(E)-N-Phenyl-N-(phenylcarbamoyl)-3-[propyl(trimethylsilyl)amino]acrylamide chloroform hemisolvate

The title compound, C22H29N3O2Si·0.5CHCl3, crystallizes in the the triclinic space group P with two host molecules and one chloroform molecule in the asymmetric unit. The core of the molecule consists of a urea unit bound to a 3-amino-acryloyl group. An intramolecular N—H⋯O hydrogen bond is present in both crystallographically independent molecules.

The title compound, C 22 H 29 N 3 O 2 SiÁ0.5CHCl 3 , crystallizes in the the triclinic space group P1 with two host molecules and one chloroform molecule in the asymmetric unit. The core of the molecule consists of a urea unit bound to a 3-amino-acryloyl group. These units are almost planar in both molecules [average deviation from plane of 0.05 (6) Å in molecule A and 0.04 (5) Å in molecule B]. The main difference between molecules A and B involves the dihedral angles of the phenyl groups. One phenyl ring makes dihedral angles of 71.14 (6) (molecule A) and 82.81 (7) (molecule B) with respect to the core (C 4 N 3 O 2 ) of the molecule [14.56 (9) (molecule A) and 5.7 (1) (molecule B) for the other phenyl ring]. Another prominent feature is the intramolecular N-HÁ Á ÁO hydrogen bond present in both crystallographically independent molecules.
Structure description (E)-N-Phenyl-N-(phenylcarbamoyl)-3-[propyl(trimethylsilyl)amino]acrylamide is an insertion product from propyl(trimethylsilyl) [2-(trimethylsilyl)ethenyl]amine and phenyl isocyanate. It was obtained in the course of our work on different types of siliconnitrogen compounds (Herbig et al., 2019a(Herbig et al., , 2021(Herbig et al., , 2022. Si-N bonds can be subjected to the insertion of different heteroallenes such as CO 2 and isocyanates (Kraushaar et al., 2012(Kraushaar et al., , 2014(Kraushaar et al., , 2017Herbig et al., 2018Herbig et al., , 2019b. In a continuation of our research in this area, the title compound was prepared and its crystal structure is reported here. The title compound, C 22 H 29 N 3 O 2 SiÁ0.5 CHCl 3 , Fig. 1, crystallizes in the triclinic space group P1 with two host molecules (Figs. 2 and 3) and one chloroform molecule in the asymmetric unit. The core of the molecule consists of a urea unit (N2, C7, O2, N3) linked data reports to a 3-amino-acryloyl group (N1/C4-C6/O1). 3-Benzylamino-2-cyano-N-[N-(2-fluorophenyl) carbamoyl]-3-(methylsulfanyl)acrylamide (Zhong et al., 2011) is only one closely related acyclic structure in the CSD (Groom et al., 2016). If the main structural elements of the title compound are allowed to occur in cyclic structures, purine derivatives are obtained, to which belongs for example, caffeine (Sutor, 1958). The formation of these cyclic structures requires a 180 rotation for the C5-C6 and C6-N2 bonds. Therefore, this structural relationship is not recognizable at first glance. There are about 1500 crystal structures of such purine derivatives.
The core of the molecule formed by N1, C4-C6, O1, N2, C7, O2 and N3 is almost planar in both molecules of the title compound [the average deviation from the plane is 0.05 (6) Å in molecule A and 0.04 (5) Å in molecule B] The planarity is presumably due to the conjugated system of double bonds. The C14-C19 phenyl rings in both molecules are not coplanar to the core of the molecules but adopt dihedral angles to the latter of 14.56 (9) (molecule A) and 5.7 (1) (molecule B). This small deviation from planarity still allows conjugation between the C14-C19 phenyl ring and the urea part of the molecule.
The C8-C13 phenyl rings in both molecules subtend dihedral angles of 71.14 (6) (molecule A) and 82.81 (7) (molecule B) with the core of the molecule. This almost perpendicular conformation may be explained by the presence of the oxygen atom O2 in a vicinal position to the respective phenyl group.
An intramolecular N3-H3Á Á ÁO1 hydrogen bond is present in both crystallographically independent molecules (see Table 1). Another intramolecular interaction is present between the ortho-phenyl hydrogen atom H19 and O2 in both molecules. The interaction C9A-H9AÁ Á ÁO1A represents an intermolecular hydrogen bond.

Figure 2
Diagram of molecule A showing the atom-labelling scheme. Atomic displacement parameters are at the 50% probability level.

Figure 3
Diagram of molecule B showing the atom-labelling scheme. Atomic displacement parameters are at the 50% probability level. Table 1 Hydrogen-bond geometry (Å , ).

Figure 1
Asymmetric unit of the crystal structure including a disordered molecule of chloroform. Atomic displacement parameters are at the 50% probability level.

data reports
IUCrData (2023). 8, x230117 Herbig and Bö hme 2C 22 H 29 N 3 O 2 SiÁCHCl 3 3 of 3 The chloroform solvent molecule is disordered in the crystal structure with site occupation factors of 72.6:27.4%. C-HÁ Á Á interactions are present between the chloroform C-H bond and the centroid of the C14A-C19A phenyl ring (see Table 1).

Synthesis and crystallization
(E)-N-phenyl-N-(phenylcarbamoyl)-3-[propyl(trimethylsilyl)amino])acrylamide was obtained from the reaction of propyl(trimethylsilyl)[2-(trimethylsilyl)ethenyl]amine and phenyl isocyanate. As shown in Fig. 4, a double insertion of Ph-NCO into the Si-C bond takes place (Herbig et al., 2018). This reaction is possible due to the lability of bonds in theposition of the enamine (Ozaki, 1972). Traces of water lead to the cleavage of one Si-C bond from the intermediate to yield the title compound.
To a solution of 0.46 g (2 mmol) propyl(trimethylsilyl)[2-(trimethylsilyl)ethenyl]amine in 10 ml n-pentane were added dropwise 0.35 g (3 mmol) phenylisocyanate at 0 C. After standing for six days at room temperature, volatiles were removed under reduced pressure. Storing the product mixture for five years at À28 C yielded crystals suitable for singlecrystal X-ray diffraction. No quantitative yield can be given here, since only a few crystals at the wall of the Schlenk tube were available. NMR spectroscopy showed that the batch product is a mixture of many components. Further purification of the product mixture was not successful.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2.

Figure 4
Proposed reaction scheme for the formation of the title compound.  Special details Geometry. 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. Refinement. Hydrogen atoms bonded to C were positioned geometrically and allowed to ride on their parent atoms, with C-H = 0.95 Å for H(phenyl), 0.99 Å for CH 2 , 0.98 Å for CH 3 and 1.0 Å for H(chloroform). U iso (H) = xU eq (C), where x = 1.2 for H(phenyl), CH 2 , and H(chloroform) and 1.5 for CH 3 . Hydrogen atoms at nitrogen atoms N3A and N3B and at olefinic carbon atoms (C4A, C4B, C5A, and C5B) were localized from residual electron density maps and were freely refined.