Molybdenum pentachloride is an inorganic compound with the chemical formula MoCl₅. It is a dark green or gray-black crystalline powder that is stable at room temperature but readily absorbs moisture in moist air and converts to hydrochloric and molybdenum acids. Molybdenum pentachloride is a strong oxidizing agent that can react with many metallic and non-metallic elements.

Molybdenum pentachloride is a versatile compound with a wide range of applications in chemical synthesis, catalysis and materials science. Here are some of the main uses of molybdenum pentachloride:

1. Catalyst: Molybdenum pentachloride is commonly used as a chlorinating agent and catalyst in organic synthesis, especially in the chlorination reaction of hydrocarbons. It is also used to catalyze the chlorination of olefins, polymerization reactions, and the chlorination of alcohols and ketones.

2. Materials Science: Molybdenum pentachloride is used in the production of other molybdenum compounds, such as oxides and salts, which are used in high-temperature lubricants, ceramic materials, pigments, and electronic materials.

3. Petroleum refining: In the petrochemical industry, molybdenum pentachloride can be used as a catalyst in catalytic cracking, isomerization, and other refining processes to improve the yield and quality of gasoline and other petroleum products.

4. Research uses: In academic and industrial research, molybdenum pentachloride is used to explore new chemical reactions and catalytic mechanisms, as well as to develop new catalytic materials.

5. Pharmaceutical and biochemistry: Although not a major field of application, molybdenum pentachloride is sometimes used in pharmaceutical and biochemical research, for example as a chlorinating agent or catalyst in the synthesis of biologically active compounds.

6. Metallurgical industry: Molybdenum pentachloride can be used in metallurgical processes as a raw material for extracting and refining molybdenum metal.