Packing polymorphism in the crystal structure of 4,5-dimethoxy-2-nitrobenzyl acetate

Abstract

The title compound, C11H13NO6, shows two polymorphs, orange and yellow forms, both of which crystallize in the space group P21/c. The molecular structures in the two polymorphs are essentially similar and adopt a planar structure, the maximum deviations for the non-H atoms being 0.1836 (13) and 0.1276 (13) Å, respectively, for the orange and yellow forms. In the orange crystal, molecules are linked by an intermolecular C—H...O interaction into a helical chain along the b-axis direction. The chains are stacked along the c axis through a π–π interaction [centroid–centroid distance = 3.6087 (11) Å], forming a layer parallel to the bc plane. In the yellow crystal, molecules are connected through C—H...O interactions into a sheet structure parallel to (-302). No significant π–π interaction is observed. The unit-cell volume of the orange crystal is larger than that of the yellow one, and this accounts for the predominant growth of the yellow crystal.

Keywords

• crystal structure
• packing polymorphism
• 2-nitrobenzyl ester
• π–π interactions
• C—H...O interactions