Plumbate

In chemistry, a plumbate often refers to compounds that can be viewed as derivatives of the hypothetical PbO3(2-) anion.

Halides
Salts of ([PbI3]−)_{n}, [Pb6I16](4-), [Pb18I44](8-), etc. are labeled as iodoplumbates. Lead perovskite semiconductors are often described as plumbates.

Lead oxyanions
Plumbates are formed by the reaction of lead(IV) oxide, PbO2, with alkali. Plumbate salts contain either the hydrated hexahydroxoplumbate(IV) or plumbate anion [Pb(OH)6](2-), or the anhydrous anions PbO3(2-) (metaplumbate) or PbO4(4-) (orthoplumbate). For example, dissolving PbO2 in a hot, concentrated aqueous solution of potassium hydroxide forms the potassium hexahydroxoplumbate(IV) salt K2[Pb(OH)6]. The anhydrous salts may be synthesized by heating metal oxides or hydroxides with PbO2.

The most widely discussed plumbates are derivatives of barium metaplumbate BaPbO3. When doped with some bismuth in place of lead, the material BaPb0.95Bi0.05O3 exhibits superconductivity at 13 K. At the time of this discovery, oxides did not show such properties. The surprise associated with this work was eclipsed by the advent of the cuprate superconductors.

Binary lead oxides
Lead tetroxide ("red lead"), a valence-mixed oxide with formula Pb3O4 (red), may be thought of as lead(II) orthoplumbate(IV), [Pb(2+)]2[PbO4(4-)]. Lead sesquioxide, Pb2O3, is also known (reddish yellow), and has the structure of lead(II) metaplumbate(IV), [Pb(2+)][PbO3(2-)].