3,4-Bis(4-nitro-phen-yl)-1,2,5-oxadiazole 2-oxide

The title compound, C(14)H(8)N(4)O(6), a new 1,2,5-oxadiazole N-oxide derivative, was formed by dimerization of 4-nitro-benz-al-de-hyde oxime. The compound crystallizes with two independent mol-ecules per asymmetric unit. The N-oxide O atom is disordered over two sites in each mol-ecule; site occupancy factors are 0.57/0.43 and 0.5/0.5. The mean planes through the two benzene rings are inclined to the planar 1,2,3-oxadiazole ring by 25.03 (11) and 41.64 (11)° in one mol-ecule, and 22.58 (11) and 42.66 (11)° in the other mol-ecule, the smaller angle being for the ring on the oxide side of the oxadiazole ring in each case. In the crystal structure, the individual mol-ecules form centrosymmetric dimers linked via C-H⋯O hydrogen bonds. The dimers of one mol-ecule are then linked to those of the other mol-ecule via C-H⋯O hydrogen bonds, forming a three-dimensional network.