Séminaire de Michael HAYWARD
Inorganic Chemistry Laboratory, University of Oxford, UK
Titre : « Low-temperature Topochemical Reactions as a Route to Novel Electronic Materials»
Lieu : Amphi ICMCB
Résumé :
The vast majority of complex solids are prepared at high temperatures under reaction conditions that apply ‘thermodynamic control’ to the selection of reaction products. This approach limits the range of solid phases which can be prepared. By utilizing the differences in mobility of the constituent species which make up a solid phase, it is possible to modify existing solids and thus apply kinetic control to product selection and prepare a wide range of metastable phases which extend the chemical and structural diversity of solid compounds.
By applying this synthetic strategy to transition metal oxides it is possible prepare extended solids containing transition metal cations with unusual combinations of oxidation state and coordination geometry (e.g. square-planar Ni1+, Fe2+, Ru2+, Ir2+). In addition, these conditions can also facilitate the substitution of oxide anions by hydride anions, to form transition-metal oxyhydride phases.
The structures and physical properties of a range of novel 3d and 3d/4d and 3d/5d reduced transition-metal oxides and oxyhydrides will be described along with the reactions that are used to prepare them.