Synthesis and Investigation of 2,6-Bis(picrylamino)-3,5-dinitro-pyridine (PYX) and Its Salts

Article abstract of DOI:10.1002/chem.201600769

2,6-Bis(picrylamino)pyridine (1; pre-PYX) and 2,6-bis(picrylamino)-3,5-dinitropyridine (2; PYX) were synthesized using an improved literature method. Compounds 1 and 2 were reinvestigated in detail and the X-ray structures (1: ρ=1.698 g cm^?3at 173 K; 2: ρ=1.757 g cm^?3at 298 K) are given. The reactions of 2 with different bases, such as alkali metal hydroxides (sodium, potassium, rubidium, cesium), and N-bases (ammonia, hydrazine, hydroxylamine, guanidinium carbonate, aminoguanidine bicarbonate) are reported, as well as metathesis reactions producing energetic salts. Several energetic compounds were synthesized and characterized for the first time using vibrational (IR, Raman) and multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, and DSC. The crystal structures of four energetic salts were determined using low temperature single-crystal X-ray diffraction. Heats of formation for the metal-free species were calculated using the Gaussian 09 software. Detonation parameters were estimated using the EXPLO5 program. The sensitivities towards impact, friction, and electrostatic discharge were also determined.

Full text of DOI:10.1002/chem.201600769

DOI: 10.1002/chem.201600769
Full Paper
&
Energetic Materials
Synthesis and Investigation of 2,6-Bis(picrylamino)-3,5-dinitro-
pyridine (PYX) and Its Salts
Thomas M. Klapçtke,* Jçrg Stierstorfer, Michael Weyrauther, and Tomasz G. Witkowski[a]
Abstract: 2,6-Bis(picrylamino)pyridine (1; pre-PYX) and 2,6-
bis(picrylamino)-3,5-dinitropyridine (2; PYX) were synthe-
sized using an improved literature method. Compounds
1 and 2 were reinvestigated in detail and the X-ray struc-
tures (1: 1=1.698 gcmÀ3 at 173 K; 2: 1=1.757 gcmÀ3 at
298 K) are given. The reactions of 2 with different bases,
such as alkali metal hydroxides (sodium, potassium, rubidi-
um, cesium), and N-bases (ammonia, hydrazine, hydroxyl-
amine, guanidinium carbonate, aminoguanidine bicarbon-
ate) are reported, as well as metathesis reactions producing
energetic salts. Several energetic compounds were synthe-
sized and characterized for the first time using vibrational
(IR, Raman) and multinuclear NMR spectroscopy, mass spec-
trometry, elemental analysis, and DSC. The crystal structures
of four energetic salts were determined using low tempera-
ture single-crystal X-ray diffraction. Heats of formation for
the metal-free species were calculated using the Gaussian 09
software. Detonation parameters were estimated using the
EXPLO5 program. The sensitivities towards impact, friction,
and electrostatic discharge were also determined.
Introduction
Thermally stable (heat-resistant) explosives are particularly in-
teresting, because they are stable at the high temperatures en-
countered in drilling deep oil wells (e.g., thermally stable per-
forators) or in space exploration (e.g., in achieving stage sepa-
ration in space rockets).[1] In this area, the following explosives
have received special attention: 1,3,5-triamino-2,4,6-trinitroben-
zene (TATB), 2,2’,4,4’,6,6’-hexanitrostilbene (HNS), and 2,6-
bis(picrylamino)-3,5-dinitropyridine (PYX), shown in Figure 1.
In 1888, Jackson and Wing prepared TATB by the reaction of
1,3,5-tribromo-2,4,6-trinitrobenzene with ammonia, yielding
TATB as a pale yellow solid.[2] TATB shows a high theoretical
maximum density (1TMD =1.93 gcmÀ3)[3] and has a high thermal
stability (3108C).[4] In addition, TATB has a high Chapman–Jou-
Figure 1. Most known heat resistant explosives: a) 1,3,5-triamino-2,4,6-trini-
trobenzene (TATB); b) 2,2’,4,4’,6,6’-hexanitrostilbene (HNS); c) 2,6-bis(picryl-
amino)-3,5-dinitropyridine (PYX).
at the Chapman–Jouguet plane and results in low-order deto-
nation.
guet (C-J) detonation velocity and pressure (DC-J =7.66 kmsÀ1
C-J =28.7 GPa at a density of 1.854 gcmÀ3; cylinder test).[5]
,
P
2,2’,4,4’,6,6’-Hexanitrostilbene (HNS) was prepared by Shipp
through the reaction of 2,4,6-trinitrobenzyl chloride with an al-
coholic potassium hydroxide solution.[9] HNS has only a moder-
ately high theoretical maximum density (1TMD =1.745 gcmÀ3)[10]
and melts with subsequent decomposition at 3188C.[6b,11] Two
polymorphs of HNS are known: HNS-I (thin, very fragile plates)
and HNS-II (rectangular shape, has a higher bulk density than
HNS-I).[12] In comparison to TATB, HNS shows lower values for
TATB is insensitive towards impact (IS) (50 J), friction (FS)
(353 N) and electrostatic discharge ignition (ESD) (2.56 J).[6]
However, TATB is difficult to initiate, since its initiation sensitivi-
ty is relatively high.[7] For example, a detonation wave generat-
ed by a cyclotol (75/25) booster did not propagate into a diam-
eter 0.64 cm TATB charge section (length: 1.27 cm, density:
1.881 gcmÀ3).[8] It could be concluded that initiation of small
TATB charges by a weak initiator causes a low reaction extent
the detonation parameters (DC-J =7000 msÀ1 at 1=1.70 gcmÀ3
C-J =6800 msÀ1 at 1=1.60 gcmÀ3,
C-J =20.0 GPa at 1=
;
D
P
1.60 gcmÀ3).[12,13] Despite this, HNS has a uniquely small critical
diameter (ca. 1.0 mm)[14] and is sensitive to several initiation
sources (IS, FS, and ESD: 5 J, >240 N, 0.66 J, respectively).[6]
The search for explosives that are thermally more stable
than HNS, but with lower sensitivities and better performances
is an ongoing process in many research groups worldwide.
The other interesting thermally stable explosives are: 3,3’-di-
[a] Prof. Dr. T. M. Klapçtke, Dr. J. Stierstorfer, M. Weyrauther, T. G. Witkowski
Department of Chemistry, Ludwig-Maximilian University
Butenandtstraße 5–13, 81377 Munich (Germany)
Fax: (+49)89218077492
E-mail: tmk@cup.uni-muenchen.de
Homepage: http://www.hedm.cup.uni-muenchen.de
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201600769.
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amino-4,4’-azofurazan (DAAzF),[15] 2,6-diamino-3,5-dinitropyra-
zine-1-oxide (LLM-105),[16] tetraazapentalenes [1,3,7,9-tetranitro-
6H-benzotriazolo[2,1-a]benzotriazol-5-ium inner salt (Z-
TACOT),[17] 2,4,8,10-tetranitro-5H-benzotriazolo[1,2-a]benzotria-
zol-6-ium inner salt (T-TACOT),[17c] and 2,4,8,10-tetranitro-5H-
pyrido[3’,2’:4,5][1,2,3]-triazolo[1,2-a]benzotriazol-6-ium
salt 2,2’,2’’,4,4’,4’’,6,6’,6’’-nonanitroterphenyl
inner
(BPTAP)[18]],
(NONA),[19] and 2,6-bis(picrylamino)-3,5-dinitropyridine (PYX).[1a]
The first synthesis of PYX was reported by Coburn and Sin-
gleton in 1970[20] in which 2,6-diaminopyridine was reacted
with picryl chloride and sodium fluoride (in situ generation of
picryl fluoride) in a polar, aprotic solvent to yield 2,6-bis(picryl-
amino)pyridine (Pre-PYX). Many different reaction conditions
were studied. Kuboszek and Pawłowski found that using mag-
nesium hydroxide instead of sodium fluoride in nitrobenzene
gives pre-PYX in high yields (87%) and purity.[21] The subse-
quent nitration of pre-PYX using fuming nitric acid results in
the formation of PYX.[20–22] PYX is characterized by an excellent
thermal stability (Tdecomp =3738C), a theoretical maximum den-
sity that is slightly higher than that of HNS (1=1.757 gcmÀ3),
Scheme 1. Synthesis of 2,6-bis(picrylamino)pyridine (pre-PYX, 1).
and good detonation parameters (DC-J =7500 msÀ1
, PC-J =
25.19 GPa at 1=1.75 gcmÀ3, calculated).[22] Also PYX shows
only moderate sensitivity towards IS, FS, and ESD (8 J, 360 N,
and 1.00 J, respectively).
Out of the thermally stable explosives described above, PYX
shows the highest thermal stability. Furthermore, only PYX
possesses acidic protons that can be deprotonated to form
ionic species. This is advantageous, since energetic materials
can often achieve higher thermal stability by the formation of
ionic compounds. Therefore, we decided to investigate these
ionic derivatives as the part of our studies on thermally stable
energetic materials.[20–22]
Results and Discussion
Synthesis
2,6-Bis(picrylamino)pyridine (pre-PYX, 1) was synthesized in
a similar manner as described by Kuboszek and Pawłowski, in
which picrylation of 2,6-diaminopyridine in nitrobenzene at
1908C was performed.[21a] After the reaction was complete, the
crude product was boiled in methanol in order to remove im-
purities. This yielded an orange product which was identified
as 1 (Scheme 1).
The highest yield of pure 1, which did not involve recrystalli-
zation, was obtained using sodium carbonate (Na2CO3) and ni-
trobenzene at 1408C for 3 h (yield 83%). The highest yield for
the synthesis of 1, in which further purification by recrystalliza-
tion was carried out, was achieved using NaF and
dimethylformamide at 1408C for 3 h (yield 88%). The charac-
terization data are consistent with that published by Kuboszek
and Pawłowski.[21a] Nitration of 1 using fuming nitric acid yield-
ed PYX (2) (Scheme 2).[20–22]
Scheme 2. Synthesis of 2,6-bis(picryl-amino)-3,5-dinitropyridine (PYX, 2) and
its salts.
(7), hydrazinium (8), hydroxylammonium (9), guanidinium (10),
aminoguanidinium (11), and triaminoguanidinium (12)
(Scheme 2).
Single-crystal X-ray analysis
The structures of 1, 2, the guanidinium monohydrate salt
10·H2O, and the mono-deprotonated potassium monohydrate
4b·H2O, rubidium 5b, and cesium 6b salts in the crystalline
state were determined by using low-temperature single-crystal
X-ray diffraction.[23] Compound 1 crystallizes in the monoclinic
space group P21 with a density of 1.698 gcmÀ3 at 173 K and
four molecules in the unit cell. The molecular structure of 1 is
shown in Figure 2. Nitration of 1 yielded 2 which crystallizes in
the orthorhombic space group P212121 with a density of
The reaction of 2 with different bases (alkali metal hydrox-
ides, N-bases) or/and by metathesis reactions resulted in the
formation of salts of PYX containing the following cations:
sodium (3), potassium (4), rubidium (5), cesium (6), ammonium
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Figure 2. Molecular structure of 1 shown with 50% probability thermal ellip-
soids.
Figure 3. Molecular structure of 2 shown with 50% probability thermal ellip-
1.757 gcmÀ3 at 298 K and eight molecules in the unit cell. The
introduction of two nitro groups in the pyridine moiety at the
3- and 5-positions in 2 has a positive impact on both the den-
sity and the thermal stability (Table 1) in comparison with 1.
The molecular structure of 2 is shown in Figure 3.
soids.
The potassium salt of mono-deprotonated 2 crystallizes with
one water molecule per 4b molecule in the monoclinic space
group P21, with a density of 1.860 gcmÀ3 at 173 K and two
molecules in the unit cell. The molecular structure of 4b·H2O is
shown in Figure 4. The rubidium salt of 2 is anhydrous and
¯
crystallizes in the triclinic space group P1 with a density of
1.959 gcmÀ3 at 173 K and two molecules in the unit cell. The
molecular structure of 5b is shown in Figure 5. The cesium salt
of 2 crystallizes in the monoclinic space group P21/c with
a density of 2.077 gcmÀ3 at 173 K and four molecules in the
unit cell. The molecular structure of 6b is shown in Figure 6.
The guanidinium salt crystallizes with one water molecule
¯
per molecule in the triclinic space group P1 with a density of
Figure 4. Molecular structure of 4b·H2O in which only a single deprotona-
tion of PYX has occurred. The thermal ellipsoids are shown with 50% proba-
bility.
1.714 gcmÀ3 at 173 K and two molecules in the unit cell. The
molecular structure of 10·H2O is shown in Figure 7.
Table 1. Physicochemical properties of PYX, and its salts in comparison to HNS.
PYX (2)
7
8
9
10
11
12
HNS
formula
MW [gmolÀ1
IS[a] [J]
C17H7N11O16
621.34
10
C17H13N13O16
655.36
40
360
27.8
C17H15N15O16
685.69
10
360
30.7
C17H13N13O18
687.36
5
324
26.5
C19H17N17O16
739.44
40
360
32.2
C19H19N19O16
769.47
40
360
34.6
C19H23N23O16
829.53
20
360
38.8
C14H6N6O12
450.23
5[1a,6b]
]
FS[b] [N]
N[c] [%]
360
240[1a,6b]
18.67
24.80
À55.36
360
1.757
43.7
W[d] [%]
À59.8
À59.5
À52.4
À66.0
À65.5
À64.6
À67.6
[e]
Tdecomp [8C]
276
205
333
227
183
233
318[1a,6b]
1.74[6b]
78.2
1[f] [gcmÀ3
]
1.72
273.5
1.65
553.9
1.71
382.1
1.62
169.0
1.67
384.2
1.62
799.0
DH(s)A[g] [kJmolÀ1
]
EXPLO5 V6.02
ÀDEUA[h] [kJkgÀ1
]
4993
3651
24.5
7713
618
5286
3634
24.9
7815
664
5486
3758
23.8
7715
699
5659
3896
26.4
7910
671
4716
3328
20.3
7343
701
4907
3364
22.6
7682
712
5171
3481
22.4
7710
754
5263
3723
23.6
7545
589
[i]
TC-J [K]
PC-J[j] [GPa]
DC-J[k] [msÀ1
]
[l]
V0 [dm3 kgÀ1
]
[a] Impact sensitivity (BAM drophammer, method 1 of 6). [b] Friction sensitivity (BAM drophammer, method 1 of 6). [c] Nitrogen content. [d] Oxygen bal-
ance. [e] Temperature of decomposition. [f] Density at 298 K. [g] Standard molar enthalpy of formation. [h] Heat of detonation. [i] Detonation temperature.
[j] Detonation pressure. [k] Detonation velocity. [l] Volume of detonation gases at standard temperature and pressure conditions.
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Figure 5. Molecular structure of 5b shown with 50% probability thermal el-
lipsoids.
Figure 7. Molecular structure of 10·H2O shown with 50% probability thermal
ellipsoids.
Figure 6. Molecular structure of 6b shown with 50% probability thermal el-
lipsoids.
Selected crystallographic data, measurement parameters
and refinement details are given in the Supporting Information
(Tables S1 and S2).
Figure 8. IR-spectra recorded for 2 before (black) and after (green) the iso-
thermal long term experiment.
Thermal stabilities, sensitivities, and energetic properties
2,6-Bis(picrylamino)pyridine (Pre-PYX, 1) has a high thermal sta-
bility and decomposes at 3048C. However, the introduction of
two further nitro groups in the 3- and 5-positions of the pyri-
dine moiety increases the thermal stability with decomposition
occurring at 3608C. The results of the isothermal long-term ex-
periment (RADEX, 100 h, 2608C) show that neither decomposi-
tion nor thermal rearrangement of compound 2 occurred
(Figure 8). The highest thermal stability within the series of
duction of two nitro groups to 1 decreases the impact and fric-
tion sensitivity from IS=9 J and FS=324 N (1) to IS=10 J and
FS=360 N (2). The most sensitive compounds towards impact
are the sodium (3, IS=3 J), cesium (6, IS=10 J) and hydroxyl-
ammonium (9, IS=10 J) salts of PYX. All of the salts which
were investigated have friction sensitivities higher than 300 N.
Since the amount of gaseous products liberated during det-
onation strongly depends on the composition of the explosive
being initiated, we decided to investigate only non-metal ener-
getic materials. The gas-phase absolute molar enthalpies at
298 K and 1 atm for the non-metal species were calculated
theoretically using the modified complete basis set method
(CBS-4M) with the Gaussian 09 software.[24] The atomization-
energy method was applied in order to calculate the gas
phase standard molar enthalpies of formation (DH(g)A) at
alkali metal salts is shown by the sodium salt (3, Tdecomp
=
3498C). However, out of the salts investigated, the hydroxylam-
monium salt (9, Tdecomp =3338C) has the highest thermal stabili-
ty. The decomposition temperature of 9 is, however, still lower
than that of covalent 2 (Tdecomp =3608C; Table 1).
Furthermore, the sensitivities of the compounds to impact
(IS) and friction (FS) were investigated. Surprisingly, the intro-
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298.15 K.[24c,25] In order to obtain the standard molar enthalpy
of formation (DH(s)A) for the prepared covalent compounds,
the values of the standard molar enthalpies of sublimation (es-
timated using Trouton’s rule) were subtracted from DH(g)A.[26] In
the case of the salts, DH(g)A of the ions as well as the calculated
standard molar lattice enthalpies were used to calculate
DH(s)A.[27] The Chapman–Jouguet (C-J) characteristics, based on
the calculated DH(s)A value and either the theoretical maximum
densities (obtained either from X-ray diffraction measurements
at 298 K) or from recalculation of the values obtained at 173 K
with a PerkinElmer Spectrum BX-FTIR spectrometer equipped with
a Smiths DuraSamplIR II ATR device. The following abbreviations
were used to characterize the relative signal intensities: vs (very
strong), s (strong), m (middle), w (weak), vw (very weak). All spectra
were recorded at ambient temperature. Elemental analyses were
performed on a Vario EL and a Vario Micro from Elementar Compa-
ny. The sensitivities towards mechanical stimuli were determined
according to the BAM (Bundesanstalt für Materialforschung und
Prüfung, English: Federal Institute for Materials Research and Test-
ing) standard for friction and impact.[30] The impact sensitivity was
tested according to STANAG 4489 modified instructions using
a BAM drophammer. The friction sensitivity was tested according
to STANAG 4487 modified instructions using a BAM friction tester.
The single-crystal X-ray diffraction measurements of pre-PYX (1),
PYX (2), guanidinium monohydrate (12·H2O) and mono-deproton-
ated (potassium monohydrate 4b·H2O, rubidium 5b, and cesium
6b) salts were collected using an Oxford Xcalibur3 diffractometer
with a Spellman generator (voltage 50 kV, current 40 mA), en-
hanced molybdenum Ka radiation source (l=0.71073 Š), Oxford
Cryosystems Cryostream cooling unit, four-circle kappa platform,
and a Sapphire CCD detector. Data collection and reduction were
performed by using the CrysAlisPro software.[31] The structure was
solved with SIR-92,[32] refined by full-matrix least-squares on F2
with SHELXL-97,[33] checked with PLATON,[34] and all integrated into
the WinGX software suite.[35] The finalized CIF files were checked
with checkCIF.[36] Intra- and intermolecular contacts were analyzed
with MERCURY.[37] The CCDC deposition numbers are given in refer-
ence [23].
(using the following equation:[28] 1298 =1T·(1+av(298ÀT))À1
;
av =1.5”10À4
;
T=173 K) were calculated using the
EXPLO5V6.02 thermochemical computer code.[29] The Becker–
Kistiakowsky–Wilson equation of state (BKW EOS) with the fol-
lowing sets of constants: a=0.5, b=0.38, k=9.4, and V=
4120 for gaseous detonation products and the Murnaghan
equation of state for condensed products (compressible solids
and liquids) were applied (Table 1).
Conclusion
The synthetic routes for the preparation of 2,6-bis(picrylami-
no)-3,5-dinitropyridine (PYX) and its salts with detailed charac-
terizations are reported. Furthermore, the crystal structures for
Pre-PYX (1), PYX (2) and four energetic salts were determined
using low-temperature single-crystal X-ray diffraction. Surpris-
ingly, compound 2 shows lower sensitivities toward impact
and friction than the non-nitrated 1. Compound 2 also shows
a higher thermal stability than 1. Moreover, an isothermal long
time stability test (RADEX) of 2 showed that no chemical
changes occurred after 100 h at 2608C. All of the salts investi-
gated showed lower thermal stabilities than 2. Using the calcu-
lated heats of formation and experimentally determined densi-
ties, the detonation parameters (heat of explosion, explosion
temperature, detonation pressure, and velocity) were calculat-
ed for non-metal species. The hydroxylammonium salt 9
showed the highest thermal stability and was calculated to
possess the best detonation performance out of the nitrogen-
based (non-metal) salts investigated. Furthermore, values of 9
are superior to corresponding values for HNS. Therefore, the
hydroxylammonium salt 9 is the most promising candidate for
further investigation and potential application among the salts
which were investigated.
Picryl chloride:[38] Picric acid (5.04 g, 22 mmol) was dissolved in
phosphoryl chloride (50 mL) and N,N-diethylaniline (3.98 mL,
25 mmol) was added drop wise under vigorous stirring. The result-
ing solution was allowed to stir at ambient temperature for 15 min
before being poured into iced water (500 mL) and stirred vigorous-
ly until all the phosphoryl chloride was hydrolyzed and picryl chlo-
ride precipitated. Picryl chloride was washed with water and dried
over calcium chloride. Yield: 92.73%, 5.05 g; DSC (58CminÀ1): 868C
(melt.); 1H NMR (400 MHz, [D6]DMSO): d=9.17 ppm (s, 2H, CH);
13C NMR (101 MHz, [D6]DMSO): d= 149.7, 146,8, 125.8, 123.3 ppm;
14N NMR (29 MHz, [D6]DMSO): d=À15 ppm (CNO2); MS (DEI+): m/
z: 247.2 [M]+; IR (ATR): n˜ =3086 (m), 1605 (m), 1533 (vs), 1407 (w),
1341 (vs), 1186 (w), 1063 (s), 936 (m), 920 (vs), 825 (w), 753 (m),
732 (s), 720 (vs), 645 cmÀ1 (m); Raman (1064 nm, 300 mW): n˜ =
3089 (15), 1604 (54), 1554 (34), 1547 (37), 1370 (62), 1353 (100),
1197 (22), 1065 (29), 937 (11), 924 (11), 824 (40), 765 (7), 754 cmÀ1
(9); elemental analysis calcd (%) for C6H2ClN3O6 (247.55): C 29.11, H
0.81, N 16.97; found: C 28.82, H 0.94, N 16.78; IS: 15 J; FS: 360 N.
2,6-Bis(picrylamino)pyridine (Pre-PYX, 1):[21b] To a solution of
picryl chloride (4.95 g, 20 mmol) in p-xylene (40 mL), magnesium
hydroxide (1.05 g, 18 mmol) and 2,6-diaminopyridine (0.98 g,
9 mmol) were added. The reaction mixture was heated at 1408C
for 3 h and then allowed to cool to room temperature. Toluene
(30 mL) was then added and the product collected by filtration,
washed with methanol, 10% HCl, and with water until it was acid
free. Yield: 60.00%, 2.97 g; DSC (58CminÀ1): 3048C (decomp);
1H NMR (400 MHz, [D6]DMSO): d=10.37 (s, 2H, NH), 8.77 (s, 4H,
CH), 7.75 (t, 1H, J=8.02 Hz, CH), 7.75 ppm (d, 2H, J=8.02 Hz, CH);
13C NMR (101 MHz, [D6]DMSO): d=154.7, 143.1, 139.4, 139.1, 136.7,
125.7, 99.2 ppm; 14N NMR (29 MHz, [D6]DMSO): d=À13 (CNO2),
À273 ppm (CNH); MS (DEI+): m/z: 531.2 [M]+; IR (ATR): n˜ =3334
(w), 3306 (w), 3098 (w), 3080 (w), 1739 (w), 1623 (m), 1596 (s), 1586
(s), 1540 (s), 1518 (m), 1480 (s), 1452 (s), 1394 (w), 1335 (vs), 1294
(vs), 1527 (s), 1216 (m), 1171 (m), 1151 (s), 1086 (s), 998 (w), 933
(m), 921 (s), 844 (w), 828 (w), 793 (s), 773 (m), 751 (m), 740 (m), 721
Experimental Section
Differential scanning calorimetry (DSC) was performed on a LINSEIS
DSC PT10 using about 1 mg substance in a perforated aluminum
vessel with a heating rate of 5 KminÀ1 and a nitrogen flow of 5
dm3 hÀ1. NMR spectra were recorded at 258C on a JEOL Eclipse 400
and JEOL ECX 400 instrument. Tetramethylsilane (1H and 13C) and
nitromethane (14N) were used as external standards. As an addi-
1
tional standard in H and 13C NMR spectroscopy, the solvent signal
was used as locking signal. Mass spectrometric data were obtained
with a JEOL MStation JMS 700 spectrometer (DEI+/FAB+/À). Raman
spectra were recorded with a Bruker MultiRAM FT-Raman instru-
ment fitted with a liquid-nitrogen-cooled germanium detector and
an Nd:YAG laser (l=1064 nm). Infrared spectra were measured
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(vs), 702 cmÀ1 (s); Raman (1064 nm, 300 mW): n˜ =1622 (33), 1544
(20), 1529 (14), 1503 (12), 1455 (11), 1354 (49), 1340 (100), 1301
(25), 1278 (20), 1173 (17), 1000 (23), 827 cmÀ1 (13); elemental analy-
sis calcd (%) for C17H9N9O12 (531,31): C 38.43, H 1.71, N 23.73;
found: C 38.29, H 1.88, N 23.57; IS: 9 J; FS: 324 N; ESD: 0.5 J.
755 (m), 738, (vw), 730 (vw), 720 (s), 704 (vw), 678 cmÀ1 (m);
Raman (1064 nm, 300 mW, 258C): n˜ =3084 (2), 1613 (18), 1595 (19),
1578 (34), 1535 (18), 1501 (20), 1432 (14), 1359 (58), 1343 (54),
1323 (100), 1300 (58), 1270 (34), 1243 (36), 1203 (38), 1174 (25),
1120 (21), 1081 (12), 945 (11), 827 (76), 803 (6), 753 (11), 741 (14),
720 cmÀ1 (11); elemental analysis calcd (%) for C17H5K2N11O16,
(697.48): C 29.27, H 0.72, N 22.09; found: C 29.05, H 1.06, N 21.65;
IS: 10 J; FS: 360 N.
2,6-Bis(picrylamino)-3,5-dinitropyridine (PYX, 2):[21a] 2,6-Bis(picryl-
amino)pyridine (1.06 g, 2 mmol) was carefully added to fuming
nitric (11 mL) stirred acid at À208C. The resulting solution was al-
lowed to warm to room temperature, stirred for 2 h, then heated
under reflux for 5 h before being cooled and diluted with 65%
nitric acid (21 mL) at 08C. The precipitated product was filtered off,
washed with 70% nitric acid (3 mL), water until acid free, and
methanol (21 mL). The product obtained was dried at 1508C. Yield:
66.80%, 0.83 g; DSC (58CminÀ1): 3608C (decomp); 1H NMR
(400 MHz, [D6]DMSO): d=11.25 (s, br, 2H, NH), 9.19 (s, 1H, CH),
8.90 ppm (s, 4H, CH); 13C NMR (101 MHz, [D6]DMSO): d=161.2,
144.4, 142.3, 137.7, 131.2, 125.1, 124.0 ppm; 14N NMR (29 MHz,
[D6]DMSO): d=À6 (CNO2), À48 (CNO2) À292 ppm (CNH); MS (DEI+
): m/z: 621.4 [M]+; IR (ATR): n˜ =3271 (w), 3087 (w), 1739 (w), 1636
(m), 1594 (vs), 1539 (vs), 1481 (s), 1422 (s), 1402 (s), 1344 (vs), 1331
(vs), 1308 (vs), 1292 (s), 1244 (m), 1194 (w), 1091 (m), 949 (m), 940
(m), 922 (m), 911 (m), 858 (w), 838 (w), 826 (w), 780 (w), 762 (s),
721 (s), 696 (m), 679 (w), 639 (m), 608 cmÀ1 (m); Raman (1064 nm,
300 mW): n˜ =3102 (4), 1626 (55), 1606 (19), 1542 (20), 1523 (16),
1483 (12), 1347 (100), 1334 (83), 1310 (37), 1294 (49), 1266 (29),
1177 (13), 1094 (8), 942 (7), 859 (4), 838 (25), 827 (13), 741 (5), 697
(4), 641 cmÀ1 (5); elemental analysis calcd (%) for C17H7N11O16
(621.30) : C 32.86, H 1.14, N 24.80; found: C 32.68, H 1.38, N 24.29;
IS: 10 J; FS: 360 N; ESD: 0.5 J.
Rubidium salt of 2,6-bis(picrylamino)-3,5-dinitropyridine (5): A
solution of rubidium hydroxide (102.5 mg, 1.00 mmol, 50 wt.% in
water) in ethanol (10 mL) was added to 2,6-bis(picrylamino)-3,5-di-
nitropyridine (310.7 mg, 0.50 mmol) in ethanol (10 mL). Immediate-
ly a red solid precipitated. Yield: 90.86%, 359 mg; DSC (58CminÀ1):
2088C (decomp); 1H NMR (400 MHz, [D6]DMSO): d=8.76 (s, 1H,
CH), 8.42 ppm (s, 4H, CH); 13C NMR (101 MHz, [D6]DMSO): d=
151.6, 144.3, 143.6, 133.6, 133.8, 124.0,122.6 ppm; MS (FABÀ): m/z:
620.2 [C17H6N11O16]À; (FAB+): m/z: 85.0 [Rb]+; IR (ATR): n˜ =3083 (w),
2358 (vw), 1610 (m), 1556 (m), 1527 (s), 1482 (m), 1466 (w), 1428
(w), 1365 (w), 1345 (s), 1325 (vs), 1251 (vs), 1215 (vs), 1167 (s), 1087
(s), 935 (m), 927 (m), 907 (w), 824 (w), 768 (vw), 756 (m), 729 (m),
718 (s), 678 cmÀ1 (m); Raman (1064 nm, 300 mW): n˜ =1611 (14),
1536 (14), 1446 (13), 1431 (15), 1360 (36), 1323 (100), 1239 (21),
1202 (45), 1174 (16), 1122 (9), 1083 (9), 945 (8), 827 (41), 769 (9),
752 (7), 740 (9), 721 (10), 627 cmÀ1 (7); elemental analysis calcd (%)
for C17H5N11O16Rb2 (790.22): C 25.84, H 0.64, N 19.50; found: C
26.03, H 0.34, N 19.89; IS: 10 J; FS: 360 N.
Cesium salt of 2,6-bis(picrylamino)-3,5-dinitropyridine (6): A so-
lution of cesium hydroxide monohydrate (167.9 mg, 1.00 mmol) in
ethanol (10 mL) was added to 2,6-bis(picrylamino)-3,5-dinitropyri-
dine (310.7 mg, 0.50 mmol) dissolved in ethanol (10 mL). Immedi-
ately a red solid precipitated. Yield: 93.37%, 413.2 mg; DSC
(58CminÀ1): 3378C (decomp); 1H NMR (400 MHz, [D6]DMSO): d=
8.77 (s, 1H, CH), 8.47 ppm (s, 4H, CH); 13C NMR (101 MHz,
[D6]DMSO): d=163.5, 153.9, 148.9, 148.5, 144.3, 143.2, 139.9, 138.6,
134.1, 128.5, 125.7, 124.7, 122.9 ppm; 14N NMR (29 MHz, [D6]DMSO):
d=À3 ppm (CNO2); IR (ATR): n˜ =3083 (vw), 1608 (w), 1550 (s),
1525 (s), 1479 (m), 1448 (w), 1425 (w), 1343 (m), 1326 (s), 1255 (vs),
1213 (s), 1166 (s), 1086 (m), 936 (w), 920 (w), 908 (w), 857 (vw), 836
(vw), 824 (w), 779 (vw), 756 (m), 717 (s), 695 (m), 678 (m), 660 cmÀ1
(m); Raman (1064 nm, 300 mW): n˜ =3240 (8), 2563 (17), 2269 (12),
2242 (14), 2221 (16), 2208 (17), 2185 (19), 2158 (21), 2136 (24),
2092 (22), 2075 (20), 2059 (21), 2043 (18), 2023 (22), 1925 (22),
1796 (22), 1625 (29), 1328 (66), 1204 (35), 1123 (34), 1090 (22), 826
(40), 723 (36), 641 (42), 98 cmÀ1 (100); MS (FABÀ): m/z: 620.5
[C17H6N11O16]À; (FAB+): m/z: 133.0 [Cs]+; elemental analysis calcd
(%) for C17H5Cs2N11O16 (885.10): C 23.07, H 0.57, N 17.41; found: C
22.98, H 0.87, N 17.27; IS: 5 J; FS: 360 N.
Sodium salt of 2,6-bis(picrylamino)-3,5-dinitropyridine (3): A so-
lution of sodium hydroxide (60.0 mg, 1.50 mmol) in ethanol
(10 mL) was added to 2,6-bis(picrylamino)-3,5-dinitropyridine
(466.0 mg, 0.75 mmol) dissolved in ethanol (10 mL). Instantly
a bright red solid precipitated. Yield: 93.80%, 468.0 mg; DSC
(58CminÀ1): 3498C (decomp); 1H NMR (400 MHz, [D6]DMSO): d=
8.74 (s, 1H, CH), 8.34 (s, 4H, CH); 13C NMR (101 MHz, [D6]DMSO):
d=153.5, 145.6, 143.6, 134.0, 131.2, 126.0, 122.9 ppm; 14N NMR
(29 MHz, [D6]DMSO): d=À20 ppm (CNO2); MS (FABÀ): m/z: 620.3
[C17H6N11O16]À; (FAB+): m/z: 23.0 [Na]+; IR (ATR): n˜ =3084 (w), 2289
(vw), 1607 (m), 1556 (m), 1520 (s), 1504 (m), 1466 (w), 1443 (w),
1413 (w), 1346 (s), 1266 (vs), 1185 (vs), 1166 (vs), 1126 (s), 1087 (s),
940 (m), 931 (m), 914 (m), 848 (w), 826 (w), 806 (vw), 782 (vw), 769
(w), 755 (m), 738 (m), 719 (vs), 678 cmÀ1 (m); Raman (1064 nm,
300 mW): n˜ =3088 (2), 1612 (28), 1541 (19), 1441 (14), 1368 (67),
1340 (86), 1325 (92), 1309 (57), 1292 (60), 1233 (33), 1187 (100),
1131 (20), 1091 (9), 945 (6), 916 (7), 832 (52), 769 (12), 739 (16), 720
(25), 385 (9), 190 (21), 170 (25), 85 cmÀ1 (68); elemental analysis
calcd (%) for C17H5N11Na2O16 (665.27): C 30.69, H 0.76, N 23.16;
found: C 30.36, H 1.09, N 22.63; IS: 3 J; FS: 360 N.
Ammonium salt of 2,6-bis(picrylamino)-3,5-dinitropyridine (7):
Method 1: The sodium (3; 0.50 mmol, 332,6 mg) or potassium (4;
0.50 mmol, 348.7 mg) salt of 2,6-bis(picrylamino)-3,5-dinitropyridine
was added to ethanol (10 mL) followed by the dropwise addition
of ammonium chloride (53.5 mg, 1.00 mmol) in water (1 mL). After
stirring at room temperature for 5 h the reaction mixture was fil-
tered and the product was obtained as brown solid. Yield: 80.32%
(263.2 mg), 80.20% (262.8 mg), respectively. Method 2: 2,6-Bis(pic-
rylamino)-3,5-dinitropyridine (1.00 g, 1.61 mmol) was dissolved in
ethanol (40 mL) and ammonia gas was slowly bubbled through
the solution for 15 min at room temperature. After stirring for 1 h,
the reaction mixture was filtered and the product was obtained as
a brown solid. Yield: 47.08%, 496.8 mg; DSC (58CminÀ1): 2768C
Potassium salt of 2,6-bis(picrylamino)-3,5-dinitropyridine (4): A
solution of potassium hydroxide (40.4 mg, 0.72 mmol) in ethanol
(10 mL) was added to 2,6-bis(picrylamino)-3,5-dinitropyridine
(223.7 mg, 0.36 mmol) in ethanol (10 mL). Immediately a red solid
precipitated. Yield: 96.38%, 242.0 mg; DSC (58CminÀ1): 2808C
(decomp); 1H NMR (400 MHz, [D6]DMSO): d=8.75 (s, 1H, CH),
8.34 ppm (s, 4H, CH); 13C NMR (101 MHz, [D6]DMSO): d=151.3,
144.1, 143.0, 134.4, 134.0, 124.2,123.0 ppm; 14N NMR (29 MHz,
[D6]DMSO): d=À32 ppm (CNO2); MS (FABÀ): m/z: 620.3
[C17H6N11O16]À; (FAB+): m/z: 39.0 [K]+; IR (ATR): n˜ =3084 (w), 2892
(vw), 2349 (vw), 2281 (vw), 1840 (vw), 1611 (w), 1594 (w), 1564 (m),
1528 (s), 1485 (m), 1444 (m), 1345 (m), 1321 (m), 1296 (s), 1252 (vs),
1216 (s), 1192 (s), 1168 (s), 1119 (m), 1088 (m), 961 (vw), 937 (w),
922 (m), 910 (w), 857 (vw), 846 (vw), 824 (w), 802 (vw), 780 (vw),
1
(decomp); H NMR (400 MHz, [D6]DMSO): d=9.04 (s, 4H, CH), 8.98
(s, 1H, CH), 7.14 ppm (s, 4H, NH4); 13C NMR (101 MHz, [D6]DMSO):
d=154.7, 143.6, 134.2, 132.6, 128.0, 125.2, 120.2 ppm; 14N NMR
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(29 MHz, [D6]DMSO): d=À18 (CNO2), À355 ppm (NH4); IR (ATR):
n˜ =3436 (w), 3326 (w), 3085 (w), 1633 (m), 1580 (m), 1523 (m),
1455 (m), 1419 (m), 1346 (m), 1269 (vs), 1161 (m), 1089 (m), 1039
(m), 933 (m), 897 (m), 827 (m), 777 (w), 763 (m), 738 (m), 727 (s),
707 (m), 689 cmÀ1 (m); Raman (1064 nm, 300 mW): n˜ =2620 (40),
1628 (52), 1530 (58), 1338 (100), 1282 (75), 1224 (56), 1166 (53),
1092 (32), 1055 (50), 940 (62), 829 cmÀ1 (90); MS (FABÀ): m/z: 620.3
[C17H6N11O16]À; (FAB+): m/z: 18.0 [NH4]+; elemental analysis calcd
(%) for C17H13N13O16 (655.36): C 31.16, H 2.00, N 27.78; found: C
30.76, H 1.61, N 28.16; IS: 40 J; FS: 360 N.
guanidinium carbonate (90.1 mg, 1.00 mmol) were added to etha-
nol (15 mL) and heated under reflux for 3 h. After cooling and fil-
tering, the product was obtained as a dark-red solid. Yield: 62.67%,
215.4 mg; DSC (58CminÀ1): 2278C (decomp); 1H NMR (400 MHz,
[D6]DMSO): d=8.82 (s 1H, CH), 8.66 (s, 4H, CH), 6.90 ppm (s, br,
6H, NH2); 13C NMR (101 MHz, [D6]DMSO): d=158.4, 154.1, 145.3,
143.1, 134.5, 125.7 ppm; 14N NMR (29 MHz, [D6]DMSO): d=À15
(CNO2), À364 ppm (CNH2); IR (ATR): n˜ =3604 (vw), 3436 (w), 3360
(w), 3190 (w), 3080 (w), 2360 (vw), 2341 (vw),1668 (m), 1006 (w),
1540 (m), 1521 (s), 1496 (m),1464 (w), 1439 (w), 1415 (w), 1341 (m),
1267 (s), 1203 (s), 1165 (s), 1084 (m), 932 (m), 924 (m), 906 (w), 824
(w), 766 (vw), 758 (w), 718 (m), 700 (vw), 683 (w), 668 cmÀ1 (vw);
Raman (1064 nm, 300 mW): n˜ =3087 (1), 1609 (23), 1573 (7), 1535
(17), 1469 (2), 1435 (11), 1364 (53), 1327 (100), 1230 (40), 1202 (58),
1173 (20), 1124 (18), 1087 (7), 1010 (3), 943 (3), 827 (39), 771 (8),
741 (8), 719 cmÀ1 (8); MS (FABÀ): m/z: 620.3 [C17H6N11O16]À; (FAB+):
m/z: 60.1 [CN3H6]+; elemental analysis calcd (%) for C19H17N17O16
(739.44): C 30.86, H 2.32, N 32.20; found: C 30.43, H 2.51, N 31.27;
IS: 40 J; FS: 360 N.
Hydrazinium salt of 2,6-bis(picrylamino)-3,5-dinitropyridine (8):
2,6-Bis(picrylamino)-3,5-dinitropyridine (453.5 mg, 0.73 mmol) was
dissolved in ethanol (10 mL) and hydrazine monohydrate (0.07 mL,
1.46 mmol) was added dropwise. Afterwards, the reaction mixture
was heated under reflux for 3 h, cooled, and the resulting dark-red
precipitate was filtered off. Yield: 62.91%, 663.8 mg; DSC
(58CminÀ1): 2058C (decomp); 1H NMR (400 MHz, [D6]DMSO): d=
8.97 (s, 1H, CH), 8.81 (s, 4H, CH), 7.31 ppm (br, 10H, NH2-NH3);
13C NMR (101 MHz, [D6]DMSO): d=155.2, 139.2, 135.8, 130.7, 120.7,
117.6, 116.7 ppm; 14N NMR (29 MHz, [D6]DMSO): d=À15 (CNO2),
À359 ppm (NH2); IR (ATR): n˜ =3474 (m), 3357 (m), 3088 (w), 2840
(vw), 2740 (vw), 2648 (vw), 2360 (vw), 1606 (vs), 1552 (w) 1526 (w),
1508 (m), 1455 (m), 1436 (m), 1389 (w) 1373 (m), 1328 (s), 1281 (s),
1269 (vw), 1217 (vs), 1180 (m), 1330 (w), 1106 (vw), 1086 (m), 1060
(vw), 1036 (s), 944 (vw), 934 (m), 922 (vw), 902 (w), 877 (vw), 864
(vw), 828 (w), 802 (m), 742 (m), 717 (m), 706 (m), 684 cmÀ1 (vw);
Raman (1064 nm, 300 mW): n˜ =3347 (8), 3297 (6), 3085 (7), 2476
(7), 1598 (17), 1554 (12), 1358 (13), 1323 (86), 1253 (9), 1185 (17),
1111 (5), 1061 (7), 1010 (5), 805 (12), 791 (7), 751 (7), 726 (6), 381
(17), 348 (6), 87 cmÀ1 (43); MS (FABÀ): m/z: 620.3 [C17H6N11O16]À;
(FAB+): m/z: 33.1 [N2H5]+; elemental analysis calcd (%) for
C17H15N15O16 (685.69): C 29.79, H 2.21, N 30.65; found: C 28.99, H
2.72, N 36.64; IS: 10 J; FS: 360 N; ESD: 0.35 J.
Aminoguanidinium salt of 2,6-bis(picrylamino)-3,5-dinitropyri-
dine (11): 2,6-Bis(picrylamino)-3,5-dinitropyridine (403.8 mg,
0.65 mmol) and aminoguanidinium bicarbonate (176.9 mg,
1.30 mmol) were added to ethanol (10 mL) and heated under
reflux for 3 h. After cooling and filtering, the product was obtained
as a dark-red solid. Yield: 61.72%, 308.7 mg; DSC (58CminÀ1):
1838C (decomp); 1H NMR (400 MHz, [D6]DMSO): d=8.75 (s, 1H,
CH), 8.58 (s, br, 2H, NH) 8.34 (s, 4H, CH), 7.26 (s, br, 2H, N-NH2),
6.79 ppm (s, br, 4H, NH2); 13C NMR (101 MHz, [D6]DMSO): d=159.2,
153.4, 145.5, 143.6, 134.0, 131.2, 126.0, 122.9 ppm; 14N NMR
(29 MHz, [D6]DMSO): d=À20 (CNO2), À264 (CNH) À369 ppm
(CNH2); IR (ATR): n=3334 (w), 3082 (w), 2280 (vw), 1682 (w), 1666
(m), 1625 (m), 1572 (m), 1527 (s), 1497 (m), 1444 (w), 1389 (w),
1344 (s), 1310 (s), 1289 (s), 1247 (m), 1184 (m), 1116 (m), 1081 (m),
957 (m), 938 (m), 924 (m), 857 (w), 923 (m), 767 (vw), 758 (m), 717
(m), 685 cmÀ1 (m); Raman (1064 nm, 300 mW,): n˜ =3065 (8), 2748
(7), 1617 (32), 1581 (78), 1503 (49), 1456 (13), 1368 (73), 1346 (100),
1317 (43), 1298 (46), 1242 (66), 1174 (41), 1119 (52), 1082 (28), 946
(10), 824 (70), 747 cmÀ1 (21); MS (FABÀ): m/z: 620.3 [C17H6N11O16]À;
(FAB+): m/z: 75.1 [CN4H7]+; elemental analysis calcd. (%) for
C19H19N19O16 (769.47): C 29.66, H 2.49, N 34.59; found: C 29.61, H
2.31, N 34.71; IS: 40 J; FS: 360 N.
˜
Hydroxylammonium salt of 2,6-bis(picrylamino)-3,5-dinitropyri-
dine (9): Method 1: The sodium (3; 0.50 mmol, 332.6 mg) or potas-
sium (4; 0.50 mmol, 348.7 mg) salt of 2,6-bis(picrylamino)-3,5-dini-
tropyridine was added to ethanol (10 mL) and hydroxylammonium
chloride (69.5 mg 1.00 mmol) in water (10 mL) was added drop-
wise. After heating at 608C for 3 h, the hot reaction mixture was fil-
tered and the product obtained as an orange solid. Yield: 68.55%
(235.6 mg), 72.68% (249.8 mg), respectively. Method 2: 2,6-Bis(pic-
rylamino)-3,5-dinitropyridine (1.00 g, 1.61 mmol) was dissolved in
ethanol (40 mL) and hydroxylamine (3.22 mmol, 0.21 mL, 50 wt.%
in H2O) was added to the reaction mixture. After stirring at room
temperature for 5 h, the reaction mixture was filtered and the
product obtained as an orange solid. Yield: 62.96%, 696.8 mg; DSC
(58CminÀ1): 3338C (decomp); 1H NMR (400 MHz, [D6]DMSO): d=
9.08 (s, 1H, CH), 8.85 (s, 4H, CH), 4.55 ppm (brs, 4H, NH3OH);
13C NMR (101 MHz, [D6]DMSO): d=149.1, 145.6, 142.8, 136.4,127.3,
124.5, 122.4 ppm; 14N NMR (29 MHz, [D6]DMSO): d=À18 (NO2),
À292 ppm (NH3); IR (ATR): n˜ =3270 (vw), 3089 (vw), 1635 (w), 1593
(vs), 1538 (s), 1480 (s), 1422 (m), 1400 (m), 1343 (vs), 1330 (vs),
1330 (vs), 1307 (vs), 1290 (s), 1243 (m), 1193 (w), 1091 (m), 948 (m),
921 (w), 910 (m), 858 (vw), 837 (w), 826 (w), 779 (vw), 761 (m), 720
(s), 695 (m), 678 cmÀ1 (w); Raman (1064 nm, 300 mW): n˜ =3263 (3),
3102 (4), 1627 (62), 1605 (18), 1542 (20), 1524 (19), 1483 (12), 1357
(84), 1347 (89), 1333 (100), 1309 (43), 1293 (64), 1293 (65), 1267
(29), 1177 (14), 942 (7), 838 (27), 827 (13), 640 cmÀ1 (6); MS (FABÀ):
m/z: 620.6 [C17H6N11O16]À; (FAB+): m/z: 34.0 [NH3OH]+; elemental
analysis calcd (%) for C17H13N13O18 (687.36): C 29.71, H 1.91, N
26.49; found: C 29.45, H 1.48, N 26.38; IS: 5 J; FS: 324 N.
Triaminoguanidinium salt of 2,6-bis(picrylamino)-3,5-dinitropyri-
dine (12): The sodium salt of 2,6-bis(picrylamino)-3,5-dinitropyr-
idine (322.6 mg, 0.50 mmol) or the potassium salt of 2,6-bis(picryl-
amino)-3,5-dinitropyridine (348.7 mg, 0.50 mmol) together with tri-
aminoguanidine hydrochloride (140.6 mg, 1.00 mmol) were added
to ethanol (10 mL) and heated under reflux for 2 h. The hot mix-
ture was filtered and the product obtained as a dark-red solid.
Yield: 71.44%, 296.3 mg; DSC (58CminÀ1): 2338C (decomp);
1H NMR (400 MHz, [D6]DMSO): d=8.81 (s, 4H, CH), 8.68 (s, 1H, CH),
8.59 (brs, 6H, NH), 4.49 ppm (brs, 12H, NH2); 13C NMR (101 MHz,
[D6]DMSO): d=160.9, 159.5, 144.7, 134.1, 130.7, 124.7, 123.5,
114.5 ppm; 14N NMR (29 MHz, [D6]DMSO): d=À19 (NO2), À170
(NH), À279 ppm (NH2); IR (ATR): n˜ =3319 (vw), 3193 (w), 3082 (w),
1681 (w), 1623 (m), 1583 (m), 1531 (s), 1500 (m), 1439 (m), 1412
(m), 1348 (vs), 1306 (vs), 1251 (s), 1200 (s), 1130 (m), 1093 (w), 1056
(w), 945 (m), 931 (m), 913 (m), 858 (w), 825 (w), 758 (m), 721 (s),
684 cmÀ1 (m); MS (FABÀ): m/z: 620.4 [C17H6N11O16]À; (FAB+): m/z:
105.2 [CN6H9]+; elemental analysis calcd (%) for C19H23N23O16
(829.53): C 27.51, H 2.79, N 38.84; found: C 27.84, H 3.25, N 38.90;
IS: 20 J; FS: 360 N.
Guanidinium salt of 2,6-bis(picrylamino)-3,5-dinitropyridine (10):
2,6-Bis(picrylamino)-3,5-dinitropyridine (310.7 mg, 0.50 mmol) and
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Acknowledgements
Financial support of this work by the Ludwig-Maximilian Uni-
versity of Munich (LMU), the Office of Naval Research (ONR)
under grant no. ONR.N00014-16-1-2062, and the Bundeswehr -
Wehrtechnische Dienststelle für Waffen und Munition(WTD 91)
under grant no. E/E91S/FC015/CF049 are gratefully acknowl-
edged. The authors acknowledge collaborations with Dr. Mila
Krupka (OZM Research, Czech Republic) in the development of
new testing and evaluation methods for energetic materials
and with Dr. Muhamed Suceska (Brodarski Institute, Croatia) in
the development of new computational codes to predict the
detonation and propulsion parameters of novel explosives. We
are indebted to and thank Drs. Betsy M. Rice, Jesse Sabatini
and Brad Forch (ARL, Aberdeen, Proving Ground, MD) for
many inspired discussions. The X-ray team around Prof. Dr.
Konstantin Karaghiosoff is gratefully thanked for the single-
crystal measurements. We thank Stefan Huber for accompany-
ing the sensitivity testing and helpful suggestions and discus-
sions. T.G.W. also thanks the DAAD for a Ph.D. scholarship.
Keywords: energetic materials · pyridine · salts · structure
elucidation · thermally stable explosive
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Received: February 18, 2016
Published online on May 4, 2016
Chem. Eur. J. 2016, 22, 8619 – 8626
www.chemeurj.org
8626
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