title: Flip-type disorder in 3-substituted 2,2':5',2''-terthiophenes.
abstract: In the crystal structures of four thiophene derivatives, (E)-3'-[2-(anthracen-9-yl)ethenyl]-2,2':5',2''-terthiophene, C(28)H(18)S(3), (E)-3'-[2-(1-pyrenyl)ethenyl]-2,2':5',2''-terthiophene, C(30)H(18)S(3), (E)-3'-[2-(3,4-dimethoxyphenyl)ethenyl]-2,2':5',2''-terthiophene, C(22)H(18)O(2)S(3), and (E,E)-1,4-bis[2-(2,2':5',2''-terthiophen-3'-yl)ethenyl]-2,5-dimethoxybenzene, C(36)H(26)O(2)S(6), at least one of the terminal thiophene rings is disordered and the disorder is of the flip type. The terthiophene fragments are far from being coplanar, contrary to terthiophene itself. The central C-C=C-C fragments are almost planar but the bond lengths suggest slight delocalization within this fragment. The crystal packing is determined by van der Waals interactions and some weak, relatively short, C-H...S and C-H...pi directional contacts.
authors.affiliation: Nanomaterials Research Centre, and MacDiarmid Institute for Advanced Materials and Nanotechnology, Massey University, Private Bag 11 222, Palmerston North, New Zealand.
authors.forename: Paweł
authors.initials: P
authors.lastname: Wagner
authors.forename: David L
authors.initials: DL
authors.lastname: Officer
authors.forename: Maciej
authors.initials: M
authors.lastname: Kubicki