Upload
anton-hammerl
View
244
Download
5
Embed Size (px)
Citation preview
Synthesis and Characterization of Hydrazinium Azide Hydrazinate
Anton Hammerl, Thomas M. Klapotke*, and Holger Piotrowski
Department of Chemistry, Ludwig-Maximilians University of Munich, Butenandtstr. 5–13 (Building D), 81377 Munich
(Germany)
Gerhard Holl and Manfred Kaiser
Wehrwissenschaftliches Institut fur Werk-, Explosiv- und Betriebsstoffe (WIWEB), Großes Cent, 53913 Swisttal (Germany)
Summary
Hydrazinium azide hydrazinate, [N2H5]þ[N3]7�N2H4 was synthe-sized from equimolar amounts of hydrazinium azide and hydrazineand characterized by single crystal X-ray diffraction: monoclinic,P 21=c, a¼ 6.3704(2), b¼ 12.1111(4), c¼ 6.9940(2) A, b¼91.8666(2) �, V¼ 539.32(3) A3, Z¼ 4, r¼ 1.320 g cm71. The com-pound is less hygroscopic and less volatile than hydrazinium azide.Explosion of [N2H5]þ[N3]7�N2H4 yielded dinitrogen (N2), ammonia(NH3) and dihydrogen (H2). Compared to hydrazinium azide, thehydrazine adduct produces larger amounts of ammonia in the explo-sion.
1. Introduction
Most high energetic materials, such as TNT, RDX, HMX
and CL-20 derive their energy from the oxidation of the
carbon backbone. Modern compounds such as CL-20(1) or
the recently reported hepta- and octanitrocubanes(2) possess
very high densities and utilize the cage strain of the
molecules. High nitrogen materials were investigated in
recent years where the energy is derived from the high
positive heat of formation of the compound. These com-
pounds are often insensitive to electrostatic discharge, fric-
tion and impact like the recent 3,30-azobis(6-amino-1,2,4,5-
tetrazine)(3).
The detonation velocity correlates to (Q=m)0.5 (Q¼ heat of
explosion, m¼ average molecular mass of products). It was
shown that the detonation velocity of hydrazinium azide at
similar densities is greater than the detonation velocity of
RDX, due to the formation of hydrogen during the explo-
sion(4). Unfortunately, hydrazinium azide is hygroscopic and
volatile and, therefore, not in commercial use. The character-
istics of hydrazinium azide were not improved by introduc-
ing organic substituents(5).
Here, the coordination of a hydrazine molecule to hydra-
zinium azide was investigated. The first indication for a
hydrazine adduct of hydrazinium azide was found by
Rieger, who isolated a colorless solid from a solution of
hydrazinium azide in a mixture of ethanol and hydrazine that
had a different melting point than hydrazinium azide(6).
Although hydrazinium azide hydrazinate was mentioned in
the literature(7) prior to this work, the compound had never
been characterized or examined thoroughly.
2. Synthesis
Hydrazinium azide hydrazinate 1 was synthesized in a
straightforward, quantitative synthesis from equimolar
amounts of hydrazinium azide and hydrazine in an evacuated
Schlenk vessel by heating the vessel for two days to 50 �C
(Eq. 1).
H2NNH3
� �þN3
� �ÿþH2NNH2 !
H2NNH3
� �þN3
� �ÿ�H2NNH2 ð1Þ
3. Analytical Data
m.p.: 65 �C;1H NMR ([D6]DMSO): d=ppm¼ 5.07 (s, NH) (Figure 1);14N NMR ([D6]DMSO): d=ppm¼ÿ133 (NNN), ÿ278
(NNN), ÿ321 (NH2NH3, NH2NH2) (Figure 2);15N NMR ([D6]DMSO): d=ppm¼ÿ133.4 (NNN),
ÿ278.2 (NNN), ÿ332.5 (NH3NH2, NH2NH2) (Figure 2);
IR (KBr): n=cmÿ1¼ 3451 w, sh, 3356 m, 3285 m, 3168 m,
3063 m, 2958 m, 2603 m, sh, 2029 s(nasðNÿ3 Þ), 1603 m,
1530 w, sh, 1342 w, 1260 w, 1096 m, 1016 w, sh, 949 w,
798 w, 649 w, 621 w, 552 w (Figure 3);
Raman (100 mW): n=cmÿ1¼ 3272 w, 3187 m, 1643 w,
1337 s(nsðNÿ3 Þ), 1250 w, 1143 w, 961 w, 942 w, 439 w,
325 w, 233 m, 195 m, 154 m, 129 m (Figure 3);
DSC: 16 �C, 65 �C (m.p.), 151.5 �C (Figure 4);
microanalysis, N7H9: (107.12): calcd.: H 8.5 %, N 91.5 %;
found: H 8.9 %, N 90.2 %.*Corresponding author; e-mail: [email protected]
# WILEY-VCH Verlag GmbH, D-69469 Weinheim, 2001 0721-3115/01/0410–0161 $17.50þ:50=0
Propellants, Explosives, Pyrotechnics 26, 161–164 (2001) 161
4. Results and Discussion
1 is a colorless solid that is, in contrast to hydrazinium
azide, not volatile and not hygroscopic. The vibrational
spectra show a larger number of absorption bands than for
hydrazinium azide, the bands of the azide group are observed
at 2029 cmÿ1 (IR, asymmetric stretch) and 1337 cmÿ1
(Raman, symmetric stretch), which are the typical values
for ionic azides (Figure 3).
The resonance of all protons in the 1H NMR spectrum was
found as a singlet at d¼ 5.07 ppm (Figure 1), which is
between the range of the proton signals for a hydrazinium
ion (hydrazinium azide, d¼ 6.97 ppm) and free hydrazine
(d¼ 3.23 ppm). The azide atoms display two signals in
the nitrogen NMR spectra, at d¼ÿ133=ÿ133.4 ppm
(14=15N NMR) for the central nitrogen atom and at
d¼ÿ278=ÿ278.2 ppm (14=15N NMR) for the two term-
inal nitrogen atoms. The hydrazine nitrogen atoms give a
signal at d¼ÿ331=ÿ332.5 ppm (14=15N NMR) that has the
same chemical shift as the signal of the hydrazine nitrogen
atoms in hydrazinium azide d¼ÿ331=ÿ332.8 ppm (14=15N
NMR). The spectroscopic data of hydrazinium azide hydra-
zinate (1) compared to hydrazinium azide are summarized in
Table 1.
Single crystals of hydrazinium azide hydrazinate (1) were
obtained by recrystallization from methanol and were sub-
jected to a single crystal X-ray diffraction study(8). The
bonding parameters of the hydrazinium ion and the hydrazine
molecule agree well with known compounds (Figure 5)(9,10).
The azide ion in 1 is connected via six hydrogen bonds to
three hydrazinium and three hydrazine molecules. The N-N
distances of NH2. . .N hydrogen bonds range from 3.070(2) to
3.135(2) A and are longer than the N-N distance of the
NH3. . .N hydrogen bond with 2.9425(2) A due to the positive
charge on the NH3 group.
The hydrazinium and hydrazine molecules are connected
by two short hydrogen bonds (N-N distance 2.747(2) and
2.875(2) A) between the two hydrogen atoms of the NH3
group of the hydrazinium ion and the ione pairs of the
nitrogen atoms of the hydrazine molecule. The bond
lengths of the azide ion show a slight difference (1.180(2)
Figure 1. 1H NMR spectrum of hydrazinium azide hydrazinate.
Figure 2. 14=15N NMR spectra of hydrazinium azide hydrazinate.
Figure 3. Vibrational (IR, top and Raman, bottom) spectra ofhydrazinium azide hydrazinate.
Figure 4. DSC spectrum of hydrazinium azide hydrazinate.
162 A. Hammerl, T. M. Klapotke, H. Piotrowski, G. Holl, and M. Kaiser Propellants, Explosives, Pyrotechnics 26, 161–164 (2001)
and 1.174(2) A) due to different hydrogen bonding on both
ends of the azide ion.
The explosion, initiated by electrical resistance heating
(Pt wire) in an evacuated steel bomb, gave dinitrogen (N2),
ammonia (NH3) and dihydrogen (H2) as decomposition
products. Compared to hydrazinium azide, 1 produces
larger amounts of ammonia in the explosion (Eqs. 2 and 3).
½N2H5�þ½N3�
ÿ:! 2:18 N2 þ 1:52 H2 þ 0:65 NH3 ð2Þ
½N2H5�þ½N3�
ÿ:N2H4 ! 2:68 N2 þ 2:02 H2 þ 1:65 NH3
ð3Þ
Compound 1 showed no sensitivity to an electrical dis-
charge of 20 kV (electrostatic), in a drop hammer test
(5 kg=50 cm) (shock)(11) and to grinding in a mortar (fric-
tion). Like hydrazinium azide, 1 does not explode when
heated slowly (10 K=min), but detonates under rapid heating
or when put on contact with a hot metal surface.
In the DSC spectrum (Mettler DSC apparatus, 10 mg
sample, hermetically sealed sample pans, see Figure 4) two
endothermic phase transitions were observed. Melting
without decomposition occurs at 65 �C, decomposition at
151 �C. The surprising endothermic decomposition may be
caused by an overlapping evaporation effect probably due to
leaking DSC pans.
We are currently studying hydrazine adducts of other
hydrazinium salts with highly nitrogen-rich anions.
5. Summary and Conclusions
Hydrazinium azide hydrazinate, [N2H5]þ[N3]7�N2H4 was
synthesized from equimolar amounts of hydrazinium azide
and hydrazine and was recrystallized from methanol. The
compound was characterized by IR, Raman, multinuclear
NMR (1H,14=15N) spectroscopy and single crystal X-ray
diffraction. Hydrazinium azide hydrazinate, [N2H5]þ[N3]7
�N2H4, is neither shock nor friction sensitive and also not
sensitive towards electrostatic discharge of 20 kV. The com-
pound, however, explodes, when heated up rapidly or when
exposed to a hot metal surface. The explosion of hydrazinium
azide hydrazinate gives more ammonia than the explosion of
hydrazine-free hydrazinium azide.
6. References
(1) R. L. Simpson, P. A. Urtiew, D. L. Ornellas, G. L. Moody, K. J.Scribner and D. M. Hofman, Propellants, Explos. Pyrotech. 22,249 (1997); and references therein.
(2) M.-X. Zhang, P. E. Eaton and R. Gilardi, Angew. Chem. 112, 422(2000); Angew. Chem., Int. Ed. Engl. 39, 409 (2000).
(3) D. E. Chavez, M. A. Hiskey and R. D. Gilardi, Angew. Chem.112, 1861 (2000); Angew. Chem. Int. Ed. Engl. 39, 1791 (2000).
(4) G. S. Yakovleva, R. Kh. Kurbangalina and L. N. Stesik, Fiz.Goreniya Vzryva 10(2), 270–274 (1974).
(5a) T. Habereder, A. Hammerl, G. Holl, T. M. Klapotke, J. Knizekand H. Noth, Eur. J. Inorg. Chem. 849–852 (1999).
(5b) T. Habereder, A. Hammerl, G. Holl, T. M. Klapotke, P. Mayerand H. Noth, 31st Int. Annual Conference of ICT, Karlsruhe,Germany, June 27–30, 2000, pp. 150.1–150.7.
(5c) A. Hammerl, G. Holl, K. Hubler, T. M. Klapotke and P. Mayer,Eur. J. Inorg. Chem. 755–760 (2000).
Table 1. Spectroscopic Data (NMR and IR, Raman) of Hydrazinium Azide Hydrazinate (1) Compared to Hydrazinium Azide
Compound 1H NMR (ppm) 14N NMR (ppm) 15N NMR (ppm) nas(N3ÿ) (IR) (cmÿ1) ns(N3
ÿ) (Ra) (cmÿ1)
[N2H5]þ[N3]ÿ 6.97 ÿ132 ÿ132.5 2033 1347ÿ281 ÿ281.0ÿ331 ÿ332.8
[N2H5]þ[N3]ÿ�N2H4 (1) 5.07 ÿ132 ÿ133.4 2029 1337ÿ281 ÿ278.2ÿ331 ÿ332.5
Figure 5. Top: hydrogen bonds to the azide ion in hydrazinium azidehydrazinate; bottom: hydrogen bonds to the hydrazinium ions andhydrazine molecules in hydrazinium azide hydrazinate.
Propellants, Explosives, Pyrotechnics 26, 161–164 (2001) Synthesis and Characterization of Hydrazinium Azide Hydrazinate 163
(5d) A. Hammerl, G. Holl, M. Kaiser, T. M. Klapotke, P. Mayer,H. Noth and M. Warchhold, Z. Anorg. Allg. Chem. 627, 1477(2001).
(6) H. D. Rieger, Ph.D. Thesis: Hydronitric acid and hydrazine tri-nitrate, Cornell University, Ithaca, New York (1910).
(7a) A. L. Dresser and A. W. Browne, J. Am. Chem. Soc. 58, 261(1933).
(7b) E. P. Kirpichev, A. P. Alekseev, Y. I. Rubtsov and G. B. Manelis,Russian Journal of Physical Chemistry 47, 1654 (1973).
(8) NONIUS KAPPA CCD diffractometer, Mo-Ka radiation,l¼ 0.71073 A, graphite monochromator. N7H9 (107.14),colorless rod, 0.3060.0760.06 mm, monoclinic, P 21=c,a¼ 6.3704(2), b¼ 12.1111(4), c¼ 6.9940(2) A, b¼ 91.8666(2) �,V¼ 539.32(3) A3, Z¼ 4, r¼ 1.320 g cmÿ1, m¼ 0.106, F(000)232, T¼ 200(2) K, ÿ8� h� 8, ÿ15� k� 15, ÿ9� l� 9, 9191reflections collected, 1226 independent reflections(Rint.¼ 0.0637), 895 observed reflections with I> 2s(I); structuresolution SIR97 (Cascarano et al., Acta Cryst. Sect. A 1996, C79);structure refinement SHELXL-97 (G. M. Sheldrick, University of
Gottingen, Germany, 1997), direct methods, free refinement ofall hydrogen atoms; final R values [I> 2s(I)]: R1¼ 0.0457,wR2¼ 0.0980; all data: R1¼ 0.0723, wR2¼ 0.1106.
(9a) P. G. Chiglien, J. Etienne, S. Jaulmes and P. Laruelle, Acta Cryst.Sect. B 30, 2229–2233 (1974).
(9b) H. Holfter, T. M. Klapotke and A. Schulz, Eur. J. Solid StateInorg. Chem. 33, 855 (1996).
(10) R. L. Collin and W. N. Lipscomb, Acta Cryst. 4, 10 (1951).(11) T. M. Klapotke and C. M. Rienacker, Propellants, Explos.,
Pyrotech. 26, 43–47 (2001).
AcknowledgementsFinancial support of this work by the University of Munich (LMU),
the Deutsche Forschungsgemeinschaft (DFG, KL 636=7-1), the Fondsder Chemischen Industrie and the German Federal Office of DefenseTechnology and Procurement (BWB) is gratefully acknowledged.
(Received April 23, 2001; Ms 2001=033)
164 A. Hammerl, T. M. Klapotke, H. Piotrowski, G. Holl, and M. Kaiser Propellants, Explosives, Pyrotechnics 26, 161–164 (2001)