9.26 (s, 1 H), 2.35 (s, 3
H) ppm. 13C NMR (126 MHz, [D6]DMSO): δ = 153.5, 152.5,
143.8, 143.5, 111.2, 8.5 ppm. IR: ν = 3278 (w), 3140 (w), 1624 (m),
˜
1606 (m), 1434 (m), 1333 (m), 1269 (vs), 1233 (s), 1130 (v), 1087
(w), 1025 (m), 954 (m), 864 (m), 821 (s), 759 (m), 734 (m), 670 (m),
624 (s), 610 (s) cm–1. Raman: ν = 1608, 1520, 1490, 1388, 1302,
˜
1234, 1182, 1128, 1082, 1006 cm–1. C7H9N13O4 (339.09): calcd. C
24.78, H 2.67, N 53.68; found C 24.90, H 2.68, N 53.65. ESD:
750 mJ. Impact friction: 32 J.
5: 0.26 g of white solid was obtained (yield 77%) 1H NMR
(500 MHz, [D6]DMSO): δ = 9.25 (s, 1 H), 8.32 (s, 1 H), 8.02 (br, 1
H), 2.35 (s, 3 H) ppm. 13C NMR (126 MHz, [D6]DMSO): δ =
154.1, 152.5, 150.2, 143.6, 138.8, 111.2, 8.5 ppm. IR: ν = 3251 (vw),
˜
3072 (vw), 1682 (s), 1624 (s), 1607 (m), 1520 (m), 1470 (m), 1412
(m), 1303 (m), 1279 (vs), 1237 (s), 1139 (w), 1092 (s), 1049 (m),
1014 (m), 948 (s), 878 (w), 827 (m), 730 (w), 671 (m), 619 (s) cm–1.
[8]
[9]
Raman: ν 1606, 1518, 1490, 1418, 1370, 1336, 1302, 1236, 1184,
˜
1138, 1092, 1046, 1012, 882 cm–1. C7H9N13O4 (339.09): calcd. C
24.78, H 2.67, N 53.68; found C 24.77, H 2.72, N 53.21. ESD:
600 mJ. Impact friction: 24 J.
Supporting Information (see footnote on the first page of this arti-
cle): Structural characterization and overview of selected crystallo-
graphic data of 1, 2, 4, and 5.
[10]
[11]
[12]
[13]
P. N. Gaponik, V. P. Karavai, Chem. Heterocycl. Compd. 1984,
20, 1388–1391.
Acknowledgments
L. X. Liang, K. Wang, C. M. Bian, L. M. Ling, Z. M. Zhou,
Chem. Eur. J. 2013, 19, 14902–14910.
a) M. J. Kamlet, S. J. Jacobs, J. Chem. Phys. 1968, 48, 23–35;
b) M. J. Kamlet, S. J. Jacobs, J. Chem. Phys. 1968, 48, 36–42;
c) V. Thottempudi, F. Forohor, D. A. Parrish, J. M. Shreeve,
Angew. Chem. Int. Ed. 2012, 51, 9881–9885.
This work was supported by the Natural Science Foundation of
Jiangsu Province (grant number BK2011696) and the National
Natural Science Foundation of China (NSFC) (grant number
21376121).
[14]
[15]
a) Y.-H. Joo, H. X. Gao, D. A. Parrish, S. G. Cho, E. M. Goh,
J. M. Shreeve, J. Mater. Chem. 2012, 22, 6123–6130; b) Q. H.
Lin, Y. C. Li, Y. Y. Li, Z. Wang, W. Liu, C. Qi, S. P. Pang, J.
Mater. Chem. 2012, 22, 666–674.
Test methods were performed according to the UN Recommen-
dations on the Transport of Dangerous Goods, Manual of Tests
and Criteria, 4th rev. ed., United Nations Publications, New
York, 2003; 13.4.2 Test 3, (ii) BAM Fallhammer, p. 75–82.
N. Fischer, T. M. Klapötke, M. Reymann, J. Stierstorfer, Eur.
J. Inorg. Chem. 2013, 2167–2180.
[1] a) Y. Q. Zhang, D. A. Parrish, J. M. Shreeve, J. Mater. Chem.
2013, 1, 585–593; b) N. Fischer, D. Fischer, T. M. Klapötke,
D. G. Piercey, J. Stierstorfer, J. Mater. Chem. 2012, 22, 20418–
20422; c) G. H. Tao, Y. Guo, D. A. Parrish, J. M. Shreeve, J.
Mater. Chem. 2010, 20, 2999–3005; d) A. A. Dippold, T. M.
Klapötke, J. Am. Chem. Soc. 2013, 135, 9931–9938; e) Y.-H.
Joo, J. M. Shreeve, Angew. Chem. 2010, 122, 7478; Angew.
Chem. Int. Ed. 2010, 49, 7320–7323; f) Y.-H. Joo, J. M. Shreeve,
J. Am. Chem. Soc. 2010, 132, 15081–15090.
[2] a) L. V. Batog, L. S. Konstantinova, O. V. Lebedev, L. I.
Khmel’nitskii, Mendeleev Commun. 1996, 6, 193–195; b) H. F.
Huang, Z. M. Zhou, L. X. Liang, J. H. Song, K. Wang, D.
Cao, W. W. Sun, C. M. Bian, M. Xue, Z. Anorg. Allg. Chem.
2012, 638, 392–400; c) P. W. Leonard, D. E. Chavez, P. F. Pago-
ria, D. L. Parrish, Propellants Explos. Pyrotech. 2011, 36, 233–
239.
[3] a) H. V. Huynh, M. A. Hiskey, D. E. Chavez, D. L. Naud,
R. D. Gilardi, J. Am. Chem. Soc. 2005, 127, 12537–12543; b)
A. Saikia, R. Sivabalan, B. G. Polke, G. M. Gore, A. Singh,
A. S. Rao, A. K. Sikder, J. Hazard. Mater. 2009, 170, 306–313;
c) M. Göbel, T. M. Klapötke, Adv. Funct. Mater. 2009, 19, 347–
365; d) J. Kerth, S. Löbbecke, Propellants Explos. Pyrotech.
2002, 27, 111–118.
[16]
[17]
[18]
R. Mayer, J. Köhler, A. Homburg, in: Explosives, vol. 5, Wiley-
VCH, Weinheim, Germany, 2002.
M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, J. A. Montgomery Jr., T.
Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N.
Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K.
Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y.
Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P.
Hratchian, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R.
Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R.
Cammi, C. Pomelli, J. W. Ochterski, P. Y. Ayala, K. Morok-
uma, G. A. Voth, P. Salvador, J. J. Dannenberg, V. G. Zakrzew-
Eur. J. Inorg. Chem. 2014, 1231–1238
1237
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org
FULL PAPER
ski, S. Dapprich, A. D. Daniels, M. C. Strain, O. Farkas, D. K.
Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. V.
Ortiz, Q. Cui, A. G. Baboul, S. Clifford, J. Cioslowski, B. B.
Stefanov, A. L. G. Liu, P. Piskorz, I. Komaromi, R. L. Martin,
D. J. Fox, T. Keith, M. A. Al-Laham, C. Peng, A. Nanayak-
kara, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen, M.
Wong, C. Gonzalez, J. A. Pople, Gaussian 03, revision D. 01,
Gaussian, Inc., Wallingford CT, 2004.
H. D. B. Jenkins, D. Tudeal, L. Glasser, Inorg. Chem. 2002, 41,
2364–2367.
APEX2, v. 2010.3-0, Bruker AXS Inc., Madison, 2010.
SAINT, v. 7.68A, Bruker AXS Inc., Madison, 2009.
[26] P. C. Hariharan, J. A. Pople, Theor. Chim. Acta 1973, 28, 213–
222.
[27] D. R. Lide, CRC Handbook of Chemistry and Physics, 88th ed.
(Internet Version 2008), CRC Press/Taylor and Francis, Boca
Raton, 2007–2008.
[28] N. Fischer, T. M. Klapötke, J. Stierstorfer, Z. Anorg. Allg.
Chem. 2009, 635, 271–281.
[29] Y.-H. Joo, J. H. Chung, S. G. Cho, E. M. Goh, New J. Chem.
2013, 37, 1180–1188.
[30] G. W. Drake, G. M. Kaplan, T. W. Hawkins, US 2005203578 .
[31] a) W. T. Quinlin, D. M. Cates, US 2005165241; b) A. N. Kost,
F. Gents, Zh. Obshch. Khim. 1958, 28, 2773–2779; c) I. Matul-
kova, I. Nemec, K. Teubner, P. Nemec, Z. Micka, J. Mol.
Struct. 2008, 873, 46–60.
[32] a) G. Sjostedt, L. Gringas, Org. Synth. 1946, 26; b) X. H. Sun,
Y. F. Liu, S. Z. Chen, B. Chen, Y. Q. Jia, Z. F. Zeng, Chin. J.
Chem. 2009, 27, 949–952.
[19]
[20]
[21]
[22] XPREP, v. 2008/2, Bruker AXS Inc., Madison, 2008.
[23] SADABS, v. 2008/1, Bruker AXS Inc., Madison, 2008.
[24] SHELXTL, v. 2008/4, Bruker AXS Inc., Madison, 2008.
[25] a) A. D. Becke, J. Chem. Phys. 1993, 98, 5648–5652; b) P. J.
Stephens, F. J. Devlin, C. F. Chabalowski, M. J. Frisch, J. Phys.
Chem. 1994, 98, 11623–11627.
Received: October 22, 2013
Published Online: January 28, 2014
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© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim