Crystal structure of bis(4-methoxyphenyl) malonate

The complete molecule of the title compound, C17H16O6, is generated by crystallographic twofold symmetry, with the central methylene C atom lying on the rotation axis. The carbonyl O atom is disordered over two adjacent positions in a 0.63 (3):0.37 (3) ratio and the dihedral angle between the benzene rings in the two halves of the molecule is 79.31 (12)°. In the crystal, molecules are connected by C—H⋯O hydrogen bonds, generating (110) sheets. Very weak intrasheet C—H⋯π interactions are also observed.


S2. Structural commentary
The molecules of the title compound, C 17 H 16 O 6 , show two fold rotation symmetry, for which the 2-fold rotation crystallographic axis passes through the C9 atom (with symmetry code -x, y, -z+1/2). The asymmetric unit of the title compound contains half molecule. The carbonyl oxygen atom is disordered over two positions due to crystallographic 2fold rotation axis (orientational disorder), the occupancy ratio being 0.63 (3)

S3. Supramolecular features
In the crystal structure, the molecules are connected via C9-H9···O3 intermolecular interactions running into C(4) chains along crystallographic a and b axis, thus forming sheets in the ab plane. These sheets are further stabilized by C4 -H4···pi and C7-H7···pi interactions (where Cg is the centroid of the phenyl ring)along [010], and thus, a two dimensional architecture is observed.

S4. Synthesis and crystallization
A mixture of malonic acid (1 mmol) and phosphorous oxychloride (POCl 3 ) was stirred for about an hour at 30°C . To this mixture, 4-methoxyphenol (2 mmol) was added and the reaction mixture was heated to 50°C for 30 minutes. The reaction mixture was poured into crushed ice and the solid obtained was thoroughly washed with water, dilute sodium hydroxide and again with water.
Colourless blocks of the title compound were obtained from slow evaporation technique using methanol as the solvent.

S5. Refinement details
Crystal data, data collection and structure refinement details are summarized in Table 1 The molecular structure of the title compound, showing displacement ellipsoids drawn at the 50% probability level.

Figure 2
The molecular packing of the title compound when viewed along c axis. Dashed lines indicate intermolecular C-H···O interactions.

Figure 3
The molecular packing of the title compound when viewed along a axis. Dashed lines indicate intermolecular C-H···π interactions.