Metal salts of the 4,5-dicyano-2H-1,2,3-triazole anion ([C 4N5]-)

Article abstract of DOI:10.1039/c2dt12100j

Diaminomaleodinitrile was reacted at low temperatures with in situ generated nitrous acid to form 4,5-dicyano-2H-1,2,3-triazole (1) in yields above 90%. Crystalline 1 was then reacted with one equivalent of a suitable alkali or alkaline earth metal base (typically a hydroxide or a carbonate) in a polar solvent to form the corresponding alkali and alkaline earth metal salts of 4,5-dicyano-2H-1,2,3-triazole (compounds 2-9). The thermal stability of the metal salts 2-9 was assessed by differential scanning calorimetry, which showed excellent thermal stabilities up to above 350 °C. Due to the energetic character of triazole-based salts, initial safety testing was used to assess the sensitivity of compounds 2-9 towards impact, friction, electrostatic discharge and fast heating. These results revealed very low sensitivities towards all four stimuli. Additionally, compounds 2-9 were characterized by mass spectrometry, elemental analysis, infrared and Raman spectroscopy and (¹H, ¹³C and ¹⁴N) NMR spectroscopy. We also determined the solid state structure of the 4,5-dicyano-2H-1,2,3-triazole anion of one of the alkali metal salts (4: Monoclinic, P2₁/c, a = 9.389(1) A, b = 10.603(1) A, c = 6.924(1) A, β = 102.75(1)° and V = 1036.58(3) A³) and one of the alkaline earth metal salts (6: Monoclinic, P2₁/c, a = 9.243(1) A, b = 15.828(2) A, c = 6.463(1) A, β = 90.23(1)° and V = 945.5(2) A³). Furthermore, we noted the hydrolysis of one of the cyano groups of the 4,5-dicyano-2H-1,2,3-triazole anion in the strontium salt 8 to form the 5-cyano-2H-1,2,3-triazole-4-carboxylic acid derivative 8b, as confirmed by X-ray studies (8b: Monoclinic, P2₁/n, a = 6.950(1) A, b = 17.769(1) A, c = 13.858(1) A, β = 92.98(1)° and V = 1709.1(1) A³). Lastly, we computed the NBO and Muelliken charges for the anion of compounds 2-9 and those of the anion of compound 8b. The Royal Society of Chemistry 2012.

Full text of DOI:10.1039/c2dt12100j

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PAPER
Metal salts of the 4,5-dicyano-2H-1,2,3-triazole anion ([C4N5]−)†
Carles Miró Sabaté,*a Erwann Jeanneaub and Henri Delalua
Received 3rd November 2011, Accepted 13th January 2012
DOI: 10.1039/c2dt12100j
Diaminomaleodinitrile was reacted at low temperatures with in situ generated nitrous acid to form
4,5-dicyano-2H-1,2,3-triazole (1) in yields above 90%. Crystalline 1 was then reacted with one equivalent
of a suitable alkali or alkaline earth metal base (typically a hydroxide or a carbonate) in a polar solvent to
form the corresponding alkali and alkaline earth metal salts of 4,5-dicyano-2H-1,2,3-triazole (compounds
2–9). The thermal stability of the metal salts 2–9 was assessed by differential scanning calorimetry, which
showed excellent thermal stabilities up to above 350 °C. Due to the energetic character of triazole-based
salts, initial safety testing was used to assess the sensitivity of compounds 2–9 towards impact, friction,
electrostatic discharge and fast heating. These results revealed very low sensitivities towards all four
stimuli. Additionally, compounds 2–9 were characterized by mass spectrometry, elemental analysis,
infrared and Raman spectroscopy and (1H, 13C and 14N) NMR spectroscopy. We also determined the
solid state structure of the 4,5-dicyano-2H-1,2,3-triazole anion of one of the alkali metal salts (4:
Monoclinic, P21/c, a = 9.389(1) Å, b = 10.603(1) Å, c = 6.924(1) Å, β = 102.75(1)° and V = 1036.58(3)
Å3) and one of the alkaline earth metal salts (6: Monoclinic, P21/c, a = 9.243(1) Å, b = 15.828(2) Å, c =
6.463(1) Å, β = 90.23(1)° and V = 945.5(2) Å3). Furthermore, we noted the hydrolysis of one of the
cyano groups of the 4,5-dicyano-2H-1,2,3-triazole anion in the strontium salt 8 to form the 5-cyano-2H-
1,2,3-triazole-4-carboxylic acid derivative 8b, as confirmed by X-ray studies (8b: Monoclinic, P21/n, a =
6.950(1) Å, b = 17.769(1) Å, c = 13.858(1) Å, β = 92.98(1)° and V = 1709.1(1) Å3). Lastly, we computed
the NBO and Mülliken charges for the anion of compounds 2–9 and those of the anion of compound 8b.
primary explosives5 and as ingredients in pyrotechnic and pro-
Introduction
pellant mixtures.6 Nitrogen-rich compounds have received con-
siderable attention due to the fact that dinitrogen formation upon
combustion leads to very negative enthalpies of combustion, i.e.,
very positive heats of formation. A prominent type of nitrogen-
rich energetic compound which has been widely studied is
azole-based energetic materials.7,8 These materials contain N–N
bonds in the ring, which are stabilized by aromaticity and show
relatively low sensitivities and high thermal stabilities.
Pyrotechnics are compounds which are generally used to cause
an audiovisual effect (e.g., light, smoke, sound, etc.) and have a
wide variety of applications in the field of fireworks, airbags, fire
extinguishers, (road) flares, matches, and production of nanopor-
ous foams and propellants. A classical pyrotechnic formulation
is composed of an oxidizer, a reducing agent, (optionally) a
binder, a propellant, a sound- or smoke-producing agent and a
colouring agent.1 However, many of the commonly used ener-
getic compounds are either toxic or form toxic decomposition
products.
The heats of formation of azoles (Fig. 1) increase in the direc-
tion 1H-pyrrole (A) to 3H-pentazole (G), in agreement with an
increase in the nitrogen content. Not surprisingly, the stability
decreases in the same direction. Triazole- and tetrazole-based
In this line, nitrogen-rich compounds were investigated for
application in the field of gas generators,2–4 blowing agents,3–5
aLaboratoire Hydrazines et Composés Ènergétiques Polyazotés,
Université Claude Bernard Lyon 1, Bâtiment Berthollet, 3è étage, 22,
avenue Gaston Berger, 69622 Villeurbanne, France. E-mail: carlos.
miro-sabate@univ-lyon1.fr; Fax: +33-472-431-291
bCentre de Diffractométrie Henri Longchambon, Université Claude
Bernard Lyon 1, 43 Bd. du 11 novembre 1918, 69622 Villeurbanne,
France. E-mail: erwann.jeanneau@univ-lyon1.fr; Fax: +33-472-431-
160
†Electronic supplementary information (ESI) available: General
method, calculated IR/Raman frequencies, X-ray tables for compounds
4, 6 and 8b and graph-set analysis of compounds 6 and 8b. CCDC refer-
ence numbers 852499–852501. For ESI and crystallographic data in CIF
or other electronic format see DOI: 10.1039/c2dt12100j
Fig. 1 Formula structure of unsubstituted neutral azoles: A = 1H-
pyrrole, B = 1H-pyrazole, C = 1H-imidazole, D = 2H-1,2,3-triazole, E =
4H-1,2,4-triazole, F = 1H-tetrazole, G = 3H-pentazole and H = 4,5-
dicyano-2H-1,2,3-triazole anion.
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energetic materials seem to exhibit the best compromise between
high energy content and good chemical and thermal stability and
in the last few years they have been investigated for application
as propellants or secondary explosives.9,10 Recently, the syn-
thesis of polycyano compounds by Shreeve et al.11 showed that
cyano groups can be used to increase the heats of formation (i.e.,
the energy content) of energetic materials. This work prompted
us to study the energetic properties of the sodium, potassium,
ammonium, hydrazinium and guanidinium salts of the 5-cyano-
tetrazole anion ([C2N5]−, Fig. 1).12
In contrast to tetrazole derivatives, triazole-based energetic
materials have been less studied.13–16 Both possible isomers of
triazole, i.e., D = 2H-1,2,3-triazole and E = 4H-1,2,4-triazole,
are known to have high positive heats of formation of 272 kJ
mol−1 and 109 kJ mol−1, respectively.17,18 Therefore, D should
be of greater interest than E for the synthesis of energetic
derivatives.
Scheme 1 Protocol for the synthesis of 4,5-dicyano-2H-1,2,3-triazole
(1) and its alkali (2–5) and alkaline earth (6–9) metal salts.
properties. Therefore, here we would like to describe our results
on the synthesis, full analytical and spectroscopic characteriz-
ation, energetic properties and X-ray structures of alkali and
alkaline earth metal salts of the 4,5-dicyano-2H-1,2,3-triazole
anion ([C4N5]−) .
The promising properties of energetic salts of the 5-cyanote-
trazole anion,12 attracted our attention to the parent 4,5-dicyano-
2H-1,2,3-triazole (1). The synthesis of neutral 4,5-dicyano-2H-
1,2,3-triazole was reported as early as 1921 by the diazotation of
aminomalononitrile with in situ generated “HNO2”.19 Shortly
after, the same authors described the characterization of the
ammonium, potassium, calcium, barium, copper and silver salts
of the 4,5-dicyano-2H-1,2,3-triazole anion mainly only by solu-
bility and melting point.19,20 In 2003 and 2004 several groups
investigated the lithium salt and characterized it only by Raman
spectroscopy.21 Unfortunately, characterization data of salts of
4,5-dicyano-2H-1,2,3-triazole were not reported. The authors of
the latter references reported on the relatively non-coordinating
behaviour of this anion for use in polymer electrolytes. In
addition to the previous studies, a high number of rhodium com-
plexes of this anion were reported22 and only recently, the syn-
thesis and crystal structure of the first actinide complex of the
4,5-dicyano-2H-1,2,3-triazole anion, namely UO2((NC)2C2-
N3)2(OPPh3)3 was reported by Crawford et al.23
In addition to the metal salts introduced above, many salts of
the 4,5-dicyano-2H-1,2,3-triazole anion with nitrogen bases have
also been described by Toshiaki et al.24 In 2007, ammonium and
imidazolium salts of the 4,5-dicyano-2H-1,2,3-triazole anion
were described by Mizuta and coworkers as a new class of ionic
liquids with potential for electrochemical applications25 and in
2010, Kitaoka et al. described the preparation and properties of
imidazolium, pyridinium, and pyrrolidinium salts of the 4,5-
dicyano-2H-1,2,3-triazole anion.26 The latter compounds were
claimed to be ionic liquids with lower viscosity and glass tran-
sition temperature than ionic liquids not containing cyano
groups. However, none of the derivatives of 4,5-dicyano-2H-
1,2,3-triazole described are energetic.19–26 Recent work by the
Klapötke group reported on the synthesis and full characteriz-
ation (including crystal structure analysis) of 4,5-dicyano-2H-
1,2,3-triazole and its sodium, silver, ammonium and guanidi-
nium salts.27 The ammonium and guanidinium salts are highly
endothermic and thermally stable energetic compounds. In view
of the interesting energetic properties of the recently reported
salts of the 5-cyanotetrazole12 and 4,5-dicyano-2H-1,2,3-tria-
zole27 anions, we became interested to investigate whether the
simple alkali and alkaline earth metal salts of 4,5-dicyano-2H-
1,2,3-triazole might also show some desirable energetic
Results and discussion
Synthesis and stability
4,5-Dicyano-2H-1,2,3-triazole (1) was obtained by a modified
literature procedure21a,23 (see Experimental section). Sublimed
crystalline 1 was then reacted with one equivalent of a suitable
alkali metal hydroxide or carbonate in alcohol or with one equiv-
alent of the corresponding alkaline earth metal hydroxide in
water to prepare the alkali metal (compounds 2–5) and alkaline
earth metal (compounds 6–9) salts of 1 (Scheme 1). The syn-
thesis and characterization of the previously reported sodium
salt23 and of the highly toxic beryllium salt were outside the
scope of this study.
Apart from the lithium salt (2), which is highly hygroscopic,
the remainder of the compounds are stable to moisture and all
salts of 1 are chemically and thermally stable over (at least)
several months. The alkali metal salts 2–5 are readily soluble in
polar solvents such as acetone, alcohol, water or DMSO and
insoluble in less polar solvents such as ether or chloroform. On
the other hand, the alkaline earth metal salts 6–9 are significantly
less soluble and do not dissolve in acetone or alcohol and they
are less soluble in water or DMSO. The solubility of compounds
6–9 in water decreases in the direction Mg (6) > Ca (7) > Sr (8)
> Ba (9) so that whereas the magnesium salt (6) is readily
soluble at room temperature, the barium derivative (9) dissolves
only in hot water. Lastly, we found that when a solution of com-
pound 8 in water is heated, hydrolysis of one of the cyano
groups takes place forming compound 8b, which is based on the
5-cyano-2H-1,2,3-triazole-4-carboxylic acid anion (see X-ray
discussion below).
Due to the endothermic character of 1,2,4-triazole (ΔfH =
26.1 kcal mol−1 28 and its salts8b and of cyano compounds,11
)
salts based on the 4,5-dicyano-2H-1,2,3-triazole anion are poten-
tially energetic compounds. Therefore, we assessed the energetic
properties of compounds 2–9 using standardized test methods.
BAM methods29–34 were used to gain insight into the sensitivity
of the compounds in this study towards impact, friction,
3818 | Dalton Trans., 2012, 41, 3817–3825
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Table 1 Physical, chemical and energetic properties of compounds 2–9
2
Na[C2N5]·H2O
3
4
5
Formula
C4H4N5O2Li
161.05
>40
>360
—
Burning
Red
43
—
C4H2N5ONa
159.08
>40
>360
—
Burning
Orange
44
C4N5K
157.17
>40
>360
—
Burning
Purple
45
C4N5Rb
203.54
>40
>360
—
Burning
Red
34
—
C4N5Cs
250.98
>40
>360
—
Burning
Pink
28
MW (g mol−1
Impact (J)a
Friction (N)a
)
Electrostatics (20 kV)a
Flame
Flame colour
N (%)b
mp (°C)c
—
305
—
314
—
294
dec (°C)d
322
297
a Impact friction and electrostatic discharge sensitivities determined by standard BAM methods (see ref. 30–33). b Nitrogen content. c Melting point
(DSC onset) from measurement with β = 5 °C min−1 d Decomposition point (DSC onset) from measurement with β = 5 °C min−1
. .
6
7
8
9
Formula
C8H16N10O8Mg
404.58
>40
>360
—
Burning
White
35
C8H16N10O8Ca
420.35
>40
>360
—
Burning
Lavender
33
—
308
C8H12N10O6Sr
431.86
>40
>360
—
Burning
Red
32
—
334
C8H12N10O6Ba
481.57
>40
>360
—
Burning
Green
29
MW (g mol−1
Impact (J)a
Friction (N)a
)
Electrostatics (20 kV)a
Flame
Flame colour
N (%)b
mp (°C)c
—
317
—
351
dec (°C)d
electrostatic discharge and heating. Table 1 contains a summary
of physical, chemical and energetic properties of compounds
2–9. According to our results, compounds 2–9 are impact
(>40 J), friction (>360 N) and electrostatics (20 kV) insensitive
and therefore classify as safe for transport according to UN rec-
ommendations.34 The low sensitivity of compounds 2–9 is a
clear advantage over the high sensitivity of previously reported
metal salts of 5-nitro-2H-tetrazole.35
The thermal stability of compounds 2–9 was assessed by
differential scanning calorimetry (DSC). All materials have
excellent thermal stabilities (generally) above 300 °C. For the
alkali metal salts 2–5 the decomposition temperatures seem to
decrease with the size of the cation (i.e., Li (2) > K (3) > Rb (4)
> Cs (5)) whereas the opposite trend is observed for the alkaline
earth metal salts (i.e., Mg (6) > Ca (7) < Sr (8) < Ba (9)). The
decomposition temperatures of compounds 2–9 are significantly
higher than those of previously reported alkali and alkaline earth
metal salts with azole-based anions.35–37
In addition to DSC analysis, all metal salts of 4,5-dicyano-
2H-1,2,3-triazole were tested in the “flame test”, where a few
milligrams of the compound were placed on a metal spatula and
the spatula was held in the open flame of a Bunsen burner. Fast
heating of the alkali metal salts of 4,5-dicyano-2H-1,2,3-triazole
results in normal burning with little smoke accompanied by the
characteristic colour of the metal cation (i.e., red (2), purple (3),
red (4) and pink (5)) whereas the alkaline earth metal salts burn
slightly more vigorously, also giving the corresponding flame
colour of the metal centre (i.e., white (6), lavender (7), red (8)
and green (9)).
NMR spectroscopy (1H, 13C and 14N NMR). The B3LYP
method was used to facilitate the assignment of the vibrational
bands observed in the IR and Raman spectra of compounds 2–9.
We used a 6-31+G(d,p) basis set to predict the (gas phase)
vibrational frequencies of the 4,5-dicyano-2H-1,2,3-triazole
anion (see Experimental part for details on the computational
method used). The supporting information (Table 1, ESI†) con-
tains a summary of the (scaled) predicted vibrational frequencies
of the 4,5-dicyano-2H-1,2,3-triazole anion with the correspond-
ing IR intensities and Raman activities and averaged experimen-
tal values. The most intense band observed in both IR and
Raman spectra of salts 2–9 corresponds to the stretching
vibrations of the two cyano groups (strong band at ca.
2250 cm−1 (νs(CuN)) with a shoulder at ca. 2240 cm−1
(νas(CuN))). The remainder of the bands are of lower intensity/
activity and can be assigned as follows: 1505–1090 cm−1 (ring
C–N and N–N stretching modes), 1010–710 cm−1 (ring N–N–N
bending vibrations), 660–430 cm−1 (ring N–C–C and N–N–C
bending modes) and 605–430 cm−1 (C–CuN bending
vibrations).
1
Due to the lack of hydrogen atoms, the H NMR spectra of
the salts of the 4,5-dicyano-2H-1,2,3-triazole anion only show
the resonances corresponding to the protons of the solvated
water molecules at δ ∼ 3.4 ppm. On the other hand, the 13C
NMR spectra show two resonances at δ ∼ 121.0 and δ ∼
114.0 ppm, corresponding to the cyano groups and triazole ring,
respectively. Additionally, the 14N NMR spectra are character-
ized by broad bands at δ ∼ +25 (ν1/2 = 700 Hz, N5), −25 (ν1/2
800 Hz, N4–N6) and −120 (ν1/2 = 700 Hz, N1–N9) ppm.
=
Spectroscopic discussion
X-ray crystal structures
All salts of the 4,5-dicyano-2H-1,2,3-triazole anion were charac-
The 4,5-dicyano-1,2,3-triazole anions in the solid state structure
terized by vibrational spectroscopy (IR and Raman) as well as
of the rubidium salt 4 and the magnesium salt 6 (Tables 2 and 3)
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do not show significant differences. A similar situation is found
for the two crystallographically independent anions 8b (1) and
8b (2) in the crystal structure of the 5-cyano-2H-1,2,3-triazole-4-
carboxylic acid salt 8b (for labelling schemes see Fig. 2). For all
three compounds 4, 6 and 8b, the N–N distances of the triazole
ring, in the range between ca. 1.33 and 1.36 Å, are between
typical N–N single (1.454 Å) and NvN double bonds
(1.245 Å).38 The cyano group C–N distances (ca. 1.14–1.15 Å)
are comparable to those of recently reported salts of 5-cyanote-
trazole12 and 4,5-dicyano-1,2,3-triazole.27 The remainder of the
C–N distances, in the range between ca. 1.33 and 1.35 Å are
also shorter than the average C–N single bond distance
(1.47 Å)39 and point at a highly delocalized electronic system.
The rubidium salt 4 crystallizes in a monoclinic cell of the
space group P21/c. The asymmetric unit of the compound is
made up of one crystallographically independent Rb+ cation and
one 4,5-dicyano-2H-1,2,3-triazole anion. All nitrogen atoms of
the anion are involved in coordination to the metal centre
(Fig. 3a) with Rb–N distances in the range 2.93–3.27 Å, compar-
able to those previously found in rubidium 5-nitrotetrazolate.35
The coordination around the rubidium atoms is completed by
interaction to seven anions (Fig. 3b) accounting for a coordi-
nation number of nine. This coordination mode is usual for rubi-
dium salts.16,40
In analogy to the rubidium salt 4, the magnesium salt 6 also
crystallizes in a monoclinic cell of the space group P21/c. In the
crystal structure of 6 the Mg2+ cations sit on a symmetry plane
with half of the solvated water molecules and half of the anions
being generated by symmetry (symmetry code: (i) 2 − x, 1 − y, 2
− z). The asymmetric unit is made up of one Mg2+ cation, one
4,5-dicyano-2H-1,2,3-triazole anion and four molecules of water
so that the overall charge is zero and, therefore, the compound is
an octahydrate. Fig. 5 shows a view of the unit cell of the salt 6.
The coordination around the metal centre is completed by inter-
action to six solvated water molecules (two times three crystallo-
graphically independent molecules) with distances between Mg
and O atoms varying within a narrow range (2.05 to 2.07 Å) and
angles close to the ideal 90 and 180° expected for a regular octa-
hedron. The octahedral geometry is common for magnesium
salts containing a nitrogen-rich anion.37b The fourth molecule of
water (O13) is not involved in coordination to the metal centre
but in hydrogen-bonding (see discussion below). The Mg2+
cations occupy the middle points of the vertices of the two faces
on the bc-plane with the 4,5-dicyano-2H-1,2,3-triazole anions
filling the unit cell. All nitrogen atoms in the anions are involved
in hydrogen-bonding to water molecules via five out of the seven
hydrogen bonds found in the structure of the compound. The
remainder of the hydrogen bonds are formed by interaction
between two solvated water molecules.
The 4,5-dicyano-2H-1,2,3-triazole anions and rubidium
cations form planar layers perpendicular to the ac-plane, which
are connected among them by the Rb–N contacts discussed
above (Fig. 4a). Additionally, the layers of anions form infinite
chains along the c-axis with each layer twisted by approximately
180° with respect to the previous one (Fig. 4b).
Recrystallization of compound 8 from hot water resulted in
hydrolysis of one of the cyano groups to form the strontium salt
Table 3 Selected bond angles (°) found experimentally for the 4,5-
dicyano-2H-1,2,3-triazole
and
the
5-cyano-2H-1,2,3-triazole-4-
carboxylic acid anions
Table 2 Selected bond distances (Å) found experimentally for the 4,5-
dicyano-2H-1,2,3-triazole
carboxylic acid anions
and
the
5-cyano-2H-1,2,3-triazole-4-
4
6
8b (1)
8b (2)
N1–C2–C3
C2–C3–N4
C2–C3–C7
N4–C3–C7
C3–N4–N5
N4–N5–N6
N5–N6–C7
C3–C7–N6
C3–C7–C8
N6–C7–C8
C7–C8–N9
C7–C8–O9
C7–C8–O10
O9–C8–O10
178.7(3)
122.5(3)
130.0(3)
107.5(3)
106.2(2)
112.1(2)
105.9(2)
108.2(3)
130.2(3)
121.6(3)
179.6(3)
178.0(6)
123.7(4)
128.7(4)
107.5(4)
107.1(4)
110.9(4)
107.0(4)
107.5(4)
128.0(4)
124.5(4)
175.9(6)
176.7(5)
121.3(4)
130.2(4)
108.2(4)
106.5(4)
110.9(3)
107.0(3)
107.3(4)
127.7(4)
125.0(4)
177.6(5)
122.2(4)
128.9(4)
108.8(4)
105.7(4)
111.5(4)
107.3(4)
106.7(4)
127.0(4)
126.2(4)
4
6
8b (1)
8b (2)
N1–C2
C2–C3
C3–N4
C3–C7
N4–N5
N5–N6
N6–C7
C7–C8
C8–N9
C8–O9
C8–O10
1.151(4)
1.423(4)
1.352(4)
1.387(4)
1.341(3)
1.355(4)
1.333(4)
1.432(4)
1.143(4)
1.144(7)
1.434(7)
1.325(6)
1.386(7)
1.328(5)
1.325(5)
1.329(6)
1.421(6)
1.139(6)
1.150(6)
1.424(6)
1.337(6)
1.380(6)
1.337(5)
1.329(5)
1.344(5)
1.488(6)
1.145(7)
1.424(7)
1.349(5)
1.394(6)
1.339(5)
1.342(5)
1.342(6)
1.476(6)
117.4(4)
118.2(4)
124.4(4)
118.2(4)
118.4(4)
123.4(4)
1.326(5)
1.237(5)
1.331(6)
1.233(6)
Fig. 2 Labelling schemes for the 4,5-dicyano-1,2,3-triazole anion (a) and the 5-cyano-2H-1,2,3-triazole-4-carboxylic acid anion (b).
3820 | Dalton Trans., 2012, 41, 3817–3825
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Fig. 5 Unit cell of compound 6 (view along the c-axis) showing the
coordination around the Mg2+ cations (dotted lines) and the labelling
scheme.
Scheme 2 Proposed mechanism for the hydrolysis of the 4,5-dicyano-
2H-1,2,3-triazole salt 8 to the 5-cyano-2H-1,2,3-triazole-4-carboxylic
acid derivative 8b.
Fig. 3 Labelling scheme and packing around the anion (a) and cation
(b) in the crystal structure of compound 4 (diamond ellipsoids rep-
resented at 50% probability). Dotted lines represent Rb–N coordination.
Fig. 6 Packing around the Sr2+ cation in the crystal structure of com-
pound 8b and labelling scheme (diamond ellipsoids represented at 50%
probability). Dotted lines represent Sr–N and Sr–O coordination.
high acidity of the triazole ring was already noticed in prelimi-
nary tests when trying to protonate 4,5-dicyano-2H-1,2,3-triazole
(1) to form the corresponding chloride and picrate salts. When
ether solutions of 1 were reacted with ether solutions of hydro-
chloric or picric acid, no precipitation of the expected chloride
and picrate salts was observed and only unreacted 1 was
recovered.
Compound 8b crystallizes in a monoclinic cell in the space
group P21/n. The asymmetric unit is made up of one Sr2+ cation,
two 5-cyano-2H-1,2,3-triazole-4-carboxylic acid anions and four
solvated water molecules. Note the existence of a longer and a
shorter C–O bond (C–O ∼1.33 Å and C–O ∼1.23 Å, respect-
ively). The coordination number around the Sr2+ cations is eight
(Fig. 6). Only one of the two oxygen atoms in the anion is
involved in the coordination around the metal centre with Sr–O
Fig. 4 View of the 2 × 2 × 2 supercell along the b-axis (a) and along
the c-axis (b) in the crystal structure of compound 4. The Rb–N coordi-
nation has been omitted for clarity purposes.
8b. The proposed mechanism for the hydrolysis of one of the
cyano groups to form salt 8b is depicted in Scheme 2. Note that
the anion of compound 8b holds a proton on the carboxylic
group whereas the triazole ring is deprotonated. This can be
explained by the high delocalization of the triazole ring negative
charge in salt 8b around the ring and over to the cyano and car-
boxylic acid groups. This delocalization increases the acidity of
the triazole proton in comparison to the carboxylic acid proton
in 5-cyano-2H-1,2,3-triazole-4-carboxylic acid. The unusually
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Table 4 Crystal data and structure refinements for compounds 4, 6 and
8b
distances in the range 2.48–2.54 Å. Additionally, the four water
molecules are involved in three short coordination bonds
(2.55–2.58 Å) and two longer contacts (2.71–2.73 Å). Lastly,
only the nitrogen atom of the –CN group is involved in coordi-
nation (Sr–N ∼2.73 Å), whereas the remainder of nitrogen atoms
are involved in hydrogen-bonding. As represented in Fig. 6, two
asymmetric units, i.e., SrA2·4H2O (A = 5-cyano-2H-1,2,3-tria-
zole-4-carboxylic acid anion) are bridged by the two longer con-
tacts to water molecules described above to form [Sr2A4·8H2O]
clusters. These “dimeric” clusters are connected to other clusters
in the structure through hydrogen-bonding.
Parameter
4
6
8b
CCDC N°
Empirical
formula
852499
C4N5Rb
852500
C8H16N10O8Mg
852501
C8H8N8O8Sr
Formula weight 203.54
404.62
431.81
[g mol−1
Habit
]
Block
Colourless
100
Needle
Colourless
100
Needle
Colourless
100
Colour
Temperature/K
Crystal size/
mm3
Crystal system
Space group
a/Å
b/Å
c/Å
α (°)
0.363 × 0.200 0.655 × 0.200 ×
0.458 × 0.182
× 0.123
Monoclinic
P21/n
6.950(1)
17.769(1)
13.858(1)
90.00
× 0.172
Monoclinic
P21/c
9.389(1)
10.603(1)
6.924(1)
90.00
0.123
Monoclinic
P21/c
9.243(1)
15.828(2)
6.463(1)
90
Experimental section
Cautionary note
Although initial safety testing indicated that compounds 2–9
have low sensitivities against classical stimuli, they ought to be
regarded as potentially explosive materials and adequate safety
practice is recommended at all times. The synthesis of these
compounds ought to be only carried out by trained personnel
using appropriate safety equipment.
β (°)
γ (°)
102.75(1)
90.00
1036.58(3)
4
2.011
7.285
90.23(1)
90
945.5(2)
2
1.421
0.153
92.98(1)
90.00
1709.1(1)
4
1.662
3.210
V
Z
UC/Å3
ρcalc/g cm–3
μ/mm−1
F (000)
384
420
864
θ range (°)
Index ranges
3.57–29.36
3.40–29.42
3.41–29.54
−9 ≤ h ≤ 9
0 ≤ k ≤ 24
0 ≤ l ≤ 19
9560
−12 ≤ h ≤ 12 −12 ≤ h ≤ 12
X-ray crystal structure determination
−14 ≤ k ≤ 14 0 ≤ k ≤ 21
–9 ≤ l ≤ 9
0 ≤ l ≤ 8
5266
Reflections
collected
Independent
reflections
Data/restraints/
parameters
3722
The crystallographic data for compounds 4, 6 and 8b (Table 4)
was collected using an Oxford Diffraction Xcalibur 3 diffract-
ometer equipped with a CCD detector. The CrysAlis Pro soft-
ware41 was used for the data collection and reduction and the
structure was solved using the WinGX software.42,43 The non-
hydrogen atoms were refined anisotropically and a multi-scan
absorption correction was applied.44 Tables 2–5 of the ESI†
contain a summary of the metal–nitrogen and metal–oxygen dis-
tances and angles and the geometry of the hydrogen bonds in
compounds 4, 6 and 8b.
1715
2361
4505
1715/0/92
2361/0/125
1.053
4505/0/226
0.954
Goodness-of-fit 0.955
on F2
Rint
0.051
0.030
0.034
0.080
0.097
0.106
0.173
0.175
0.068
0.057
0.071
0.121
0.136
R1 [F > 4σ(F)]
R1 (all data)
wR2 [F > 4σ(F)] 0.071
wR2 (all data) 0.075
2
2
R1 = ∑||Fo| − |Fc||/∑|Fo|; Rw = [∑(Fo − Fc )/∑w(Fo)2]1/2; w =
[σc (Fo ) + (xP)2 + yP]−1, P = (Fo2 − 2Fc )/3.
2
2
2
Computational section
The gas phase geometry of the 4,5-dicyano-2H-1,2,3-triazole
anion was optimized using DFT calculations (B3LYP/6-311+G
(d,p)).45,46 No imaginary frequencies were found and the opti-
mized structure was a true minimum on the potential energy
surface. The optimized structure of the 4,5-dicyano-1,2,3-triazo-
late anion was then used to compute the harmonic vibrational
frequencies, the infrared intensities and the Raman activities
using Gaussian 03W.47 The computed frequencies were scaled
by a factor of 0.9613.48
ether (6 × 100 mL) and the volatiles were eliminated under
reduced pressure at 45 °C giving a pale orange liquid, which
solidified upon cooling. The crude product was dried under high
vacuum (10.756 g, 92%). The crude product can be purified by
sublimation at 90 °C under high vacuum to yield white crystals
of 1 (8.972 g, 77%). DSC (Tonset, 5 °C min−1): 147.4 °C (mp),
1
>220 °C (dec); H NMR (DMSO-d6, 25 °C, ppm): δ = 7.58 (s
(br), 1 H, N–H); 13C NMR (DMSO-d6, 25 °C, ppm): δ = 111.6
(2 C, –CN), 123.7 (2 C, triazole); EA (C4HN5, 119.10): calcd C
40.34, H 0.85; N 58.81%; found: C 40.18, H 1.01 N 58.54%.
4,5-Dicyano-2H-1,2,3-triazole (1). 1 was synthesized by the
following modified literature procedure:27,49 98% diaminomaleo-
dinitrile (10.81 g, 98.00 mmol) was dissolved in 1 N hydro-
chloric acid (100 mL) and cooled to 0 °C. A solution of sodium
nitrite (6.89 g, 100.0 mmol) in distilled water (125 mL) was
added to the above solution taking care that the temperature in
the reaction flask did not exceed 5 °C. After stirring for 30 min
in the cold, the reaction mixture was allowed to reach room
temperature and was further stirred for 1 h. The dark brown sol-
ution that had formed was filtered and the insoluble materials
were washed with water. The filtrates were extracted with diethyl
General procedure for the synthesis of alkali metal salts of 1
(compounds 2–5). 1 (0.476 g, 4.0 mmol) was dissolved in
ethanol (15 mL) and reacted with one equivalent of an alkali
metal base, i.e., 98% lithium hydroxide (0.098 g, 4.0 mmol),
potassium hydroxide (0.224 g, 4.0 mmol), rubidium carbonate
(0.462 g, 2.0 mmol) or cesium carbonate (0.652 g, 2.0 mmol).
The reaction mixture was stirred for 1 h at room temperature
(CO2 evolution was observed for the synthesis of salts 4 and 5),
3822 | Dalton Trans., 2012, 41, 3817–3825
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Cesium 4,5-dicyano-1,2,3-triazolate (5). White powder
(0.972 g, 97% yield). DSC (Tonset, 5 °C min−1): 294 °C (dec);
refluxed briefly and the solvent was removed under reduced
pressure at 40 °C. The elemental analysis of compounds 2–5
showed the presence of two solvated water molecules for salt 2
whereas the remainder of the materials where obtained as anhy-
drous compounds.
MS (−c ESI): m/z = 118.0 (72, [A−]−), 368.6 (100, [2A−
+
Cat+]−); IR (golden gate, cm−1, rel. int.): ν˜ = 3743(w), 3302(w),
2241(s), 2193(w), 1635(w), 1500(m), 1421(w), 1379(m), 1288
(w), 1243(w), 1181(m), 1146(m), 1115(w), 1059(w), 1003(w),
946(w), 859(w), 733(w), 708(w), 635(m), 606(w), 588(w), 576
(w), 567(w), 529(m), 515(w), 487(w), 479(w); Raman
(1064 nm, 200 mW, 25 °C, cm−1): ν˜ = 2250 (100), 1510 (19),
1381 (11), 1289 (8), 1157 (3), 1083 (9), 1001 (4), 712 (2), 655
(5), 525 (6), 468 (5); 13C NMR (DMSO-d6, 25 °C, ppm): δ =
120.99 (2 C, –CN), 113.85 (2 C, triazole); 14N NMR (DMSO-
d6, 25 °C, ppm): δ = +24 (1 N, s(br), ν1/2 = 645 Hz, N5), −18 (2
N, s(br), ν1/2 = 760 Hz, N4–N6), −122 (2 N, s(br), ν1/2 = 710
Hz, N1–N9); EA (C4N5Cs 250.98): calcd C 19.14, N 27.91%;
found: C 18.89, N 27.68%.
Lithium 4,5-dicyano-1,2,3-triazolate dihydrate (2). White
powder (0.602 g, 93% yield). DSC (Tonset, 5 °C min−1): 322 °C
(dec); MS (–c ESI): m/z = 117.9 (5, [A−]−), 243.0 (100, [2A− +
Cat+]−), 368.3 (12, [3A− + 2Cat+]−); IR (golden gate, cm−1, rel.
int.): ν˜ = 3408(w), 3377(w), 2252(s), 2147(m), 1504(m), 1421
(w), 1368(m), 1280(w), 1247(m), 1188(m), 1165(m), 1154(m),
1008(w), 947(w), 861(w), 707(w), 651(m), 630(m), 525(w), 501
(w), 492(w), 475(m), 447(w); Raman (1064 nm, 200 mW,
25 °C, cm–1): ν˜ = 2246 (100), 1511 (16), 1390 (7), 1295 (12),
1155 (3), 1084 (8), 1001 (11), 717 (2), 658 (2), 524 (3), 469 (3);
1H NMR (DMSO-d6, 25 °C, ppm): δ = 3.58 (H2O); 13C NMR
(DMSO-d6, 25 °C, ppm): δ = 121.08 (2 C, –CN), 113.94 (2 C,
triazole); 14N NMR (DMSO-d6, 25 °C, ppm): δ = +26 (1 N, s
(br), ν1/2 = 690 Hz, N5), −24 (2 N, s(br), ν1/2 = 785 Hz, N4/N6),
−122 (2 N, s(br), ν1/2 = 705 Hz, N1–N9); EA (C4H4N5O2Li,
161.05): calcd C 29.83, H 2.50, N 43.49%; found: C 29.63, H
2.48, N 43.61%.
General procedure for the synthesis of alkaline earth metal salts
of 1 (compounds 6–9). 1 (0.476 g, 4.0 mmol) was dissolved in
distilled water (10 mL) and reacted with one equivalent of an
alkali earth metal hydroxide, i.e., 99% magnesium hydroxide
(0.117 g, 2.0 mmol), 96% calcium hydroxide (0.154 g,
2.0 mmol), 95% strontium hydroxide (0.256 g, 2.0 mmol) or
98% barium hydroxide octahydrate (0.644 g, 2.0 mmol). An
exothermic reaction was observed and the reaction mixture was
stirred for 1 h at room temperature and briefly refluxed. The inso-
luble alkaline earth metal carbonate was filtered while hot and
the solvent was eliminated under reduced pressure. Elemental
analysis of the products showed the presence of eight solvated
water molecules for compounds 6 and 7 and six solvated water
molecules for compounds 8 and 9.
Potassium 4,5-dicyano-1,2,3-triazolate (3). White powder
(0.761 g, 94% yield). DSC (Tonset, 5 °C min–1): 314 °C (dec);
MS (−c ESI): m/z = 118.0 (22, [A−]−), 274.7 (38, [2A−
+
,
Cat+]−), 431.6 (100, [3A− + 2Cat+]−); IR (golden gate, cm−1
rel. int.): ν˜ = 3428(w), 2248(s), 1528(w), 1503(w), 1421(w),
1377(m), 1283(w), 1243(w), 1189(m), 1170(m), 1159(m), 1110
(w), 1086(w), 986(w), 863(w), 709(w), 657(w), 634(m), 527(m),
501(w), 476(m), 456(w); Raman (1064 nm, 200 mW, 25 °C,
cm−1): ν˜ = 2252 (100), 1504 (20), 1378 (12), 1284 (7), 1157 (2),
1083 (10), 999 (8), 711 (2), 656 (4), 529 (5), 473 (4); 13C NMR
(DMSO-d6, 25 °C, ppm): δ = 121.10 (2 C, –CN), 113.66 (2 C,
triazole); 14N NMR (DMSO-d6, 25 °C, ppm): δ = +24 (1 N, s
(br), ν1/2 = 700 Hz, N5), −22 (2 N, s(br), ν1/2 = 790 Hz, N4/N6),
−121 (2 N, s(br), ν1/2 = 725 Hz, N1/N9); EA (C4N5K 157.17):
calcd C 30.57, N 44.56%; found: C 30.48, N 44.37%.
Magnesium
4,5-dicyano-1,2,3-triazolate
octahydrate
(6). White powder (0.761 g, 94% yield). X-ray quality single
crystals of 6 were grown by recrystallization from hot water.
DSC (Tonset, 5 °C min−1): 317 °C (dec); MS (−c ESI): m/z =
118.0 (100, [A−]−), 236.5 (17, [2A]−), 378.8 (39, [3A−
+
Cat2+]−), 413.1 (34); IR (golden gate, cm−1, rel. int.): ν˜ = 3635
(w), 3487(s), 3332(m), 3223(s), 2256(s), 2241(s), 1665(s), 1506
(w), 1385(m), 1300(w), 1239(w), 1190(m), 1103(w), 996(w),
662(m), 639(m), 523(w), 506(w), 475(w), 462(w); Raman
(1064 nm, 200 mW, 25 °C, cm−1): ν˜ = 2258 (100), 2243 (71),
1507 (18), 1494 (14), 1387 (13), 1300 (11), 1191 (4), 1103 (17),
Rubidium 4,5-dicyano-1,2,3-triazolate (4). White powder
(0.778 g, 96% yield). Single crystals of 4 suitable for X-ray
analysis were grown by slow evaporation of a solution of the
compound in alcohol or hot water. DSC (Tonset, 5 °C min−1):
297 °C (dec); MS (−c ESI): m/z = 118.0 (74, [A−]−), 320.6
(100, [2A– + Cat+]−), 479.5 (11); IR (golden gate, cm−1, rel.
int.): ν˜ = 3326(w), 2245(s), 2161(w), 1503(w), 1419(w), 1375
(m), 1283(w), 1242(w), 1189(m), 1169(m), 1159(m), 1109(w),
1000(w), 943(w), 863(w), 708(w), 655(w), 634(m), 554(w), 528
(m), 506(w), 493(w), 474(m), 459(w); Raman (1064 nm,
200 mW, 25 °C, cm−1): ν˜ = 2248 (100), 1504 (24), 1376 (13),
1284 (6), 1160 (2), 1082 (11), 999 (5), 710 (3), 654 (7), 530 (8),
473 (6); 13C NMR (DMSO-d6, 25 °C, ppm): δ = 120.96 (2 C,
–CN), 113.84 (2 C, triazole); 14N NMR (DMSO-d6, 25 °C,
ppm): δ = +22 (1 N, s(br), ν1/2 = 715 Hz, N5), −20 (2 N, s(br),
ν1/2 = 750 Hz, N4–N6), −120 (2 N, s(br), ν1/2 = 690 Hz, N1–
N9); EA (C4N5Rb 203.54): calcd C 23.60, N 34.41%; found: C
23.45, N 34.12%.
1
1019 (7), 710 (3), 658 (4), 525 (9), 471 (2); H NMR (DMSO-
d6, 25 °C, ppm): δ = 3.83 (H2O); 13C NMR (DMSO-d6, 25 °C,
ppm): δ = 121.49 (4 C, –CN), 114.17 (4 C, triazole); 14N NMR
(DMSO-d6, 25 °C, ppm): δ = +23 (1 N, s(br), ν1/2 = 700 Hz,
N5), −22 (2 N, s(br), ν1/2 = 780 Hz, N4–N6), −121 (2 N, s
(br),ν1/2 = 700 Hz, N1–N9); EA (C8H16N10O8Mg 404.58): calcd
C 23.75, H 3.99, N 34.62%; found: C 23.53, H 4.12, N 34.48%.
Calcium 4,5-dicyano-1,2,3-triazolate octahydrate (7). White
powder (0.802 g, 95% yield). DSC (Tonset, 5 °C min−1): 308 °C
(dec); MS (−c ESI): m/z = 118.0 (29, [A−]−), 236.7 (32, [2A]−),
394.2 (100, [3A− + Cat2+]−), 413.2 (29); IR (golden gate, cm−1
,
rel. int.): ν˜ = 3574(w), 3467(w), 3394(m), 3231(s), 2252(m),
2242(m), 2114(w), 1653(s), 1599(s), 1548(w), 1462(w), 1416
(m), 1368(w), 1302(w), 1277(w), 1192(w), 1179(m), 1141(w),
1115(w), 1093(w), 1061(w), 790(m), 698(m), 633(w), 577(m),
515(m), 483(w); Raman (1064 nm, 200 mW, 25 °C, cm−1): ν˜ =
This journal is © The Royal Society of Chemistry 2012
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2253 (100), 1609 (14), 1550 (26), 1416 (7), 1368 (8), 1302 (6),
1193 (7), 1179 (4), 1110 (15), 1099 (22), 1014 (12), 794 (3),
715 (11), 647 (3), 504 (4), 475 (4), 407 (6); H NMR (DMSO-
of the 4,5-dicyano-2H-1,2,3-triazole anion of one of the alkali
(4) and one of the alkaline earth (6) metal salts. Except for the
lithium salt (2), which is hygroscopic, the remainder of the com-
pounds are stable to moisture, do not show any sign of decompo-
sition upon storage and have good solubility properties.
Interestingly, the strontium salt 8 hydrolyses in hot water to form
the previously unknown 5-cyano-2H-1,2,3-triazole-4-carboxylic
acid salt (compound 8b), as supported by X-ray measurements.
For both the 4,5-dicyano-2H-1,2,3-triazole and the 5-cyano-2H-
1,2,3-triazole-4-carboxylic acid anions we computed the NBO
and Mülliken charges. Lastly, we assessed the thermal stabilities
of compounds 2–9 by means of differential scanning calorimetry
and the sensitivities towards classical stimuli were measured
using standard BAM tests. Compounds 2–9 combine good
burning behaviours with excellent thermal stabilities and low
sensitivities, making the materials of prospective interest for
energetic applications.
1
d6, 25 °C, ppm): δ = 3.60 (H2O); 13C NMR (DMSO-d6, 25 °C,
ppm): δ = 121.21 (4 C, –CN), 114.04 (4 C, triazole); 14N NMR
(DMSO-d6, 25 °C, ppm): δ = +20 (1 N, s(br), ν1/2 = 680 Hz,
N5), −20 (2 N, s(br), ν1/2 = 780 Hz, N4/N6), −126 (2 N, s(br),
ν1/2 = 710 Hz, N1/N9); EA (C8H16N10O8Ca 420.35): calcd C
22.86, H 3.84, N 33.32%; found: C 22.57, H 4.08, N 33.09%.
Strontium 4,5-dicyano-1,2,3-triazolate hexahydrate (8). White
powder (0.798 g, 92% yield). Slow evaporation of a solution of
8 in hot water resulted in the formation of X-ray quality crystals
of the tetrahydrate strontium salt of 5-cyano-2H-1,2,3-triazole-4-
carboxylic acid (8b). DSC (Tonset, 5 °C min−1): 334 °C (dec);
MS (−c ESI): m/z = 118.0 (25, [A−]−), 236.7 (28, [2A]−), 442.1
(100, [3A− + Cat2+]−), 495.9 (46); IR (golden gate, cm−1, rel.
int.): ν˜ = 3615(w), 3462(w), 3240(m), 2246(m), 2163(w), 1662
(s), 1588(s), 1454(w), 1417(m), 1355(w), 1301(w), 1280(w),
1203(m), 1185(m), 1150(w), 1112(w), 1039(w), 790(w), 698
(m), 644(m), 545(w), 508(w), 482(m), 459(w); Raman
(1064 nm, 200 mW, 25 °C, cm−1): ν˜ = 2247 (100), 1668 (4),
1592 (14), 1541 (21), 1418 (5), 1359 (2), 1301 (2), 1184 (5),
1113 (11), 1016 (9), 791 (2), 701 (9), 650 (2), 496 (2), 429 (2);
1H NMR (DMSO-d6, 25 °C, ppm): δ = 3.52 (H2O); 13C NMR
(DMSO-d6, 25 °C, ppm): δ = 121.17 (4 C, –CN), 114.02 (4 C,
triazole); 14N NMR (DMSO-d6, 25 °C, ppm): δ = +22 (1 N, s
(br), ν1/2 = 665 Hz, N5), −20 (2 N, s(br), ν1/2 = 815 Hz, N4/N6),
−124 (2 N, s(br), ν1/2 = 700 Hz, N1/N9); EA (C8H12N10O6Sr
431.86): calcd C 22.24, H 2.80, N 32.43%; found: C 21.93, H
3.02, N 32.14%.
Acknowledgements
Financial support by the Centre National de la Recherche Scien-
tifique and the University Claude Bernard of Lyon are gratefully
acknowledged.
Notes and references
1 T. M. Klapötke and G. Steinhauser, Angew. Chem., Int. Ed., 2008, 47,
3330–3347.
2 K. Redecker, W. Weuter, U. Bley and D. Schmittner, DE Pat., 19 730
873, 1998..
3 Y. Peng and C. Wong, US Pat., 5 877 300, 1999..
4 M. Kaiser and U. Ticmanis, Inorg. Chem., 2001, 40, 3570–3575;
K. Karaghiosoff, T. M. Klapötke, P. Mayer, C. Miró Sabaté, A. Penger
and J. M. Welch, Inorg. Chem., 2008, 47, 1007–1019; T. M. Klapötke
and C. Miró Sabaté, Heteroat. Chem., 2008, 19, 301–306.
5 J. Duguet, US Pat., 4 566 921, 1986;; T. M. Klapötke and C. Miró
Sabaté, New Trends in Research of Energetic Materials Proceedings of
the 10th Seminar, Pardubice, Czech Republic, 2007..
Barium 4,5-dicyano-1,2,3-triazolate hexahydrate (9). White
powder (0.924 g, 96% yield). DSC (Tonset, 5 °C min−1): 351 °C
(dec); MS (−c ESI): m/z = 118.0 (39, [A−]−), 236.7 (38, [2A]−),
492.0 (100, [3A− + Cat2+]−), 546.0 (17); IR (golden gate, cm−1
,
6 L. V. De Yong and G. Campanella, J. Hazard. Mater., 1989, 21, 125–
133.
rel. int.): ν˜ = 3454(m), 3322(w), 3128(m), 2240(m), 2114(w),
1657(s), 1577(m), 1523(s), 1434(s), 1356(m), 1289(w), 1175
(m), 1151(m), 1086(w), 1011(w), 798(m), 781(w), 739(w), 718
(m), 633(w), 558(m), 502(w), 483(w); Raman (1064 nm,
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1
1087 (5), 1012 (9), 786 (1), 723 (7), 495 (3), 427 (5); H NMR
(DMSO-d6, 25 °C, ppm): δ = 3.43 (H2O); 13C NMR (DMSO-d6,
25 °C, ppm): δ = 121.06 (4 C, –CN), 113.93 (4 C, triazole); 14
N
NMR (DMSO-d6, 25 °C, ppm): δ = +25 (1 N, s(br), ν1/2 = 680
Hz, N5), −26 (2 N, s(br), ν1/2 = 790 Hz, N4–N6), −120 (2 N, s
(br), ν1/2 = 700 Hz, N1–N9); EA (C8H12N10O6Ba 481.57): calcd
C 19.95, H 2.51, N 29.08%; found: C 19.77, H 2.73, N 28.87%.
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Conclusion
We considered 4,5-dicyano-2H-1,2,3-triazole (1) for the syn-
thesis of energetic salts with alkali (2–5) and alkaline earth
(6–9) metals. All materials were readily synthesized from cheap
starting materials in excellent yields and high purities and
characterized by analytical (mass spectrometry and elemental
analysis) and spectroscopic (infrared, Raman and multinuclear
NMR) methods. Additionally, we solved the solid state structure
3824 | Dalton Trans., 2012, 41, 3817–3825
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