Chromium(II) bromide

Chromium(II) Bromide

Chromium(II) bromide is an inorganic compound with the chemical formula CrBr₂. It is one of the several bromides of chromium and is known for its distinctive properties and uses in various chemical reactions.

Properties

Chromium(II) bromide is a dark green crystalline solid. It is a paramagnetic compound, which means it has unpaired electrons and is attracted to magnetic fields. The compound is typically prepared by the reduction of chromium(III) bromide (CrBr₃) using hydrogen gas or by the direct combination of chromium metal and bromine.

Chemical Structure

Chromium(II) bromide adopts a layered structure similar to that of cadmium chloride (CdCl₂). In this structure, each chromium atom is surrounded by six bromine atoms, forming an octahedral geometry. The layers are held together by van der Waals forces, allowing them to be easily cleaved.

Synthesis

Chromium(II) bromide can be synthesized through several methods:

• Reduction of Chromium(III) Bromide:

 \[
 \text{CrBr}_3 + \frac{1}{2} \text{H}_2 \rightarrow \text{CrBr}_2 + \text{HBr}
 \]
 This reaction involves the reduction of CrBr₃ using hydrogen gas.

• Direct Combination:

 \[
 \text{Cr} + \text{Br}_2 \rightarrow \text{CrBr}_2
 \]
 This method involves the direct reaction of chromium metal with bromine.

Applications

Chromium(II) bromide is used in various chemical reactions, particularly in organic synthesis. It serves as a reducing agent and is involved in the formation of carbon-carbon bonds. Its ability to donate electrons makes it useful in the reduction of organic compounds.

Safety and Handling

Chromium(II) bromide should be handled with care, as it can be hazardous to health. It is important to use appropriate personal protective equipment (PPE) such as gloves and goggles when handling the compound. It should be stored in a cool, dry place, away from moisture and incompatible substances.

Also see

• Chromium(III) bromide
• Chromium compounds
• Inorganic chemistry
• Paramagnetism