Three derivatives of 4-fluoro-5-sulfonyl-isoquinoline

In 4-fluoro-isoquinoline-5-sulfonyl chloride, C₉H ₅ClFNO₂S, (I), one of the two sulfonyl O atoms lies approximately on the isoquinoline plane as a result of minimizing the steric repulsion between the chloro-sulfonyl group and the neighbouring F atom. In (S)-(-)-4-fluoro-N-(1-hy-droxy-propan-2-yl)isoquinoline-5-sulfonamide, C ₁₂H₁₃FN₂O₃S, (II), there are two crystallographically independent molecules (Z′ = 2). The mol-ecular conformations of these two molecules differ in that the amine group of one forms an intra-molecular bifurcated hydrogen bond with the F and OH groups, whilst the other forms only a single intra-molecular 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-fluoro-isoquinolin-5-yl)sulfon-yl]-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.