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.