Bismuthyl (ion)

Bismuthyl is an inorganic oxygen-containing singly charged ion with the chemical formula BiO⁺, and is an oxycation of bismuth in the +3 oxidation state. Most often it is formed during the hydrolysis of trivalent bismuth salts, primarily nitrate, chloride and other halides. In chemical compounds, bismuthyl plays the role of a monovalent cation.

In inorganic chemistry bismuthyl has been used to describe compounds such as BiOCl which were assumed to contain the diatomic bismuthyl, BiO⁺, cation, that was also presumed to exist in aqueous solution.

This diatomic ion is not now believed to exist. Unlike other inorganic radicals such as hydroxyl, carbonyl, chromyl, uranyl or vanadyl, according to the current IUPAC rules, the name bismuthyl for BiO⁺ is not recommended, since individual molecules of these groups are not identifiable but atomic layers of Bi and O. Their presence in compounds preferably should be referred to as oxides.^: 16 However, the latter position remains controversial. For example, to this day the Russian school of inorganic chemistry still operates with bismuthyl and stibil (antimonyl) cations as actually existing radicals.