Three 2-(methysulfanyl)­nicotinamides

The mol­ecular conformations of three N-alkyl-2-(methyl­sulfan­yl)nicotinamide derivatives, namely N-cyclo­hexyl-2-(methyl­sulfan­yl)nicotinamide, C₁₃H₁₈N₂OS, (I), N-isopropyl-2-(methyl­sulfan­yl)nicotinamide, C₁₀H₁₄N₂OS, (II), in which there are two mol­ecules in the asymmetric unit which were chosen to form a hydrogen-bonded pair, and N-(2-hy­droxy­eth­yl)-2-(methyl­sulfan­yl)nicotinamide dihydrate, C₉H₁₂N₂O₂S·2H₂O, (III), are compared with those of four unsubstituted N-alkyl­nicotinamide compounds. The substituted com­pounds show a higher degree of torsion of the pyridine ring with respect to the amide group than do the unsubstituted compounds, with dihedral angles in the range 40-60° for the former and 20-35° for the latter. In (I) and (II), the supra­molecular structure is defined by amide-N to carbonyl-O chains. In (III), the nicotinamide mol­ecules are linked by hydrogen bonds to two water mol­ecules resulting in two linked chains of rings which form the three-dimensional network.