68029-38-9Relevant articles and documents
Polymorphism and solvolysis of 2-cyano-3-[4-(N,N-diethylamino)-phenyl]prop- 2-enethioamide
Nesterov, Vladimir N.,Nesterov, Volodymyr V.
, p. o781-o785 (2004)
Two new polymorph forms, (Ia) and (Ib), of the title compound, C 14H17N3S, and its solvate with acetonitrile, C14H17N3S-0.25C2H3N, (Ic), have been investigated. Crystals of the two polymorphs were grown from different solvents, viz. ethanol and N,N-dimethylformamide, respectively. The polymorphs have different orientations of the thioamide group relative to the CN substituent, with s-cis and s-trans geometry of the C=C-C=S diene fragment, respectively. Compound (Ic) contains two independent molecules, A and B, with s-cis geometry, and the solvate molecule lies on a twofold axis. The core of each molecule is slightly non-planar; the dihedral angles between the conjugated C=C-CN linkage and the phenyl ring, and between this linkage and the thioamide group are 13.4 (2) and 12.0 (2)° in (Ia), 14.0 (2) and 18.2 (2)° in (Ib), 2.3 (3) and 12.7 (4)° in molecule A of (Ic), and 23.2 (3) and 8.1 (4)° in molecule B of (Ic). As a result of strong conjugation between donor and acceptor parts, the substituted phenyl rings have noticeable quinoid character. In (Ib), there exists a very strong intramolecular steric interaction (H...H = 1.95 A) between the bridging and thioamide parts of the molecule, which makes such a form less stable. In the crystal structure of (Ia), intermolecular N-H...N and N-H...S hydrogen bonds link molecules into infinite tapes along the [110] direction. In (Ib), such intermolecular hydrogen bonds link molecules into infinite (101) planes. In (Ic), intermolecular N-H...N hydrogen bonds link molecules A and B into dimers, which are connected via N-H...S hydrogen bonds and form infinite chains along the c direction.
