Hybrid and Inorganic Vacancy-Ordered Double Perovskites A₂WCl₆

We report hybrid and all-inorganic, vacancy-ordered double perovskites of d(2) W4+ with the formula A(2)WCl(6) (A = CH3NH3+, Rb+, and Cs+). These compounds, which are reddish in color, can be distinguished from structurally similar compounds obtained by hydrothermal methods on the basis of structure, spectroscopic, and magnetic properties. The latter are green and incorporate oxygen, with the actual formula Cs2WO x Cl6-x and distinct optical absorption and emission behavior. The local-moment magnetism of the pure-red d(2) compounds reported here does not correspond to the appropriate Kotani model, suggesting as-yet undiscovered physics in these systems.