Manganese(II) nitrate Manganese(II) nitrate Manganese(II) nitrate are the inorganic compounds with formula Mn(NO)(HO). Each formula unit is composed of one Mn cation and two NO anions and varying amounts of water. Most common is the tetrahydrate Mn(NO)·4HO, but mono- and hexahydrates are also known as well as the anhydrous compound. Some of these compounds are useful precursors to the oxides of manganese. Manganese(II) nitrate is prepared by dissolving manganese(II) oxide in nitric acid: It can also be prepared from manganese dioxide and nitrogen dioxide: On heating to 300 °C, aqueous solutions of manganese(II) nitrate thermally decompose to form MnO and NO. Manganese(II)
Manganese function as cofactors for a large variety of enzymes with many functions. Manganese enzymes are particularly essential in detoxification of superoxide free radicals in organisms that must deal with elemental oxygen. Manganese also functions in the oxygen-evolving complex of photosynthetic plants. While the element is a required trace mineral for all known living organisms, it also acts as a neurotoxin in larger amounts. Especially through inhalation, it can cause manganism, a condition in mammals leading to neurological damage that is sometimes irreversible. Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to fuse, but