2-tert-Butyl-1-(4-nitroamino-1,2,5-oxadiazol-3-yl)diazene 1-oxide

In the title compound, C6H10N6O4, the nitroamine –NHNO2 substituent and the C–N=N(→ O) unit of the other substituent of the oxadiazole ring are nearly coplanar with the five-membered ring [dihedral angles = 5.7 (1) and 3.0 (1)°]. The amino group of the –NHNO2 substituent is a hydrogen-bond donor to the two-coordinate N atom of the C—N=N(→ O) unit.

In the title compound, C 6 H 10 N 6 O 4 , the nitroamine -NHNO 2 substituent and the C-N N(! O) unit of the other substituent of the oxadiazole ring are nearly coplanar with the five-membered ring [dihedral angles = 5.7 (1) and 3.0 (1) ]. The amino group of the -NHNO 2 substituent is a hydrogenbond donor to the two-coordinate N atom of the C-N N(! O) unit.

Comment
The title compound (Scheme I) as well as the precusor compounds (Churakov et al., 1995;Li et al., 2008;Mel'nikova et al., 2001) represent a class of high energy materials that has a low hydrogen content in the molecular formula. The nitroamine -NHNO 2 substituent and the C-N═ N(→O) unit of the second substituent of the oxadiazole ring of C 6 H 10 N 6 O 4 are nearly coplanar with the five-membered ring [dihedral angles 5.7 (1), 3.0 (1) °] (Fig. 1). The amino group of the -NHNO 2 substituent is hydrogen bond donor to the two-coordinate N atom of C-N═ N(→O) ( Table 1).

Synthesis of 3-amino-4-nitrosofurazan
To a mixture of benzene (200 ml), 30% hydrogen peroxide (145 ml, 1.29 mol) and sodium tungstate dihydrate (16.5 g, 0.05 mol), concentrated sulfuric acid (10 ml, 180 mmol) was added dropwise at 278-283 K followed by diaminofurazan (10.8 g, 0.10 mmol). The mixture was kept stirred at 288 K for 1.5 h. The organic layer was separated, washed with water and dried over magnesium sulfate. The solvent was removed to yield a yellow solid (

Synthesis of 3-nitramino-4-(tert-butyl-NNO-azoxy)furazan
To a stirred and cooled (273 K) solution of the above compound (2 g, 10.8 mmol) in carbon tetrachloride, concentrated nitric acid (2.72 g, 21.6 mmol) was added. Thesolution was stirred for 2 h after after which the temperature was raised to room temperature. The solvent was removed. Dichloromethane (100 ml) was added and the organic phase was washed with cold water (20 ml). The aqueous layer was extracted with more dichloromethyane (2×50 ml

Refinement
Carbon-bound H-atoms were placed in calculated positions (C-H 0.96 Å) and were included in the refinement in the riding model approximation, with U(H) set to 1.5U(C).
The amino H-atom was located in a difference Fourier map, and was refined with a distance restraint of N-H 0.84±0.01 Å; its temperature factor was refined.