The compound with the formula Co(NO2)2 is known as cobalt(II) nitrate.
To break this down, cobalt (Co) is a transition metal that can exhibit multiple oxidation states. In this compound, cobalt has a +2 oxidation state, which is indicated by the Roman numeral (II) in its name. The (NO2)2 part refers to two nitrate ions, each having a -1 charge. Therefore, two nitrate ions together balance the +2 charge of the cobalt ion.
Cobalt(II) nitrate can be found in various forms, including as a hexahydrate (Co(NO2)2ยท6H2O), which means it typically forms with water molecules attached. This compound is often used in laboratory settings, especially in coordination chemistry.