ChromiumIV

Chromium(IV) is the oxidation state of chromium in which the element has a formal valence of +4. This oxidation state is much less common than chromium(III) and chromium(VI) and is found in a smaller subset of compounds. The most well-known example is chromium(IV) oxide, CrO2, a solid that exhibits ferromagnetism at room temperature and has historical significance in magnetic tape technology.

In Cr(IV) compounds, chromium typically adopts a d2 electronic configuration, which influences magnetic properties and reactivity. Cr(IV) species can act as intermediates in oxidation or catalytic processes, and they often behave as oxidants relative to Cr(III) but can be less stable than Cr(VI) or Cr(III) in common environments. Their chemical behavior is strongly influenced by the ligands bound to chromium and by the surrounding matrix, which can stabilize the +4 state in oxo- or fluoride-rich environments.

Occurrence and preparation: Beyond CrO2, Cr(IV) motifs appear in inorganic and organometallic chemistry. Many Cr(IV) compounds are prepared under controlled conditions and can be air- or moisture-sensitive, requiring stabilizing ligands or low temperatures to be isolated.

Applications: Cr(IV) chemistry is primarily of interest in research contexts. CrO2’s historical use in magnetic storage remains the most notable example, while contemporary work explores oxidation states, spin states, and catalytic activity in Cr(IV) systems.

Safety: Like other chromium compounds, Cr(IV) substances require careful handling due to potential toxicity and environmental hazards. Hexavalent chromium is a well-known carcinogen, and Cr(IV) compounds are treated with appropriate caution, with attention to material-specific hazards.