PCl6

PCl6 refers to the hexachlorophosphate anion, [PCl6]-. It is an inorganic chemical species composed of one phosphorus atom and six chlorine atoms, with an overall negative charge. The phosphorus atom is located at the center of an octahedron, with the six chlorine atoms positioned at the vertices. This symmetrical structure is a common motif for anions with a central atom surrounded by six ligands.

The hexachlorophosphate anion is typically encountered as a counterion in various salts. Examples include potassium hexachlorophosphate (K[PCl6]), cesium hexachlorophosphate (Cs[PCl6]), and tetrabutylammonium hexachlorophosphate ([N(C4H9)4][PCl6]). These salts are often crystalline solids and their properties vary depending on the cation.

[PCl6]- is generally considered a stable anion, particularly in anhydrous conditions. However, in the presence of water, it can undergo hydrolysis, leading to the formation of various phosphorus oxychlorides and hydrochloric acid. This reactivity is a consideration when handling hexachlorophosphate compounds.

The synthesis of hexachlorophosphate salts often involves the reaction of phosphorus pentachloride (PCl5) with a suitable chloride salt in a non-aqueous solvent, such as sulfuryl chloride or thionyl chloride. The reaction typically proceeds through the formation of PCl6- as an intermediate or product. Due to the corrosive nature of the reactants and products involved, these syntheses are usually conducted under controlled laboratory conditions.