1,3-Diethyl-1,3-diphenylurea

The molecule of the title compound, C17H20N2O, a symmetrical derivative of urea, shows non-crystallographic C 2 symmetry. Interaction with the aromatic system of the phenyl substituents as well as amide-type resonance is responsible for the marked planarization of the coordination environments of the N atoms. C—H⋯O contacts give rise to the formation of centrosymmetric dimers in the crystal structure. The closest distance between the centroids of two adjacent rings is 3.8938 (11) Å.

The molecule of the title compound, C 17 H 20 N 2 O, a symmetrical derivative of urea, shows non-crystallographic C 2 symmetry. Interaction with the aromatic system of the phenyl substituents as well as amide-type resonance is responsible for the marked planarization of the coordination environments of the N atoms. C-HÁ Á ÁO contacts give rise to the formation of centrosymmetric dimers in the crystal structure. The closest distance between the centroids of two adjacent rings is 3.8938 (11) Å .

Related literature
For the crystal structure of a uranium coordination compound with the title compound as a ligand, see: Zhu et al. (2008). For graph-set analysis of hydrogen bonds, see: Etter et al. (1990); Bernstein et al. (1995).  Table 1 Hydrogen-bond geometry (Å , ).

Comment
Chelate ligands are an important class of molecules in coordination chemistry due to the increased thermodynamic stability of coordination compounds obtainable in comparison to those derived from monodentate ligands only. Derivatives of urea are of particular interest in this aspect due to a number of reasons: firstly, urea itself can act as a neutral or -upon deprotonation -anionic ligand. Secondly, apart from exclusive N-donor action, the carbonyl O-atom may serve as donor as well. Thirdly, the possible derivatization of the N-atoms allows for the fine-tuning of the nucleophilicity of these atoms, such that a vast series of different symmetric, as well as asymmetric, derivatives is at hand. A crystal structure of a uranium coordination compound utilising the title compound as ligand has been published (Zhu et al., 2008). At the beginning of a bigger study to elucidate the rules guiding the formation of urea-derivative-supported coordination compounds we determined the structure of the title compound to allow for comparisons with the ligand in such compounds.
In the molecule (Fig. 1), the coordination environment around both nitrogen atoms is almost planar due to the interaction of the free electron pair not only in terms of amide-type resonance but also with the phenyl-moiety. The N-atoms are displaced by only 0.183 (1) Å and -0.180 (1) Å from the planes defined by the atoms bonded to them.
The least-squares planes defined by the carbon atoms of the phenyl rings enclose an angle of 40.31 (4) °.
In the crystal structure, C-H···O contacts are present whose range falls sightly below the sum of van-der-Waals radii of the atoms involved. They involve one of the phenyl hydrogen atoms which is meta to the nitrogen atom and connect the molecules into centrosymmetric dimers (Fig. 2). In terms of graph-set analysis, the descriptor for these contacts on the unitary level is R 2 2 (14) (Etter et al., 1990;Bernstein et al., 1995). The closest distance between two centers of gravity was measured at 3.8938 (11) Å.
The packing of the title compound is shown in Fig. 3.

Experimental
The compound was obtained commercially (Aldrich). Crystals suitable for the X-ray diffraction study were taken directly from the provided compound.