sulfiide

Sulfiide refers to a class of chemical compounds containing the sulfide ion (S²⁻), which is composed of a sulfur atom with a −2 oxidation state. These compounds are distinct from sulfides, which are binary compounds of sulfur with less electronegative elements, and from sulfur-containing organic compounds. Sulfiides are primarily found in inorganic chemistry and are characterized by their reactivity and diverse applications.

The sulfide ion (S²⁻) is isoelectronic with oxygen (O²⁻) and selenium (Se²⁻), meaning it has the same number of electrons as these elements in their −2 oxidation states. Sulfiides are typically formed through the reaction of sulfur with metals or metal oxides, often in reducing conditions. For example, hydrogen sulfide (H₂S) can react with metal ions to produce metal sulfiides, such as iron(II) sulfide (FeS) or zinc sulfide (ZnS).

Metal sulfiides exhibit a wide range of physical and chemical properties. Many are insoluble in water and exhibit semiconductor behavior, making them useful in electronics and optoelectronics. For instance, cadmium sulfide (CdS) is a yellow semiconductor used in solar cells and photodetectors. Others, like copper(I) sulfide (Cu₂S), have applications in battery technology and as pigments.

Sulfiides also play a role in environmental processes, particularly in the formation of ores and the behavior of heavy metals in natural systems. Some metal sulfiides are toxic and can pose health risks, particularly in mining and industrial settings where exposure to hydrogen sulfide gas or dust may occur.

In organic chemistry, the term "sulfide" is sometimes used to describe thioethers, which contain a sulfur atom bonded to two carbon atoms (R–S–R). These differ from inorganic sulfiides and are classified separately due to their distinct chemical behavior and applications in organic synthesis.