Three isomeric 1-(2-chloronicotinoyl)-2-(nitrophenyl)hydrazines, including three polymorphs of 1-(2-chloronicotinoyl)-2-(2-nitrophenyl)hydrazine: hydrogen-bonded supramolecular structures in two and three dimensions

1-(2-Chloronicotinoyl)-2-(2-nitrophenyl)hydrazine, C12H9CI-N4O3, crystallizes in three polymorphic forms, two monoclinic forms in space groups Cc (Ia) and P2(1) (Ib), and an orthorhombic form in space group Pbcn (Ic). In the Cc polymorph (Ia) the molecules are linked into sheets by combinations of one N-(HO)-O-... and two C-(HO)-O-... hydrogen bonds, while in the P2(1) polymorph (Ib) the molecules are linked into sheets by combinations of three hydrogen bonds, one each of N-(HO)-O-..., C-(HN)-N-... and C-(HO)-O-... types. In the orthorhombic polymorph (Ic) the molecules are linked into a complex three-dimensional framework structure by a combination of one N-(HO)-O-..., one N-(HN)-N-... and three C-(HO)-O-... hydrogen bonds, and an aromatic pi(...)pi stacking interaction. In the isomeric compound 1-(2-chloronicotinoyl)-2-(3-nitrophenyl)hydrazine (II) the molecules are again linked into a three-dimensional framework, this time by a combination of three hydrogen bonds, one each of N-H-... O, N-(HN)-N-... and C-(HO)-O-... types, weakly augmented by a pi(...)pi stacking interaction. The molecules of 1-(2-chloronicotinoyl)-2-(4nitrophenyl)hydrazine (III) are linked into sheets by a combination of three hydrogen bonds, one each of (NHO)-O-..., N-(HN)-N-... and C-(HO)-O-... types.