thiopyrylium

Thiopyrylium is a cation with the chemical formula C5H5S+. It is analogous to the pyrylium cation with the oxygen atom replaced by a sulfur atom.

Thiopyrylium salts are less reactive than the analogous pyrylium salts due to the higher polarizability of the sulfur atom. Among the chalcogenic 6-membered unsaturated heterocycles, thiopyrylium is the most aromatic, due to sulfur having the similar Pauling electronegativity as carbon and only a slightly higher covalent radius. In water, thiopyrylium reacts to it and forms a mixture of 2-hydroxythiopyran and 4-hydroxythiopyran.