Lead(II) hydroxide


Lead hydroxide, Pb2, is a hydroxide of lead, with lead in oxidation state +2. It is doubtful that such a simple compound exists. Lead basic carbonate or lead oxide is encountered in practice where lead hydroxide is expected. This has been a subject of considerable confusion in the past.

Preparation

When a hydroxide is added to a solution of a lead salt, a hydrated lead oxide PbO·xH2O is obtained. Careful hydrolysis of lead acetate solution yields a crystalline product with a formula 6PbO·2H2O = Pb6O44. This material is a cluster compound, consisting of an octahedron of Pb centers, each face of which is capped by an oxide or a hydroxide. The structure is reminiscent of the Mo6S8 subunit of the Chevrel phases.

Reactions

In solution, lead hydroxide is a somewhat weak base, forming lead ion, Pb2+, under weakly acidic conditions. This cation hydrolyzes and, under progressively increasing alkaline conditions, forms Pb+, Pb2, Pb3−, and other species, including several polynuclear species, e.g., Pb444+, Pb342+, Pb6O64+.

Lead hydrate

The name Lead hydrate has sometimes been used in the past but it is unclear whether this refers to Pb2 or PbO·xH2O.