Crystal structures of (1E,4E)-1,5-bis-(5-bromo-thio-phen-2-yl)-2,4-di-methyl-penta-1,4-dien-3-one and (E)-4-(5-bromo-thio-phen-2-yl)-1,3-di-phenyl-but-3-en-2-one.

The title compounds, C15H12Br2OS2, (I), and C20H15BrOS, (II), were synthesized by employing Claisen-Schmidt condensation of pentan-3-one and di-benzyl-acetone with 5-bromo-thio-phene-2-carbaldehyde in the presence of methano-lic KOH. Even though 1:2 products were expected in both of the reactions, 1:2 and 1:1 products were obtained as (I) and (II), respectively. In (I), the two methyl groups are trans to each other, 29.5 (7) and 28.7 (7)° away from the central carbonyl bond between them, whereas the two phenyl rings of di-benzyl-acetone subtend a dihedral angle of 53.09 (18)°. In the crystal of (I), C-H⋯O hydrogen bonds define mol-ecular chains along c. A second type of mol-ecular chain is formed along b by means of C-Br⋯π inter-actions. These two families of mol-ecular chains are stacked by π-π inter-actions, forming a three-dimensional supra-molecular architecture. In (II), similar C-H⋯O hydrogen bonds as in (I) define inversion dimers, whilst C-H⋯.π inter-actions build a staircase structure along the a axis.