Nickel(II) nitrate

Nickel nitrate is the inorganic compound Ni(NO3)2 or any hydrate thereof. In the hexahydrate, the nitrate anions are not bonded to nickel. Other hydrates have also been reported: Ni(NO3)2.9H2O, Ni(NO3)2.4H2O, and Ni(NO3)2.2H2O.

It is prepared by the reaction of nickel oxide with nitric acid:
 * NiO +  2 HNO3  +  5 H2O    →    Ni(NO3)2.6H2O

The anhydrous nickel nitrate is typically not prepared by heating the hydrates. Rather it is generated by the reaction of hydrates with dinitrogen pentoxide or of nickel carbonyl with dinitrogen tetroxide:
 * Ni(CO)4 +   2 N2O4   →   Ni(NO3)2  +  2 NO  +  4 CO

The hydrated nitrate is often used as a precursor to supported nickel catalysts.

Structure
Nickel(II) compounds with oxygenated ligands often feature octahedral coordination geometry. Two polymorphs of the tetrahydrate Ni(NO3)2.4H2O have been crystallized. In one the monodentate nitrate ligands are trans while in the other they are cis.

Reactions and uses
Nickel(II) nitrate is primarily used in electrotyping and electroplating of metallic nickel.

In heterogeneous catalysis, nickel(II) nitrate is used to impregnate alumina. Pyrolysis of the resulting material gives forms of Raney nickel and Urushibara nickel. In homogeneous catalysis, the hexahydrate is a precatalyst for cross coupling reactions.