On the reaction of W3O with iodine: Preparation, crystal structure, and properties of WOI3

The novel tungsten oxide iodide WOI3 is obtained from the reaction of the metal-rich tungsten oxide W3O (also known as 'β-tungsten') with iodine in a sealed glass tube placed in a temperature gradient (440-400 0C). In the low-temperature region WOI3 is formed as mouse-grey intergrown needle-like crystals. WOI3 crystallizes in the tetragonal NbOCl3 structure type, space group P42/mnm, with a = 12.346(2), c = 3.765(1) A (20 0C). The crystal structure at -130 0C was determined from single-crystal diffractometer data (R = 0.023). Results of magnetic susceptibility and vibrational spectroscopic measurements are given together with the mass spectrum of WOI3 obtained on heating. (author)