title: o-Quinonoid heterocycles: synthesis and crystal structure of 2,3-dicyano-5,7-bismethylthieno[3,4-b]pyrazine.
abstract: 2,3-Dicyano-5,7-bismethylthieno[3,4-b]pyrazine (5), has been obtained as a minor product from reactions of S-nucleophiles with 5,6-di(1-bromoethyl)pyrazine-2,3-dicarbonitrile (3), or from a condensation of 4-hydroxy-2,5-dimethyl-2,3-dihydrothiophen-3-one (4) with diaminomaleonitrile. The molecular structure of compound 5 has been confirmed by X-ray diffraction. A partial separation of charge causes a donor-acceptor type arrangement of the planar molecules in uniform parallel stacks with an interplanar spacing of 3.334(2) A at 100 K.
authors.affiliation: Department of Chemistry, Norwegian University of Science and Technology, N-7491 Trondheim, Norway. eva.morkved@chem.ntnu.no
authors.forename: Eva H
authors.initials: EH
authors.lastname: Mørkved
authors.forename: Jon A
authors.initials: JA
authors.lastname: Beukes
authors.forename: Frode
authors.initials: F
authors.lastname: Mo
mesh_terms: D003460:Crystallization; D006571:Heterocyclic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008968:Molecular Conformation; D011719:Pyrazines / Q000138:chemical synthesis / Q000737:chemistry*; D013876:Thiophenes / Q000138:chemical synthesis / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: C524602:2,3-dicyano-5,7-bismethylthieno(3,4-b)pyrazine; D006571:Heterocyclic Compounds; D011719:Pyrazines; D013876:Thiophenes