A thiophosphate (or phosphorothioate) is a family of compounds and anions with the general chemical formula PS4-xOx3- (x = 0, 1, 2, or 3). The state of protonation is usually not specified. They could be bound to as many as three protons for the neutral H3PS4-xOx species. Two protons correspond to the related monoanions, and one proton for the dianions. The trianions are highly basic and do not exist in appreciable concentrations in solution. Thiophosphates are tetrahedral anions, with the phosphorus at the center of the tetrahedron.