Diethyl 2-[(N-benzyl-N-methylamino)(phenyl)methyl]propanedioate

In the title compound, C22H27NO4, the mean planes of the two benzene rings form a dihedral angle of 73.54 (13)°. One of the methyl groups is disordered over two sites, with site occupation factors of 0.47 (15) and 0.53 (15). The crystal packing is controlled by van der Waals forces and a possible C—H⋯O interaction, forming a chain running parallel to the a axis.

In the title compound, C 22 H 27 NO 4 , the mean planes of the two benzene rings form a dihedral angle of 73.54 (13) . One of the methyl groups is disordered over two sites, with site occupation factors of 0.47 (15) and 0.53 (15). The crystal packing is controlled by van der Waals forces and a possible C-HÁ Á ÁO interaction, forming a chain running parallel to the a axis.
Thereby, several bimetallic metal complexes, in many cases exploring the known-well polydentate ligands, appear in this scenario as the most promising concept to employ in either enzyme / drug interaction or electron transfer process, in the later case involving the biological oxygen transfer (Sechi et al., 2009b;Ramkumar et al., 2008). Another exciting example of application of such polydentate ligand involves the synergic water activation, that occurs via the so-called, remote metallic atoms. Such organometallic compounds are structurally deemed to promote or block the H-I activity (Zeng et al., 2008b).
The explanations given above clearly demonstrate that polydentate ligands are of special interest in the bioorganometallic chemistry (Patil et al., 2007). Looking for the design of new bimetallic coordinating ligands to further explore in the building of intermolecular system involving H-I/ inhibitor/ metal complexation, we have targeted to study the crystallographic structure of a polydendate malonate N,O,O-ligand, the title compound (I).
In the molecule of (I) (Fig. 1 The Bond lengths and angles in the title compound have normal values (Allen et al., 1987). The only significant intermolecular interaction in (I), as identified by PLATON (Spek, 2003) is a C32-H32A···O3 H-bond (Table 1).

Experimental
The title compound, (I), was synthesized from 2-(benzylidene)-malonic acid diethyl esters in the presence of benzyl methylamine, in an aqueous medium at room temperature following the procedures reported earlier (Pommier & Neamati, 2006).
To a solution of 2-(benzylidene)-malonic acid diethyl ester (1.24 g, 5 mmol) in water (20 ml) was added the benzyl methylamine (0.60 g, 6 mmol) and the stirring was continued at room temperature until the complete consumption of the starting material. After removing solvent, the crude products were dissolved in diethyl ether (2x40 ml) and washed with water until the pH became neutral. The organic solvent layer was dried with sodium sulphate and then evaporated. The residue was purified by recrystallization from a mixture of diethylether/hexane (2:1) to give the pure compound (I) as colorless crystals in 78% yield.
One of the methyl group is disordered over two positions with roughly identical occupation factors (0.47 and 0.53). These occupation factors were initially refined restraining their sum to be equal to 1 and applying an overall isotropic thermal parameter for the C atom. Moreover, C-C distances were restraint to have reasonable values. Once the occupation factors have been determined, they were fixed and not refined and the temperature factors were refined freely.    The purity of the compound was checked by determining its melting point (380-382 K). Suitable single crystal of malonate derivative (I) was obtained by recrystallization from ethanol. A colorless crystal of (I) having approximate dimensions of 0.24 x 0.20 x 0.09 mm was mounted on a glass fibre. All measurements were made in the φ and ω scans technique on a CCD X8 Bruker diffractometer with graphite monochromatized MoKα radiation at room temperature (296 (2) K).
The data collection nominally covered a sphere of reciprocal space, by a combination of five sets of exposures; each set had a different φ angle for the crystal and each exposure covered 0.5° in ω and 30 seconds in time. The crystal-to-detector distance was 37.5 mm.
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.