Multidimensional mixed anion materials and their intercalation chemistry

Mixed anion materials have become a very interesting field of study for solid state chemists due to the large number of variables and wealth of tunable properties. Utilizing more than one anion allows for modification of ion size, crystal structures, metal oxidation states, electronic and magnetic properties. One specific system which will be the focus of much of this talk are the tungsten oxyhalides. The end members WCl6 and WO3 are molecular and 3D extended structures respectively, as seen in the figure below. Once multiple anions are coordinated to the tungsten center, the material can form either 1D chains of WOCl4 or 2D sheets of WO2Cl2. These materials include robust tungsten oxygen linkages which are also useful in understanding the bonding and changes that occur upon reaction of these materials. Intercalation chemistry in these materials has also shown promise for new ways to modify the properties of the host material as well as development of new materials with multiple metal sites and complex behavior. Through intercalation chemistry, we have observed a variety of physical, electronic, and magnetic properties that can be easily tuned through changes in the halide (Cl, Br, or I) or using simple intercalation chemistry where ions are inserted between the metal oxide matrix. In addition, by studying the underlying intercalation reactions, we can improve our knowledge of the reaction kinetics and the limiting factors in these reactions which will lead to novel materials with a broader range of intercalation species.