Crystal Structure of Pinacol Hexahydrate

The crystal structure of pinacol hexahydrate, C6H14O2·6H2O, has been determined at room temperature from diffractometer data with CuKα radiation. The structure is tetragonal space group P42 / mnm, with two formula units per unit cell of dimensions a = b = 6.398(3) Å, c = 15.926(8) Å. The intensity data were measured with CuKα radiation on a Picker FACS I diffractometer. The parameters were refined anisotropically by least squares to a final R = 0.06 for 294 observed reflections. The hydrogen-bonded water and pinacol molecules form a framework structure which is isostructural with that of piperazine hexahydrate. The water molecules form puckered layers consisting of edge-sharing pentagons. These layers are linked into a three-dimensional framework through the hydroxyls of the pinacol molecules. The pinacol molecules are in voids within this framework structure with twofold orientational disorder. Although this is not a clathrate hydrate, there is a marked structural similarity to that series of compounds.