HexaamminenickelII

Hexaamminenickel(II) is an inorganic compound with the chemical formula [Ni(NH₃)₆]Cl₂. It is a coordination complex where a central nickel(II) ion is surrounded by six ammonia ligands. The counterions are chloride ions. This compound typically appears as a pale violet or blue crystalline solid. It is soluble in water, forming a blue solution, and also dissolves in liquid ammonia.

The preparation of hexaamminenickel(II) chloride often involves reacting a nickel(II) salt, such as nickel(II) chloride hexahydrate, with an excess of aqueous ammonia. The ammonia ligands replace the water molecules coordinated to the nickel ion.

Hexaamminenickel(II) chloride is a paramagnetic compound due to the presence of unpaired electrons in the nickel(II) ion's d-orbitals. In solution, it can undergo ligand exchange reactions, where the ammonia ligands are replaced by other ligands. It is sometimes used as a source of nickel(II) ions in aqueous solutions or as a precursor in the synthesis of other nickel-containing compounds. The compound is relatively stable under normal conditions but can decompose upon heating, releasing ammonia gas.