Crystal Structure of N-(2-Benzoyl-4,5-dimethoxyphenethyl)-2-phenylacetamide

: The crystal structure of N -(2-benzoyl-4,5-dimethoxyphenethyl)-2-phenylacetamide indi-cates that the compound crystallizes in the monoclinic C 2/ c space group with eight molecules in the unit cell. The heteroatoms from the amide group form a chain of intermolecular N-H ··· O hydrogen bonds propagating along the b axis. The carbonyl group from the benzoyl substituent participates in short contacts with two H-atoms from the ethyl or phenyl groups.


Introduction
The title compound was synthesized as a precursor for the synthesis of a series of differently substituted 1,2,3,4-tetrahydroisoquinolines and its molecular structure (Figure 1) was described on the basis of spectroscopic data (IR, 1 H and 13 C NMR) [1]. Besides their use as synthetic scaffolds, 2-phenylacetamides are also known for their application in medicinal chemistry as they possess a variety of biological activities depending on the structural features of the substituents. Their anticonvulsant [2], antidepressant [3] and antiproliferative [4] activities are only a few to mention. Herein, we report the crystal structure of N-(2-benzoyl-4,5-dimethoxyphenethyl)-2-phenylacetamide obtained by singlecrystal X-ray diffraction analysis. The presence of suitable coordination groups in the studied ketoamide have provoked systemic study on its coordination properties and some data have recently been published [5]. The data showed that complexation with metal ions is strongly ruled by the coordination ability of the used metal ion. This could be explained with the conformational flexibility of the title compound and its intrinsic ability to form various types of intermolecular hydrogen bonding. In this short note, we provide data on these structural features as observed in the crystal packing.

Results
The studied ketoamide compound crystallizes in the monoclinic C2/c space group. The structure of the asymmetric unit is depicted in Figure 2, along with the atom numbering. All three aromatic rings in the molecule are almost orthogonal to each other. The unit cell contains eight molecules and is depicted in Figure 3, where the short contacts between the C-H and C-O groups from adjacent molecules are highlighted. All oxygen atoms participate in the formation of short contacts, whereas the C=O and N-H from the amide group participate in the formation of an intermolecular hydrogen-bonding chain. The propagation of this chain is shown in Figure 4, and the structural features of all hydrogen bonds are summarized in Table 1.

Results
The studied ketoamide compound crystallizes in the monoclinic C2/c space group. The structure of the asymmetric unit is depicted in Figure 2, along with the atom numbering. All three aromatic rings in the molecule are almost orthogonal to each other. The unit cell contains eight molecules and is depicted in Figure 3, where the short contacts between the C-H and C-O groups from adjacent molecules are highlighted. All oxygen atoms participate in the formation of short contacts, whereas the C=O and N-H from the amide group participate in the formation of an intermolecular hydrogen-bonding chain. The propagation of this chain is shown in Figure 4, and the structural features of all hydrogen bonds are summarized in Table 1.

Results
The studied ketoamide compound crystallizes in the monoclinic C2/c space group. The structure of the asymmetric unit is depicted in Figure 2, along with the atom numbering. All three aromatic rings in the molecule are almost orthogonal to each other. The unit cell contains eight molecules and is depicted in Figure 3, where the short contacts between the C-H and C-O groups from adjacent molecules are highlighted. All oxygen atoms participate in the formation of short contacts, whereas the C=O and N-H from the amide group participate in the formation of an intermolecular hydrogen-bonding chain. The propagation of this chain is shown in Figure 4, and the structural features of all hydrogen bonds are summarized in Table 1.     The title compound has previously been studied for its complexation ability with metal ions (Pd(II) and Zn(II)) and detailed spectroscopic data have been provided [5]. The crystal structure described herein corroborates with the findings from IR, Raman and NMR spectroscopies. The earlier reported IR stretching vibration for the carbonyl groups with frequencies lower than 1700 cm −1 (namely 1662 cm −1 for the C=O from the keto group and 1652 cm −1 for the C=O from the amide group [5]) may suggest that these groups are engaged in moderate intermolecular hydrogen bonding in the solid state, as evidenced by the crystal structure described here.  The title compound has previously been studied for its complexation ability with metal ions (Pd(II) and Zn(II)) and detailed spectroscopic data have been provided [5]. The crystal structure described herein corroborates with the findings from IR, Raman and NMR spectroscopies. The earlier reported IR stretching vibration for the carbonyl groups with frequencies lower than 1700 cm −1 (namely 1662 cm −1 for the C=O from the keto group and 1652 cm −1 for the C=O from the amide group [5]) may suggest that these groups are engaged in moderate intermolecular hydrogen bonding in the solid state, as evidenced by the crystal structure described here.

D-H•••A D-H H•••A D•••A D-H•••A
In summary, the crystal structure of the studied ketoamide reveals the participation of all oxygen atoms in the formation of either intermolecular hydrogen bonding of C=O . . . H-N type or short contacts with the C-H groups. The latter are CH-π interactions and are quite common in systems featuring aromatic rings. Positively charged hydrogen atoms willingly interact with the electron densities above and below the planes of aromatic rings and are part of Van der Waals interactions. In summary, the crystal structure of the studied ketoamide reveals the participation of all oxygen atoms in the formation of either intermolecular hydrogen bonding of C=O…H-N type or short contacts with the C-H groups. The latter are CH---π interactions and are quite common in systems featuring aromatic rings. Positively charged hydrogen atoms willingly interact with the electron densities above and below the planes of aromatic rings and are part of Van der Waals interactions.

Experimental Section
Good quality single crystals from the title compound were obtained from DMSO-d6 solution in an NMR tube after 1 month of slow evaporation. Yellow prisms with 0.54 × 0.26 × 0.11 mm were analyzed on a 2-circle diffractometer STOE IPDS 2T using GeniX Mo, 0.05 × 0.05 mm 2 microfocus as a source for monochromated MoKα radiation (λ = 0.71073 Å) at 120(2) K. Crystal data, data collection and structure refinement details are summarized in Table 2.
The diffraction data were corrected for absorption effects by the Gaussian integration method implemented in the STOE X-Red32 software. Unit cell parameters were calculated and refined from the full data set. The structures were solved by a full-matrix least squares procedure based on F 2 using the SHELX-2014 program package [6], implemented in the Olex [7] and Wingx [8] suites of programs. All non-hydrogen atoms were refined anisotropically, and the positions of the hydrogen atoms were either calculated using a riding

Experimental Section
Good quality single crystals from the title compound were obtained from DMSOd 6 solution in an NMR tube after 1 month of slow evaporation. Yellow prisms with 0.54 × 0.26 × 0.11 mm were analyzed on a 2-circle diffractometer STOE IPDS 2T using GeniX Mo, 0.05 × 0.05 mm 2 microfocus as a source for monochromated MoKα radiation (λ = 0.71073 Å) at 120(2) K. Crystal data, data collection and structure refinement details are summarized in Table 2.
The diffraction data were corrected for absorption effects by the Gaussian integration method implemented in the STOE X-Red32 software. Unit cell parameters were calculated and refined from the full data set. The structures were solved by a full-matrix least squares procedure based on F 2 using the SHELX-2014 program package [6], implemented in the Olex [7] and Wingx [8] suites of programs. All non-hydrogen atoms were refined anisotropically, and the positions of the hydrogen atoms were either calculated using a riding model in isotropic approximation or deduced from the electron density map (N-H1) Table S1 in the Supplementary Materials along with the 1 H and 13 C NMR spectra.  Table S1: Geometric parameters (bond lengths in Å, and angles in º) for N-(2-benzoyl-4,5-dimethoxyphenethyl)-2-phenylacetamide, along with the cif and check-cif files. 1 H and 13 C NMR spectra are given in Figures S1 and S2, respectively.