Crystal structure of 4-bromophenyl-2-oxo-2H-chromene-3-carboxylate

In the title compound, C16H9BrO4, the coumarin ring system is approximately planar, with an r.m.s deviation of the ten fitted non-H atoms of 0.031 Å, and forms a dihedral angle of 25.85 (10)° with the bromobenzene ring. The carbonyl atoms are syn. In the crystal, molecules are connected along [001] via C—H⋯O interactions, forming C(6) chains. Neighbouring C(6) chains are connected via several π–π interactions [range of centroid–centroid distances = 3.7254 (15)–3.7716 (16) Å], leading to sheets propagating in the bc plane.


S4. Synthesis and crystallization
Coumarin 3-carboxylic acid (1.0 mmol), 4-bromophenol (1.0 mmol) and a catalytic amount of N,N-dimethylaminopyrimidine (DMAP) were dissolved in anhydrous CH 2 Cl 2 . To this solution, a solution of dicyclohexylcarbodimide (DCC) in dried CH 2 Cl 2 was added and stirred. After 24 h of stirring, dicyclohexylurea was filtered off and the solution was concentrated. The solid residue obtained was purified by column chromatography on silica gel using CHCl 3 as the eluent.
Single crystals suitable for X-ray studies were grown by slow evaporation technique at room temperature using ethanol as the solvent.

S5. Refinement
The H atoms were positioned with idealized geometry using a riding model with C-H = 0.93Å, and with 1.2U eq (C).

Figure 1
The molecular structure of the title compound, showing the atom labelling and displacement ellipsoids drawn at the 50% probability level.

Figure 2
The Various π-π interactions observed in the crystal packing