Polymorphism and solvolysis of 2-cyano-3-[4-(N,N-diethylamino)phenyl]prop-2-enethioamide

Abstract

Two new polymorph forms, (Ia) and (Ib), of the title compound, C(14)H(17)N(3)S, and its solvate with acetonitrile, C(14)H(17)N(3)S.0.25C(2)H(3)N, (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) degrees in (Ia), 14.0 (2) and 18.2 (2) degrees in (Ib), 2.3 (3) and 12.7 (4) degrees in molecule A of (Ic), and 23.2 (3) and 8.1 (4) degrees 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 [1-10] 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.

N-phosphorylated 3,5-bis(arylidene)4-piperidones: Synthesis, X-ray structure, and evaluation of antitumor activity

“…The substituent at the N1 atom adopts axial position similar to what was found in [9,11]. Both olefinic bonds have E configuration, which is in agreement with the results obtained earlier for similar compounds [12][13][14][15]. Taking into consideration the general similarity of the spectral data, we also assigned the structures of compounds 2b,c to E,E-isomers.…”

Powder study of propanthioamide dervative C8H6N2S2

“…Taking into consideration that the cyano group satisfies the triple bond character, C8-N9 exists in sp (hybridisation) whith a C8-N9 bond length of 1.173(4) Å and an C7-C8-N9 angle of 177.5(3)°, these values agree well those of related compounds [23]. From table 3 it is clear, that the molecule possesses a strong conjugation in thioamide fragment, resulting in the elongation of the C=S bond while the C-N bond have a partial double bond character [24]. Moreover the deviation of the thioamide group from the bridged plane is not significant, but the C7-C10 bond length 1.534(4) Å is elongated compared with the conjugated C-C bond of other compound [25].…”

N‐alkylated 3,5‐bis(arylidene)‐4‐piperidones. Synthetic approaches, X‐ray structure and anticancer activity

“…Both olefinic bonds have E configuration, which is in agreement with the results obtained earlier for similar compounds [6,7,8,[11][12][13][14][15]. Taking into consideration the general similarity of the spectral data we also assigned the structures of compounds 4a-c to E,E-isomers.…”

“…The heterocyclic piperidone ring of 4d has the flattened chair conformation (Figure 1) with the significant deviation of N(1) and slight deviation of C(1) atoms by 0.701(4) and -0.109(4) Å respectively from the plane formed by C(2), C(3), C(4) and C(5) atoms (rms deviation 0.012 Å) caused by sp 2 character of carbon atom C(1). It should be noted that for similar compounds deviation of C(1) atom from such plane might be positive or negative [11][12][13][14][15] so central core conformation of these molecules might be described as flattened chair or boat; this conformation also can be characterized as a sofa.…”