HgBr2

Mercury(II) bromide, HgBr2, is an inorganic compound of mercury in the +2 oxidation state. It consists of Hg2+ ions coordinated to two bromide ligands. In the solid state, HgBr2 forms a red-to-brown crystalline material and is sparingly soluble in water, with greater solubility in some organic solvents. The compound has a molar mass of approximately 360.4 g/mol.

Preparation and structure: HgBr2 can be prepared by direct reaction of elemental mercury with bromine at elevated temperature: Hg + 2 Br2 → HgBr2. It can also arise via halide exchange from mercury(II) salts, for example HgCl2 + 2 HBr → HgBr2 + 2 HCl. In the solid, mercury(II) bromide commonly adopts a polymeric network rather than discrete diatomic molecules.

Uses and reactions: HgBr2 is used mainly as a laboratory reagent in inorganic synthesis and in older organic chemistry as a source of bromide and as a precursor to other mercury compounds. It has been employed in certain specialized reactions as a brominating reagent and in the preparation of organomercury compounds, though its use has diminished due to toxicity and environmental concerns.

Safety and regulatory: Mercury(II) bromide is highly toxic. Mercury compounds can cause serious health effects through inhalation, ingestion, or skin contact. It should be handled in a fume hood with appropriate personal protective equipment, and waste must be collected as hazardous mercury-containing waste and disposed of according to applicable regulations. Environmental release should be avoided.