title: Weak inter-actions in the crystal structures of two indole derivatives.
abstract: We describe the syntheses and crystal structures of two indole derivatives, namely a second monoclinic polymorph of ethyl 5-chloro-1H-indole-2-carboxyl-ate C11H10ClNO2, (I), and ethyl 5-chloro-3-iodo-1H-indole-2-carboxyl-ate, C11H9ClINO2, (II). In their crystal structures, both compounds form inversion dimers linked by pairs of N-H⋯O hydrogen bonds, which generate R 2 (2)(10) loops. The dimers are linked into double chains in (I) and sheets in (II) by a variety of weak inter-actions, including π-π stacking, C-I⋯π, C-Cl-π inter-actions and I⋯Cl halogen bonds.
authors.affiliation: Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland.
authors.forename: Jamie R
authors.initials: JR
authors.lastname: Kerr
authors.affiliation: Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland.
authors.forename: Laurent
authors.initials: L
authors.lastname: Trembleau
authors.affiliation: Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland.
authors.forename: John M D
authors.initials: JM
authors.lastname: Storey
authors.affiliation: Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland; Fundação Oswaldo Cruz, Instituto de Tecnologia em Fármacos-Far Manguinhos, 21041-250 Rio de Janeiro, RJ, Brazil.
authors.forename: James L
authors.initials: JL
authors.lastname: Wardell
authors.affiliation: Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland.
authors.forename: William T A
authors.initials: WT
authors.lastname: Harrison
keywords: N—H⋯O hydrogen bonds; crystal structure; indole; inversion dimers; weak inter­actions