organic compounds 4,10-Dinitro-2,6,8,12-tetraoxa-4,10- diazaisowurtzitane (TEX): a nitramine with an exceptionally high density

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1 organic compounds Acta Crystallographica Section C Crystal Structure Communications ISSN ,10-Dinitro-2,6,8,12-tetraoxa-4,10- diazaisowurtzitane (TEX): a nitramine with an exceptionally high density Konstantin Karaghiosoff, a Thomas M. KlapoÈtke, a * Alexej Michailovski a and Gerhard Holl b a Department of Chemistry, Ludwig-Maximilias-UniversitaÈt, Butenandtstraûe 5-13 (Haus D), D MuÈnchen, Germany, and b Wehrwissenschaftliches Institut fuèr Werk-, Explosiv- und Betriebsstoffe, Grosses Cent, D Swisttal, Germany Correspondence thomas.m.klapoetke@cup.uni-muenchen.de Received 19 July 2002 Accepted 14 August 2002 Online 31 August 2002 are linked by four O atoms, and by two N atoms bearing nitro groups (Fig. 1). The seven-membered rings put a strain on the cage and thus increase the energy content of the molecule. A part of the explosive power of TEX is derived from this cage strain. The extraordinarily high density of TEX may be explained by the compactness of the molecule, which can be described, except for the nitro groups, as nearly spherical (Fig. 1). Atoms N11 and N31 are coordinated, as expected, in a planar manner [both angle sums are (4) ]. There is signi cant deviation from planarity in the coordination of atoms N1 and N3, with an angle sum of (3) for N1 and (4) for N3. Atoms C1±C4 deviate only slightly from the planes de ned by the respective nitro groups. The NÐN bond length appears in both cases (N1ÐN11 and N3ÐN31) to be shorter (1.40± 1.41 A Ê ) than a single NÐN bond (1.48 A Ê ), but much longer than a double bond (1.20 A Ê ). The C1ÐC2 and C3ÐC4 bond distances [both 1.56 (2) A Ê ] are slightly shorter than that of C5ÐC6 [1.58 (1) A Ê ]. A possible reason for this difference is the fact that both the C1ÐC2 and C3ÐC4 bonds connect a The title compound (systematic name: 4,10-dinitro-2,6,8,12- tetraoxa-4,10-diazatetracyclo[ ,11.0 5,9 ]dodecane), C 6 H 6 - N 4 O 8, exhibits the highest density among known N-nitramines, due to its close-packed crystal structure. It may be regarded as consisting of a distorted hexagonal close-packed lattice formed by the isowurtzitane cages, with the nitro groups occupying the free space between the cages. Comment 4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane, hereinafter TEX, is an insensitive highly energetic material which was rst described by Ramakrishnan and co-workers in 1990 (Ramakrishnan et al., 1990). It displays the highest density recorded for a nitramine and therefore a very high detonation velocity (7470 m s 1 ), according to both Jacob et al. (2000), Li et al. (2001) and KlapoÈ tke & Ang (2001), while its sensitivity towards shock, impact or friction is extremely low, as mentioned by Vagenknecht (2000) and Zeman (1999) [cf. also KlapoÈ tke et al. (1999)]. These and other features make TEX a highly interesting model compound for the investigation of explosion processes. Figure 1 A view of the molecule of TEX showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii. A recently published X-ray structure of TEX (Yu et al., 1996) did not provide any information about the crystal lattice (such as lattice constants, space group, atom positions in the unit cell etc.). Since the density of an explosive compound is closely related to its explosion properties, we were prompted to investigate closely the crystal lattice of TEX in order to nd an explanation for its extraordinarily high density. The molecule shows a cage structure composed of three C 2 units, which Figure 2 Close OH contacts in the crystal structure of TEX, forming a threedimensional network. o580 # 2002 International Union of Crystallography DOI: /S Acta Cryst. (2002). C58, o580±o581

2 organic compounds ve-membered and a seven-membered ring and are thus less strained than the C5ÐC6 bond, which connects two sevenmembered rings. The Pitzer strain destabilizes the sevenmembered rings to a higher degree than the ve-membered rings. TEX crystallizes in a structure that is remarkably similar to a distorted hexagonal close packing of spheres. The crystal lattice of TEX contains molecules in two different orientations (Fig. 2). Within the structure, the shortest distances between molecule cages are O1O4 i [ (15) A Ê ], O111O111 ii [2.999 (2) A Ê ]andc6o1 i [ (18) A Ê ], all of which are signi cantly shorter than the sum of the van der Waals radii (3.0 A Ê for OO and 3.2 A Ê for CO; Holleman et al., 1995) [symmetry codes: (i) x, 1 y, 1 z; (ii) x, 1 y, z]. Relatively short distances are observed for H2O4, H3O211 and H4O111 (Table 2 and Fig. 2). However, due to the comparatively long HO distances and CÐHO angles deviating signi cantly from linearity, we may assume that the contacts cannot be regarded as bonding. Experimental The title compound was synthesized as described by Ramakrishnan et al. (1990). Crystallization by slow evaporation from a saturated solution of TEX in acetone afforded colourless crystals suitable for X-ray analysis. Crystal data C 6 H 6 N 4 O 8 M r = Triclinic, P1 a = (12) A Ê b = (14) A Ê c = (16) A Ê = (2) = (2) = (2) V = (14) A Ê 3 Data collection Stoe IPDS diffractometer ' scans Absorption correction: numerical (X-RED; Stoe & Cie, 1997) T min = 0.958, T max = measured re ections 1911 independent re ections Re nement Re nement on F 2 R[F 2 >2(F 2 )] = wr(f 2 ) = S = re ections 187 parameters All H-atom parameters re ned Z =2 D x = (1) Mg m 3 Mo K radiation Cell parameters from 3304 re ections = 2.4±27.9 = 0.19 mm 1 T = 200 (2) K Prismatic, colourless mm 1555 re ections with I > 2(I) R int = max = 28.1 h = 8! 9 k = 10! 10 l = 11! 10 w = 1/[ 2 (F o 2 ) + (0.0684P) P] where P =(F o 2 +2F c 2 )/3 (/) max < max = 0.25 e A Ê 3 min = 0.25 e A Ê 3 Data collection: EXPOSE in IPDS (Stoe & Cie, 1997); cell re nement: CELL in IPDS; data reduction: INTEGRATE in IPDS; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to re ne structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1996). The authors thank Dr H. Piotrowski for the X-ray data and Dr B. Krumm for his experience in the synthesis of TEX, and Table 1 Selected geometric parameters (A Ê, ). N1ÐN (16) N1ÐC (2) N1ÐC (18) N11ÐO (19) N11ÐO (2) C1ÐO (17) C1ÐC (19) C2ÐO (17) C2ÐN (19) N3ÐN (16) N3ÐC (19) N11ÐN1ÐC (11) N11ÐN1ÐC (12) C1ÐN1ÐC (11) O211ÐN11ÐN (14) O111ÐN11ÐN (12) C1ÐN1ÐN11ÐO (18) C4ÐN1ÐN11ÐO (17) Table 2 Hydrogen-bond and short-contact geometry (A Ê, ). also Ludwig-Maximilias University, Munich, for nancial support. Supplementary data for this paper are available from the IUCr electronic archives (Reference: GG1130). A packing diagram is also available. Services for accessing these data are described at the back of the journal. References N31ÐO (19) N31ÐO (18) C3ÐO (17) C3ÐC (19) C4ÐO (17) O1ÐC (16) O2ÐC (17) O3ÐC (17) O4ÐC (17) C5ÐC (2) N31ÐN3ÐC (12) N31ÐN3ÐC (12) C3ÐN3ÐC (11) O131ÐN31ÐN (13) O231ÐN31ÐN (13) C2ÐN3ÐN31ÐO (18) C3ÐN3ÐN31ÐO (17) DÐHA DÐH HA DA DÐHA C2ÐH2O4 i 0.95 (2) 2.49 (2) (2) (14) C3ÐH3O211 ii (16) (16) (2) (14) C4ÐH4O231 iii (18) (16) (2) (14) C4ÐH4O111 iv (18) 2.49 (2) (2) (14) C6ÐH6O3 v (19) (18) (2) (12) Symmetry codes: (i) 1 x; y; z; (ii) x; y 1; z; (iii) 1 x; y; z; (iv) x; 1 y; z; (v) x; y; 1 z. Altomare, A., Burla, M. C., Camalli, M., Cascarano, G., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115±119. Brandenburg, K. (1996). DIAMOND. University of Bonn, Germany. Holleman, A. F., Wiberg, E. & Wiberg, N. (1995). Lehrbuch der Anorganischen Chemie, 101st ed., Appendix 5. Berlin: Walter de Gruyter. Jacob, G., Lacroix, G. & Destombes, J. (2000). 31st International Annual Conference of ICT (Energetic Materials), pp. 1±12, 106. Karlsruhe: Fraunhofer Institute. KlapoÈ tke, T. M. & Ang, H.-G. (2001). Propellants Explos. Pyrotech. 26, 221± 224. KlapoÈ tke, T. M., Krumm, B., Holl, G. & Kaiser, M. (1999). In Energetic Materials: Modeling of Phenomena, Experimental Characterization, Environmental Engineering. Karlsruhe: Fraunhofer Institut (Hrsg.). Li, Z.-X., Ou, Y.-X. & Chen, B.-R. (2001). Hanneng Cailiao, 9, 104±106. Ramakrishnan, V. T., Vedachalam, M. & Boyer, J. H. (1990). Heterocycles, 31, 479±480. Sheldrick, G. M. (1997). SHELXL97. University of GoÈttingen, Germany. Stoe & Cie (1997). IPDS (Version 2.87) and X-RED (Version 1.09). Stoe & Cie GmbH, Darmstadt, Germany. Vagenknecht, J. (2000). Hanneng Cailiao, 8, 56±59. Yu, Y.-Z., Guan, X.-P., Chen, F.-B., Duan, B.-R. & Sun, J.-G. (1996). Proc. Int. Pyrotech. Semin. 22, 425±432. Zeman, S. (1999). J. Energ. Mater. 17, 305±330. Acta Cryst. (2002). C58, o580±o581 Konstantin Karaghiosoff et al. C 6 H 6 N 4 O 8 o581

3 supporting information [doi: /s ] 4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane (TEX): a nitramine with an exceptionally high density Konstantin Karaghiosoff, Thomas M. Klapötke, Alexej Michailovski and Gerhard Holl Computing details Data collection: EXPOSE in IPDS (Stoe & Cie, 1997); cell refinement: CELL in IPDS; data reduction: INTEGRATE in IPDS; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandeburg, 1996); software used to prepare material for publication: SHELXL97. 4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane Crystal data C 6 H 6 N 4 O 8 M r = Triclinic, P1 Hall symbol: -P 1 a = (12) Å b = (14) Å c = (16) Å α = (2) β = (2) γ = (2) V = (14) Å 3 Data collection Stoe IPDS diffractometer Radiation source: fine-focus sealed tube Graphite monochromator φ scans Absorption correction: numerical (X-RED; Stoe & Cie, 1997) T min = 0.958, T max = Refinement Refinement on F 2 Least-squares matrix: full R[F 2 > 2σ(F 2 )] = wr(f 2 ) = S = reflections 187 parameters 0 restraints Z = 2 F(000) = 268 D x = (1) Mg m 3 Melting point: decomp. > 473 K Mo Kα radiation, λ = Å Cell parameters from 3304 reflections θ = µ = 0.19 mm 1 T = 200 K Prismatic, colourless mm 3698 measured reflections 1911 independent reflections 1555 reflections with I > 2σ(I) R int = θ max = 28.1, θ min = 2.4 h = 8 9 k = l = Primary atom site location: structure-invariant direct methods Secondary atom site location: difference Fourier map Hydrogen site location: inferred from neighbouring sites All H-atom parameters refined sup-1

4 w = 1/[σ 2 (F o2 ) + (0.0684P) P] where P = (F o 2 + 2F c2 )/3 (Δ/σ) max < Δρ max = 0.25 e Å 3 Δρ min = 0.25 e Å 3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wr and goodness of fit S are based on F 2, conventional R-factors R are based on F, with F set to zero for negative F 2. The threshold expression of F 2 > σ(f 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger. Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 ) x y z U iso */U eq N (18) (15) (14) (3) N (19) (16) (16) (3) O (19) (16) (16) (3) O (2) (15) (17) (3) C (2) (18) (17) (3) H (3) (2) (2) (4)* C (2) (18) (17) (3) H (3) (2) (2) (4)* N (18) (15) (15) (3) N (19) (16) (15) (3) O (17) (15) (16) (3) O (19) (14) (14) (3) C (2) (18) (17) (3) H (3) (2) (2) (4)* C (2) (17) (17) (3) H (3) (2) (2) (4)* O (16) (13) (12) (2) O (16) (14) (12) (2) O (15) (13) (12) (2) O (15) (13) (12) (2) C (2) (18) (17) (3) H (3) (2) (2) (4)* C (2) (18) (17) (3) H (3) (2) (2) (4)* Atomic displacement parameters (Å 2 ) U 11 U 22 U 33 U 12 U 13 U 23 N (6) (5) (6) (4) (5) (4) N (6) (6) (6) (4) (5) (5) O (6) (6) (7) (5) (6) (5) O (8) (5) (7) (5) (6) (5) sup-2

5 C (6) (6) (7) (5) (6) (5) C (7) (6) (7) (5) (6) (5) N (6) (5) (6) (4) (5) (4) N (6) (6) (6) (4) (5) (4) O (5) (6) (7) (4) (5) (5) O (6) (5) (6) (4) (5) (4) C (6) (6) (7) (5) (6) (5) C (6) (6) (7) (5) (6) (5) O (5) (5) (5) (4) (4) (4) O (5) (5) (5) (4) (4) (4) O (5) (4) (5) (4) (4) (4) O (5) (5) (5) (4) (4) (4) C (7) (6) (7) (5) (6) (5) C (6) (6) (7) (5) (6) (5) Geometric parameters (Å, º) N1 N (16) N31 O (18) N1 C (2) C3 O (17) N1 C (18) C3 C (19) N11 O (19) C3 H (18) N11 O (2) C4 O (17) C1 O (17) C4 H (19) C1 C (19) O1 C (16) C1 H (19) O2 C (17) C2 O (17) O3 C (17) C2 N (19) O4 C (17) C2 H (19) C5 C (2) N3 N (16) C5 H (2) N3 C (19) C6 H (18) N31 O (19) N11 N1 C (11) N3 C3 C (11) N11 N1 C (12) O3 C3 H (10) C1 N1 C (11) N3 C3 H (11) O211 N11 O (13) C4 C3 H (11) O211 N11 N (14) O4 C4 N (11) O111 N11 N (12) O4 C4 C (11) O1 C1 N (12) N1 C4 C (11) O1 C1 C (11) O4 C4 H (10) N1 C1 C (11) N1 C4 H (10) O1 C1 H (11) C3 C4 H (10) N1 C1 H (11) C5 O1 C (10) C2 C1 H (11) C5 O2 C (11) O2 C2 N (11) C6 O3 C (10) O2 C2 C (11) C4 O4 C (10) N3 C2 C (12) O2 C5 O (11) O2 C2 H (11) O2 C5 C (11) sup-3

6 N3 C2 H (11) O1 C5 C (12) C1 C2 H (10) O2 C5 H (12) N31 N3 C (12) O1 C5 H (11) N31 N3 C (12) C6 C5 H (12) C3 N3 C (11) O3 C6 O (11) O131 N31 O (13) O3 C6 C (11) O131 N31 N (13) O4 C6 C (11) O231 N31 N (13) O3 C6 H (10) O3 C3 N (12) O4 C6 H (11) O3 C3 C (10) C5 C6 H (11) C1 N1 N11 O (18) N11 N1 C4 C (11) C4 N1 N11 O (13) C1 N1 C4 C (15) C1 N1 N11 O (12) O3 C3 C4 O (14) C4 N1 N11 O (17) N3 C3 C4 O (12) N11 N1 C1 O (14) O3 C3 C4 N (12) C4 N1 C1 O (15) N3 C3 C4 N (15) N11 N1 C1 C (10) N1 C1 O1 C (13) C4 N1 C1 C (14) C2 C1 O1 C (14) O1 C1 C2 O (14) N3 C2 O2 C (13) N1 C1 C2 O (12) C1 C2 O2 C (14) O1 C1 C2 N (12) N3 C3 O3 C (13) N1 C1 C2 N (14) C4 C3 O3 C (14) O2 C2 N3 N (14) N1 C4 O4 C (13) C1 C2 N3 N (11) C3 C4 O4 C (14) O2 C2 N3 C (16) C2 O2 C5 O (14) C1 C2 N3 C (15) C2 O2 C5 C (13) C3 N3 N31 O (12) C1 O1 C5 O (14) C2 N3 N31 O (18) C1 O1 C5 C (13) C3 N3 N31 O (17) C3 O3 C6 O (13) C2 N3 N31 O (12) C3 O3 C6 C (13) N31 N3 C3 O (14) C4 O4 C6 O (13) C2 N3 C3 O (15) C4 O4 C6 C (13) N31 N3 C3 C (11) O2 C5 C6 O (15) C2 N3 C3 C (15) O1 C5 C6 O (12) N11 N1 C4 O (15) O2 C5 C6 O (12) C1 N1 C4 O (15) O1 C5 C6 O (15) Hydrogen-bond geometry (Å, º) D H A D H H A D A D H A C2 H2 O4 i 0.95 (2) 2.49 (2) (2) (14) C3 H3 O211 ii (16) (16) (2) (14) C4 H4 O231 iii (18) (16) (2) (14) C4 H4 O111 iv (18) 2.49 (2) (2) (14) C6 H6 O3 v (19) (18) (2) (12) Symmetry codes: (i) x+1, y, z; (ii) x, y 1, z; (iii) x+1, y, z; (iv) x, y+1, z; (v) x, y, z+1. sup-4