A thiophosphate is a family of compounds and anions with the general chemical formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 PS_4-xO_x^3- (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 H₃PS_4-xO_x 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.

Monothiophosphate

Monothiophosphates are formally derived from the anion PO₃S^3-, which has C_3v symmetry

Symmetry group

The symmetry group of an object is the group of all isometries under which it is invariant with composition as the operation...

.. A number of insecticides feature organic

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 monothiophosphate center, including diazinon

Diazinon

Diazinon , a colorless to dark brown liquid, is a thiophosphoric acid ester developed in 1952 by Ciba-Geigy, a Swiss chemical company...

, parathion

Parathion

Parathion, also called parathion-ethyl or diethyl parathion, is an organophosphate compound. It is a potent insecticide and acaricide. It was originally developed by IG Farben in the 1940s. It is highly toxic to non-target organisms, including humans. Its use is banned or restricted in many...

, and malathion

Malathion

Malathion is an organophosphate parasympathomimetic which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity, however one recent study has shown that children with higher levels of organophosphate pesticide metabolites in their urine are more likely...

. They have the formula (RO)₂PS(OAr), where R = methyl or ethyl

Ethyl group

In chemistry, an ethyl group is an alkyl substituent derived from ethane . It has the formula -C2H5 and is very often abbreviated -Et.Ethylation is the formation of a compound by introduction of the ethyl functional group, C2H5....

 and Ar = an aryl

Aryl

In the context of organic molecules, aryl refers to any functional group or substituent derived from an aromatic ring, be it phenyl, naphthyl, thienyl, indolyl, etc....

 or related group. Coordination complexes of are known.

In the laboratory monothiophosphate is used as an analogue of phosphate in biochemistry

Biochemistry

Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...

. Monothiophosphate esters are biochemical reagent

Reagent

A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...

s used in the study transcription

Transcription (genetics)

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...

, substitution interference assays.

Dithiophosphates

Dithiophosphates are formally derived from the anion PO₂S₂^3-, which has C_2v symmetry

Symmetry group

The symmetry group of an object is the group of all isometries under which it is invariant with composition as the operation...

. This species is the major product from the reaction of base (e.g., NaOH) with phosphorus pentasulfide

Phosphorus pentasulfide

Phosphorus pentasulfide is the inorganic compound with the formula P4S10. This yellow solid is the one of two phosphorus sulfides of commercial value...

. The sodium salt has the nominal formula Na₃PO₂S₂

Sodium dithiophosphate

Sodium dithiophosphate is the salt Na3PS2O2. This salt is used as a flotation agent in molybdenite mineral concentration from ores, where it is usually known as "Nokes reagent." The salt is generated by the reaction of phosphorus pentasulfide with sodium hydroxide, often using impure reagents to...

, but is invariably hydrated. The main application of this dithiophosphate salt is in the purification of molybdenite

Molybdenite

Molybdenite is a mineral of molybdenum disulfide, MoS2. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum atoms sandwiched between sheets of sulfur atoms...

 ore. Organic thiophosphates feature the (RO)₂PS₂^- anion (R = alkyl, aryl). Zinc dithiophosphate, e.g., Zn(S₂P(OR)₂)₂, are used as oil additives (R = alkyl).

Tri- and tetrathiophosphates

Trithiophosphates are formally derived from the anion POS₃^3-, which has C_3v symmetry. Tetrathiophosphate has the formula PS₄^3-. Derivatives of these two anions are less commonly encountered.