organic papers 2,6-Diamino-3,5-dinitro-1,4-pyrazine 1-oxide Comment

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1 organic papers Acta Crystallographica Section E Structure Reports Online ISSN ,6-Diamino-3,5-dinitro-1,4-pyrazine 1-oxide Richard D. Gilardi a * and Ray J. Butcher b a Laboratory for the Structure of Matter, Naval Research Laboratory, Washington, DC , USA, and b Department of Chemistry, Howard University, 525 College Street, NW, Washington DC 20059, USA Correspondence gilardi@nrl.navy.mil Key indicators Single-crystal X-ray study T = 294 K Mean (C±C) = AÊ R factor = wr factor = Data-to-parameter ratio = 11.3 For details of how these key indicators were automatically derived from the article, see The title compound, C 4 H 4 N 6 O 5, crystallizes in the monoclinic space group P2 1 /n, and is an energetic compound containing only C, H, N, and O with a density of Mg m 3. Among other reasons, this remarkably high density is attributed to an extensive system of intra- and intermolecular hydrogen bonds which results in a packing scheme involving zigzag sheets. Comment The title compound, 2,6-diamino-3,5-dinitro-1,4-pyrazine 1-oxide (ANPZO), (I), is a very stable and relatively insensitive energetic material with a very high density of Mg m 3. Every H atom is involved in intramolecular hydrogen-bonding interactions to its neighboring O atom as well as participating in intermolecular interactions with adjoining molecules. Thus, it is related to other similar compounds, such as 1,3,5-triamino-2,4,6-trinitrobenzene (TATB; Cady & Larson, 1965; Kolb & Rizzo, 1979) and 2,6- diamino-3,5,-dinitropyrazine (ANPZ; Gilardi & George, 1984), which have a similar extensive system of intra- and intermolecular hydrogen-bonding interactions resulting in a sheet-like packing system, high densities (1.937 and Mg m 3, respectively), and relative insensitivity. These intermolecular hydrogen-bonding interactions result in ruf ed parallel sheets in the [101] direction. One of the potentially useful features of ANPZO is its relative insensitivity. Sensitivity is often tested via the drop-height method, i.e. the height of the drop of a steel ball required to detonate the compound, with large values re ecting insensitivity. In such testing, the parent molecule, ANPZ (2,6-diamino-3,5-dinitro-1,4-pyrazine), has values which are so large they cannot be accurately measured, while ANPZO has a value of 117 cm (Pagoria, 2001). These values indicate that ANPZO is safer than other commonly used energetic compounds such as trinitrotoluene (80 cm) and HMX (32 cm). Fig. 1 shows the structure and labeling scheme for the title compound. Hydrogen-bonding metrical parameters are given in Table 1. Received 4 June 2001 Accepted 21 June 2001 Online 29 June 2001 # 2001 International Union of Crystallography Printed in Great Britain ± all rights reserved Acta Cryst. (2001). E57, o657±o658 DOI: /S Gilardi and Butcher C 4 H 4 N 6 O 5 o657

2 organic papers Figure 1 View of 2,6-diamino-3,5-dinitro-1,4-pyrazine 1-oxide showing the labeling of all non-h atoms. Displacement ellipsoids are at the 20% probability level. H atoms are drawn as small circles of arbitrary radii. Data collection Bruker P4 diffractometer 2/! scans Absorption correction: by integration (Wuensch & Prewitt, 1965) T min = 0.990, T max = measured re ections 1716 independent re ections 1185 re ections with I > 2(I) Re nement Re nement on F 2 R[F 2 >2(F 2 )] = wr(f 2 ) = S = re ections 152 parameters H atoms treated by a mixture of independent and constrained re nement Table 1 Hydrogen-bonding geometry (A Ê, ). R int = max = 27.5 h =0! 7 k = 20! 18 l = 10! 10 3 standard re ections every 97 re ections intensity decay: 1.0% w = 1/[ 2 (F o 2 ) + (0.0410P) P] where P =(F o 2 +2F c 2 )/3 (/) max < max = 0.23 e A Ê 3 min = 0.21 e A Ê 3 DÐHA DÐH HA DA DÐHA N2ÐH2AO1 i 0.90 (2) 2.05 (2) (2) 149 (2) N2ÐH2AO (2) 2.10 (2) (2) (18) N2ÐH2BO3A 0.93 (3) 2.08 (3) (2) 123 (2) N2ÐH2BO3A ii 0.93 (3) 2.36 (3) (2) 154 (2) N6ÐH6AO5B iii 0.91 (2) 2.10 (2) (2) 160 (2) N6ÐH6AO5A 0.91 (2) 2.12 (2) (2) (18) N6ÐH6AN4 iii 0.91 (2) 2.69 (2) (2) (18) N6ÐH6BO3B iv 0.90 (2) 2.51 (2) (2) (19) Symmetry codes: (i) 1 x; 2 y; 1 z; (ii) x; 2 y; 2 z; (iii) x 1 2 ; 3 2 y; z 1 2 ; (iv) x 1; y; z 1. Data collection: XSCANS (Bruker, 1994); cell re nement: XSCANS; data reduction: SHELXTL (Sheldrick, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to re ne structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL. Figure 2 Packing diagram of 2,6-diamino-3,5-dinitro-1,4-pyrazine 1-oxide, viewed down the [101] direction. Experimental Crystals of the title compound were supplied by Dr Philip Pagoria, Energetic Materials Laboratory, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA. Crystal and re ection data were obtained using standard procedures (Butcher et al., 1995). Crystal data C 4 H 4 N 6 O 5 M r = Monoclinic, P2 1 /n a = (8) A Ê b = (14) A Ê c = (7) A Ê = (7) V = (14) A Ê 3 Z =4 D x = Mg m 3 Mo K radiation Cell parameters from 58 re ections = 2.8±18.3 = 0.18 mm 1 T = 294 (2) K Chunky prism, yellow mm The authors wish to acknowledge the nancial support from the Of ce of Naval Research, Mechanics Division. RJB wishes to acknowledge the ASEE/Navy Summer Faculty Research Program for support during the summer of References Bruker (1994). XSCANS and XPREP. Bruker AXS Inc., Madison, Wisconsin, USA. Butcher, R. J., Bashir-Hashemi, A. & Gilardi, R. D. (1995). J. Chem. Crystallogr. 25, 661±670. Cady, H. H. & Larson, A. C. (1965). Acta Cryst. 18, 485±496. Gilardi, R. D. & George, C. F. (1984). Acta Cryst. A40, C432. Kolb, J. R. & Rizzo, H. F. (1979). Propel. Explos. 4, 10±16. Pagoria, P. (2001). Private communication. Sheldrick, G. M. (1990). Acta Cryst. A46, 467. Sheldrick, G. M. (1997). SHELXTL. Version Bruker AXS Inc., Madison, Wisconsin, USA. Wuensch, B. & Prewitt, C. (1965). Z. Kristallogr. 122, 24±59. o658 Gilardi and Butcher C 4 H 4 N 6 O 5 Acta Cryst. (2001). E57, o657±o658

3 supporting information [doi: /s ] 2,6-Diamino-3,5-dinitro-1,4-pyrazine 1-oxide Richard D. Gilardi and Ray J. Butcher S1. Comment The title compound, 2,6-diamino-3,5-dinitro-1,4-pyrazine 1-oxide (ANPZO), (I), is a very stable and relatively insensitive energetic material with a very high density of Mg m -3. Every H atom is involved in intramolecular hydrogen-bonding interactions to its neighboring oxygen atom as well as participating in intermolecular interactions with adjoining molecules. Thus, it is related to other similar compounds, such as 1,3,5-triamino-2,4,6-trinitrobenzene (TATB; Cady & Larson, 1965; Kolb & Rizzo, 1979) and 2,6-diamino-3,5,-dinitropyrazine (ANPZ; Gilardi & George, 1984), which have a similar extensive system of intra- and intermolecular hydrogen-bonding interactions resulting in a sheet-like packing system, high densities (1.937 and Mg m -3, respectively), and relative insensitivity. These intermolecular hydrogen-bonding interactions result in ruffled parallel sheets in the [101] direction. One of the potentially useful features of ANPZO is its relative insensitivity. Sensitivity is often tested via the drop-height method, i.e. the height of the drop of a steel ball required to detonate the compound, with large values reflecting insensitivity. In such testing, the parent molecule, ANPZ (2,6-diamino-3,5-dinitro-1,4-pyrazine), has values which are so large they cannot be accurately measured, while ANPZO has a value of 117 cm (Pagoria, 2001). These values indicate that ANPZO is safer compared to other commonly used energetic compounds such as trinitrotoluene (80 cm) and HMX (32 cm). Fig. 1 shows the structure and labeling scheme for the title compound. Hydrogen-bonding metrical parameters are given in Table 1. S2. Experimental Crystals of the title compound were supplied by Dr Philip Pagoria, Energetic Materials Laboratory, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA. Crystal and reflection data were obtained using standard procedures (Butcher et al., 1995). sup-1

4 Figure 1 View of 2,6-diamino-3,5-dinitro-1,4-pyrazine 1-oxide showing the labeling of all non-h atoms. Displacement ellipsoids are at the 20% probability level. H atoms are drawn as small circles of arbitrary radii. sup-2

5 Figure 2 Packing diagram of 2,6-diamino-3,5-dinitro-1,4-pyrazine 1-oxide, viewed down the [101] direction. 2,6-diamino-3,5-dinitro-1,4-pyrazine-1-oxide Crystal data C 4 H 4 N 6 O 5 M r = Monoclinic, P2 1 /n a = (8) Å b = (14) Å c = (7) Å β = (7) V = (14) Å 3 Z = 4 Data collection Bruker P4 diffractometer Radiation source: fine-focus sealed tube Graphite monochromator 2θ/ω scans Absorption correction: integration (Wuensch & Prewitt, 1965) T min = 0.990, T max = measured reflections F(000) = 440 D x = Mg m 3 Mo Kα radiation, λ = Å Cell parameters from 58 reflections θ = µ = 0.18 mm 1 T = 294 K Chunky prism, yellow mm 1716 independent reflections 1185 reflections with I > 2σ(I) R int = θ max = 27.5, θ min = 2.6 h = 0 7 k = l = standard reflections every 97 reflections intensity decay: 1.0% sup-3

6 Refinement Refinement on F 2 Least-squares matrix: full R[F 2 > 2σ(F 2 )] = wr(f 2 ) = S = reflections 152 parameters 0 restraints Primary atom site location: structure-invariant direct methods Secondary atom site location: difference Fourier map Hydrogen site location: inferred from neighbouring sites H atoms treated by a mixture of independent and constrained refinement w = 1/[σ 2 (F o2 ) + (0.041P) P] where P = (F o 2 + 2F c2 )/3 (Δ/σ) max < Δρ max = 0.23 e Å 3 Δρ min = 0.21 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 (3) (9) (18) (4) O (2) (9) (17) (4) C (3) (11) (2) (4) N (3) (11) (2) (4) H2A (4) (15) (3) (7)* H2B (4) (16) (3) (8)* C (3) (11) (2) (4) N (3) (10) (19) (4) O3A (3) (10) (17) (4) O3B (3) (10) (17) (4) N (3) (9) (18) (4) C (3) (11) (2) (4) N (3) (10) (18) (4) O5A (3) (11) (16) (4) O5B (3) (10) (17) (4) C (3) (11) (2) (4) N (3) (11) (2) (4) H6A (4) (15) (3) (7)* H6B (4) (15) (3) (7)* Atomic displacement parameters (Å 2 ) U 11 U 22 U 33 U 12 U 13 U 23 N (8) (8) (8) (7) (7) (6) sup-4

7 O (7) (9) (8) (6) (6) (6) C (9) (9) (9) (8) (8) (7) N (9) (10) (9) (8) (8) (7) C (9) (10) (9) (8) (8) (7) N (9) (9) (8) (7) (7) (7) O3A (10) (10) (8) (8) (7) (7) O3B (8) (11) (8) (8) (6) (7) N (8) (8) (8) (7) (6) (6) C (9) (9) (9) (8) (7) (7) N (8) (9) (8) (7) (7) (7) O5A (9) (12) (7) (8) (6) (7) O5B (9) (10) (8) (8) (7) (7) C (9) (9) (9) (8) (7) (7) N (9) (10) (9) (8) (7) (7) Geometric parameters (Å, º) N1 O (19) N3 O3A (2) N1 C (2) N4 C (2) N1 C (2) C5 C (3) C2 N (2) C5 N (2) C2 C (3) N5 O5B (2) N2 H2A 0.90 (2) N5 O5A (19) N2 H2B 0.93 (3) C6 N (2) C3 N (2) N6 H6A 0.91 (2) C3 N (2) N6 H6B 0.90 (2) N3 O3B (2) O1 N1 C (15) O3A N3 C (16) O1 N1 C (15) C5 N4 C (16) C6 N1 C (15) N4 C5 C (17) N2 C2 N (17) N4 C5 N (15) N2 C2 C (17) C6 C5 N (15) N1 C2 C (16) O5B N5 O5A (17) C2 N2 H2A (15) O5B N5 C (15) C2 N2 H2B (16) O5A N5 C (15) H2A N2 H2B 128 (2) N6 C6 N (17) N4 C3 C (17) N6 C6 C (18) N4 C3 N (16) N1 C6 C (16) C2 C3 N (16) C6 N6 H6A (14) O3B N3 O3A (17) C6 N6 H6B (15) O3B N3 C (16) H6A N6 H6B 122 (2) O1 N1 C2 N2 0.4 (2) C3 N4 C5 C6 0.8 (3) C6 N1 C2 N (17) C3 N4 C5 N (16) O1 N1 C2 C (15) N4 C5 N5 O5B 19.2 (3) C6 N1 C2 C3 0.4 (2) C6 C5 N5 O5B (18) N2 C2 C3 N (19) N4 C5 N5 O5A (17) sup-5

8 N1 C2 C3 N4 1.2 (3) C6 C5 N5 O5A 18.1 (3) N2 C2 C3 N3 1.5 (3) O1 N1 C6 N6 0.7 (2) N1 C2 C3 N (15) C2 N1 C6 N (17) N4 C3 N3 O3B 3.7 (3) O1 N1 C6 C (15) C2 C3 N3 O3B (17) C2 N1 C6 C5 1.2 (2) N4 C3 N3 O3A (17) N4 C5 C6 N (18) C2 C3 N3 O3A 2.6 (3) N5 C5 C6 N6 1.3 (3) C2 C3 N4 C5 1.8 (3) N4 C5 C6 N1 0.7 (3) N3 C3 N4 C (16) N5 C5 C6 N (15) Hydrogen-bond geometry (Å, º) D H A D H H A D A D H A N2 H2A O1 i 0.90 (2) 2.05 (2) (2) 149 (2) N2 H2A O (2) 2.10 (2) (2) (18) N2 H2B O3A 0.93 (3) 2.08 (3) (2) 123 (2) N2 H2B O3A ii 0.93 (3) 2.36 (3) (2) 154 (2) N6 H6A O5B iii 0.91 (2) 2.10 (2) (2) 160 (2) N6 H6A O5A 0.91 (2) 2.12 (2) (2) (18) N6 H6A N4 iii 0.91 (2) 2.69 (2) (2) (18) N6 H6B O3B iv 0.90 (2) 2.51 (2) (2) (19) Symmetry codes: (i) x 1, y+2, z+1; (ii) x, y+2, z+2; (iii) x 1/2, y+3/2, z 1/2; (iv) x 1, y, z 1. sup-6