Crystal structure of 4-bromo-cinnamic anhydride

In the crystal, mol-ecules of the title compound [systematic name: (E)-3-(4-bromo-phen-yl)prop-2-enoyl (E)-3-(4-bromo-phen-yl)prop-2-enoate], C₁₈H₁₂Br₂O₃, reside across twofold axes passing through the central O atom of the C(O)-O-C(O) linkage [Z' = ½]. The mol-ecule framework adopts an E configuration across the C=C bonds and a gauche conformation across the anhydride bridge, with a O-C-O-C torsion angle of 31.70 (11)°. The three-dimensional supra-molecular structure is governed by the inter-play of C-H⋯O hydrogen bonds and slipped stacking inter-actions involving carbon-yl/C₆H₄Br and anti-parallel C₆H₄Br/C₆H₄Br pairs. Hirshfeld surface and fingerprint plot analyses reveal major contributions from Br⋯H/H⋯Br and O⋯H/H⋯O contacts. The largest inter-action energies (up to -48.9 kJ mol^-1) are associated with stacking of the mol-ecules, which highlight the dispersion-dominated stabilization. The comparable energetics of hydrogen-bonded pairs (-37.9 kJ mol^-1) is a result of as many as four synergetic geometrically favorable C-H⋯O inter-actions. The study represents the first structural characterization of a p-halogenated cinnamic anhydride and these findings could be applicable to crystal design with cinnamic derivatives.