The crystal structures and Hirshfeld surface analysis of three new bromo-substituted...

Three new 1H-indole derivatives, namely, 2-(bromo-meth-yl)-3-methyl-1-(phenyl-sulfon-yl)-1H-indole, C₁₆H₁₄BrNO₂S, (I), 2-[(E)-2-(2-bromo-5-meth-oxy-phen-yl)ethen-yl]-3-methyl-1-(phenyl-sulfon-yl)-1H-indole, C₂₄H₂₀BrNO₃S, (II), and 2-[(E)-2-(2-bromo-phen-yl)ethen-yl]-3-methyl-1-(phenyl-sulfon-yl)-1H-indole, C₂₃H₁₈BrNO₂S, (III), exhibit nearly orthogonal orientations of their indole ring systems and sulfonyl-bound phenyl rings. Such conformations are favourable for inter-molecular bonding involving sets of slipped π-π inter-actions between the indole systems and mutual C-H⋯π hydrogen bonds, with the generation of two-dimensional monoperiodic patterns. The latter are found in all three structures, in the form of supra-molecular columns with every pair of successive mol-ecules related by inversion. The crystal packing of the compounds is additionally stabilized by weaker slipped π-π inter-actions between the outer phenyl rings (in II and III) and by weak C-H⋯O, C-H⋯Br and C-H⋯π hydrogen bonds. The structural significance of the different kinds of inter-actions agree with the results of a Hirshfeld surface analysis and the calculated inter-action energies. In particular, the largest inter-action energies (up to -60.8 kJ mol^-1) are associated with pairing of anti-parallel indole systems, while the energetics of weak hydrogen bonds and phenyl π-π inter-actions are comparable and account for 13-34 kJ mol^-1.