nickeldichloride

Nickel dichloride, or nickel(II) chloride, is an inorganic salt with the formula NiCl2. It occurs predominantly as anhydrous NiCl2 and as hydrates, most commonly nickel dichloride hexahydrate, NiCl2·6H2O. The solid forms are typically green to blue‑green crystals, and in water it forms the hexaaquanickel(II) ion [Ni(H2O)6]2+, which imparts a blue color to solutions.

Preparation and properties

NiCl2 can be prepared by direct chlorination of nickel metal:

Ni + Cl2 → NiCl2

It can also be obtained by dissolving nickel or nickel-containing material in hydrochloric acid under appropriate conditions and crystallizing the nickel(II) chloride hydrate from the solution. In solution, NiCl2 behaves as a typical nickel(II) salt, providing Ni2+ ions that form various coordination complexes with ligands such as amines and phosphines. The compound serves as a versatile nickel(II) source in inorganic and organometallic synthesis.

Uses

NiCl2 is widely used as a precursor to other nickel complexes and compounds. In the laboratory, it is employed in catalytic applications, including nickel-catalyzed cross-coupling and hydrogenation reactions, and as a starting material for preparing nickel-containing catalysts. It also serves in electroplating and electrodeposition processes to introduce nickel coatings and as a reagent in materials science and coordination chemistry.

Safety

Nickel compounds, including NiCl2, can be irritants and sensitizers and may cause dermatitis upon skin contact. They pose inhalation and ingestion hazards and are subject to regulatory controls due to potential carcinogenicity of nickel compounds. Proper handling requires gloves, eye protection, ventilation, and avoidance of inhalation, with waste disposed of according to local regulations.