Chalcogenides, lead compounds

Ternary and quaternary rare earth—lead compounds in the R2X3—PbX and R2X3-Cu2X-PbX (X = S, Se) systems are listed in Table 58. The ternary and quaternary chalcogenides have very similar structures for... 

The compounds HgaY2X2 (Y = S, Se, Te X = Cl, Br, I) are insoluble in water, dilute acids, and cone. HCl, and they are not attacked by these solvents. Cone. HNO3 converts the sulfide chloride into the sulfide nitrate HgsSalNOsla (20, 290). With bases, rapid decomposition occurs, leading to the formation of oxide chacogenides (20), or a mixture of oxide and chalcogenide (111), a matter on which agreement has not yet been reached. 

Basically, when analysing the band structures, the equivalent observations apply to typical solid state compounds like thallium halides and lead chalcogenides. In studies on the origin of distortion in a-PbO, it was found that the classical theory of hybridization of the lead 6s and 6p orbitals is incorrect and that the lone pair is the result of the lead-oxygen interaction [44]. It was also noted... 

Thiosulphate and sulphite are sufficiently reducing to reduce Cu to Cu. Therefore the Cu in solutions of Cu containing sufficient thiosulphate, seleno-sulphate, or sulphite should be predominantly in the monovalent form. This would lead to the expectation that the main product will be something close to Cu2S(e). While this is often the case, CuS(e) is deposited in some cases. However, it is arguable whether this reduction of Cu is, in fact, important in practice. The reason is based on an XPS study that showed that Cu in its compounds with S, Se, and Te is normally in the monovalent state it is the chalcogenide ion (or polyion) that is believed to change oxidation states in these compounds [41]. 

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