The polar (WO(sub 2)F(sub 4))(super 2-) anion in the solid state

The polar (WO(sub 2)F(sub 4))(super 2-) anion is crystallized with two different cations in the solid state to order one of the two W=O bonds. Close examination of bond lengths and anisotropic thermal ellipsoids in disordered (WO(sub 2)F(sub 4))(super 2-) compounds elucidates the disorder mechanisms and suggests strategies for eliminating orientational disorder. The anion is inherently acentric and consists of polarizable W=O bonds.