Download citation
Download citation
link to html
The title compound, C4H6N8O8, represents the energetic mol­ecule commonly called `bi­cyclo-HMX'. It was synthesized because it was expected to be denser than the powerful energetic material HMX, and thus exhibit improved energetic performance. X-ray diffraction analysis showed that this mol­ecule was actually slightly less dense than HMX.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802013582/ya6116sup1.cif
Contains datablocks global, II

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536802013582/ya6116IIsup2.hkl
Contains datablock II

CCDC reference: 197460

Key indicators

  • Single-crystal X-ray study
  • T = 294 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.036
  • wR factor = 0.091
  • Data-to-parameter ratio = 7.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes

REFLT_03 From the CIF: _diffrn_reflns_theta_max 66.70 From the CIF: _reflns_number_total 1442 Count of symmetry unique reflns 1020 Completeness (_total/calc) 141.37% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 422 Fraction of Friedel pairs measured 0.414 Are heavy atom types Z>Si present no WARNING: CuKa measured Friedel data can be used to determine absolute structure in a light-atom study only if the Friedel fraction is large.

Comment top

The title compound, (II), was synthesized from the dipropionyl precursor, (I), with the use of powerful and quite dangerous new nitrolysis agents (Pagoria et al., 1996; Gilardi et al., 2002). This synthesis succeeded only after several more direct synthetic routes from simpler precursors had failed, leading often to the decomposition of the tetraaza ring system. Molecule (II) (Fig. 1) was a target material for several US Department of Defense and Department of Energy laboratories because of its close resemblance to HMX, which is one of the most powerful energetic compounds in explosive and propellant formulations used by the military. The density of (II) was expected to be slightly greater than HMX since it contains fewer H atoms, and its heat of formation was expected to be slightly greater due to added ring strain. However, its density, found in this X-ray analysis to be 1.87 Mg m−3, is slightly less than that of β-HMX (1.91 Mg m−3). Since the detonation pressure and velocity of an explosive are closely correlated with the density, this slight difference was enough to make the calculated properties of (II) equivalent to, but no better than, HMX as an energetic material, despite the added strain of the five-membered ring closures. It is difficult to explain a slight difference in density, but the rigid butterfly shape of the ring system in (II) may have led to inefficient packing. There are three short intermolecular distances, shown as dashed lines in Fig. 2, found in the crystal; N8A···O6Ai [symmetry code: (i) 1 − x, y − 0.5, 1 − z] has a distance of 2.843 (4) Å, which is slightly less than van der Waals (3.07 Å) and two intermolecular C—H.·O hydrogen bonds (Table 1), at H···O 2.43 and 2.53 Å versus the van der Waals distance of 2.72 Å (Rowland & Taylor, 1996). The crystal structure of the precursor molecule, (I), is reported in the preceeding article (Gilardi et al., 2002).

Experimental top

A sample of the title compound was synthesized and crystallized by Clifford L. Coon of the Lawrence Livermore National Laboratory, using methods described in Pagoria et al. (1996).

Refinement top

H atoms were placed at ideal (Sheldrick, 1997) tetrahedral positions and allowed to ride on their bonded neighbors during the refinement, with periodic re-idealization. The H-atom displacement parameters were set to be isotropic, with a value equal to 1.2 times the Ueq value of the neighboring C atom.

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SMART; data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1997); software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. A view of the title compound, bicyclo-HMX, with 50% probability displacement ellipsoids.
[Figure 2] Fig. 2. A view of the packing of the title compound down the b axis.
cis-2,4,6,8-Tetranitro-1H,5H-2,4,6,8-tetraazabicyclo[3.3.0]octane top
Crystal data top
C4H6N8O8F(000) = 300
Mr = 294.17Dx = 1.861 Mg m3
Monoclinic, P21Cu Kα radiation, λ = 1.54178 Å
a = 8.5979 (2) ÅCell parameters from 2531 reflections
b = 6.9495 (2) Åθ = 5.0–66.8°
c = 8.9726 (2) ŵ = 1.60 mm1
β = 101.783 (2)°T = 294 K
V = 524.83 (2) Å3Rectangular prism, colorless
Z = 20.6 × 0.14 × 0.10 mm
Data collection top
Bruker 6K CCD area detector
diffractometer
1442 independent reflections
Radiation source: fine-focus sealed tube1400 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.027
ϕ and ω scansθmax = 66.7°, θmin = 5.0°
Absorption correction: multi-scan
SADABS, V.2.03 (Bruker, 2001).
h = 99
Tmin = 0.384, Tmax = 0.853k = 67
2607 measured reflectionsl = 910
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.036 w = 1/[σ2(Fo2) + (0.0562P)2 + 0.0158P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.091(Δ/σ)max = 0.007
S = 1.15Δρmax = 0.22 e Å3
1442 reflectionsΔρmin = 0.23 e Å3
182 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.077 (4)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 484 Friedel pairs
Secondary atom site location: difference Fourier mapAbsolute structure parameter: 0.1 (3)
Crystal data top
C4H6N8O8V = 524.83 (2) Å3
Mr = 294.17Z = 2
Monoclinic, P21Cu Kα radiation
a = 8.5979 (2) ŵ = 1.60 mm1
b = 6.9495 (2) ÅT = 294 K
c = 8.9726 (2) Å0.6 × 0.14 × 0.10 mm
β = 101.783 (2)°
Data collection top
Bruker 6K CCD area detector
diffractometer
1442 independent reflections
Absorption correction: multi-scan
SADABS, V.2.03 (Bruker, 2001).
1400 reflections with I > 2σ(I)
Tmin = 0.384, Tmax = 0.853Rint = 0.027
2607 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.036H-atom parameters constrained
wR(F2) = 0.091Δρmax = 0.22 e Å3
S = 1.15Δρmin = 0.23 e Å3
1442 reflectionsAbsolute structure: Flack (1983), 484 Friedel pairs
182 parametersAbsolute structure parameter: 0.1 (3)
1 restraint
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
C10.1760 (3)0.1529 (3)0.2716 (2)0.0369 (5)
H1A0.15790.04360.33510.044*
N20.0277 (2)0.2328 (3)0.1859 (2)0.0467 (5)
N2A0.0923 (3)0.1093 (5)0.1244 (2)0.0601 (7)
O2A0.2217 (2)0.1836 (5)0.0775 (2)0.0816 (8)
O2B0.0570 (3)0.0609 (4)0.1172 (3)0.0761 (7)
C30.0147 (3)0.4210 (4)0.2334 (3)0.0509 (6)
H3B0.10920.41610.27660.061*
H3C0.03100.51210.14970.061*
N40.1255 (2)0.4685 (3)0.3480 (2)0.0411 (5)
N4A0.1029 (3)0.5762 (3)0.4688 (3)0.0557 (6)
O4A0.0202 (3)0.6709 (4)0.4475 (3)0.0750 (7)
O4B0.2032 (3)0.5730 (4)0.5844 (3)0.0849 (8)
C50.2508 (2)0.3261 (3)0.3678 (3)0.0372 (5)
H5A0.28870.29190.47510.045*
N60.3803 (2)0.3785 (3)0.2938 (2)0.0441 (5)
N6A0.5115 (2)0.4669 (3)0.3746 (3)0.0568 (6)
O6A0.5030 (3)0.5300 (4)0.4998 (3)0.0753 (6)
O6B0.6228 (2)0.4830 (4)0.3108 (4)0.0868 (8)
C70.3858 (3)0.2678 (4)0.1574 (3)0.0507 (6)
H7A0.49320.22600.15640.061*
H7B0.34560.34210.06620.061*
N80.2824 (2)0.1037 (3)0.1698 (2)0.0424 (5)
N8A0.3583 (3)0.0773 (3)0.1965 (3)0.0516 (5)
O8A0.2907 (3)0.2001 (3)0.2538 (3)0.0713 (6)
O8B0.4802 (3)0.0977 (3)0.1505 (3)0.0730 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0357 (11)0.0338 (12)0.0428 (10)0.0018 (8)0.0114 (9)0.0001 (9)
N20.0319 (10)0.0551 (13)0.0522 (10)0.0002 (9)0.0063 (7)0.0067 (9)
N2A0.0412 (13)0.093 (2)0.0468 (11)0.0141 (11)0.0100 (9)0.0120 (12)
O2A0.0392 (12)0.136 (2)0.0637 (11)0.0056 (13)0.0039 (8)0.0003 (13)
O2B0.0696 (13)0.0732 (17)0.0866 (14)0.0237 (13)0.0185 (11)0.0329 (12)
C30.0439 (12)0.0584 (16)0.0509 (12)0.0153 (11)0.0106 (10)0.0049 (11)
N40.0406 (10)0.0355 (11)0.0516 (10)0.0035 (8)0.0197 (8)0.0017 (7)
N4A0.0587 (14)0.0478 (13)0.0689 (13)0.0044 (10)0.0325 (11)0.0147 (10)
O4A0.0735 (14)0.0643 (14)0.0988 (16)0.0199 (11)0.0445 (12)0.0115 (11)
O4B0.0783 (15)0.0970 (19)0.0768 (13)0.0006 (13)0.0099 (12)0.0435 (13)
C50.0343 (11)0.0337 (12)0.0448 (10)0.0028 (9)0.0104 (8)0.0002 (8)
N60.0323 (9)0.0412 (11)0.0615 (11)0.0035 (8)0.0158 (8)0.0042 (9)
N6A0.0333 (11)0.0443 (13)0.0910 (17)0.0017 (8)0.0088 (10)0.0059 (11)
O6A0.0593 (12)0.0818 (16)0.0775 (12)0.0232 (11)0.0031 (9)0.0162 (12)
O6B0.0380 (12)0.0825 (17)0.146 (2)0.0125 (10)0.0333 (13)0.0024 (16)
C70.0498 (15)0.0456 (15)0.0641 (14)0.0011 (10)0.0287 (12)0.0040 (11)
N80.0415 (11)0.0377 (11)0.0515 (10)0.0028 (8)0.0176 (8)0.0012 (8)
N8A0.0539 (12)0.0422 (12)0.0614 (12)0.0059 (9)0.0179 (10)0.0048 (9)
O8A0.0890 (14)0.0354 (10)0.0979 (15)0.0046 (9)0.0385 (13)0.0051 (10)
O8B0.0633 (13)0.0661 (14)0.0976 (15)0.0230 (10)0.0351 (11)0.0065 (12)
Geometric parameters (Å, º) top
C1—N21.457 (3)N4A—O4A1.228 (3)
C1—N81.460 (3)C5—N61.455 (3)
C1—C51.543 (3)C5—H5A0.9800
C1—H1A0.9800N6—N6A1.357 (3)
N2—N2A1.369 (3)N6—C71.454 (3)
N2—C31.446 (4)N6A—O6B1.216 (3)
N2A—O2A1.221 (3)N6A—O6A1.222 (4)
N2A—O2B1.227 (4)C7—N81.464 (3)
C3—N41.453 (3)C7—H7A0.9700
C3—H3B0.9700C7—H7B0.9700
C3—H3C0.9700N8—N8A1.415 (3)
N4—N4A1.364 (3)N8A—O8A1.206 (3)
N4—C51.447 (3)N8A—O8B1.211 (3)
N4A—O4B1.206 (3)
N2—C1—N8110.59 (18)N4—C5—N6113.10 (18)
N2—C1—C5102.56 (17)N4—C5—C1104.48 (16)
N8—C1—C5106.84 (17)N6—C5—C1102.14 (17)
N2—C1—H1A112.1N4—C5—H5A112.1
N8—C1—H1A112.1N6—C5—H5A112.1
C5—C1—H1A112.1C1—C5—H5A112.1
N2A—N2—C3118.1 (2)N6A—N6—C5120.0 (2)
N2A—N2—C1118.7 (2)N6A—N6—C7121.49 (19)
C3—N2—C1115.81 (19)C5—N6—C7114.30 (19)
O2A—N2A—O2B127.4 (3)O6B—N6A—O6A126.9 (2)
O2A—N2A—N2115.7 (3)O6B—N6A—N6116.0 (3)
O2B—N2A—N2116.8 (2)O6A—N6A—N6117.0 (2)
N2—C3—N4101.03 (18)N6—C7—N8102.92 (16)
N2—C3—H3B111.6N6—C7—H7A111.2
N4—C3—H3B111.6N8—C7—H7A111.2
N2—C3—H3C111.6N6—C7—H7B111.2
N4—C3—H3C111.6N8—C7—H7B111.2
H3B—C3—H3C109.4H7A—C7—H7B109.1
N4A—N4—C5120.05 (19)N8A—N8—C1115.36 (18)
N4A—N4—C3117.05 (19)N8A—N8—C7116.06 (18)
C5—N4—C3114.89 (18)C1—N8—C7109.46 (17)
O4B—N4A—O4A125.9 (2)O8A—N8A—O8B126.1 (2)
O4B—N4A—N4118.7 (2)O8A—N8A—N8117.13 (19)
O4A—N4A—N4115.4 (2)O8B—N8A—N8116.6 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1A···O8A0.982.252.661 (3)104
C7—H7A···O8B0.972.252.671 (3)105
C5—H5A···O6Ai0.982.533.017 (3)111
C3—H3B···O6Bii0.972.433.357 (3)160
Symmetry codes: (i) x+1, y1/2, z+1; (ii) x1, y, z.

Experimental details

Crystal data
Chemical formulaC4H6N8O8
Mr294.17
Crystal system, space groupMonoclinic, P21
Temperature (K)294
a, b, c (Å)8.5979 (2), 6.9495 (2), 8.9726 (2)
β (°) 101.783 (2)
V3)524.83 (2)
Z2
Radiation typeCu Kα
µ (mm1)1.60
Crystal size (mm)0.6 × 0.14 × 0.10
Data collection
DiffractometerBruker 6K CCD area detector
diffractometer
Absorption correctionMulti-scan
SADABS, V.2.03 (Bruker, 2001).
Tmin, Tmax0.384, 0.853
No. of measured, independent and
observed [I > 2σ(I)] reflections
2607, 1442, 1400
Rint0.027
(sin θ/λ)max1)0.596
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.036, 0.091, 1.15
No. of reflections1442
No. of parameters182
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.22, 0.23
Absolute structureFlack (1983), 484 Friedel pairs
Absolute structure parameter0.1 (3)

Computer programs: SMART (Bruker, 2001), SMART, SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL (Sheldrick, 1997), SHELXTL.

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1A···O8A0.982.252.661 (3)104
C7—H7A···O8B0.972.252.671 (3)105
C5—H5A···O6Ai0.982.533.017 (3)111
C3—H3B···O6Bii0.972.433.357 (3)160
Symmetry codes: (i) x+1, y1/2, z+1; (ii) x1, y, z.
 

Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds