N 1-(4-Methylphenyl)piperidine-1,4-dicarboxamide

In the title compound, C14H19N3O2, the heterocycle adopts a 1 C 4 conformation with the N atom being one of the flap atoms. In the crystal, classical N—H⋯O hydrogen bonds and C—H⋯O contacts connect the molecules into a three-dimensional network.

In the title compound, C 14 H 19 N 3 O 2 , the heterocycle adopts a 1 C 4 conformation with the N atom being one of the flap atoms. In the crystal, classical N-HÁ Á ÁO hydrogen bonds and C-HÁ Á ÁO contacts connect the molecules into a three-dimensional network.
Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2010); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 2012) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009  Piperidine and its derivatives are ubiquitous building blocks in the synthesis of pharmaceuticals and fine chemicals (Chen et al., 2012;Boja et al., 2011, Jakubowska et al., 2012. Members of this family have found a wide range of applications in pharmacology and are used as antidepressants (e.g. Paroxetine) and analgesics (e.g. meperidine hydrochloride) or to control attention-deficit hyperactivity disorder (e.g. Methylphenidate). In view of the biological importance, the title compound was synthesized to study its crystal structure.
According to a puckering analysis (Cremer & Pople, 1975;Boeyens, 1978), the piperidine ring adopts a 1 C 4 conformation with the the nitrogen atom as well as the carbon atom in para position to it acting as the flap atoms ( N2 C C5 ).
The primary amide group occupies an equatorial position. Due to amide-type resonance, the intracyclic nitrogen atom is present in an almost planar environment, the least-squares plane defined by the urea moiety (N2-C2-O1-N1) featuring the carbon atom as the one atom deviating most from this plane by 0.010 (1) Å (r.m.s. of all fitted atoms = 0.0057 Å). The least-squares planes through the atoms of the heterocycle and the phenyl groups define an angle of 48.15 (7) °. The planes defined by the non-hydrogen atoms of the amide groups intersect the least-squares plane defined by the intracyclic atoms of the heterocycle at angles of 29.22 (15) ° and 71.8 (2) ° with the smaller angle found for the secondary amide group ( Fig. 1).
In the crystal, non-classical C-H..O bonds as well as classical hydrogen bonds of the N-H···O type coexist. The former ones take part between one of the intracyclic methylene groups directly bonded to the nitrogen atom of the piperidine moiety and the oxygen atom of the secondary amide group (which also acts as acceptor for one set of N-H···O hydrogen bonds). The hydrogen atoms of the primary amide group, in turn, link the oxygen atom of its own functional group in neighbouring molecules as acceptor. Metrical parameters as well as information about the symmetry of these contacts are summarized in Table 1. In total, these contacts connect the molecules to a three-dimensional network. According to a graph-set analysis (Etter et al., 1990;Bernstein et al., 1995), the descriptor for the C-H···O contacts is C 1 1 (5) on the unitary level while the descriptor found for the hydrogen bonds fostered by the secondary amide group necessitates a C 1 1 (4) on the same level. The description of the hydrogen bonding pattern created by the primary amide group is best achieved by a binary descriptor of R 2 4 (8). The shortest intercentroid distance between two aromatic systems corersponds to a [100] translation (Fig. 2).

Refinement
Carbon-bound H atoms were placed in calculated positions (C-H 0.95 Å for aromatic carbon atoms, C-H 0.99 Å for methylene groups and C-H 1.00 Å for methine groups) and were included in the refinement in the riding model approximation, with U(H) set to 1.2U eq (C). The H atoms of the methyl groups were allowed to rotate with a fixed angle around the C-C bond to best fit the experimental electron density (HFIX 137 in the SHELX program suite (Sheldrick, 2008)), with U(H) set to 1.5U eq (C). All nitrogen-bound H atoms were located on a difference Fourier map and refined freely.