Cobalt nitrate is an inorganic compound with the formula Co(NO3)2.xH2O, which is cobalt(II)’s salt. It is most often found as the hexahydrate Co(NO3)2*6H2O, a red-brown deliquescent crystal that dissolves in water and other polar solvents. Several other hydrates exist, with the chemical formula Co(NO3)2*nH2O where n = 0, 2, 4, and 6. Anhydrous cobalt(II) nitrate adopts a three-dimensional polymeric network structure, with each cobalt (II) atom approximately octahedrally coordinated by six oxygen atoms from nitrate ions, each nitrate ion coordinating to two cobalt atoms.
Cobalt(II) nitrate is used as a surface treatment and in the manufacture of cobalt pigments, invisible inks, stoneware, and porcelain. It is also used in the plating industry and as a catalyst.
When inhaled, this substance can cause irritation of the nose and throat and bronchoconstriction. Chronic exposure can result in asthma. This chemical is also corrosive to metals and is toxic to aquatic organisms.
When administered to guinea pigs, cobalt(II) nitrate causes an increase in the number of endocrine islands of the pancreas. The majority of the alpha cells are degranulated with nuclei surrounded by colorless cytoplasm, but beta cells remain normal. This effect is similar to that produced by cobaltous chloride. Injection of cobalt(II) nitrate to rats sc twice over 24 hr increased the erythropoietic activity of the serum and reduced renal blood flow. It also caused a decrease in the maximal response of cholinergic receptors to a muscarinic agonist. The authors conclude that this cobalt(II) nitrate toxicity in rats is not related to its bioavailability in human plasma or urine because the toxicity was observed even at a low concentration of the compound.