Manganese is also used in portland cement mixtures. Manganese is an important element for human health, essential for development, metabolism, and the antioxidant system. Nevertheless, excessive exposure or intake may lead to a condition known as manganism, a neurodegenerative disorder that causes dopaminergic neuronal death and symptoms similar to Parkinson's disease. The classes of enzymes that have manganese cofactors is large and includes oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases, lectins, and integrins. The reverse transcriptases of many retroviruses (though not lentiviruses such as HIV) contain manganese. The best-known manganese-containing polypeptides may be arginase, the diphtheria toxin, and Mn-containing superoxide dismutase (Mn-SOD).
Manganese(IV) fluoride of the grains. The reaction can also be carried out starting from manganese powder in a fluidized bed. Other preparations of MnF include the fluorination of MnF with krypton difluoride, or with F in liquid hydrogen fluoride solution under ultraviolet light. Manganese tetrafluoride has also been prepared (but not isolated) in an acid–base reaction between antimony pentafluoride and KMnF as part of a chemical synthesis of elemental fluorine. Manganese tetrafluoride is in equilibrium with manganese(III) fluoride and elemental fluorine: Decomposition is favoured by increasing temperature, and disfavoured by the presence of fluorine gas, but the exact parameters of the equilibrium