Iron(II) hydroxide
Iron(II) hydroxide or ferrous hydroxide is an inorganic compound with the formula Fe(OH). It is produced when iron(II) salts, from a compound such as iron(II) sulfate, are treated with hydroxide ions. Iron(II) hydroxide is a white solid, but even traces of oxygen impart a greenish tinge. The air-oxidized solid is sometimes known as "green rust".
Lead
Lead monoxide exists in two polymorphs, litharge α-PbO (red) and massicot β-PbO (yellow), the latter being stable only above around 488 °C. Litharge is the most commonly used inorganic compound of lead. There is no lead(II) hydroxide; increasing the pH of solutions of lead(II) salts leads to hydrolysis and condensation.
Lead commonly reacts with heavier chalcogens. Lead sulfide is a semiconductor, a photoconductor, and an extremely sensitive infrared radiation detector. The other two chalcogenides, lead selenide and lead telluride, are likewise photoconducting. They are unusual in that their color becomes lighter going down the group.
Lead dihalides are well-characterized; this includes the diastatide, and mixed halides, such as PbFCl. The relative insolubility of the latter forms a useful basis for the gravimetric determination of fluorine. The difluoride was the first solid ionically conducting compound to be discovered (in 1834, by Michael Faraday). The other dihalides decompose on exposure to ultraviolet or visible light, especially the diiodide. Many lead(II) pseudohalides are known, such as the cyanide, cyanate, and thiocyanate. Lead(II) forms an extensive variety of halide coordination complexes, such as [PbCl], [PbCl], and the [PbCl] chain anion.