title: Monoclinic polymorph of 2,5-bis[4-(dimethyl-amino)-styr-yl]-3,6-dimethyl-pyrazine.
abstract: The title compound, C(26)H(30)N(4), was prepared by condensation of tetra-methyl-pyrazine and dimethyl-amino-benzaldehyde and crystallizes from chloro-form/methanol in two different forms. Block-shaped crystals belong to the monoclinic crystal system and plates to the triclinic system. The two crystal forms differ in the arrangement of the centrosymmetric mol-ecules, which have nearly identical geometries. In the monoclinic crystals reported here, planar mol-ecules [maximum deviation = 0.062 (2) Å], with a transoid arrangement of the (E)-styryl units and completely planarized dimethylamino groups [sum of the C-N bond angles = 359.9 (2)°], form layers connected via H-π-stacking. The dihedral angle between the central and pendant rings is 1.30 (8)°. The triclinic polymorph contains two half molecules, both completed by crystallographic inversion symmetry.
authors.affiliation: University Mainz, Duesbergweg 10-14, 55099 Mainz, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Fischer
authors.forename: Volker
authors.initials: V
authors.lastname: Schmitt
authors.forename: Dieter
authors.initials: D
authors.lastname: Schollmeyer
authors.forename: Heiner
authors.initials: H
authors.lastname: Detert