title: 1,8-Bis(phenylethynyl)anthracene - gas and solid phase structures.
abstract: 1,8-Bis(phenylethynyl)anthracene (1,8-BPEA) was synthesized by a twofold Kumada cross-coupling reaction. The molecular structure of 1,8-BPEA was determined using a combination of gas-phase electron diffraction (GED), mass spectrometry (MS), quantum chemical calculations (QC) and single-crystal X-ray diffraction (XRD). Five rotamers of the molecule with different orientations of phenylethynyl groups were investigated by DFT calculations. According to these, molecules of C2 symmetry with co-directional rotation of the phenylethynyl groups are predicted to exist in the gas phase at 498 K. This was confirmed by a GED/MS experiment at this temperature. The bonding of this conformer was studied and described in terms of an NBO-analysis. Dispersion interactions in the solid state structure and in the free molecule are discussed. In the solid this symmetry is broken; the asymmetric unit of the single crystal contains 3.5 molecules and a herringbone packing motif of π-stacked dimers and trimers. The π-stacking in the dimers is between the anthracene units, and the trimers are linked by π-stacking between phenyl and anthracene units. The interaction between these stacks can be described in terms of σ(C-H)π interactions.
authors.affiliation: Universität Bielefeld, Fakultät für Chemie, Lehrstuhl für Anorganische Chemie und Strukturchemie, Centre for Molecular Materials CM2, Universitätsstraße 25, D-33615 Bielefeld, Germany. mitzel@uni-bielefeld.de.
authors.forename: Jan-Hendrik
authors.initials: JH
authors.lastname: Lamm
authors.forename: Jan
authors.initials: J
authors.lastname: Horstmann
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Stammler
authors.forename: Norbert W
authors.initials: NW
authors.lastname: Mitzel
authors.forename: Yuriy A
authors.initials: YA
authors.lastname: Zhabanov
authors.forename: Natalya V
authors.initials: NV
authors.lastname: Tverdova
authors.forename: Arseniy A
authors.initials: AA
authors.lastname: Otlyotov
authors.forename: Nina I
authors.initials: NI
authors.lastname: Giricheva
authors.forename: Georgiy V
authors.initials: GV
authors.lastname: Girichev