Crystal structure of the 1:1 complex formed by 4-nitropyridine N-oxide and 4-nitrophenol

The title complex (C₆H₅NO₃·C₅H₄N₂O₃,M _r =279.21) crystallizes in the orthorhombic space groupPna2₁ witha=18.862(2),b=5.876(1),c=10.803(2) Å,V=1197.3(6) ų,D _c =1.549 g cm^–3 forZ=4,F(000)=576, (MoK)=0.71073 Å,=0.84 mm^–1,T=297 K. The structure was solved by direct methods and refined by block matrix least-squares. FinalR=0.032, wR=0.037 for 904 observed reflections. The complex is held together by an intermediate hydrogen bond between the hydroxyl and the N-oxide group with an OO distance equal to 2.618(3) Å. The stacking of thea glide related complex molecules by translation in theb direction results in a herringbone structure with an overlap of the nitrophenol and 4-nitropyridine N-oxide rings and a mean interplanar distance of 3.4(1) Å between those rings.On leave from Universidad del Valle, Departamento de Quimica, Cali, Colombia.