Diethyl 2-{(dibenzylamino)[4-(trifluoromethyl)phenyl]methyl}malonate

The asymmetric unit of the title compound, C29H30F3NO4, contains two independent molecules. In each independent molecule, one of two terminal ethyl groups is disordered over two conformations: the occupancies of major components were fixed at 0.53 and 0.64 in the two molecules. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds link molecules into chains propagating along [10].

The asymmetric unit of the title compound, C 29 H 30 F 3 NO 4 , contains two independent molecules. In each independent molecule, one of two terminal ethyl groups is disordered over two conformations: the occupancies of major components were fixed at 0.53 and 0.64 in the two molecules. In the crystal structure, weak intermolecular C-HÁ Á ÁO hydrogen bonds link molecules into chains propagating along [101]. 10 restraints H-atom parameters constrained Á max = 0.51 e Å À3 Á min = À0.41 e Å À3 Table 1 Hydrogen-bond geometry (Å , ).   et al., 2007), is fundamentally based on intermolecular coordination between H-I / chemical inhibitor / metals (Mg +2 and Mn +2 , co-factors of the enzyme) leading to formation of bimetallic complexes (Zeng, Zhang et al., 2008;Sechi, Carta et al., 2009). Thereby, several bimetallic complexes, in many cases exploring the well-known polydentate ligands, appear in this scenario as the most promising concept to employ in either enzyme / drug interaction or electron transfer process involving the biological oxygen transfer (Sechi, Rizzi et al., 2009 ;Ramkumar et al., 2008). Another exciting example of application for such polydentate ligand involves the synergic water activation, that occurs via so-called "remote metallic atoms". Such organometallic compounds are structurally deemed to promote or block the H-I activity (Zeng, Jiang et al., 2008). These explanations clearly demonstrate that polydentate ligands are of specific interest in the field of bioorganometallic chemistry (Patil et al., 2007;Pommier & Neamati, 2006).

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We have undertaken the X-ray diffraction study of the title compound, in order to understand the molecular features which stabilize its conformation. The asymmetric unit contains two crystallographically independent molecules. Each molecule contains three aromatic rings (Fig. 1). The difference between the two molecules lies in the orientations of these three rings and carbonyl groups as shown in the fitting drawing ( The planes of the two carbonyl groups (O11,O12,C141) and (O13,O14,C142) are twisted by a dihedral angles of 18.4 (4)°a nd 88.9 (4)°, respectively, with respect to the (C11,C14,N1) plane. In the second independent molecule, the dihedral angles between the two carbonyls (O21,O22,C241), (O23,O24,C242) and the (C21,C24,N2) plane are 25.9 (4)°, 87.1 (4)°, respectively. The angles between the planes of the two sites of disordered ethyl groups are 83.9 (15)° and 33.0 (2)° in the two molecules of the asymmetric unit.
In the crystal structure, weak intermolecular C-H···O hydrogen bonds (Table 1)
Then the mixture was stirred at refluxing temperature of ethanol for 12 h, until thin-layer chromatography indicated the complete consumption of the starting material. After removing solvent, the crude product was washed with a saturated solution of sodium bisulfite (20 ml). The product was extracted by diethyl ether (2x20 ml), dried with sodium sulphate and evaporated to give the respective pure oil.

supplementary materials sup-2
To a solution of the 2-(4-trifloromethyl-benzylidene)-malonic acid diethyl ester (5 mmol) in water (25 ml) was added the dibenzylamine (6 mmol) in the presence of Acetic acid (0.1% mol) and the mixture and the stirring was continued at room temperature until the complete consume of the starting material (Pommier & Neamati, 2006).
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 was dried with sodium sulphate and then evaporated to give the respective pure compounds as white solids. The residue was purified by recrystallization from a mixture ether/hexane (1:1) to give white solid in 96% yield.
In asymmetric unit, two (of four) ethyl fragments were treated as disordered, and the occupancies of the major parts were initially refined, and then fixed to 0.53 and 0.64, respectively, in the final cycles of the refinement. Similarity restraints with tolerance s.u.s of 0.02 Å were applied to the chemically equivalent bond lengths and angles involving all disordered atoms.
Refinement were carried out using the DFIX, SAME and PART instruction within SHELXL97 (Sheldrick, 2008). Fig. 1. Two independent molecules of the title compound showing the atom-labelling scheme and 30% probability displacement ellipsoids. Only major parts of disordered ethyl groups are shown.

Special details
Experimental. 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.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )