Energetic derivatives of 4, 4',5, 5'-Tetranitro-2, 2'-bisimidazole (TNBI)

Article abstract of DOI:10.1002/zaac.201200188

4, 4',5, 5'-Tetranitro-2, 2'-bisimidazole (TNBI) was synthesized by nitration of bisimidazole (BI) and recrystallized from acetone to form a crystalline acetone adduct. Its ammonium salt (1) was obtained by the reaction with gaseous ammonia. In order to explore new explosives or propellants several energetic nitrogen-rich 2:1 salts such as the hydroxylammonium (3), guanidinium (4), aminoguanidinium (5), diaminoguanidinium (6) and triaminoguanidinium 7 4, 4',5, 5'-tetranitro-2, 2'-bisimidazolate were prepared by facile metathesis reactions. In addition, methylated 1, 1'-dimethyl-4, 4',5, 5'-tetranitro-2, 2'-bisimidazole (Me₂TNBI, 8) was synthesized by the reaction of 2 and dimethyl sulfate. Metal salts of TNBI can also be easily synthesized by using the corresponding metal bases. This was proven by the synthesis of pyrotechnically relevant dipotassium 4, 4',5, 5'-tetranitro-2, 2'-bisimidazolate (2), which is a brilliant burning component e.g. in near-infrared flares. All compounds were characterized by single crystal X-ray diffraction, NMR and vibrational spectroscopy, elemental analysis and DSC. The sensitivities were determined by BAM methods (drophammer and friction tester). The heats of formation were calculated using CBS-4M electronic enthalpies and the atomization method. With these values and mostly the X-ray densities different detonation parameters were computed by the EXPLO5 computer code. Due to the great thermal stability and calculated energetic properties, especially guanidinium salt 4 could be served as a HNS replacement. Copyright

Full text of DOI:10.1002/zaac.201200188

ARTICLE
DOI: 10.1002/zaac.201200188
Energetic Derivatives of 4,4Ј,5,5Ј-Tetranitro-2,2Ј-bisimidazole (TNBI)
[a]
[a]
[a]
Thomas M. Klapötke,* Andreas Preimesser, and Jörg Stierstorfer
Keywords: Explosives; Structure elucidation; TNBI; Sensitivities; Performance
Abstract. 4,4Ј,5,5Ј-Tetranitro-2,2Ј-bisimidazole (TNBI) was synthe- by using the corresponding metal bases. This was proven by the syn-
sized by nitration of bisimidazole (BI) and recrystallized from acetone thesis of pyrotechnically relevant dipotassium 4,4Ј,5,5Ј-tetranitro-2,2Ј-
bisimidazolate (2), which is a brilliant burning component e.g. in near-
infrared flares. All compounds were characterized by single crystal X-
ray diffraction, NMR and vibrational spectroscopy, elemental analysis
and DSC. The sensitivities were determined by BAM methods (dro-
phammer and friction tester). The heats of formation were calculated
using CBS-4M electronic enthalpies and the atomization method. With
these values and mostly the X-ray densities different detonation param-
eters were computed by the EXPLO5 computer code. Due to the great
thermal stability and calculated energetic properties, especially guani-
to form a crystalline acetone adduct. Its ammonium salt (1) was ob-
tained by the reaction with gaseous ammonia. In order to explore new
explosives or propellants several energetic nitrogen-rich 2:1 salts such
as the hydroxylammonium (3), guanidinium (4), aminoguanidinium
(5), diaminoguanidinium (6) and triaminoguanidinium 7 4,4Ј,5,5Ј-tet-
ranitro-2,2Ј-bisimidazolate were prepared by facile metathesis reac-
tions. In addition, methylated 1,1Ј-dimethyl-4,4Ј,5,5Ј-tetranitro-2,2Ј-
bisimidazole (Me TNBI, 8) was synthesized by the reaction of 2 and
2
dimethyl sulfate. Metal salts of TNBI can also be easily synthesized dinium salt 4 could be served as a HNS replacement.
Introduction
mostly results in higher thermal stability and a more positive
oxygen balance, which was also observed in the case of the
pernitrated species TNBI. The thermal stability can be further
improved by deprotonation and the formation of nitrogen rich
Most commercial secondary explosives like RDX (hexogen)
and HNS (hexanitrostilbene) are highly toxic for human and
animal. In terms of performance secondary explosives have
parameters like a detonation velocity (Vdet.), detonation pres-
2:1 salts. Synthesis of the 2,2Ј-bisimidazole was already de-
scribed by Italian researchers in 1981 in two steps via an bisul-
fite adduct. It was used for the investigation of methylated
copper and zinc dinitrate complexes due to their interesting
sure (PC–J), heat of detonation (–Δ U°) and a volume of gases
Ex
[
1]
(V0) which is created during their detonation. It is a recent
goal to create energetic materials with higher thermostability
and lower sensitivity (towards impact (IS), friction (FS), elec-
trostatic discharge (ESD)) and lower toxicity[ than the current
used ones. One approach is the use of azoles in combination
with energetic substituents at the carbon atom(s) like nitro or
azide groups. Nitrated imidazoles in general were already in-
[5]
electronic spectra and ESR data.
Also 4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazole (TNBI) was al-
ready described by Cho et al. in 2005 as a potentially RDX
1]
[6]
replacement which suffers hygroscopic properties. In 1990
Cromer et al. described the crystal structures of TNBI dihy-
[7,8]
drate and its water-free bis-ammonium salt.
In 1999 the
vestigated by Korean scientists and also in our research group
due to their thermostabilities and energetic properties.[
3
,6-bishydrazine-1,2,4,5-tetrazinium-TNBI salt was described
2,3]
For
[9]
by Chavez et al. showing a thermal stability up to 217 °C.
example 1-methyl-2,4,5-trinitroimidazole was investigated,
which shows a thermal stability of at least 190 °C[ . In 2007
Damavarapu et al. characterized the potassium salt of 2,4,5-
trinitroimidazole . The synthesis is based upon an alternat-
ing nitration/rearrangement strategy starting with commercial
available 4-nitroimidazole. Our article reports on derivatives
of 4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazole (TNBI). The connec-
tion of two imidazole rings obtaining 2,2Ј-bisimidazoles fol-
lows the trend of generating larger energetic molecules. This
Oxley et al. carried out thermochemical studies (isothermal
2,4]
[10]
thermolysis) on several tetrazine based salts.
We today re-
port on several further nitrogen-rich derivatives of TNBI and
on its methylated sister compound and their potential use in
explosive formulations. In addition, metal salts like the pre-
pared bispotassium salt 2 could serve as pyrotechnically rel-
evant candidates in near IR or visible flares.
[2,4]
Results and Discussion
*
Prof. Dr. T. M. Klapötke
Fax: + 49-89-2180-77492
Synthesis
E-Mail: tmk@cup.uni-muenchen.de
[
a] Department of Chemistry
Ludwig-Maximilian University of Munich
An overall synthetic protocol is displayed in Scheme 1. The
synthesis of 2,2Ј-bisimidazole (BI) was carried out as de-
scribed by Bernaducci et al.[ The oxidation of glyoxal with
sodium-bisulfite leads to a glyoxal-sodium bisulfite adduct.
8
1377 Munich, Germany
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201200188 or from the au-
thor.
5]
1
278
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 638, (9), 1278–1286

Energetic Derivatives of 4,4Ј,5,5Ј-Tetranitro-2,2Ј-bisimidazole (TNBI)
Scheme 1. Synthesis of TNBI salts 2–7 and 1,1Ј-dimethyl-4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazole (8).
This adduct is more activated to react with concentrated am- respectively, to reflux until a solution is obtained. 6 crystallizes
monia in an ammonium bicarbonate buffered solution to yield very quickly at approx. 60 °C, 7 crystallizes at 4 °C overnight.
1
BI. The synthesis was carried out in a scale of 12 g BI. The In general the purity of all salts can be established best via H
nitration was performed in conc. sulfuric acid (96–98%) using and 13C NMR spectroscopy and elemental analysis.
eight equivalents sodium nitrate and a catalytic amount of urea.
1,1Ј-Dimethyl-4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazole
The nitration worked best by stirring the suspension at 85 °C (Me TNBI, 8) was obtained by the reaction of 2 with 2.5
2
for 16 hours. The maximum yield was 6 g TNBI·2H O when equivalents of dimethylsulfate in CH CN/DMF (9:1). We con-
2
3
5
g BI was used. After the nitration is poured onto ice-water sidered that the lack of hydrogen bonds yields to a low melting
TNBI can be easily extracted with diethyl ether. The already point but a high decomposition temperature of 8. A crystalline
known bis-ammonium 4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazolate sample could be obtained from acetone.
[9]
(1) is synthesized by the reaction with gaseous ammonia.
During our syntheses we additionally got single crystals of
Compound 1 serves as a valuable starting material to generate the TNBI·2H O, potassium-TNBI monohydrate, 4·DMSO, 1:1
2
several salts because of their lower solubility in aqueous solu- diaminoguanidinium salt (DAGTNBI·H O) and 6, which are
2
tion. The reaction of TNBI with aqueous potassium hydroxide, all presented in the Supporting Information. Investigations of
hydroxylamine solution, guanidinium carbonate or aminogua- the alkaline earth metal salts e.g. CaTNBI·8H O and
2
nidinium bicarbonate, respectively, afforded salts 2 (bispotas- BaTNBI·3H O will be presented separately with respect to
2
sium TNBI), 3 (bishydroxylammonium TNBI dihydrate), 4 their potential use as pyrotechnic colorants.
(bisguanidinium TNBI) and 5 (bisaminoguanidinium TNBI) in
good yields and high purities.
Alternatively, the diethyl ether can be evaporated for the
most part and KOH/EtOH is added to yield the bispotassium
Crystal Structures
Due to the moderate water solubility, all compounds except
salt 2. However, it would also be possible to synthesize salts of 4 (from DMSO) were recrystallized from water. TNBI can
–7 directly starting with TNBI and the corresponding bases. be either recrystallized from water and acetone yielding the
2
Crystalline samples of 2, 5 and 6 (bis-diaminoguanidinium corresponding dihydrate or diacetone adduct, respectively. The
TNBI) and 7 (bis-triaminoguanidinium TNBI) could be ob- structures of compounds 2–8 as well as the monoprotonated
tained by recrystallization from water. 2 and 6 crystallize with- potassium salt (KTNBI·H O) and the 1:1 diaminoguanidinium
2
out inclusion of water, 3 as a dihydrate. 4 is only soluble in salt (DAGTNBI·H O) were determined by low temperature
2
DMSO and crystallizes with two additional DMSO molecules. (173 K) X-ray diffraction. Selected data and parameters of the
Salts 6 and 7 were synthesized by heating a suspension of 1 X-ray determinations are given in the Supporting Information
with diaminoguanidinium and triaminoguanidinium chloride, (Tables S1 and S2). Further crystallographic data for the struc-
Z. Anorg. Allg. Chem. 2012, 1278–1286
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1279

T. M. Klapötke, A. Preimesser, J. Stierstorfer
ARTICLE
tures have been deposited with the Cambridge Crystallo- are not co-planar with the imidazole rings to avoid electrostatic
graphic Data Centre (CCDC-876136 (TNBI·2H O), -876137 repulsion of the nitro oxygen atoms. For example, the torsion
2
(
TNBI·2 acetone), -877533 (2), KTNBI·H O, 876398 (3), angle (in TNBI·2 acetone) between the atoms O2–N3–N4–O3
2
8
76140 (4·2DMSO), 876143 (5), 877534 (6), 876141 is 44°. The acetone molecules are connected to the
[11]
DAGTNBI·H O, 876142 (7), and 876138 (8))
The molecu- TNBI molecules by strong NH···O hydrogen bonds (e.g.
2
lar structures of TNBI·2H O, KTNBI·H O, 4·2DMSO, N1–H1···O5ii: d(D–H) 0.890(18) Å, d(H···A) 1.807(19) Å,
2
2
DAGTNBI·H O and 6 are shown in the Supporting Infor- d(D···A) 2.6951(16) Å, Є(D–H···A) 175.3(16)°.
2
mation.
The potassium salt of TNBI (K TNBI 2) crystallizes in the
2
As mentioned in the introduction the structure of TNBI at monoclinic space group P2 /c with two formula units per unit
1
room temperature has been described in literature.[ A redeter- cell. The calculated density at –100 °C is 2.126 g·cm . The
mination of this structure at 173 K is presented in the Support- molecular moiety is displayed in Figure 2.
ing Information. First we would like to present the structure of
8]
–3
TNBI with two molecules of acetone (Figure 1), which crys-
tallizes in the monoclinic space group C2/c with four formula
-3
units per unit cell and calculated density of 1.581 g·cm . The
structure is similar to that of the dihydrate.[ Basically, the
bisimidazole backbone is found to be planar in all structures
except for 8. The bond length within the imidazoles are be-
tween typical C–N single and C=N double bonds representing
the aromatic character. The C–C bond connecting both imid-
azole rings in all structure is significantly shorter (approx.
8]
1.46 Å) than a typical C–C single bond (1.54 Å). Nitro groups
2
Figure 2. Molecular structure of K TNBI (2) showing the labeling
scheme. The non-hydrogen atoms are represented by displacement el-
lipsoids at the 50% probability level. Symmetry code (i) 1–x, 1–y, –z.
Selected bond lengths /Å: K–N1 2.8213(19), K–N2i 2.948(10), O1–
N3 1.230(2), O2–N3 1.236(2), O3–N4 1.226(2), O4–N4 1.231(2), N1–
C2 1.343(3), N1–C1 1.348(3), N2–C3 1.342(3), N2–C1 1.353(3), N3–
C2 1.435(3), N4–C3 1.438(3), C1–C1i 1.460, C2–C3 1.390(3). Se-
lected bond angles /°: N1–K–N2i 59.90(5). Selected torsion angles /°:
O1–N3–C2–N1 28.3(3), O2–N3–C2–N1 –151.7(2), O3–N4–C3–C2
20.5(4), O4–N4–C3–C2 –160.2(2), N1–C1–C1–N2 1.0(3).
As mentioned before, in the molecular structure of 8 which
¯
crystallizes in the triclinic space group P1, the imidazole rings
are not co-planar (torsion Є N1–C1–C5–N6 = 36.7(4)°). How-
ever the C1–C5 bond length is in the same range observed for
the other structures. Since no classical hydrogen bonds can be
formed the density of 1.703 g cm–3 is lower than that of the
solvent free compounds investigated in this work. On the other
Figure 1. Molecular structure of TNBI·2 acetone showing the labeling hand, weak non-classical C–H···OH bonds as well as nitro-
12]
scheme. The non-hydrogen atoms are represented by displacement el- nitro interactions[ are present. The nitro groups next to the
lipsoids at the 50% probability level. Symmetry codes (i) 0.5–x, 1.5–
y, –z; (ii) 0.5–x, 0.5+y, 0.5–z. Selected bond lengths /Å: O1–N3
methyl substituents are twisted significantly more out of the
ring plane which can be seen in Figure 3.
1
1
1
.2267(17), O2–N3 1.2241(17), O3–N4 1.2234(17), O4–N4
.2229(17), N1–C1 1.3527(19), N1–C2 1.3584(19), N2–C1
.3312(18), N2–C3 1.3463(19), N3–C2 1.435(2), N4–C3 1.4555(18), P2 /n with a cell volume of 763.6(5) Å and two formula units
Compound 3 crystallizes in the monoclinic space group
3
1
C1–C1i 1.449(3), C2–C3 1.375(2), O5–C5 1.2234(18), C4–C5
per unit cell. The molecular moiety is shown in Figure 4. Its
1
1
.489(2), C5–C6 1.489(2). Selected bond angles /°: C1–N1–C2
05.92(12), C1–N2–C3 104.21(12), O2–N3–O1 125.22(14), O2–N3–
–3
density of 1.810 g·cm is the highest of the metal-free com-
pounds within this work. Next to the hydroxylammonium cat-
C2 118.06(13), O1–N3–C2 116.69(12), O4–N4–O3 125.16(13), O4–
N4–C3 116.74(13), O3–N4–C3 118.09(13), N2–C1–N1 112.76(13), ions also the water molecules participate in a strong hydrogen
N2–C1–C1 124.25(17), N1–C1–C1i 122.99(16), N1–C2–C3 bond network. This may be the reason that it is not possible
1
06.18(13), N1–C2–N3 119.33(13), C3–C2–N3 134.29(13), N2–C3–
to dehydrate 3 before decomposition by heating.
C2 110.92(12), N2–C3–N4 118.87(13), C2–C3–N4 130.15(14), C4–
C5–C6 116.95(16). Selected torsion angles /°: O1–N3–C2–N1
In contrast to compound 4 which could only be obtained
crystalline with inclusion of two molecules of dimethylsulfox-
ide, compound 5 was obtained free of water by recrystalli-
–14.47(19), O2–N3–C2–C3 –10.7(2), O3–N4–C3–N2 149.92(13),
O4–N4–C3–N2 –29.1(2), N1–C1–C1i–N2 i –0.1(2).
1
280
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© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 1278–1286

Energetic Derivatives of 4,4Ј,5,5Ј-Tetranitro-2,2Ј-bisimidazole (TNBI)
2
Figure 3. Molecular structure of Me TNBI (8) showing the labeling
scheme. The non–hydrogen atoms are represented by displacement el-
lipsoids at the 50% probability level. Selected bond lengths /Å: O1–
N3 1.201(4), O2–N3 1.205(4), O3–N4 1.223(3), O4–N4 1.218(3), O5–
N7 1.226(4), O6–N7 1.204(4), O7–N8 1.228(4), O8–N8 1.222(4), N1–
C2 1.359(4), N1–C1 1.368(4), N1–C4 1.473(4), N2–C1 1.326(4), N2–
C3 1.351(4), N3–C2 1.459(4), N4–C3 1.440(4), N5–C6 1.366(4), N5–
C5 1.367(4), N5–C8 1.479(4), N6–C5 1.321(4), N6–C7 1.349(4), N7–
C6 1.454(4), N8–C7 1.440(4), C1–C5 1.461(4), C2–C3 1.358(4), C6–
C7 1.357(4). Selected bond angles /°: C2–N1–C1 104.9(2), C2–N1–
C4 125.7(3), C1–N1–C4 128.9(3), C1–N2–C3 103.9(2), O1–N3–O2
Figure 4. Molecular structure of bishydroxylammonium tetranitrobisi-
midazolate dihydrate (3) showing the labeling scheme. The non-hydro-
gen atoms are represented by displacement ellipsoids at the 50% prob-
ability level. Symmetry codes (i) 1–x, –y, –z; (ii) 1–x, 1–y, –z; (iii)
0.5+x, 0.5–y, –0.5+z; (iv) x, –1+y, z; (v) 0.5–x, –0.5+y, 0.5–z. Selected
bond lengths /Å: O1–N3 1.2269(17), O2–N3 1.2193(17),O3–N4
1
1
1
1
24.8(3), O1–N3–C2 118.4(3), O2–N3–C2 116.8(3), O4–N4–O3
24.9(3), O4–N4–C3 118.8(3), O3–N4–C3 116.4(3), C6–N5–C5
04.8(2), C6–N5–C8 126.3(3), C5–N5–C8 128.6(3), C5–N6–C7
04.1(2), O6–N7–O5 125.6(3), O6–N7–C6 117.9(3), O5–N7–C6
1
1
1
.2207(16), O4–N4 1.2256(17), N1–C1 1.3474(18), N1–C2
.3484(19), N2–C3 1.3409(18), N2–C1 1.3469(19), N3–C2
.4391(19), N4–C3 1.445(2), C2–C3 1.394(2), O5–N5 1.4141(17); Se-
lected bond angles /°: C1–N1–C2 –103.20(12), C3–N2–C1 103.89(12),
O2–N3–O1 123.56(13), O2–N3–C2 119.39(12), O1–N3–C2
1
1
16.5(3), O8–N8–O7 125.2(3), O8–N8–C7 119.0(3), O7–N8–C7
15.9(3), N2–C1–N1 112.9(3), N2–C1–C5 124.9(3), N1–C1–C5
117.05(13), O3–N4–O4 123.13(14), O3–N4–C3 119.77(13), O4–N4–
1
1
1
1
1
1
22.0(3), C3–C2–N1 107.0(2), C3–C2–N3 132.2(3), N1–C2–N3
20.7(3), N2–C3–C2 111.2(3), N2–C3–N4 121.7(3), C2–C3–N4
27.0(3), N6–C5–N5 113.0(3), N6–C5–C1 124.1(3), N5–C5–C1
22.7(3), C7–C6–N5 106.7(3), C7–C6–N7 132.0(3), N5–C6–N7
21.4(3), N6–C7–C6 111.3(3), N6–C7–N8 121.1(3), C6–C7–N8
27.6(3). Selected torsion angles /°: N1–C1–C5–N6 36.7(4), O1–N3–
C3 117.09(12), N2–C1–N1 114.85(13), N2–C1–C1 122.03(16), N1–
C1–C1 123.11(16), N1–C2–C3 109.29(13), N1–C2–N3 117.99(13),
C3–C2–N3 132.71(14), N2–C3–C2 108.77(13), N2–C3–N4
117.21(13), C2–C3–N4 134.02(13); Selected torsion angles /°: O2–
N3–C2–N1 –174.21(13), O1–N3–C2–N1 5.3(2), O3–N4–C3–N2
i
–
176.41(13), O4–N4–C3–N2 3.3(2), N1–C2–C3–N2 0.21(17).
C2–N1 –60.9(4), O2–N3–C2–N1 –119.8(4), O4–N4–C3–N2 –11.0(4),
O3–N4–C3–N2 –169.8(3), O6–N7–C6–N5 124.5(3), O5–N7–C6–N5
–
54.3(4), O8–N8–C7–N6 –13.6(5), O7–N8–C7–N6 166.3(3).
tween 152 (7) and 206 °C (5). DSC plots are shown in Figure
. Compound 8 has an melting area at approx. 236 °C. Unfor-
tunately, the gap between the melting and decomposition point
Tdec. = 258 °C) is too small for being a suitable meltcast ex-
plosive (for comparison TNT (2,4,6-trinitrotoluene) melts at
7
zation from water. It crystallizes in the triclinic space group
P1 with one formula unit per unit cell and a calculated density
of 1.751 g·cm . All hydrogen atoms of the aminoguanidinium
cation participate in hydrogen bonds, a few of them illustrated
in Figure 5.
¯
(
–
3
[12]
8
0 °C and decompose not before 310 °C)
For safety issues the sensitivities towards impact, friction
and electrostatic discharge were determined by BAM methods
see Experimental Section) and listed in Table 1. Regarding
.
The triaminoguanidinium salt 7 also crystallizes in the tri-
¯
clinic space group P1 with one formula unit per unit cell. The
molecular structure is shown in Figure 6. Its calculated crystal
density (1.722 g·cm ) is slightly lower than those of 5
(
the impact values, 3 and 7 are the most sensitive (6 J) ones.
–
3
This value is in the range of those observed for RDX (7 J) and
–
3
–3
(1.806 g·cm ) and 6 (1.758 g·cm ). In the crystal packing the
[15]
PETN (5 J).
According to the “UN recommendations of the
anions and cations are orientated almost perpendicularly to
each other.
[16]
transport of dangerous goods”
they are classified as sensi-
tive. Compounds 4 and 8 are completely insensitive towards
impact (Ͼ40 J). Compounds 4 and 5 are insensitive (Ͼ 360 N)
in terms of their friction sensitivity. Interestingly, salt 6 is the
most sensitive one (252 N) which is classified as sensitive. All
Energetic Properties
Due to their high combined nitrogen and oxygen content compounds are not susceptible towards electrical sparks.
N+O ≈ 70%), but low sensitivities (see below) TNBI and its Several detonation parameters of 3–8 were calculated by the
salts are energetic materials which could serve as high-explos- EXPLO5.04 computer code.[
(
17–19]
The program is based on
–1
–3
ives or also propellants. With respect to the thermal stability, the input of the energy of formation (kJ·kg ), density (g·cm )
compound 4 (without DMSO) shows the highest decomposi- and the sum formula. For all compounds, except for 4, their
tion temperature (Tdec. = 328 °C) and is a potential HNS re- maximum X-ray densities at –173 K were used. The density
placement (T . = 337 °C[13] but lower explosive performance of 4 (1.80 g·cm ) was measured with a Quantachrome helium
–3
dec
1[14]
–
7000 ms
). The other salts show thermal-stabilities be- gas pycnometer. The heats of formation (Table 1) were calcu-
www.zaac.wiley-vch.de 1281
Z. Anorg. Allg. Chem. 2012, 1278–1286
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T. M. Klapötke, A. Preimesser, J. Stierstorfer
ARTICLE
Figure 6. Molecular structure of bistriaminoguanidinium tetranitrobisi-
midazolate (7) showing the labeling scheme. The non-hydrogen atoms
are represented by displacement ellipsoids at the 50% probability
level. Symmetry codes: (i) 2–x, 1–y, 1–z. Selected bond lengths /Å:
Figure 5. Molecular structure of bisaminoguanidinium tetranitrobisim-
idazolate (4) showing the labeling scheme. The non-hydrogen atoms
are represented by displacement ellipsoids at the 50% probability
level. Symmetry codes: (i) –x, 1–y, –z; (ii) 1–x, 1–y, –z; (iii) –1+x, y, O1–N3 1.2313(17), O2–N3 1.2390(17), O3–N4 1.2320(17), O4–N4
z., Selected bond lengths /Å: O1–N3 1.2286(19), O2–N3 1.2405(18), 1.2258(17), N1–C1 1.3454(19), N1–C2 1.3458(19), N2–C3
O3–N4 1.2281(19), O4–N4 1.2356(19), N1–C1 1.352(2), N1–C2
1.3467(19), N2–C1 1.3528(19), N3–C2 1.4429(19), N4–C3
1.4384(19), C1–C1i 1.465(3), C2–C3 1.400(2); Selected bond angles /°:
.436(2), C1–C1 1.461(3), C2–C3 1.387(2), N5–C4 1.335(2), N5–N6 C1–N1–C2 102.95(12), C3–N2–C1 103.26(12), O1–N3–O2
.411(2), N7–C4 1.318(2), N8–C4 1.324(2); Selected bond angles /
123.40(13), O1–N3–C2 117.48(13), O2–N3–C2 119.12(13), O4–N4–
1
1
1
.354(2), N2–C3 1.344(2), N2–C1 1.358(2), N3–C2 1.423(2), N4–C3
°
1
:C1–N1–C2 102.57(14), C3–N2–C1 102.50(14), O1–N3–O2 O3 122.73(13), O4–N4–C3 118.23(12), O3–N4–C3 119.02(12), N1–
22.54(14), O1–N3–C2 119.73(14), O2–N3–C2 117.71(14), O3–N4– C1–N2 115.54(12), N1–C1–C1i 123.04(16), N1–C2–C3 109.58(13),
O4 123.35(15), O3–N4–C3 119.09(15), O4–N4–C3 117.54(14), N1– N1–C2–N3 117.98(13), C3–C2–N3 132.40(13), N2–C3–C2
i
C1–N2 115.66(15), N1–C1–C1 122.28(19), N2–C1–C1 122.06(19), 108.67(13), N2–C3–N4 118.20(13), C2–C3–N4 133.12(13); Selected
N1–C2–C3 109.34(14), N1–C2–N3 121.10(15), C3–C2–N3 torsion angles /°: O1–N3–C2–N1 12.79(19), O2–N3–C2–N1
129.26(15), N2–C3–C2 109.94(14), N2–C3–N4 119.58(15), C2–C3–
–166.49(13), O4–N4–C3–N2 17.5(2), O3–N4–C3–N2 –161.12(14),
N4 130.38(15), C4–N5–N6 118.05(15), N7–C4–N8 121.32(17), N7– N1–C1–C1i–N2i 1.2 (2).
C4–N5 120.12(17), N8–C4–N5 118.56(16); Selected torsion angles /°:
O1–N3–C2–N1 18.6(2), O2–N3–C2–N1 –160.03(15), O3–N4–C3–N2
i
i
1
46.31(16), O4–N4–C3–N2 32.0(2), N2–C1–C1 –N1 0.56 (3).
lated with the atomization method (Equation 1) using CBS-
M enthalpies summarized in Table 2.[
20,21]
The gas phase en-
4
thalpies of formation ΔH (g) were converted into the solid
m
state enthalpies of formation (ΔH (s)) either by using the Jen-
m
[22]
kins’ equations for X Y salts
(for ionic derivatives) or the
2
23]
Trouton rule[ (8).
Δ
f
H°(g, M, 298) = H(M, 298) – ∑H°(Atoms, 298) + ∑Δ
f
H°(Atoms, 298)
(1)
Lastly, the molar standard enthalpies of formation (ΔHm)
were used to calculate the molar solid state energies of forma-
tion (ΔU ) according to Equation (2) (Table 1).
m
Figure 7. DSC plots of compounds 4–7 measured with a heating rate
–
1
of 5 K·min (exo-up). Onset temperatures: 328 °C (4), 206 °C (5),
97 (6), 152 °C (7).
ΔU
m
= ΔH
m
– Δn RT (Δn being the change of moles of gaseous com-
1
ponents)
(2)
–
1
–1 [14]
The most positive heat of formation (639 kJ·mol ) was for 7, which is much higher than that of HNS (7000 m·s )
–1 [13]
achieved for the triaminoguanidinium salt 7, which has the and in the range that of PETN (8400 m·s ). Most thermally
largest number of N–N single bonds. The hydroxylammonium stable 4 has also a good calculated detonation performance. In
–
1
salt 3 has a negative value (–516 kJ·mol ) due to the inclusion order to investigate the ignitability and explosiveness of 4, a
of two molecules of crystal water. Although of this negative small scale reactivity test (SSRT)[ was performed.
24]
value 3 is one of the best compounds investigated in this work
in terms of performance (detonation energy, velocity and pres- a defined volume (HNS: 470 mg, density: 1.74 g·cm , 4:
sure). The guanidinium salts show the general trend of im- 485 mg, density: 1.80 g·cm ) was pressed into a perforated
proving performance with rising number of N–N single bonds steel block (Figure 8). This was topped with a commercially
in the cations. The highest detonation velocity was calculated available detonator (Orica, DYNADET-C2–0ms). Initiation of
The SSRT was carried out in comparison to HNS in which
–3
–3
1
282
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© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 1278–1286

Energetic Derivatives of 4,4Ј,5,5Ј-Tetranitro-2,2Ј-bisimidazole (TNBI)
Table 1. Energetic properties of compounds 3–8.
3*
4
5
6
7
8
Formula
C
6
H
12
N
10
O
14
C
8
H
12
N
14
O
8
C
8
H
12
N
16
O
8
C
8
H
16
N
18
O
8
C
8
H
18
N
20
O
8
C
8 6 8 8
H N O
–1
FW /g·mol
416.22
Ͼ 6
432.27
Ͼ 40
462.39
Ͼ 20
492.33
Ͼ 17
522.36
Ͼ 6
342.01
Ͼ 40
a)
IS /J
(
500 μm)
Ͼ 288
500 μm)
Ͼ 0.3
500 μm)
(500 μm)
Ͼ 360
(500 μm)
Ͼ 1.0
(500 μm)
45.36
–51.8
328
1.80 (pyc.)
–114.5
–17.0
(500 μm)
Ͼ 360
(500 μm)
Ͼ 1.0
(500 μm)
48.48
–51.91
206
1.75
(500 μm)
Ͼ252
(500 μm)
Ͼ 0.4
(500 μm)
51.21
–51.99
197
1.76
(500 μm)
Ͼ 288
(500 μm)
Ͼ 0.2
(500 μm)
53.63
–52.1
152
1.71
638.7
(500 μm)
Ͼ 292
(500 μm)
Ͼ 0.1
(500 μm)
32.75
–51.34
FS /N b)
ESD /J c)
N /% d)
(
(
33.65
–23.06
186
1.81
–515.9
–1138.1
e)
Ω /%
f)
T
Dec. /°C
m
236(T ), 258 (Tdec)
–
3 g)
ρ /g·cm
1.70
145.3
504.1
–
1 h)
Δ
Δ
f
H
m
° /kJ·mol
171.1
473.4
399.3
916.6
–
1 i)
f
U° /kJ·kg
1319.0
EXPLO5.04 values:
–1 j)
–
Δ
det /K
ExU° /kJ·kg
5015
3619
311
8362
740
4172
3098
266
8070
429
4486
3229
268
8138
750
4770
3351
286
8377
769
5030
3418
281
8388
785
4984
3732
242
7604
624
k)
T
P
V
l)
CJ /kbar–
1 m)
Det. /m·s
V
o
/L·kg–
1 n)
a) Impact sensitivity (BAM drophammer, 1 of 6); b) friction sensitivity (BAM friction tester 1 of 6); c) electrostatic discharge device (OZM);
d) nitrogen content; e) oxygen balance; f) decomposition temperature from DSC (β = 5 °C); g) from X-ray diffraction; h) calculated (CBS-4M)
heat of formation; i) energy of formation; j) energy of explosion; k) explosion temperature; l) detonation pressure; m) detonation velocity; n)
assuming only gaseous products; * all values for dihydrate.
Table 2. CBS-4M calculation results and molecular volumes.
M
–H298 /a.u.
Δ
f
H°(g,M) /kcal·mol–1
V
M
/nm3
Me
2
TNBI
1346,195338
1266.677508
205.453192
260.701802
315.949896
371.197775
131.863229
57.5
–8.1
2–
TNBI
+
G
136.6
160.4
184.5
208.8
164.1
320.1*
265.1
312.7
361.0
409.5
+
AG
DAG
TAG
NH
3
4
5
6
7
+
+
O+
4
0.333*
0.417
0.439
0.465
0.504
*
without crystal water
the tested explosive resulted in denting a separate aluminum
block, which was placed right underneath the steel block. The
volume of the dent was then filled with sand to compare the
performance of HNS and 4. The test showed that HNS is supe-
rior and the dent could be filled with 672 mg sand in compari-
son to 4 (472 mg). The smaller dent of 4 could be caused by a
larger critical diameter of 4, which should influence the SSRT
dramatically.
Conclusions
From this experimental study the following conclusions can
be drawn:
-
TNBI can be synthesized in good yields and purities by ni-
tration of 2,2Ј-bisimidazole.
The bis-potassium salt (2) crystallizes without crystal water
-
and could be used for near infrared based combustion mix-
tures.
-
2:1 salts of TNBI can be synthesized either with correspond-
ing bases (e.g. hydroxides, carbonates) or metathesis reactions
using hydrochloride derivatives.
Figure 8. Dented steel block of HNS (left) and 4 (right).
Z. Anorg. Allg. Chem. 2012, 1278–1286
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1283

T. M. Klapötke, A. Preimesser, J. Stierstorfer
ARTICLE
-
Enhanced performance of compounds 3–7 correlates with Synthesis of 2,2Ј-Bisimidazole (BI)
higher sensitivities towards impact, friction and electrostatic
discharge.
Sodium bisulfite (36.6 g, 351 mmol) was dissolved in water (180 mL)
and ethanol (100 mL) was added. Afterwards, an aqueous glyoxal solu-
tion (25.54 g, 176 mmol, 40%) was added. The solution was stirred
for 1.5 hours at ambient temperature. The white adduct was filtered
-
Bis-hydroxylammonium TNBI (3) although crystallizing as a
dihydrate has the best energetic properties related to secondary
explosive applications (highest detonation pressure), highest and washed with ethanol and diethyl ether to yield the glyoxal-sodium
–
3
density (1.81 g·cm ).
bisulfite-hydrate adduct (50.6 g, 175 mmol). The adduct was dissolved
-
Bis-guanidinium TNBI (4) has a high decomposition tem- in aqueous ammonia (275 mL, 25%) and ammonium carbonate (10 g)
was added. The solution was heated to reflux for 4 hours and cooled
down to ambient temperature. After filtration and washing with ethanol
and diethyl ether 2.2 g (16 mmol 40%) could be obtained. The synthe-
sis can be up-scaled by using the fivefold amount of each reagent
perature (328 °C), low sensitivities and was successfully deto-
nated in a small-scale reactivity test.
-
Me TNBI (8) cannot be used as a suitable melt castable ex-
2
plosive because of its small melting range.
All crystal structures of the herein investigated compounds
–
1
6 6 4
yielding 12 g BI. EA (C H N 134.14 g·mol ) exp.(calc.): C: 53.50
-
1
(
6
53.72), H: 4.16 (4.51), N: 41.54 (41.77) %; H NMR (d DMSO,
were determined by low temperature single crystal X-ray dif-
fraction.
2
H
5 °C, ): δ = 12.58 (s, br, 1H, NH), 7.13 (s, 1 H, Harom.), 7.00 (s, 1H,
arom.) ppm; C{ H} NMR (d DMSO, 25 °C): δ = 139.8 (s, 2C, C2/
6
13
1
2’), 128.8 (s, 2C, C4/4’), 117.9 (s, 2C, C5/5’) ppm.
Experimental Section
Synthesis of 4,4Ј,5,5Ј-Tetranitro-2,2Ј-bisimidazole (TNBI)
General Procedures
Sodium nitrate (18 g 0.2 mol) and urea (0.02 g 0.33 mmol) were sus-
pended in concentrated sulfuric acid (30 mL) at 0 °C. Afterwards, bisi-
midazole (5.0 g 37.0 mmol) was added in small portions. The suspen-
sion was stirred for one hour at ambient temperature and was sub-
sequently heated to 85–90 °C for 16 hours. After that the suspension
was put onto ice-water (100 mL). The product precipitated immedi-
ately. It was filtered off and washed with ice water (4 ϫ 50 mL) to
Raman spectra were recorded with a Bruker MultiRAM FT–Raman
fitted with a liquid nitrogen cooled germanium detector and a Nd:YAG
laser (λ = 1064 nm), infrared spectra were measured with a Perkin–
Elmer Spectrum BXFTIR spectrometer equipped with a Smiths DuraS-
amplIR II ATR device. All spectra were recorded at ambient tempera-
ture, the samples were solids. NMR spectra were recorded at 25 °C
with a JEOL Eclipse 400 ECX instrument, and chemical shifts were
obtain 6.6 g TNBI·2H
2
O (51%) as a pale yellow powder. EA
–
1
1
13
(C H N O ·2H O, 350.14 g·mol ): exp. (calc.): C: 22.52 (22.58), N:
determined with respect to external Me
4
Si ( H, 400.2 MHz; C,
6
2
8
8
2
1
1
4
6
31.71 (32.00), H: 1.55 (1.73) %; H NMR (d -DMSO, 25 °C): δ =
1
00.6 MHz), MeNO
2
( N, 29.0 MHz;). Mass spectrometric data were
1
3
1
8
.95 (2H, N–H) ppm; C{ H} NMR (d
6
-DMSO, 25 °C): δ = 138.8
obtained with a JEOL MStation JMS 700 spectrometer (DCI+). Ele-
mental analysis (C/H/N) were performed with a Elementar Vario EL
analyzer. Melting points were determined in capillaries with a Büchi
Melting Point B–540 instrument and are uncorrected. Decomposition
points were determined by Differential Scanning Calorimetry (DSC)
measurements with a Linseis DSC–PT10, using a heating rate of
(
1C, C–C), 139.1 (1C, C4,C5–NO ) ppm; Sensitivities: IS Ͼ 40 J; FS:
2
Ͼ 240 N; ESD: Ͼ 1.0 J
Bisammonium-4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazolate (1)
–1
5
K·min . Pycnometric measurements were carried out with a Quant-
When TNBI was extracted with diethyl ether (starting with 5 g BI)
anhydrous ammonia was bubbled through the solution. The ammonium
salt precipitated immediately. The solid was filtered and washed with
achrome helium gas pycnometer. Sensitivity data (impact and friction)
were performed using a drophammer and friction tester analog to BAM
[
25]
(Bundesanstalt für Materialforschung und -prüfung) . Electrostatic
diethyl ether to obtain 6.5 g of 1 (95% relating to TNBI). EA
sensitivities were measured with a OZM small scale electrostatic dis-
charge tester.[ Quantum chemical calculations were performed with
–1
(
(
6 8 10 8
C H N O 348.20 g·mol ) exp. (calc.): C: 19.98 (20.37), N: 39.96
26]
1
40.23), H: 2.11 (2.32) %; H NMR (d
6
-DMSO, 25 °C): δ = 7.25 (8H,
-DMSO, 25 °C): δ = 141.0 (1C, C–C),
) ppm; Raman: 1/λ [(%)] = 1562 (100),
540 (15), 1496 (10), 1478 (20), 1389 (12), 1344 (19), 1302 (57), 1257
[
27]
the Gaussian09 software.
+
13
1
4 6
NH ) ppm; C{ H} NMR (d
1
1
44.9 (1C, C4,C5–NO
2
XRD was performed on an Oxford Xcalibur3 diffractometer with a
Spellman generator (voltage 50 kV, current 40 mA) and a KappaCCD
(
3
88), 1026 (19), 867 (21), 771 (8), 758 (10), 688 (2), 432 (3),
97 (6) cm ; IR: (ATR) 1/λ = 3262 (m, br), 1492 (s), 1481 (s), 1440
detector using Mo-K
α
radiation (λ = 0.71073 Å). The data collection
–
1
[
28]
and reduction was carried out using the CRYSALISPRO software.
The structures were solved either with SHELXS-97
(
(
(
w), 1390 (s), 1368 (s), 1306 (s), 1246 (s), 1114 (m), 951 (m), 855
m), 802 (vs), 754 (m), 706 (m) cm ; MS (FAB (–)): m/z = 311.98
100), 312.99 (10), 313.99 (2); (FAB (+) m/z): 18.03 (100). Sensitivi-
[
29]
[30]
or SIR-92,
–
1
[
31]
refined with SHELXL-97
and finally checked using the PLA-
TON[ software integrated in the WINGX[33] software suite. The ab-
sorptions were corrected with a Scale3 Abspack multi-scan method.
Cif files can be obtained free of charge using the CCDC Nos. from
the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
32]
ties: IS Ͼ 9 J; FS : Ͼ 240 N; ESD: Ͼ 1.0 J.
Bispotassium-4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazolate (2)
2
The precipitated TNBI·2H O can be purified by extraction with diethyl
CAUTION! All high nitrogen and oxygen containing compounds are
ether (4 ϫ 100 mL). After evaporation of the solvent until a remaining
potentially explosive energetic materials, although no hazards were of 5–10 mL, an excess (approx. 50 mL) KOH/EtOH (0.5 M) was added
observed during preparation and handling these compounds. Neverthe- and the water-free orange bis-potassium salt (2) precipitated. To get
less, this necessitates additional meticulous safety precautions (earthed rid of the precipitated excess KOH, the solid was washed with ice
equipment, Kevlar® gloves, Kevlar® sleeves, face shield, leather coat,
and ear plugs).
water and EtOH. EA (K
(18.46), N: 28.66 (28.71), H: 0.0 (0.0) %; H NMR (d
–1
2 6 8 8
C N O 390.31 g·mol ) exp. (calc.): C: 18.52
1
6
-DMSO,
1
284
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© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 1278–1286

Energetic Derivatives of 4,4Ј,5,5Ј-Tetranitro-2,2Ј-bisimidazole (TNBI)
1
2
5 °C): δ = 8.95 (2H, N–H) ppm; 13C{ H} NMR (d
6
-DMSO, 25 °C): General Procedure for the Syntheses of Compounds 6 and 7
δ = 141.0 (1C, C–C), 144.9 (1C, C4, C5–NO
Ͼ 40 J; FS: Ͼ 240 N; ESD: Ͼ 1.0 J.
2
) ppm; Sensitivities: IS
Compound 1 (348 mg 1 mmol) was suspended in water (10 mL). Af-
terwards, DAG·HCl (260 mg, 1.1 mmol) or TAG·HCl (300 mg,
1
.1 mmol), respectively, was added. The corresponding suspension
was heated to reflux for 1 h. The DAG TNBI precipitated immediately,
whereas the TAG TNBI crystallized overnight in the fridge at 4 °C.
2
Synthesis of Bishydroxylammonium 4,4Ј,5,5Ј-Tetranitro-
,2Ј-bisimidazolate Dihydrate (3)
2
2
Both compounds can be filtered and washed with ice water to yield
2
TNBI·2H O (350 mg 1mmol) was dissolved in diethyl ether (20 mL). 400 mg of 6 (81%) and 420 mg of 7 (80%).
Hydroxylamine-monohydrate (0.25 mL, 50 wt.-%) was added and the
resulting suspension was stirred for 30 min at ambient temperature.
After filtering and washing with diethyl ether, the crude product can
Bis-diaminoguanidinium-4,4Ј,5,5Ј-tetranitro-2,2Јbisimidazolate
–
1
(
4
6): DSC (5 K·min ):
T
dec
=
195 °C; EA (C
8 16 18 8
H N O
–
1
92.33 g·mol ) (exp. (calc.): C: 19.82 (19.52), N: 50.56 (51.21), H:
be recrystallized from water to yield
3 (300 mg 72%). DSC
1
–1
–1
6
3.14 (3.28) %; H NMR (d -DMSO, 25 °C): δ = 4.48 (s, br, 4H, N–
NH ), 7.12 (s, br, 2H, –NH ), 8.57 (s, br, 2H, C–NH) ppm; C{ H}
2 2
(
5 K·min ): Tdec = 186 °C; EA (C
6
H
8
N
10
O10·2H
2
O 416.22 g·mol )
1
3
1
1
exp. (calc.): C: 17.50 (17.31), N: 33.36 (33.65), H: 2.61 (2.91) %; H
1
3
1
6
NMR (d -DMSO, 25 °C): δ = 140.9 (2C, C2,2‘), 144.7 (4C,
NMR (d
NMR (d
C4,4‘,5,5‘ –NO
4N, –NO ), –349 (1N, O–NH
603 (19), 1564 (100), 1486 (35), 1388 (22), 1352 (28), 1304 (53),
6
-DMSO, 25 °C): δ = 10.35 (s, br, 1H, N–OH) ppm; C{ H}
1
4
1
C4,4‘,5,5‘ –NO
2
), 160.2 (1C, diaminoguanidine) ppm; N{ H} NMR
6
-DMSO, 25 °C): δ = 140.4 (2C, C2,2‘), 143.4 (4C,
) ppm; 1 N NMR{ H} (d
4
1
(d -DMSO, 25 °C): δ = –18 (4N, –NO ) ppm; MS: (FAB (–))
-DMSO, 25 °C) δ = –25
6
2
2
6
m/z = 311.98 (100), 312.99 (10), 313.99 (2); (FAB (+) m/z) : 90.08
100), 91.08 (3); Raman: 1/λ [(%)] = 1553 (100), 1542 (43), 1447
(25), 1380 (10), 1346 (18), 1307 (46), 1224 (50), 1182 (18), 1029 (10),
(
2
3
) ppm; Raman: 1/λ [(%)] = 2060 (8),
(
1
1
–
1
266 (64), 1217 (19), 1043 (20), 870 (26), 757 (17), 397 (18) cm ;
–
1
9
1
1
89 (6), 930 (5), 866 (23), 700 (5), 527 (5), 434 (5) cm ; IR (ATR):
/λ = 3480 (w), 3376 (w), 3348 (w), 3312 (w), 3055 (w, br), 1675 (s),
562 (w), 1516 (m), 1489 (m), 1443 (s), 1393 (s), 1361 (vs), 1300
IR (ATR): 1/λ = 3638 (m, br), 3332 (vw), 3274 (vw), 3216 (vw), 2504
w), 2086 (vw), 1609 (vw), 1594 (vw), 1509 (s), 1462 (s), 1399 (s),
(
1
9
6
348 (m), 1311 (s), 1262 (vs), 1226 (m), 1187 (s), 1115 (m), 996 (w),
66 (w), 927 (vw), 855 (vs), 752 (m), 697 (m), 655 (w),
14 (vw) cm ; Sensitivities: IS Ͼ 6 J; FS: 288 N; ESD: 0.2 J.
(
vs), 1264 (w), 1212 (s), 1172 (vs), 986 (s), 962 (vs), 946 (s), 856 (s),
–
1
–1
811 (vs), 756 (m), 698 (s), 637 (vs, br) cm ; Sensitivities: IS Ͼ 17 J;
FS: 252 N; ESD: 0.4 J
Bis-triaminoguanidinium-4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazolate
General Procedure for the Syntheses of Compounds 4 and 5
–
1
–1
(
7): DSC (5 K·min ): 152; EA (C
8
H
18
N
20
O
8
522,36 g·mol ) exp.
1
TNBI dihydrate (350 mg, 1mmol) was suspended in water (10 mL).
Adding guanidinium carbonate (200 mg, 1.1 mmol) or aminoguanidi-
(calc.): C: 18.65 (18.39), N: 53.48 (53.63), H: 3.34 (3.47) %; H NMR
(d -DMSO, 25 °C): δ = 4.48 (s, br, 6H, N–NH ), 8.59 (s,br, 3H, C–
6
2
1
3
1
nium bicarbonate (300 mg, 2.2 mmol) resulted in precipitation of the NH) ppm; C{ H} NMR (d -DMSO, 25 °C): δ = 141.0 (2C, C2,2‘),
6
1
4
1
corresponding orange 2:1 salt. Afterwards, the salts could be washed 144.9 (4C, C4,4‘,5,5‘ –NO ), 159,6 (1C, guanidine) ppm; N{ H}
2
with a lot of water to yield 400 mg of 4 (93%) and 425 mg of 5 (92%).
6 2
NMR (d -DMSO, 25 °C): δ = –26 (4N, –NO ) ppm; MS:(FAB (+))
m/z = 105.12 (100), 104.12 (3); Raman: 1/λ [(%)] = 1557 (100), 1545
39), 1517 (8), 1451 (17), 1443 (17), 1379 (9), 1340 (14), 1299 (52),
Bisguanidinium-4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazolate (4): DSC
(
–1
–1
(
(
(
5 K·min ): Tdec = 328 °C; EA (C
8
H
12
N
14
O
8
432.27 g·mol ) exp.
1
4
223 (66), 1145 (4), 1027 (14), 865 (15), 754 (5), 697 (3), 527 (4),
05 (5) cm ; IR (ATR): 1/λ = 3381 (vw), 3340 (w), 3144 (w), 2430
1
calc.): C:22.38 (22.23); N: 45.09 (45.36); H: 2.67 (2.80) %; H NMR
–1
6 2 6
d -DMSO, 25 °C): δ = 7.12 (s, br, 6H, NH -
) ppm; 13C{ H} NMR (d
1
(
vw, br), 1670 (m), 1589 (w, br), 1519 (m), 1495 (m), 1445 (m, br),
DMSO, 25 °C): δ = 140.8 (2C, C2,2‘), 144.1 (4C, C4,4‘,5,5‘ –NO
2
),
-DMSO, 25 °C): δ = –20
) ppm; MS: (FAB (–)) m/z = 311.98 (100), 312.99 (10),
13.99 (2); (FAB (+)) m/z = 60.06 (100), 61.06 (2); Raman: 1/λ
1
8
389 (s), 1361 (s), 1306 (s), 1219 (s, br), 1108 (m), 1027 (m), 945 (s),
86 (s, br), 854 (vs), 752 (s) 705 (vs) 639 (vs) 606 (s) cm ; Sensitivi-
1
1
58.4 (1C, –(NH
2
) ppm; 14N{ H} NMR (d
6
–1
(4N, –NO
2
ties: IS Ͼ 6 J; FS: 288 N; ESD: 0.2 J
3
[(%)] = 1551 (100), 1536 (18), 1490 (5), 1465 (19), 1396 (7), 1348
(
17), 1303 (42), 1363 (6), 1216 (60), 1111 (3), 1026 (15), 868 (16),
62 (6), 684 (4), 517 (3) cm ; IR (ATR): 1/λ = 3424 (m), 3280 (w),
116 (m), 1738 (w), 1664 (s), 1650 (s), 1574 (w), 1483 (s), 1460 (s),
1
,1Ј-Dimethyl,4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazole (8)
–1
7
3
1
Bispotassium-4,4Ј,5,5Ј-tetranitro-bisimidazolate
(390.1 mg 1mmol)
385 (s), 1372 (vs), 1304 (s), 1197 (vs), 1111 (m), 1015 (w), 1015 was suspended in acetonitrile (20 mL) and dimethylsulfate (0.2 mL,
–1
2 mmoL) was added at ambient temperature. The suspension was
heated to reflux and DMF (2–3 mL) was added until a solution had
been obtained. After heating to reflux for 16 h, all solvents were re-
moved in vacuo. The residue was boiled in water, hot filtered and
(
w), 945 (w), 858 (m), 820 (vs) cm ; Sensitivities: IS Ͼ 40 J;
FS: Ͼ 240 N; ESD: Ͼ 1.0 J
Bisaminoguanidinium-4,4Ј,5,5Ј-tetranitro-2,2Ј-bisimidazolate (5):
–1
–1
DSC (5 K·min ): Tdec = 206 °C; EA (C
exp. (calc.): C: 21.17 (20.48), N: 48.55 (48.48), H: 2.82 (3.05) %; H
NMR (d -DMSO, 25 °C): δ = 4.70 (s, 2H, N–NH ), 7.02 (s, br, 4H,
), 8.85 (s, br, 1H, C–NH) ppm; 13C{ H} NMR (d
-DMSO, (28.08), N: 32.44 (32.75); H: 1.92 (1.77) %; H NMR (d
5 °C): δ = 140,6 (2C, C2,2‘), 144.5 (4C, C4,4‘,5,5‘ –NO
8 14 16 8
H N O 462.30 g·mol ) washed with water to yield bright-shining 8 (212 mg 62%) after drying
1
–1
in = 236 °C,
a
60 °C oven for 12 h. DSC (5 K·min ):
T
m
–
1
6
2
Tdec = 258 °C; EA (C H N O 342.04 g·mol ): exp.(calc.): C: 27.91
8 6 8 8
1
1
–
2
NH
2
6
6
-DMSO,
-DMSO, 25 °C):
-DMSO, 25 °C): δ = 35.7 (2C, C1,C1’) 132.2 (2C, C3,C3’), 133.3 (1C, C4–NO ), 139.6
1
3
1
2
3 6
), 159.41 25 °C): δ = 4.28 (6H,CH ) ppm, C{ H} NMR (d
14
1
(1C, aminoguanidine) ppm; N{ H} NMR (d
6
2
+
δ = –25 (4N, –NO ) ppm, IR (ATR): 1/λ = 3423 (m), 3382 (w), 3290 (1C, C5–NO ) ppm. MS (EI) m/z = 343.03 (12.94% MH ), 342.03
2
2
+
+
(m), 3109 (m, br), 2649 (w), 2408 (vw), 1666 (s), 1593 (w), 1519 (m), (100%, M ), 326.03 (11.45%MH –CH
3
), 325.03 (97.67%), 313.02
1
464 (vs), 1373 (vs), 1302 (vs), 1258 (m), 1238 (m), 1192 (vs, br), (14.07%, M–2CH
3
+1H), 312.02 (61.83%, M–2CH +2H). IR (ATR)
3
1
111 (vs), 994 (m), 946 (m), 910 (s, br), 856 (s), 811 (vs), 750 (vs), 723 1/λ = 1567 (w), 1534 (s), 1454 (m), 1408 (m), 1384 (m), 1342 (m),
–1
(m), 702 (s) cm ; Sensitivities: IS Ͼ 20 J; FS : 360 N; ESD: Ͼ 1.0 J
1301 (s), 1164 (w), 1082 (w), 1040 (w), 850 (s), 813 (vs), 744 (m),
Z. Anorg. Allg. Chem. 2012, 1278–1286
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.zaac.wiley-vch.de 1285

T. M. Klapötke, A. Preimesser, J. Stierstorfer
ARTICLE
–1
6
1
87 (m) cm . Raman 1/λ [(%)] = 2977 (8), 1584 (100), 1567 (51),
534 (31), 1490 (4), 1387 (16), 1344 (54), 1312 (56), 1208 (8), 1145
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(
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3) cm . Sensitivities: IS Ͼ 40 J; FS: 292 N; ESD: 0.1 J.
–1
1
0th Symposium (International) on Detonation, ONR 33395–12,
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Acknowledgments
[
Financial support of this work by the Ludwig-Maximilian University
of Munich (LMU), the U.S. Army Research Laboratory (ARL) under
grant no. W911NF-09–2-0018, the Armament Research, Development
and Engineering Center (ARDEC), and the Office of Naval Research
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(
1
and evaluation methods for energetic materials and with Dr. Muhamed
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and Brad Forch (ARL, Aberdeen, Proving Ground, MD). Stefan Huber
is thanked for assistance with sensitivity measurements. Lorenz Mitter-
meier and Raphael Wildermuth are thanked for help with the syntheses.
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very sensitive Յ 3 J; Friction Insensitive Ͼ 360 N, less sensitive
=
360 N, sensitive Ͻ 360 N and. Ͼ 80N, very sensitive Յ 80 N,
Received: April 23, 2012
extremely sensitive Յ 10 N.
Published Online: June 29, 2012
1
286
www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 1278–1286