ABSTRACT

A kind of polysubstituted benzene, 3-amino-5,6-dimethyl-2-nitrobiphenyl-4-carbonitrile(C₁₅H₁₃N₃O₂), was synthesized and its crystal structure was determined. The molecule is composed of two phenyl moieties, two methyl groups, a cyano group, an amino group and a nitro group. The methyl groups, cyano group and amino group are nearly coplanar with the connected benzene ring. Because of the large volume, the nitro group and the connected benzene ring are twisted. The dihedral angle between the two benzene rings is 83.51˚. In the crystal, molecules are linked by N—H···N and C—H···O hydrogen bonds.

1. Introduction

Polysubstituted benzenes and aromatic compounds are widely used in the chemical industry as well in the laboratory [1]. Many liquid crystals belong to the group of polysubstituted benzenes and their derivatives [2-6]. Such compounds can be used for Organic Light Emitting Diode [7-10]. Heteroaromatic components and their derivatives play important parts in pharmaceutical and agrochemical chemicals [11-13]. Hence, more and more researchers have concerned about these compounds. The determination of crystal structure is helpful for its application and realization of property. In this paper, we report about the synthesis and structure of a kind of polysubstituted benzene, 3-amino-5,6-dimethyl-2-nitrobiphenyl-4-carbonitrile.

2. Experimental

2.1. Synthesis of the Compound

A 25 mL round bottom flask was charged with 120 mg 2- sec-Butylidene-malononitrile, 149 mg (2-nitrovinyl) benzene and 68 mg EtONa. The mixture was refluxed with vigorous stirring for 50 hours. The solvent was removed under reduced pressure. The yellow needle product was purified by column chromatography (EtOAc/ hexanes, 1:8). The product was recrystallized from n-hexane and single crystals suitable for X-ray diffraction were obtained.

2.2. Determination of the Crystal Structure

The crystal Structure was characterized by X-ray diffraction (XRD) using Bruker Smart-1000 X-ray single crystal Diffractometer equipped with graphite monochromatized MoKa radiation (λ = 0.71073 Å). The diffraction data were obtained at the temperature of 296 K and analyzed by the software of SHELXTL-97 [14]. The details were shown in Table 1.

3. Results and Discussions

3.1. Refinement Details

All reflections were defined based on F^­2. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ (F²) is used only for calculating R-factors (gt) etc., and is not relevant to the choice of reflections for refinement. Rfactors based on F² are statistically about twice as large as those based on F, and R-factors based on all data will be even larger.

3.2. Geometry Details

All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion

angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

3.3. Structure Details

The structure was solved by direct methods [14], then refined by full-matrix least-squares technique, the position and anisotropic parameters of all the non-hydrogen atoms were obtained. Table 2 showed some crystal and refinement parameters. The crystal system of the title compound belongs to Triclinic and the space group is P-1, with cell parameters a = 8.607(3)Å, b = 8.616(3)Å, c = 10.540(3)Å. Atomic coordinates and displacement parameters of the compound were shown in Table 3, from these data the structure was gained, which was shown in Figure 1. This compound is composed of two phenyl moieties, two methyl groups, a cyano group, an amino group and a nitro group. In the crystal, the methyl groups, cyano group and amino group are nearly coplanar with the connected benzene ring (C7-C12; A). Because of the large volume, the nitro group and the benzene ring A are twisted, the torsion angles are −80.2(6)˚ (O1-N3-C8-C7) and 99.3(5)˚ (O2-N3-C8-C7). To avoid steric conflicts, the two benzene rings are not coplanar, the dihedral angle between them is 83.51 (0.13)˚. Figure 2 showed packing diagram of the title compound. Hydrogen bonds are shown as dashed line.There are two kinds of hydrogen bonds in the crystal, N—H···N and C—H···O. In the crystal, Crosslinks among the molecules are provided by the hydrogen bonds (Figure 2), leading to one-dimensional supermolecular structure.

4. Conclusion

A kind of polysubstituted benzene, C₁₅H₁₃N₃O₂, was synthesized and its crystal structure was determined. In the crystal, methyl groups, cyano group and amino group are nearly coplanar with the connected benzene ring.

Because of the large volume, the nitro group and the connected benzene ring are twisted. The dihedral angle between the two benzene rings is 83.51˚. In the crystal, molecules are linked by N—H···N and C—H···O hydrogen bonds.

REFERENCES