NiCl42

NiCl42 refers to the tetrachloridonickelate(II) complex anion, [NiCl4]2-. It consists of a nickel(II) center coordinated by four chloride ligands in a tetrahedral geometry, giving the overall 2− charge. This species commonly appears in chloride-rich solutions or as the anionic component of salts such as K2[NiCl4] and (NH4)2[NiCl4].

In solution, [NiCl4]2− is the predominant nickel(II) complex when chloride concentration is high. The four-coordinate, tetrahedral coordination is favored under these conditions, whereas other nickel(II) chloride species may form under different ligand environments. In solid form, salts containing the [NiCl4]2− anion can be isolated, typically paired with alkali or ammonium countercations.

Chemically, nickel in this complex is in the +2 oxidation state and the ion is paramagnetic, possessing two unpaired electrons. The complex is part of broader nickel chloride coordination chemistry and serves as a convenient reservoir of Ni2+ in chloride media. Its properties, including magnetic behavior and electronic spectra, are influenced by the tetrahedral ligand field created by the chloride ligands.

Preparation and use: [NiCl4]2− can be generated by reacting Ni2+ sources with excess chloride, such as NiCl2 in concentrated chloride solutions. It functions as a source of nickel(II) in chloride-rich media and is used in inorganic synthesis and catalysis studies as a reagent and precursor for further nickel complexes.

Safety: Nickel compounds, including coordination complexes like [NiCl4]2−, can be toxic and pose health risks with prolonged exposure. They should be handled with appropriate protective equipment and disposed of according to hazardous waste guidelines.