A triclinic polymorph of (−)-(S)-N-benzyl-2-[(R)-6-fluoro­chroman-2-yl]-2-hy­droxy­ethanaminium bromide

The title salt, C₁₈H₂₁FNO₂⁺·Br⁻, determined at 115 K, crystallizes in the triclinic space group P1. The previously reported polymorph occurs in the monoclinic space group P2₁ and has two independent mol­ecules in the asymmetric unit [Peeters et al. (1993). Acta Cryst. C49, 2157–2160]. In the title molecule, the pyran rings adopt half-chair conformations. The absolute configuration is S for the hy­droxy-bearing C atom and R for the asymmetric C atom in the di­hydro­pyran unit. In the crystal, the components are linked by N—H...Br and O—H...Br hydrogen bonds, forming chains along the c-axis direction. The crystal studied was refined as an inversion twin.