Structures are reported here for eight further substituted N-aryl-2-chloronicotinamides, 2-ClC(5)H(3)NCONHC(6)H(4)X-4'. When X = H, compound (I) (C(12)H(9)ClN(2)O), the molecules are linked into sheets by N-H...N, C-H...pi(pyridyl) and C-H...pi(arene) hydrogen bonds. For X = CH(3), compound (II) (C(13)H(11)ClN(2)O, triclinic P1 with Z' = 2), the molecules are linked into sheets by N-H...O, C-H...O and C-H...pi(arene) hydrogen bonds. Compound (III), where X = F, crystallizes as a monohydrate (C(12)H(8)ClFN(2)O.H(2)O) and sheets are formed by N-H...O, O-H...O and O-H...N hydrogen bonds and aromatic pi...pi stacking interactions. Crystals of compound (IV), where X = Cl (C(12)H(8)Cl(2)N(2)O, monoclinic P2(1) with Z' = 4) exhibit inversion twinning: the molecules are linked by N-H...O hydrogen bonds into four independent chains, linked in pairs by C-H...pi(arene) hydrogen bonds. When X = Br, compound (V) (C(12)H(8)BrClN(2)O), the molecules are linked into sheets by N-H...O and C-H...N hydrogen bonds, while in compound (VI), where X = I (C(12)H(8)ClIN(2)O), the molecules are linked into a three-dimensional framework by N-H...O and C-H...pi(arene) hydrogen bonds and an iodo...N(pyridyl) interaction. For X = CH(3)O, compound (VII) (C(13)H(11)ClN(2)O(2)), the molecules are linked into chains by a single N-H...O hydrogen bond. Compound (VIII) (C(13)H(8)ClN(3)O, triclinic P1 with Z' = 2), where X = CN, forms a complex three-dimensional framework by N-H...N, C-H...N and C-H...O hydrogen bonds and two independent aromatic pi...pi stacking interactions.
