Different supramolecular interactions mediated by Br atoms in the crystal structures of three anisole derivatives

Three anisole building blocks featuring bis(hydroxymethyl) or bis(bromomethyl) pendants have been analyzed with regard to their molecular structures and packing behaviour. The compounds are ethyl 3,5-bis(hydroxymethyl)-4-methoxybenzoate, C₁₂H₁₆O₅, (I), [5-bromo-3-(hydroxymethyl)-2-methoxyphenyl]methanol [or 4-bromo-2,6-bis(hydroxymethyl)anisole], C₉H₁₁BrO₃, (II), and 5-bromo-1,3-bis(bromomethyl)-2-methoxybenzene [or 4-bromo-2,6-bis(bromomethyl)anisole], C₉H₉Br₃O, (III). A typical supramolecular pattern involved C-H...π interactions generating molecular stacks, while π-π interactions were only observed in the absence of bromine, indicating a striking influence on the distances between adjacent aromatic moieties. When comparing bis(hydroxymethyl) compound (II) with bis(bromomethyl) compound (III), we found that the strong O-H...O hydrogen bonds in a zigzag arrangement in the first are replaced by C-H...Br interactions in the second without a change in the general packing.