TungstenVI

TungstenVI refers to the oxidation state +6 of tungsten, the highest common oxidation state for the element. In this state, tungsten forms a variety of oxo and halide compounds, and its chemistry is dominated by oxygen ligands in oxoanions and by highly reactive fluorides in some precursors.

Common examples of tungsten(VI) compounds include tungsten trioxide, WO3, a widely studied oxide. In aqueous and acidic media, tungsten(VI) exists as tungstic acid, H2WO4, and forms soluble tungstate salts such as Na2WO4. The coordination chemistry also features oxo anions like [WO4]2− and related polyoxometalates. Well-known tungsten(VI) fluorides and chlorides include tungsten hexafluoride, WF6, a volatile and moisture-sensitive precursor used in chemical vapor deposition, and tungsten hexachloride, WCl6, a volatile halide.

Occurrence: In nature, tungsten exists predominantly in the +6 state within minerals such as scheelite (CaWO4) and wolframite ((Fe,Mn)WO4), which are the principal ore sources for tungsten.

Applications: Tungsten(VI) compounds are important in industry as catalysts for oxidation reactions and as precursors for tungsten oxides and thin films. WF6, for example, is widely used in semiconductor manufacturing for deposition of tungsten-containing films. Tungsten oxide species are also employed in pigments and various catalytic processes.

Safety: Compounds in the +6 state can be hazardous. Fluorides like WF6 react with water to release corrosive HF and oxygen-containing species, requiring careful handling, proper containment, and appropriate protective equipment.