Crystal structure of a clathrate inclusion compound of hydroquinone and hydrogen sulphide

Abstract

The crystal structure of a β-hydroquinone clathrate of stoicheiometry 3C₆H₄(OH)₂·xH₂S (x= 0.768) has been determined from three-dimensional X-ray data. The hydrogen-bonded [OH]₆hexagonal rings are nearly but not exactly planar, and a difference map revealed an ordered proton arrangement. The clathration cavity is roughly, spherical with a free diameter of ca. 4.8 Å. Analysis of the thermal parameters showed that the hydroquinone molecule behaves as a rigid body, and that vibration of the S atom is very pronounced, particularly in the direction of the c axis. The structure was refined by full-matrix anisotropic least-squares to R 0.089 for 635 visual reflections. Crystals are rhombohedral, space group R, with Z= 3 in a hexagonal unit cell of dimensions: a= 16.67(1) and c= 5.518(5)Å. Bond distances and angles are all as expected.