Crystal structures and Hirshfeld surface analyses of 6,8-dimethoxy-3-methyl-1H-isochromen-1-one and 5-bromo-6,8-dimethoxy-3-methyl-1H-isochromen-1-one chloroform monosolvate

Abstract

In the molecule of 6,8-dimethoxy-3-methyl-1H-isochromen-1-one, C12H12O4, (I), the two methoxy groups are directed anti with respect to each other. In the molecule of the brominated derivative, 5-bromo-6,8-dimethoxy-3-methyl-1H-isochromen-1-one, that crystallized as a chloroform monosolvate, C12H11BrO4·CHCl3, (II·CHCl3 ), the methoxy groups are directed syn to each other. In the crystal of I, molecules are linked by bifurcated C—H...O hydrogen bonds, forming chains along the c-axis direction. The chains are linked by C—H...π interactions, forming a supramolecular framework. In the crystal of II·CHCl3 , molecules are linked by C—H...O hydrogen bonds forming 21 helices parallel to the b-axis direction. The chloroform solvate molecules are linked to the helices by C—H...O(carbonyl) hydrogen bonds. The helices stack up the c-axis direction and are linked by offset π–π interactions [intercentroid distance = 3.517 (3) Å], forming layers parallel to the (100) plane. Compound II·CHCl3 was refined as a two-component twin. Two chlorine atoms of the chloroform solvate are disordered over two positions and were refined with a fixed occupancy ratio of 0.5:0.5.