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The title compound (systematic name: 4,10-di­nitro-2,6,8,12-tetraoxa-4,10-di­aza­tetra­cyclo­[5.5.0.03,11.05,9]­do­decane), C6H6N4O8, 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.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270102014774/gg1130sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270102014774/gg1130Isup2.hkl
Contains datablock I

pdf

Portable Document Format (PDF) file https://doi.org/10.1107/S0108270102014774/gg1130Isup3.pdf
Packing diagram

CCDC reference: 195633

Comment top

4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane, TEX, hereinafter (I), is an insensitive highly energetic material which was first described by Ramakrishnan and coworkers in 1990 (Ramakrishnan et al., 1990). It displays the highest density ever recorded for a nitramine and therefore a very high detonation velocity (7470 m s-1), according to both Jacob et al. (2000) and Li et al. (2001), while its sensitivity towards shock, impact or friction is extremely low, as mentioned by Vagenknecht (2000) and Zeman (1999). These and other features make (I) a highly interesting model compound for the investigation of explosion processes. \sch

A recently published X-ray structure of (I) (Yu et al., 1996) does 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 (I) in order to find an explanation for its extraordinarily high density. The molecule shows a cage structure composed of three C2 units, which are linked by four O atoms and two N atoms which bear a nitro group (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 (I) is derived from this cage strain. The extraordinarily high density of (I) 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 [sums of angles both 359.9 (4)°]. There is a significant deviation from planarity in the coordination of atoms N1 and N3, with angle sums of 343.2 (3)° for N1 and 351.2 (4)° for N3. Atoms C1—C4 deviate only slightly from the planes defined by the respective nitro groups. The N—N bond length appears in both cases (N1—N11 and N3—N31) to be shorter (1.40–1.41 Å) than a single N—N bond (1.48 Å), but much longer than a double bond (1.20 Å). The C3—C4 and C1—C2 bond distances [both 1.56 (2) Å] are slightly shorter than that of C5—C6 [1.58 (1) Å]. A possible reason for this difference is the fact that the C1—C2 and C3—C4 bonds connect a five-membered and a seven-membered ring and are thus less strained than the C5—C6 bond, which connects two seven-membered rings. The Pitzer strain destabilizes the seven-membered rings to a higher degree than the five-membered ones.

Compound (I) crystallizes in a structure that is remarkably similar to a distorted hexagonal close packing of spheres. The crystal lattice of (I) contains molecules in two different orientations (Fig. 2). Within the structure, the shortest distances between molecule cages are O1···O4i [2.8773 (15) Å], O111···O111ii [2.999 (2) Å] and C6···O1i [2.9974 (18) Å], all of which are significantly shorter than the sum of Van der Waals radii (3.0 Å for O···O and 3.2 Å for C···O; Holleman et al., 1995) [symmetry codes: (i) -x, 1 - y, 1 - z; (ii) -x, 1 - y, -z].

Relatively short distances are observed for H2···O4 [2.49 (2) Å], H3···O211 [2.394 (16) Å] and H4···O111 [2.49 (2) Å], with C—H···O angles of 174.9 (14)° for C2—H2···O4, 140.5 (14)° for C3—H3···O211 and 133.4 (14)° for C4—H4···O111, (Table 2 and Fig. 2). However, due to the comparatively long H···O distances and C—H···O angles deviating significantly from linearity, we may assume that the contacts cannot be regarded as bonding.

Table 2. C—H···O hydrogen-bonding and contact geometry (Å, °).

Experimental top

The title compound was synthesized as described by Ramakrishnan et al. (1990). Crystallization by slow evaporation from a saturated solution of (I) in acetone afforded colourless crystals suitable for X-ray analysis.

Computing details top

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.

Figures top
[Figure 1] Fig. 1. A view of the molecule of (I) 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.
[Figure 2] Fig. 2. Close O—H contacts in the crystal structure of (I), forming a three-dimensional network.
4,10-Dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane top
Crystal data top
C6H6N4O8Z = 2
Mr = 262.15F(000) = 268
Triclinic, P1Dx = 2.008 (1) Mg m3
Hall symbol: -P 1Melting point: decomp. > 473 K
a = 6.8360 (12) ÅMo Kα radiation, λ = 0.71073 Å
b = 7.6404 (14) ÅCell parameters from 3304 reflections
c = 8.7765 (16) Åθ = 2.4–27.9°
α = 82.37 (2)°µ = 0.19 mm1
β = 75.05 (2)°T = 200 K
γ = 79.46 (2)°Prismatic, colourless
V = 433.64 (14) Å30.27 × 0.27 × 0.20 mm
Data collection top
Stoe IPDS
diffractometer
1911 independent reflections
Radiation source: fine-focus sealed tube1555 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.023
ϕ scansθmax = 28.1°, θmin = 2.4°
Absorption correction: numerical
(X-RED; Stoe & Cie, 1997)
h = 89
Tmin = 0.958, Tmax = 0.971k = 1010
3698 measured reflectionsl = 1110
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.034Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.099All H-atom parameters refined
S = 1.05 w = 1/[σ2(Fo2) + (0.0684P)2 + 0.0238P]
where P = (Fo2 + 2Fc2)/3
1911 reflections(Δ/σ)max < 0.001
187 parametersΔρmax = 0.25 e Å3
0 restraintsΔρmin = 0.25 e Å3
Crystal data top
C6H6N4O8γ = 79.46 (2)°
Mr = 262.15V = 433.64 (14) Å3
Triclinic, P1Z = 2
a = 6.8360 (12) ÅMo Kα radiation
b = 7.6404 (14) ŵ = 0.19 mm1
c = 8.7765 (16) ÅT = 200 K
α = 82.37 (2)°0.27 × 0.27 × 0.20 mm
β = 75.05 (2)°
Data collection top
Stoe IPDS
diffractometer
1911 independent reflections
Absorption correction: numerical
(X-RED; Stoe & Cie, 1997)
1555 reflections with I > 2σ(I)
Tmin = 0.958, Tmax = 0.971Rint = 0.023
3698 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0340 restraints
wR(F2) = 0.099All H-atom parameters refined
S = 1.05Δρmax = 0.25 e Å3
1911 reflectionsΔρmin = 0.25 e Å3
187 parameters
Special details top

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 F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 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 (Å2) top
xyzUiso*/Ueq
N10.33969 (18)0.44852 (15)0.16131 (14)0.0147 (3)
N110.25635 (19)0.61331 (16)0.09075 (16)0.0190 (3)
O1110.16876 (19)0.60570 (16)0.01222 (16)0.0287 (3)
O2110.2887 (2)0.74885 (15)0.13161 (17)0.0334 (3)
C10.4157 (2)0.46362 (18)0.29802 (17)0.0160 (3)
H10.492 (3)0.561 (2)0.277 (2)0.016 (4)*
C20.5403 (2)0.28002 (18)0.34348 (17)0.0159 (3)
H20.677 (3)0.291 (2)0.341 (2)0.015 (4)*
N30.53746 (18)0.15391 (15)0.23494 (15)0.0156 (3)
N310.69513 (19)0.00807 (16)0.21436 (15)0.0176 (3)
O1310.84518 (17)0.01483 (15)0.26158 (16)0.0276 (3)
O2310.67333 (19)0.11302 (14)0.14468 (14)0.0258 (3)
C30.3375 (2)0.12532 (18)0.22548 (17)0.0152 (3)
H30.354 (3)0.042 (2)0.149 (2)0.012 (4)*
C40.2130 (2)0.30791 (17)0.17962 (17)0.0143 (3)
H40.169 (3)0.310 (2)0.082 (2)0.010 (4)*
O10.25545 (16)0.49642 (13)0.43588 (12)0.0175 (2)
O20.43333 (16)0.23317 (14)0.50157 (12)0.0179 (2)
O30.21710 (15)0.06749 (13)0.37520 (12)0.0169 (2)
O40.03965 (15)0.33142 (13)0.30945 (12)0.0161 (2)
C50.2302 (2)0.32432 (18)0.51536 (17)0.0169 (3)
H50.166 (3)0.336 (2)0.625 (2)0.017 (4)*
C60.1002 (2)0.22496 (18)0.44005 (17)0.0162 (3)
H60.018 (3)0.193 (2)0.516 (2)0.013 (4)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0162 (6)0.0117 (5)0.0171 (6)0.0031 (4)0.0057 (5)0.0003 (4)
N110.0173 (6)0.0155 (6)0.0219 (6)0.0023 (4)0.0029 (5)0.0024 (5)
O1110.0274 (6)0.0277 (6)0.0353 (7)0.0085 (5)0.0187 (6)0.0100 (5)
O2110.0486 (8)0.0136 (5)0.0407 (7)0.0049 (5)0.0160 (6)0.0010 (5)
C10.0165 (6)0.0156 (6)0.0166 (7)0.0048 (5)0.0029 (6)0.0027 (5)
C20.0152 (7)0.0170 (6)0.0169 (7)0.0035 (5)0.0051 (6)0.0026 (5)
N30.0134 (6)0.0144 (5)0.0194 (6)0.0004 (4)0.0047 (5)0.0046 (4)
N310.0162 (6)0.0168 (6)0.0170 (6)0.0018 (4)0.0026 (5)0.0006 (4)
O1310.0184 (5)0.0276 (6)0.0378 (7)0.0016 (4)0.0121 (5)0.0023 (5)
O2310.0304 (6)0.0206 (5)0.0261 (6)0.0061 (4)0.0088 (5)0.0111 (4)
C30.0157 (6)0.0145 (6)0.0167 (7)0.0029 (5)0.0047 (6)0.0033 (5)
C40.0135 (6)0.0143 (6)0.0164 (7)0.0040 (5)0.0042 (6)0.0025 (5)
O10.0208 (5)0.0140 (5)0.0164 (5)0.0030 (4)0.0009 (4)0.0041 (4)
O20.0171 (5)0.0204 (5)0.0159 (5)0.0010 (4)0.0051 (4)0.0013 (4)
O30.0171 (5)0.0125 (4)0.0205 (5)0.0037 (4)0.0036 (4)0.0001 (4)
O40.0126 (5)0.0160 (5)0.0188 (5)0.0019 (4)0.0037 (4)0.0007 (4)
C50.0183 (7)0.0155 (6)0.0148 (7)0.0010 (5)0.0017 (6)0.0008 (5)
C60.0140 (6)0.0146 (6)0.0182 (7)0.0017 (5)0.0022 (6)0.0009 (5)
Geometric parameters (Å, º) top
N1—N111.4162 (16)N31—O2311.2247 (18)
N1—C11.450 (2)C3—O31.4214 (17)
N1—C41.4672 (18)C3—C41.5574 (19)
N11—O2111.2139 (19)C3—H30.956 (18)
N11—O1111.218 (2)C4—O41.4196 (17)
C1—O11.4222 (17)C4—H40.975 (19)
C1—C21.5628 (19)O1—C51.4222 (16)
C1—H10.958 (19)O2—C51.4174 (17)
C2—O21.4243 (17)O3—C61.4162 (17)
C2—N31.4480 (19)O4—C61.4215 (17)
C2—H20.949 (19)C5—C61.577 (2)
N3—N311.3962 (16)C5—H50.96 (2)
N3—C31.4476 (19)C6—H60.950 (18)
N31—O1311.2128 (19)
N11—N1—C1114.58 (11)N3—C3—C4108.98 (11)
N11—N1—C4113.14 (12)O3—C3—H3111.4 (10)
C1—N1—C4115.51 (11)N3—C3—H3109.4 (11)
O211—N11—O111125.88 (13)C4—C3—H3111.2 (11)
O211—N11—N1117.19 (14)O4—C4—N1111.36 (11)
O111—N11—N1116.79 (12)O4—C4—C3104.26 (11)
O1—C1—N1112.64 (12)N1—C4—C3108.86 (11)
O1—C1—C2104.09 (11)O4—C4—H4110.0 (10)
N1—C1—C2109.16 (11)N1—C4—H4109.1 (10)
O1—C1—H1107.2 (11)C3—C4—H4113.3 (10)
N1—C1—H1109.7 (11)C5—O1—C1104.89 (10)
C2—C1—H1114.0 (11)C5—O2—C2105.36 (11)
O2—C2—N3112.57 (11)C6—O3—C3105.63 (10)
O2—C2—C1103.42 (11)C4—O4—C6105.37 (10)
N3—C2—C1108.68 (12)O2—C5—O1104.12 (11)
O2—C2—H2110.0 (11)O2—C5—C6112.09 (11)
N3—C2—H2110.4 (11)O1—C5—C6112.07 (12)
C1—C2—H2111.5 (10)O2—C5—H5108.9 (12)
N31—N3—C3117.11 (12)O1—C5—H5109.1 (11)
N31—N3—C2117.67 (12)C6—C5—H5110.3 (12)
C3—N3—C2116.42 (11)O3—C6—O4104.40 (11)
O131—N31—O231125.47 (13)O3—C6—C5111.58 (11)
O131—N31—N3117.40 (13)O4—C6—C5111.20 (11)
O231—N31—N3117.07 (13)O3—C6—H6108.1 (10)
O3—C3—N3112.19 (12)O4—C6—H6109.6 (11)
O3—C3—C4103.64 (10)C5—C6—H6111.6 (11)
C1—N1—N11—O21112.66 (18)N11—N1—C4—C3168.67 (11)
C4—N1—N11—O211147.93 (13)C1—N1—C4—C356.49 (15)
C1—N1—N11—O111171.48 (12)O3—C3—C4—O40.65 (14)
C4—N1—N11—O11136.20 (17)N3—C3—C4—O4118.99 (12)
N11—N1—C1—O175.85 (14)O3—C3—C4—N1119.59 (12)
C4—N1—C1—O158.34 (15)N3—C3—C4—N10.05 (15)
N11—N1—C1—C2169.05 (10)N1—C1—O1—C593.25 (13)
C4—N1—C1—C256.76 (14)C2—C1—O1—C524.87 (14)
O1—C1—C2—O20.09 (14)N3—C2—O2—C592.23 (13)
N1—C1—C2—O2120.41 (12)C1—C2—O2—C524.88 (14)
O1—C1—C2—N3119.90 (12)N3—C3—O3—C692.86 (13)
N1—C1—C2—N30.59 (14)C4—C3—O3—C624.56 (14)
O2—C2—N3—N3189.44 (14)N1—C4—O4—C693.86 (13)
C1—C2—N3—N31156.62 (11)C3—C4—O4—C623.36 (14)
O2—C2—N3—C357.19 (16)C2—O2—C5—O141.71 (14)
C1—C2—N3—C356.76 (15)C2—O2—C5—C679.64 (13)
C3—N3—N31—O131161.29 (12)C1—O1—C5—O241.58 (14)
C2—N3—N31—O13114.90 (18)C1—O1—C5—C679.78 (13)
C3—N3—N31—O23121.39 (17)C3—O3—C6—O440.32 (13)
C2—N3—N31—O231167.78 (12)C3—O3—C6—C579.89 (13)
N31—N3—C3—O389.65 (14)C4—O4—C6—O339.73 (13)
C2—N3—C3—O357.16 (15)C4—O4—C6—C580.73 (13)
N31—N3—C3—C4156.16 (11)O2—C5—C6—O30.26 (15)
C2—N3—C3—C457.03 (15)O1—C5—C6—O3116.40 (12)
N11—N1—C4—O476.93 (15)O2—C5—C6—O4116.39 (12)
C1—N1—C4—O457.91 (15)O1—C5—C6—O40.27 (15)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2···O4i0.95 (2)2.49 (2)3.439 (2)174.9 (14)
C3—H3···O211ii0.956 (16)2.394 (16)3.192 (2)140.5 (14)
C4—H4···O231iii0.976 (18)2.546 (16)3.238 (2)127.9 (14)
C4—H4···O111iv0.976 (18)2.49 (2)3.240 (2)133.4 (14)
C6—H6···O3v0.953 (19)2.559 (18)3.365 (2)142.7 (12)
Symmetry codes: (i) x+1, y, z; (ii) x, y1, z; (iii) x+1, y, z; (iv) x, y+1, z; (v) x, y, z+1.

Experimental details

Crystal data
Chemical formulaC6H6N4O8
Mr262.15
Crystal system, space groupTriclinic, P1
Temperature (K)200
a, b, c (Å)6.8360 (12), 7.6404 (14), 8.7765 (16)
α, β, γ (°)82.37 (2), 75.05 (2), 79.46 (2)
V3)433.64 (14)
Z2
Radiation typeMo Kα
µ (mm1)0.19
Crystal size (mm)0.27 × 0.27 × 0.20
Data collection
DiffractometerStoe IPDS
diffractometer
Absorption correctionNumerical
(X-RED; Stoe & Cie, 1997)
Tmin, Tmax0.958, 0.971
No. of measured, independent and
observed [I > 2σ(I)] reflections
3698, 1911, 1555
Rint0.023
(sin θ/λ)max1)0.662
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.034, 0.099, 1.05
No. of reflections1911
No. of parameters187
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.25, 0.25

Computer programs: EXPOSE in IPDS (Stoe & Cie, 1997), CELL in IPDS, INTEGRATE in IPDS, SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandeburg, 1996), SHELXL97.

Selected geometric parameters (Å, º) top
N1—N111.4162 (16)N31—O1311.2128 (19)
N1—C11.450 (2)N31—O2311.2247 (18)
N1—C41.4672 (18)C3—O31.4214 (17)
N11—O2111.2139 (19)C3—C41.5574 (19)
N11—O1111.218 (2)C4—O41.4196 (17)
C1—O11.4222 (17)O1—C51.4222 (16)
C1—C21.5628 (19)O2—C51.4174 (17)
C2—O21.4243 (17)O3—C61.4162 (17)
C2—N31.4480 (19)O4—C61.4215 (17)
N3—N311.3962 (16)C5—C61.577 (2)
N3—C31.4476 (19)
N11—N1—C1114.58 (11)N31—N3—C3117.11 (12)
N11—N1—C4113.14 (12)N31—N3—C2117.67 (12)
C1—N1—C4115.51 (11)C3—N3—C2116.42 (11)
O211—N11—N1117.19 (14)O131—N31—N3117.40 (13)
O111—N11—N1116.79 (12)O231—N31—N3117.07 (13)
C1—N1—N11—O21112.66 (18)C2—N3—N31—O13114.90 (18)
C4—N1—N11—O11136.20 (17)C3—N3—N31—O23121.39 (17)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2···O4i0.95 (2)2.49 (2)3.439 (2)174.9 (14)
C3—H3···O211ii0.956 (16)2.394 (16)3.192 (2)140.5 (14)
C4—H4···O231iii0.976 (18)2.546 (16)3.238 (2)127.9 (14)
C4—H4···O111iv0.976 (18)2.49 (2)3.240 (2)133.4 (14)
C6—H6···O3v0.953 (19)2.559 (18)3.365 (2)142.7 (12)
Symmetry codes: (i) x+1, y, z; (ii) x, y1, z; (iii) x+1, y, z; (iv) x, y+1, z; (v) x, y, z+1.
 

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