Crystal structures and Hirshfeld analysis of 4,6-di-bromo-indole-nine and its quaternized salt

Acta Crystallogr E Crystallogr Commun. 2021 Nov 2;77(Pt 12):1203-1207. doi: 10.1107/S2056989021011385. eCollection 2021 Dec 1.

Abstract

4,6-Di-bromo-2,3,3-trimethyl-3H-indole, C11H11Br2N, exists as a neutral mol-ecule in the asymmetric unit. The asymmetric unit of 4,6-di-bromo-2,3,3-trimethyl-3H-indol-1-ium iodide, C12H14Br2N+·I-, contains one organic cation and one iodine anion. The positive charge is localized on the quaternized nitro-gen atom. In the crystal, mol-ecules of 4,6-di-bromo-indole-nine are linked by C-Br⋯π halogen bonds, forming zigzag chains propagating in the [001] direction. The mol-ecules of the salt form layers parallel to the (010) plane where they are linked by C-H⋯Br hydrogen bonds, C-Br⋯Br and C-Br⋯I halogen bonds. The Hirshfeld surface analysis and two dimensional fingerprint plots were used to analyse the inter-molecular contacts present in both crystals.

Keywords: 4,6-di­bromo-2,3,3-trimethyl-3H-indole; Hirshfeld surface; crystal structure; quaternized salt.

Grants and funding

This work was funded by National Academy of Sciences of Ukraine grant 0120U102660.