Three derivatives of 4-fluoro-5-sulfonyl­isoquinoline

In 4-fluoro­isoquinoline-5-sulfonyl chloride, C₉H₅ClFNO₂S, (I), one of the two sulfonyl O atoms lies approximately on the isoquinoline plane as a result of minimizing the steric repulsion between the chloro­sulfonyl group and the neighbouring F atom. In (S)-(−)-4-fluoro-N-(1-hy­droxy­propan-2-yl)isoquinoline-5-sulfonamide, C₁₂H₁₃FN₂O₃S, (II), there are two crystallographically independent mol­ecules (Z′ = 2). The mol­ecular conformations of these two mol­ecules differ in that the amine group of one forms an intra­molecular bifurcated hydrogen bond with the F and OH groups, whilst the other forms only a single intra­molecular N—H...F hydrogen bond. The N—H...F hydrogen bonds correspond to weak coupling between the N(H) and ¹⁹F nuclei, observed in the ¹H NMR solution-state spectra. In (S)-(−)-4-[(4-fluoro­isoquinolin-5-yl)sulfon­yl]-3-methyl-1,4-diazepan-1-ium chloride, C₁₅H₁₉FN₃O₂S⁺·Cl⁻, (III), the isoquinoline plane is slightly deformed, suggestive of a steric effect induced by the bulky substituent on the sulfonyl group.