A comparative study of the crystal structures of tetrahalogenated hydroquinones and γ-hydroquinone

Abstract

γ-Hydroquinone (1) and its tetrafluoro, tetrachloro and tetrabromo derivatives (2), (3) and (4) adopt crystal structures that have an almost invariant system of O-HO hydrogen bonds. However, within this O-H…O framework, the four structures display variations that are characteristic of the C-H, C-F, C-Cl and C-Br groups. In the parent compound (1) aromatic rings are packed with a herringbone geometry, whilst in the halogenated derivatives (3) and (4), polarization-type halogenhalogen contacts are optimized. The fluoro derivative (2) is exceptional in that neither of the above possibilities is adopted, even though the O-H…O scaffolding does not per se prohibit either of them geometrically.γ-Hydroquinone (1) and its tetrafluoro, tetrachloro and tetrabromo derivatives (2), (3) and (4) adopt crystal structures that have an almost invariant system of O-HO hydrogen bonds. However, within this O-H…O framework, the four structures display variations that are characteristic of the C-H, C-F, C-Cl and C-Br groups. In the parent compound (1) aromatic rings are packed with a herringbone geometry, whilst in the halogenated derivatives (3) and (4), polarization-type halogenhalogen contacts are optimized. The fluoro derivative (2) is exceptional in that neither of the above possibilities is adopted, even though the O-H…O scaffolding does not per se prohibit either of them geometrically.