HexamminenickelII

Hexamminenickel(II) is an inorganic coordination compound with the chemical formula [Ni(NH₃)₆]Cl₂. It consists of a central nickel(II) ion coordinated to six ammonia ligands, forming the complex cation [Ni(NH₃)₆]²⁺. The counterions are chloride ions. This compound is typically encountered as a blue crystalline solid.

The synthesis of hexamminenickel(II) often involves reacting a nickel(II) salt, such as nickel(II) chloride, with an excess of ammonia. The ammonia molecules displace other ligands, or in some cases, solvate the nickel ion, leading to the formation of the hexammine complex. This reaction can be carried out in aqueous or alcoholic solutions.

Hexamminenickel(II) is soluble in water, forming a blue solution. In the presence of acids, the ammonia ligands are protonated, leading to the dissociation of the complex and the release of free ammonia. This property can be used for qualitative analysis of nickel ions. The compound is relatively stable under normal conditions but can decompose upon heating, releasing ammonia gas and leaving behind nickel(II) compounds. Its magnetic properties are consistent with a high-spin d⁸ electronic configuration for the nickel(II) ion in an octahedral ligand field.