Manganese diselenide is the inorganic compound

Inorganic compound

Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

 with the formula MnSe₂. This rarely encountered solid is structurally similar to that of iron pyrite (FeS₂). Analogous to the description of iron pyrite, manganese diselenide is sometimes viewed as being composed of Mn²⁺ and Se₂^2- ions, although being a semiconductor

Semiconductor

A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...

, MnSe₂ is not appropriately described in formal oxidation states.