Pyridine-4-carboxamidoxime N-oxide

Our work in the area of synthesis of metal–organic frameworks (MOFs) based on organic N-oxides led to the crystallization of pyridine-4-carboxamidoxime N-oxide. Herein we report the first crystal structure of the title compound, C6H7N3O2 [systematic name: (Z)-4-(N′-hy­droxy­carbamimido­yl)pyridine N-oxide]. The hy­droxy­carbamimidoyl group is essentially coplanar with the aromatic ring, r.m.s.d. = 0.112 A. The compound crystallizes in hydrogen-bonding layers built from the formation of strong O—H⋯O hydrogen bonds between the oxime oxygen atom and the oxygen atom of the N-oxide, and the formation of N—H⋯O hydrogen bonds between one amine nitro­gen atom and the N-oxide oxygen atom. These combined build R34(24) ring motifs in the crystal. The crystal structure has no π–π inter­actions.