Synthesis, characterization and energetic properties of novel 1-methyl-1,2,4-triazolium N-aryl/N-pyridinyl ylids

Article abstract of DOI:10.1016/j.tetlet.2016.12.016

Synthesis, characterization and energetic properties of novel, nitrogen-rich 1-methyl-1,2,4-triazolium N-aryl/N-pyridinyl ylids 3a–m are reported.

Full text of DOI:10.1016/j.tetlet.2016.12.016

Accepted Manuscript
Synthesis, Characterization and Energetic Properties of Novel 1-Methyl-1,2,4-
Triazolium N-Aryl / N-Pyridinyl Ylids
Hong Zhang, Zuoquan Wang, Ion Ghiviriga, Girinath G. Pillai, Farukh Jabeen,
Justin A. Arami, Wenfeng Zhou, Peter J. Steel, C. Dennis Hall, Alan R. Katritzky
PII:
S0040-4039(16)31643-4
DOI:
http://dx.doi.org/10.1016/j.tetlet.2016.12.016
TETL 48428
Reference:
Tetrahedron Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
29 September 2016
1 December 2016
6 December 2016
Please cite this article as: Zhang, H., Wang, Z., Ghiviriga, I., Pillai, G.G., Jabeen, F., Arami, J.A., Zhou, W., Steel,
P.J., Dennis Hall, C., Katritzky, A.R., Synthesis, Characterization and Energetic Properties of Novel 1-Methyl-1,2,4-
Triazolium N-Aryl / N-Pyridinyl Ylids, Tetrahedron Letters (2016), doi: http://dx.doi.org/10.1016/j.tetlet.
2016.12.016
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Graphical Abstract
Synthesis, Characterization and Energetic
Properties of Novel 1-Methyl-1,2,4-
Triazolium N-Aryl / N-Pyridinyl Ylids
Leave this area blank for abstract info.
Hong Zhang, Zuoquan Wang, Ion Ghiviriga, Girinath G. Pillai, Farukh Jabeen, Justin A. Arami, Wenfeng Zhou,
Peter J. Steel, C. Dennis Hall, and the late Alan R. Katritzky
Ar-X
Py-X
Me
Me
MeCN or EtOH
Et3N or K2CO3
N+
N
N+
N
N N- Ar/Py
N NH2
I-
+
2a-m
X = Cl, Br, NO2
1
3a-m

1
Tetrahedron Letters
Synthesis, Characterization and Energetic Properties of Novel 1-Methyl-1,2,4-
Triazolium N-Aryl / N-Pyridinyl Ylids
Hong Zhang,a,b,§ Zuoquan Wang,a,§ Ion Ghiviriga,a Girinath G. Pillai,a,c Farukh Jabeen,a Justin A. Arami,a
Wenfeng Zhou,d,e Peter J. Steel,f C. Dennis Hall,a,* and the late Alan R. Katritzkya
a Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA
b School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Guangzhou, Guangdong 510006, China
c Department of Applied Chemistry, China Agricultural University, Beijing 100193, China
d Department of Applied Chemistry, China Agricultural University, Beijing 100193, China
e Department of Chemistry, University of Idaho, Moscow, Idaho 83844-2343, USA
f Chemistry Department, University of Canterbury, Christchurch, New Zealand
ARTICLE INFO
ABSTRACT
Article history:
Received
Synthesis, characterization and energetic properties of novel, nitrogen-rich 1-methyl-1,2,4-
triazolium N-aryl/N-pyridinyl ylids 3a-m are reported.
Received in revised form
Accepted
2009 Elsevier Ltd. All rights reserved.
Available online
Keywords:
synthesis
triazolium ylids
pyridinyl ylids
energetics
X-ray
1. Introduction
Synthetic energetic materials are widely used in military
applications and numerous current research programs aim to
develop new explosives and propellants with higher performance
or reduced sensitivity to thermal shock or impact. Over the last
several decades, the synthesis of energetic, heterocyclic
compounds has made a substantial contribution to this area.1,2,3
Energetic heterocycles such as pyridines,4,5triazoles6-9 and
tetrazoles2,10-12 generally have higher heats of formation, density,
and oxygen balance than their carbocyclic analogues. Thus,
formulations containing compounds of this type are potentially
useful as novel explosives.1-3 and this prompted us to synthesize
novel 1-methyl-1,2,4-triazolium N-aryl / N-pyridinyl ylids in
order to evaluate their properties as energetic materials.
Scheme 1. Synthesis of triazolium N-aryl / N-pyridinyl ylids.
All of the starting materials were commercially available
except 1-chloro-2,4,6-trinitrobenzene (2c) which was synthesized
from picric acid 4 using a modified literature procedure.13
(Scheme 2).
2. Results and Discussion
1-Methyl-4-H-1,2,4-triazol-4-ium ylids 3a-m were prepared in
34–90% yields by treatment of 4-amino-1-methyl-1H-1,2,4-
triazol-4-ium iodide 1 with nitrobenzenes 2a-c, nitropyridines
2d-l and a pyridinium salt, 2m in acetonitrile or ethanol in the
presence of triethylamine or potassium carbonate (Table 1,
Scheme 1).
Scheme 2. Synthesis of 1-chloro-2,4,6-trinitrobenzene.

2
Tetrahedron Letters
Table 1. Preparation of aryl/pyridinyl(1-methyl-4-H-1,2,4-triazol-4-ium-4-yl)amide 3a-m
Base
Et3N
Yield (%)
54
Solvent
MeCN
Mp (°C)
2
3
221– 223
3a
2a
Et3N
MeCN
143– 145
52
3b
3c
2b
Et3N
Et3N
EtOH
220–222
234–236
62
34
2c
MeCN
3d
3e
2d
2e
Et3N
EtOH
202–203
173–175
45
48
K2CO3
MeCN
2f
3f
Et3N
K2CO3
Et3N
EtOH
MeCN
MeCN
211–213
182–184
197–199
60
42
3g
2g
3h
3i
2h
2i
44[a]
Et3N
MeCN
195–197
16[a]
2i
2j
3i′
3j
Et3N
Et3N
MeCN
MeCN
227–229
212–213
56
59
3k
2k
Et3N
Et3N
MeCN
MeCN
190–192
211–213
80
90
3l
2l
2m
3m
a Two regioisomers isolated in the same reaction.
Products 3a-l were obtained in moderate yields after 1–3 days
stirring at ambient temperature but 3m required heating in
acetonitrile. Compounds 2a-g have only one replaceable halogen
and give rise to compounds 3a-g all of which were characterized
by elemental analysis, mass spectrometry, 1H, and 13C nmr.
Substrates 2h, 2i, 2j and 2k, all have two non-equivalent
chlorines and regioselectivity was a potential issue. NMR
revealed that in substrates with chlorine ortho and meta to the
nitro group (2h) or meta and para to the nitro group (2j) only the
ortho or para chlorines were displaced to give 3h and 3j
the triazole ring is anti to the nitro group in 3k but syn to the
pyridine N in 3e due to lone pair repulsion in 3e (Fig. 2)
1
respectively. Comparison of the H, 13C and 15N nmr data of 3h
with 3d and of 3j with 3e reveals a striking similarity which
serves to reinforce the structures assigned to 3h and 3j.
Replacement of the chlorine ortho to the nitro group in 2h and
para to the nitro group in 2j is, of course, expected of a SNAr
mechanism.
In the case of 2k, one might have expected the formation of
two products since both halogens are activated by hetero-N and
the nitro group but in fact only one isomer was obtained (3k)
analogous to 3f.
Assignments of the 1H,13C and 15N chemical shifts of
3d,e,h,i,i’j and k based on cross peaks in the 1H-13C gHMBC and
1H-15N gHMBC spectra, are given in Fig. 1. The proton at 6.12
in 3k is β to the pyridine nitrogen (based on its chemical shift and
1
that of the carbon attached to it) and a cross peak in the H-15N
gHMBC spectrum between this proton and ylid N at 186.9 ppm
indicates that it is ortho to the ylid nitrogen consistent with
structure 3k. Confirmation of this conclusion is provided by a
nOe between the signal at 6.12 and the protons of the triazole
ring at 9.09 and 9.96 ppm. An analogous nOe was not however,
detected in 3e. A possible explanation for this observation is that
Figure 1. 1H, 13C and 15N chemical shifts in 3d, e, h,i, i’, j and k.

3
The crystal structure of 3k confirms the proposed structure
and stereochemistry (Fig. 3). It exists in the solid state as a
trihydrate involving a complex hydrogen bonded network with
all six water hydrogens strongly interacting with nitrogen
acceptors or other water oxygens. The conformation of the
molecule is as shown in Fig. 3 with the planes of the two
yield, in which the nitro group was substituted, an observation
that has analogies in the literature.14-17
Reaction with 2-chloro-1-methylpyridin-1-ium iodide 2m
gave rise to the expected novel iodide 3m in 90% yield, the
structure of which was confirmed by single crystal X-ray
crystallography (Fig. 4). In this case the planes of the two rings
are inclined at an angle of 98.8 o.
heterocyclic rings inclined at an angle of 96.3 o.
Figure 2. Proposed stereochemistry of compounds 3k and 3e.
Figure 4. X-ray crystal structure of 3m (CCDC 1429988).
2.1. Properties
Table 2 shows the heats of decomposition (Hd) of a selection
of the triazolium ylids as determined by differential scanning
calorimetry. As expected, the heats of decomposition increase
with the number of nitro groups present in the compounds.
Table 3 reports the heats of formation (Hf) as calculated by
PM6 together with calculated and experimental values of the
densities of 3a,b,c,e,f,g,k, and m.
The experimental densities of the compounds were determined
by gas pycnometry and these values, coupled with the Hf
values, were used to calculate the explosion parameters (Table 3)
by the Explo 5 program. In parallel with the Hd data, the Hf
values increase with the number of nitro groups in each type of
molecule. Experimental densities also increase in line with the
calculated values with one notable exception,- compound 3e,
which had an experimental density of 2.01, far in excess of the
expected value based on PM6 calculations. Duplicate
measurements on a second sample arrived at the same figure and
gave rise to a set of explosion parameters close to those of RDX.
There is no obvious explanation for this anomalous result. The
HRMS and nmr data were exactly as expected and the only
unusual feature of 3e was its extremely dark red color. This
suggests the compound may have adopted an unusual crystal
form but unfortunately we were unable to obtain crystals suitable
for X-ray analysis.
Figure 3. X-ray crystal structure of 3k (CCDC 1431437).
In the case of substrate 2i, the ylid nucleophile could, in
principle, displace chlorine either at position 6 or position 2 of
the pyridine ring to give 3i or 3i’ respectively. In fact both were
observed and the structures of 3i and 3i’ were assigned on the
basis of their 1H-15N gHMBC spectra. In the major isomer (75%)
the ylid nitrogen at 204.4 couples with protons at 6.23 and 8.15
over three and four bonds respectively. In the minor isomer the
ylid nitrogen at 208.4 couples only with the proton at 7.93, para
to pyridine nitrogen. Unfortunately attempts to form suitable
crystals for X-ray confirmation of the proposed structures were
unsuccesful.
The reaction of 4-amino-1-methyl-4H-1,2,4-triazole-1-ium
iodide 1 with 2,6-dichloro-4-nitropyridine 2l gave ylid 3l in 80%
Table 2. Heats of decomposition (Hd) of triazolium ylids
N+
N
N
N
n = 1-3
(NO2)n
2a) Compounds of general formula:
Compound
(NO2)n
2,4-di-NO2
2,6-di-NO2
2,4,6-tri-NO2
Texo (°C)
229.2
152.9
ΔHd (kJ/mol)
ΔHd (J/g)
–384
–255
–101
–67.4
–173
3a
3b
3c
227.7
–560
N+
N
N
N
(NO2)n
n = 1-2
N
2b) Compounds of general formula:
Compound
2-ylid, (NO2)n
Texo (°C)
ΔHd (kJ/mol)
ΔHd (J/g)
5-NO2
3,5-di-NO2
203.2
186.1
-41.6
-86.7
-189
-327
3e
3g
N+
N
N
N
N
O2N
2c) Compounds of general formula:
Compound
4-ylid, NO2
3-NO2
Texo (°C)
220.5
ΔHd (kJ/mol)
–46.2
ΔHd (J/g)
–210
3f

4
Tetrahedron Letters
Table 3. Calculated heats of formation (ΔHf), densities (ρcalc), experimental densities (ρpyc) and calculated detonation parameters (PD,
VD and Isp)
N+
N
N
N
n = 1-3
NO2
3a) Compounds of general formula:
Compound (NO2)n
ΔHf(calc)[a]
ρ ρ
calc
Ρ
pyc
PD(calc)
(GPa)
VD(calc)
(m/s)
Isp(calc)
(s)
(kJ mol-1)
3a, 2,4-di-NO2
3b, 2,6-di-NO2
3c, 2,4,6-tri-NO2
397
423
404
1.246
1.231
1.340
1.56
1.56
1.63
17.02
17.25
21.38
6959
6990
7460
212.9
215.3
225.3
a Determined by PM6
N+
N
N
(NO2)n
n = 1-2
N
N
3b) Compounds of general formula:
Compound, ylid
position in Py n
Positions of
(NO2)n in Py
ΔHf(calc)[a]
ρ ρ
PD(calc)
(GPa)
VD(calc)
(m/s)
Isp(calc)
(s)
(kJ mol-1)
calc
exp
3e, 2
5
3
3,5
438
460
437
1.178
1.171
1.268
2.01
1.56
1.64
34.83
16.47
20.44
9498
6986
7438
208.3
205.7
218.1
3f,
4
3g, 2
a Determined by PM6
Cln
n = 1-2
N+
N
N
N
N
NO2
3c) Compounds of general formula:
Compound, ylid
position in Py n
Positions of
Cl/NO2
ΔHf(calc)[a]
ρ ρ
PD(calc)
(GPa)
VD(calc)
(m/s)
Isp(calc)
(s)
(kJ mol-1)
calc
exp
3k, 2
3m, 4
3/5
2,6-di-Cl
424
430
1.271
1.235
1.68
1.57
16.53
10.18
6732
5411
196.8
173.6
The detonation velocities (VD), detonation pressures(PD) and
3. Conclusions
specific impulses (Isp) were calculated based on the experimental
densities and calculated heats of formation using Explo5 v.6.01
(OZN Research, Czechoslovakia).
In summary we have developed a practical synthesis of novel,
nitrogen-rich 1-methyl-1,2,4-triazolium N-aryl/N-pyridinyl ylids
3a-n from readily available precursors and evaluated their
properties as potential energetic materials.
Calculation of heats of formation and densities
The compounds were drawn in ChemDraw followed by 2D to
3D conversion using MM219 minimization in Chem3D.20 The 3D
geometries were parameterized using PM621 for further semi-
empirical calculation. Geometry optimization followed by
frequency calculation, was performed using AMPAC software.22
The geometries were optimized to their energy minima using
Trust algorithm which reduces the number of cycles and refines
the precision of the calculations at each step. The optimized
geometries were loaded to Codessa III23 software for the
calculation of heats of formation, van der Waal’s volume and
densities.
4. Experimental
General Methods and Materials. Melting points were
determined on a capillary tube melting point apparatus equipped
with a digital thermometer and are uncorrected. NMR spectra
were recorded for most compounds on a Varian Mercury
spectrometer operating at 300 MHz for 1H. The H and 13C
1
chemical shifts are reported on the TMS scale and were
referenced to the residual peak of the solvent (DMSO, 2.50 ppm
1
for H and 39.5 ppm for 13C. For compounds 3d, 3e, 3h, 3i, 3j,
3k, 3l and 5 the spectra were recorded on a Varian Inova
operating at 500 MHz for protons. The 15N chemical shifts are
given on the ammonia scale, and were referenced with the
frequency ratio,  = 10.1329120. Elemental analyses were
performed on a Carlo Erba EA 1108 elemental analyzer, Dept. of
Chem., University of Florida. All reactions were carried out
under nitrogen atmosphere. All reagents were purchased from
commercial sources and used as received unless otherwise
indicated. Column chromatography was performed with S733-1
silica gel (200425 mesh). Heats of decomposition were
determined using a DuPont Instruments DSC 2910 differential
scanning calorimeter. Samples were heated from 100 ºC–500 ºC
in hermetic aluminum pans, with helium as the purge gas. All
sample pan lids were perforated to allow venting of gaseous
products.
X-Ray Crystallography
The X-ray single crystal diffraction data for
(CCDC1431437) and 3m (CCDC 1429988) were collected at 120
on an Agilent SuperNova instrument with focussed
3k
K
microsource Cu Kα radiation (λ = 1.5418 Å) and ATLAS CCD
area detector. The structures were solved using direct methods
with SHELXS and refined on F2 using all data by full–matrix
least square procedures with SHELXL–97.24 Multiscan
absorption corrections were done using SCALE3 ABSPACK.
The non–hydrogen atoms were refined with anisotropic
displacement parameters. All hydrogen atoms were included in
calculated positions with isotropic displacement parameters 1.2
times the isotropic equivalent of their carrier atoms.
General procedure for the preparation of 1-methyl-1,2,4-
triazolium N-aryl/N-pyridinyl ylids 3a-m. Potassium carbonate
or trimethylamine (9.0 mmol) was added to a solution of 4-
amino-1-methyl-1H-1,2,4-triazol-4-ium iodide, 1 (3.0 mmol) in
acetonitrile or ethanol (25 mL) and each reaction mixture was
vigorously stirred at room temperature for 20 min to give a
purple solution, to which nitrophenyl halides 2a-c nitropyridinyl
halides 2d-l or pyridinium iodide 2m (3.0 mmol) were added in
Densities were determined at room temperature by employing
a Micromeritics AccuPyc 1330 gas pycnometer. The masses of
the samples were determined on a METTLER TOLEDO AB104-
S balance, and the volumes of the samples were measured using
the pycnometer; an average of 3 measured volumes was used to
calculate the density. Sample density was calculated from the
ratio of mass (m) to volume (V). (d(g/cm3) = m(g)/V(cm3)).

5
one portion. Each mixture was stirred at rt for 72 h except for 2l
(rt for 24 h) and 2m (82 °C for 72 h). The mixtures were
concentrated in vaccuo and the residues purified either by
gradient elution chromatography over silica gel or by
recrystallization.
(3,5-Dinitropyridin-2-yl)(1-methyl-4H-1,2,4-triazol-1-
ium-4-yl)amide (3g). Base: Et3N (3/1 molar ratio to 2g), 72 h, rt,
in EtOH; mixture cooled in fridge, precipitate filtered, washed
with EtOH/AcOEt and dried. Yield 60%, orange solid, mp 211–
213 °C; 1H NMR (300 MHz, DMSO-d6): δ 10.23 (s, 1H), 9.26 (s,
1H), 8.80 (dd, J = 2,4, 0.6 Hz, 1H), 8.66 (d, J = 2.7 Hz, 1H), 4.06
(s, 3H); 13C NMR (75 MHz, DMSO-d6): δ 157.6, 149.5, 143.5,
140.5, 129.4, 129.3, 128.3, 38.8. HRMS (ESI-TOF) m/z: [M +
H]+ Calcd for C8H8N7O4 266.0632; Found, 266.0643.
(2,4-Dinitrophenyl)(1-methyl-4H-1,2,4-triazol-1-ium-4-
yl)amide (3a). Base: Et3N (3/1 molar ratio to 2a), 72 h, rt, in
MeCN; product recrystallized from acetone/hexanes. Yield 54%,
golden solid, mp 221–223 °C; 1H NMR (300 MHz, DMSO-d6): δ
10.06 (s, 1H), 9.19 (s, 1H), 8.62 (d, J = 2.7 Hz, 1H), 7.77 (dd, J =
9.9, 2.7 Hz, 1H), 6.32 (d, J = 9.9 Hz, 1H), 4.04 (s, 3H); 13C NMR
(75 MHz, DMSO-d6): δ 158.6, 143.2, 140.9, 131.2, 129.8, 127.9,
124.5, 112.1, 39.0. HRMS (ESI-TOF) m/z: [M + H]+ Calcd for
C9H9N6O4 265.0680; Found, 265.0678.
(5-Chloro-3-nitropyridin-2-yl)(1-methyl-4H-1,2,4-triazol-
1-ium-4-yl)amide (3h). Base: K2CO3 (3/1 molar ratio to 2h), 72
h, rt, in MeCN; purified by column chromatography eluted with
acetone/hexanes, then acetone; product recrystallized from
MeCN/AcOEt. Yield 42%, red solid, mp 182–184 °C; NMR data
in figure 1. HRMS (ESI-TOF) m/z: [M + H]+ Calcd for
C8H8ClN6O2 , 255.0392; Found, 255.0404
(2,6-Dinitrophenyl)(1-methyl-4H-1,2,4-triazol-1-ium-4-
yl)amide (3b). Base: Et3N (3/1 molar ratio to 2b), 72 h, rt, in
MeCN; residue purified by column chromatography, eluted first
with AcOEt/hexanes and then AcOEt/acetone; product
recrystallized from acetone/hexanes. Yield 52%, dark red solid,
(6-Chloro-5-nitropyridin-2-yl)(1-methyl-4H-1,2,4-triazol-
1-ium-4-yl)amide (3i). Base: Et3N (3/1 molar ratio to 2i), 72 h,
rt, in MeCN. The solution was cooled to 0oC, the mixture of 3i
and 3i’ filtered off and the filter cake washed with cold AcOEt.
The mixture was recrystallized twice from acetone/hexanes to
give the first crop of pure 3i. After evaporation of the mother
liquor, the resultant mixture of orange and yellow crystals was
separated by hand. Recrystallization of the separated crystals
(from acetone/hexane) gave a second crop of 3i and pure 3i’.
Yield of 3i, 44%, yellow fibers, mp 195–197 °C (dec); NMR data
in Figure 1. HRMS (ESI-TOF) m/z: [M + H]+ Calcd for
C8H8ClN6O2 255.0392; Found, 255.0402.
1
mp 143–145 °C; H NMR (300 MHz, DMSO-d6): δ 10.03 (s,
1H), 9.12 (s, 1H), 7.75 (d, J = 8.1 Hz, 2H), 6.25 (t, J = 8.1 Hz,
1H), 3.97 (s, 3H); 13C NMR (75 MHz, DMSO-d6): δ 147.7,
141.4, 139.1, 138.2, 130.0, 108.0, 38.6. HRMS (ESI-TOF) m/z:
[M + H]+ Calcd for C9H9N6O4 265.0680; Found, 265.0675.
(2,4,6-Trinitrophenyl)(1-methyl-4H-1,2,4-triazol-1-ium-4-
yl)amide (3c).Base: Et3N (3/1 molar ratio to 2c), 72 h, rt, in
MeCN; residue purified by column chromatography, eluted first
with AcOEt/hexanes and then acetone; product recrystallized
from acetone/hexanes. Yield 62%, yellow solid, mp 220–222 °C;
1H NMR (300 MHz, DMSO-d6): δ 10.24 (s, 1H), 9.31 (s, 1H),
8.58 (s, 2H), 4.02 (s, 3H); 13C NMR (75 MHz, DMSO-d6): δ
149.3, 140.9, 139.4, 127.8, 38.9. HRMS (ESI-TOF) m/z: [M +
H]+ Calcd for C9H8N7O6 310.0531; Found, 310.0542.
(6-Chloro-3-nitropyridin-2-yl)(1-methyl-4H-1,2,4-triazol-
1-ium-4-yl)amide (3i’). Yield 16%, coral red prisms, mp 197–
199 °C (dec); NMR data in Figure 1. HRMS (ESI-TOF) m/z: [M
+ H]+ Calcd for C8H8ClN6O2 255.0392; Found, 255.0403.
(3-Chloro-5-nitropyridin-2-yl)(1-methyl-4H-1,2,4-triazol-
1-ium-4-yl)amide (3j). Base: Et3N (3/1 molar ratio to 2j), 72 h,
rt, in MeCN, mixture concentrated to dryness, residue washed
with MeCN/AcOEt and recrystallized from acetone. Yield 56%,
yellow solid, mp 227–229 °C; NMR data in figure 1. HRMS
(ESI-TOF) m/z: [M + H]+ Calcd for C8H8ClN6O2 255.0392;
Found, 255.0388.
(3-Nitropyridin-2-yl)(1-methyl-4H-1,2,4-triazol-1-ium-4-
yl)amide (3d). Base: Et3N (3/1 molar ratio to 2d), 72 h, rt, in
MeCN; purified by column chromatography, eluted first with
AcOEt/hexanes and then acetone; product recrystallized from
1
acetone/hexanes. Yield 34%, yellow solid, mp 234–236 °C; H
NMR (300 MHz, DMSO-d6): δ 10.62 (s, 1H), 9.51 (s, 1H), 8.67
(m, 1H), 8.49 (m, 1H) 7.29(m, 1H), 4.20 (s, 3H); 13C NMR (75
MHz, DMSO-d6): δ 154.7, 149.8, 146.7, 140.9, 135.4, 131.1,
118.7, 40.0. HRMS (ESI-TOF) m/z: [M + H]+ Calcd for
C8H9N6O2 , 221.0781; Found, 221.0790.
(2-Chloro-3-nitropyridin-4-yl)(1-methyl-4H-1,2,4-triazol-
1-ium-4-yl)amide (3k). Base: Et3N (3/1 molar ratio to 2k), 72 h,
rt, in MeCN; purified by column chromatography eluted with
AcOEt/hexanes and acetone, then recrystallized from
acetone/hexanes. Yield 59%, yellow solid, mp 212–213 °C;
NMR data in figure 1. HRMS (ESI-TOF) m/z: [M + H]+ Calcd
for C8H8ClN6O2 255.0392; Found, 255.0380.
(5-Nitropyridin-2-yl)(1-methyl-4H-1,2,4-triazol-1-ium-4-
yl)amide (3e). Base: Et3N (3/1 molar ratio to 2e), 72 h, rt, in
EtOH; purified by column chromatography, eluted with
MeOH/MeCN and MeCN/MeOH; product recrystallized from
MeCN/AcOEt. Yield 45%, dark brown solid, mp 202–203 °C; 1H
NMR (300 MHz, DMSO-d6): δ 10.21 (s, 1H), 9.64(s, 1H), 9.09
(s, 1H), 7.77 (d, 1H), 6.24 (d, 1H), 4.01 (s, 3H); 13C NMR (75
MHz, DMSO-d6): δ 165.7, 143.9, 148.5, 140.6, 131.3, 130.5,
110.1, 39.1. HRMS (ESI-TOF) m/z: [M + H]+ Calcd for
C8H9N6O2 221.0781; Found, 221.0778.
(2,6-Dichloropyridin-4-yl)(1-methyl-4H-1,2,4-triazol-1-
ium-4-yl)amide (3l). Base: Et3N (3/1 molar ratio to 4l), 24 h, rt,
in MeCN; purified by column chromatography eluted with
hexanes/AcOEt and acetone/AcOEt, then recrystallized from
1
acetone/hexanes. Yield 80%, colorless solid, mp 190–192 °C; H
NMR (300 MHz, DMSO-d6): δ 9.88 (s, 1H), 9.02 (s, 1H), 6.14
(d, J = 2.1 Hz, 1H), 5.69 (d, J = 1.5 Hz, 1H), 3.99 (s, 3H); 13C
NMR (75 MHz, DMSO-d6): δ 167.1, 149.0, 144.0, 141.3, 103.0–
101.9 (m). HRMS (ESI-TOF) m/z: [M + H]+ Calcd for C8H8Cl2N5
244.0151; Found, 244.0143.
(3-Nitropyridin-4-yl)(1-methyl-1H-1,2,4-triazol-4-ium-4-
yl)amide (3f). Base: K2CO3 (3/1 molar ratio to 2f), 72 h, rt, in
MeCN; purified by column chromatography eluted with
AcOEt/hexanes and MeCN/MeOH; product recrystallized from
MeCN. Yield 48%, yellow solid, mp 173–175 °C; 1H NMR (300
MHz, DMSO-d6): δ 9.98 (s, 1H), 9.11 (s, 1H), 8.68 (s, 1H), 7.68
(d, J = 6.3 Hz, 1H), 6.07 (d, J = 6.3 Hz, 1H), 4.03 (s, 3H); 13C
NMR (75 MHz, DMSO-d6): δ 157.9, 150.2, 148.2, 143.7, 141.1,
130.0, 106.7, 38.9. HRMS (ESI-TOF) m/z: [M + H]+ Calcd for
C8H9N6O2 221.0781; Found, 221.0782.
(1-Methylpyridin-1-ium-2-yl)(1-methyl-4H-1,2,4-triazol-1-
ium-4-yl)amide iodide (3m). Base: Et3N (3/1 molar ratio to 2m),
72 h, 82 °C, in MeCN; mixture concentrated to dryness, residue
washed with MeOH/MeCN and recrystallized from
1
MeCN/AcOEt. Yield 90%, colorless prisms, mp 211–213 °C; H
NMR (300 MHz, DMSO-d6): δ 10.08 (s, 1H), 9.17 (s, 1H), 7.93
(dd, J = 6.6, 1.2 Hz, 1H), 7.51 (ddd, J = 9.0, 6.9, 1.7 Hz, 1H),

6
Tetrahedron Letters
8.
Thottempudi, V.; Shreeve, J. M. J. Amer. Chem. Soc. 2011,
133(49), 19982–19992.
6.52 (d, J = 9.0 Hz, 1H), 6.45 (td, J = 6.8, 1.2 Hz, 1H), 4.05 (s,
3H), 3.63 (s, 3H); 13C NMR (75 MHz, DMSO-d6): δ 161.3,
143.3, 141.4, 140.6, 140.0, 109.4, 107.5, 39.9, 39.1. HRMS (ESI-
TOF) m/z: [M – I]+ Calcd for C9H12N5 190.1087; Found,
190.1082.
9.
Xue, H.; Gao, H.; Twamley, B.; Shreeve, J. M. Chem. Mater.
2007, 19(7), 1731–1739.
10. Klapoetke, T. M.; Mayer, P.; Miro Sabate, C.; Welch, J. M.;
Wiegand, N. Inorg. Chem. 2008, 47(13), 6014–6027.
11. Klapoetke, Thomas M.; Miro Sabate, C.; Rasp, M. J. Mater Chem.
2009, 19(15), 2240–2252.
12. Li, Y.; Liu, W.; Pang, S. Molecules 2012, 17, 5040–5049.
13. Badgujar, D. M.; Talawar, M.B.; Harlapur, S. F.; Asthana, S. N.;
Mahulikar, P. P. J. Hazard. Mater. 2009, 172, 276–279.
14. Kommu, N.; Ghule, V. D.; Kumar, A. S.; Sahoo, A. K. Chem.
Asian J. 2014, 9, 166–178.
15. Connon, S. J.; Hegarty, A. F. Eur. J. Org. Chem. 2004, (16),
3477–3483.
16. Menichincheri, M.; Bassini, D. F.; Gude, M.; Angiolini, M.
Tetrahedron Lett. 2003, 44(3), 519–522.
Acknowledgments
We are indebted to the US Navy for financial support and to
Dr B Killian of the University of Florida for advice and use of
DSC equipment. We are also extremely grateful for the
cooperation of Professor Jean’ne Shreeve and Mr. Deepak Chand
(University of Idaho) in the measurement of densities and
calculation of detonation parameters.
17. Schroeder, L.; Mengel, R.; Stransky, W.; Linden, G.; Lust, S.
(Celamerck G.m.b.H. und Co. K.-G., Fed. Rep. Ger.) Pyridine
Derivatives and Their Herbicidal Use. DE 3,242,519, May 24,
1984.
18. Shanley, E. S.; Melhem, G. A. Process Safety Progress 1995,
14(9), 29–31.
19. Allinger, N. L. J. Amer. Chem.Soc. 1977, 99, 8127-8134.
20. Chem. Office 15.0, Perkin Elmer Inc., USA
21. Stewart, J. J. P. J. Mol. Model. 2007, 13, 1173-1213.
22. AMPAC 10.0, 2014, SemiChem, Inc. USA.
23. CODESSA 3.2, 2014, SemiChem, Inc., USA
24. Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112–122.
References and notes
1.
2.
3.
4.
Klapötke, T. M.; Sabate, C. M. Chem. Mater. 2008, 20 (11),
3629–3637.
Gobel, M.; Karaghiosoff, K.; Klapötke, T. M.; Piercey, D. G.;
Stierstorfer, J. J. Am. Chem. Soc., 2010, 132(48), 17216–17226.
Huang, Y. G.; Gard, G. L.; Shreeve, J. M. Tetrahedron Lett. 2010,
51(52), 6951–6954.
Wang, Q.; Li, J.; Yu, H.; Fu, X.; Shao, C.; Wu, S.; Fan, X. Huaxue
Tuijinji Yu Gaofenzi Cailiao 2010, 8(5), 32–36.
Balachari, D.; Trudell, M. L. Tetrahedron Lett. 1997, 38(50), 8607–
8610.
5.
Supplementary Material
6.
7.
Yin, P.; Zhang, J.; He, C.; Parrish, D. A.; Shreeve, J. M. J. Mater.
Chem. A: Materials for Energy and Sustainability (2014), 2(9),
3200–3208.
Dippold, A. A.; Klapoetke, T. M. J. Amer. Chem. Soc. 2013,
135(26), 9931–9938.
1H NMR, 13C NMR and MS spectra

7
Tables
Table 1. Preparation of aryl/pyridinyl(1-methyl-4-H-1,2,4-triazol-4-ium-4-yl)amide 3a-m
Base
Et3N
Solvent
MeCN
Mp (°C)
Yield (%)
54
2
3
221– 223
3a
2a
Et3N
MeCN
143– 145
52
3b
3c
2b
Et3N
Et3N
EtOH
220–222
234–236
62
34
2c
MeCN
3d
3e
2d
2e
Et3N
EtOH
202–203
173–175
45
48
K2CO3
MeCN
2f
3f
Et3N
K2CO3
Et3N
EtOH
MeCN
MeCN
211–213
182–184
197–199
60
42
3g
2g
3h
3i
2h
2i
44[a]
Et3N
MeCN
195–197
16[a]
2i
2j
3i′
3j
Et3N
Et3N
MeCN
MeCN
227–229
212–213
56
59
3k
2k
Et3N
Et3N
MeCN
MeCN
190–192
211–213
80
90
3l
2l
2m
3m
Table 2. Heats of decomposition (Hd) of triazolium ylids
N+
N
N
N
n = 1-3
(NO2)n
2a) Compounds of general formula:
Compound
(NO2)n
Texo (°C)
ΔHd (kJ/mol)
ΔHd (J/g)
2,4-di-NO2
2,6-di-NO2
2,4,6-tri-NO2
229.2
152.9
227.7
–101
–67.4
–173
–384
–255
–560
3a
3b
3c
N+
N
N
N
(NO2)n
n = 1-2
N
2b) Compounds of general formula:
Compound
2-ylid, (NO2)n
Texo (°C)
ΔHd (kJ/mol)
ΔHd (J/g)
5-NO2
3,5-di-NO2
203.2
186.1
-41.6
-86.7
-189
-327
3e
3g
N+
N
N
N
N
O2N
2c) Compounds of general formula:
Compound
4-ylid, NO2
3-NO2
Texo (°C)
220.5
ΔHd (kJ/mol)
–46.2
ΔHd (J/g)
–210
3f

8
Tetrahedron Letters
Table 3. Calculated heats of formation (ΔHf), densities (ρcalc), experimental densities (ρpyc) and calculated detonation parameters (PD,
VD and Isp)
N+
N
N
N
n = 1-3
NO2
3a) Compounds of general formula:
Compound (NO2)n
ΔHf(calc)[a]
ρ ρ
calc
Ρ
pyc
PD(calc)
(GPa)
VD(calc)
(m/s)
Isp(calc)
(s)
(kJ mol-1)
3a, 2,4-di-NO2
3b, 2,6-di-NO2
3c, 2,4,6-tri-NO2
397
423
404
1.246
1.231
1.340
1.56
1.56
1.63
17.02
17.25
21.38
6959
6990
7460
212.9
215.3
225.3
a Determined by PM6
N+
N
N
(NO2)n
n = 1-2
N
N
3b) Compounds of general formula:
Compound, ylid
position in Py n
Positions of
(NO2)n in Py
ΔHf(calc)[a]
ρ ρ
PD(calc)
(GPa)
VD(calc)
(m/s)
Isp(calc)
(s)
(kJ mol-1)
calc
exp
3e, 2
5
3
3,5
438
460
437
1.178
1.171
1.268
2.01
1.56
1.64
34.83
16.47
20.44
9498
6986
7438
208.3
205.7
218.1
3f,
4
3g, 2
a Determined by PM6
Cln
n = 1-2
N+
N
N
N
N
NO2
3c) Compounds of general formula:
Compound, ylid
position in Py n
Positions of
Cl/NO2
ΔHf(calc)[a]
ρ ρ
PD(calc)
(GPa)
VD(calc)
(m/s)
Isp(calc)
(s)
(kJ mol-1)
calc
exp
3k, 2
3m, 4
3/5
2,6-di-Cl
424
430
1.271
1.235
1.68
1.57
16.53
10.18
6732
5411
196.8
173.6
Legends
Figure 1. 1H, 13C and 15N chemical shifts in 3d, e, h,i, i’, j and k.
Figure 2. Proposed stereochemistry of compounds 3k and 3e.
Figure 3. X-ray crystal structure of 3k (CCDC 1431437).
Figure 4. X-ray crystal structure of 3m (CCDC 1429988).
Scheme 1. Synthesis of 1-chloro-2,4,6-trinitrobenzene.

9
Figures
Figure 1. 1H, 13C and 15N chemical shifts in 3d, e, h,i, i’, j and k.
Figure 2. Proposed stereochemistry of compounds 3k and 3e.
Figure 3. X-ray crystal structure of 3k (CCDC 1431437).

10
Tetrahedron Letters
Figure 4. X-ray crystal structure of 3m (CCDC 1429988).
Scheme 1. Synthesis of 1-chloro-2,4,6-trinitrobenzene.

11
1. Synthesis of thirteen novel 1,2,4-triazolium ylids
1
2. Characterization by elemental analysis, mass spectrometry and H,13C and 15N nmr
3. X-ray crystallographic structures of two examples
4. Determination of heats of decomposition of six examples
5. Calculation of detonation parameters (PD,VD, and ISP) of eight examples