Similarities and differences between bis[2-(bromomethyl)phenyl] diselenide, bis[2-(chloromethyl)phenyl] diselenide and bis[2-(hydroxymethyl)phenyl] diselenide.

The title compounds, C14H12Br2Se2, (I), C14H12Cl2Se2, (II), and C14H14O2Se2, (III), feature a diselenide bridge between two o-benzyl bromide [in (I)], two o-benzyl chloride [in (II)] or two o-benzyl alcohol units [in (III)]. In the molecular structure of (I) and in both independent molecules of (II), close contacts are observed between the halogen centres and the diselenide unit. In the case of modification (IIIa), strong hydrogen bonds between the -OH groups dominate, whereas the molecular structures of modification (IIIb) and bis{2-[(dimethylamino)methyl]phenyl} diselenide, C18H24N2Se2, (IV), are comparable with those of (I) and (II). A correlation between the strength of the contacts and the angle between the benzene planes and the Se-Se units is found.