title: Crystal structure of 1-iodo-3-{[4-(tert-butyl-sulfan-yl)phen-yl]ethyn-yl}azulene.
abstract: The title compound, C20H19IS, features a 1,3-disubstituted azulene involving an ethynylene elongated 4-(tert-butyl-sulfanyl)-phenyl sidearm and an iodine atom as the substituents. The azulene ring system is almost planar (r.m.s. deviation = 0.012 Å) and subtends a dihedral angle of 35.7 (1)° with the benzene ring. As a result of the inherent dipole character of the azulene core, a supra-molecular π-π dimer [separation between the centroids of the five- and seven-membered rings = 3.7632 (10) Å] with anti-parallel orientated mol-ecules can be observed in the crystal. The packing is consolidated by an unusual I⋯π(acetyl-ene) contact [I⋯Cg = 3.34 Å, C-I⋯Cg = 173.3°], and a very weak C-H⋯π inter-action is also found in the structure, with the azulene five-membered ring as the acceptor.
authors.affiliation: Institut für Organische Chemie, TU Bergakademie Freiberg, Leipziger Strasse 29, D-09596 Freiberg/Sachsen, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Förster
authors.affiliation: Institut für Organische Chemie, TU Bergakademie Freiberg, Leipziger Strasse 29, D-09596 Freiberg/Sachsen, Germany.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Seichter
authors.affiliation: Institut für Organische Chemie, TU Bergakademie Freiberg, Leipziger Strasse 29, D-09596 Freiberg/Sachsen, Germany.
authors.forename: Edwin
authors.initials: E
authors.lastname: Weber
keywords: 1,3-disubstitution; C—H⋯π inter­action; I⋯π contact; azulene; crystal structure