Cations

A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 e (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an electron (the proton-to-electron mass ratio). Protons and neutrons, each with a mass of approximately one dalton, are jointly referred to as nucleons (particles present in atomic nuclei).

Thiamine, also known as thiamin and vitamin B1, is a vitamin – an essential micronutrient for humans and animals. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thiamine are required for some metabolic reactions, including the breakdown of glucose and amino acids.

Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged (cationic) molecular ion with the chemical formula or . It is formed by the addition of a proton (a hydrogen nucleus) to ammonia (). Ammonium is also a general name for positively charged (protonated) substituted amines and quaternary ammonium cations (), where one or more hydrogen atoms are replaced by organic or other groups (indicated by R). Not only is ammonium a source of nitrogen and a key metabolite for many living organisms, but it is an integral part of the global nitrogen cycle. As such

In chemistry, the hydron, informally called proton, is the cationic form of atomic hydrogen, represented with the symbol . The general term "hydron", endorsed by IUPAC, encompasses cations of hydrogen regardless of isotope: thus it refers collectively to protons (H) for the protium isotope, deuterons (H or D) for the deuterium isotope, and tritons (H or T) for the tritium isotope.

onium ion of helium; protonated helium

chemical compound

thumb|140px|right|class=skin-invert|Phosphonium ion 140px|right|thumb|Structure of , the parent phosphonium cation.

thumb|Structure of (CH3)3S+. The C-S-C angles are 102° and C-S bond distance is 177 picometers.

molecular ion

Ethylmercury (sometimes ethyl mercury) is a cation composed of an organic CH3CH2— species (an ethyl group) bound to a mercury(II) centre, making it a type of organometallic cation, and giving it a chemical formula C2H5Hg+. The main source of ethylmercury is thiomersal.

The fluoronium ion is an inorganic cation with the chemical formula . It is one of the cations found in fluoroantimonic acid. The structure of the salt with the anion, has been determined. The fluoronium ion is isoelectronic with the water molecule and the azanide ion.

In chemistry, the pentazenium cation (also known as pentanitrogen) is a positively-charged polyatomic ion with the chemical formula and structure . Together with solid nitrogen polymers and the azide anion, it is one of only three poly-nitrogen species obtained in bulk quantities.

Pyrylium is a cation (positive ion) with formula , consisting of a six-membered ring of five carbon atoms, each with one hydrogen atom, and one positively charged oxygen atom. The bonds in the ring are conjugated as in benzene, giving it an aromatic character. In particular, because of the positive charge, the oxygen atom is trivalent. Pyrilium is a mono-cyclic and heterocyclic compound, one of the oxonium ions.

Tetraethylammonium (TEA) is a quaternary ammonium cation with the chemical formula , consisting of four ethyl groups (, denoted Et) attached to a central nitrogen atom. It is a counterion used in the research laboratory to prepare lipophilic salts of inorganic anions. It is used similarly to tetrabutylammonium, the difference being that its salts are less lipophilic, more easily crystallized and more toxic.

Tetraxenonogold(II), gold tetraxenide(II) or '''''' is a cationic complex consisting of a central gold atom surrounded by four xenon atoms. It is a covalent complex with a square planar configuration of atoms. The complex is found in the compound (tetraxenonogold(II) undecafluorodiantimonate). This compound, which exists in triclinic and tetragonal crystal modifications, has the ion that is stabilised by interactions with the fluoride atoms of the counterion. The bond length is . Tetraxenonogold(II) is unusual in that it is a coordination complex of xenon, which is weakly basic. It is also unu

any onium ion containing a halogen atom carrying a positive charge

Tetramethylammonium (TMA) is the simplest quaternary ammonium cation. It has the chemical formula and consists of four methyl groups (, denoted Me) attached to a central nitrogen atom. The cation is isoelectronic with neopentane (). It is positively-charged and can only be isolated in association with a counter-ion. Common salts include tetramethylammonium chloride and tetramethylammonium hydroxide. Tetramethylammonium salts are used in chemical synthesis and in pharmacological research. It confers no color to its salts.

class of ions

'''S-Adenosylmethioninamine' is a substrate that is required for the biosynthesis of polyamines including spermidine, spermine, and thermospermine. It is produced by decarboxylation of S''-adenosyl methionine.

Chlormequat is an organic compound with the formula that is used as a plant growth regulator. It is typically sold as the chloride salt, chlormequat chloride (C5H13Cl2N), a colorless hygroscopic crystalline substance that is soluble in water and ethanol. It is an alkylating agent and a quaternary ammonium salt. Chlormequat is one of the onium-type growth regulators.

In chemistry, chloryl refers to a triatomic cation with chemical formula . This species has the same general structure as chlorite () but it is electronically different, with chlorine having a +5 oxidation state (rather than the +3 of chlorite). This makes it a rare example of a positively charged oxychloride. Chloryl compounds, such as Chloryl fluoride| and [ClO2][RuF6], are all highly reactive and react violently with water and most organic compounds.

The tetrafluoroammonium cation (also known as perfluoroammonium) is a positively charged polyatomic ion with chemical formula . It is equivalent to the ammonium ion where the hydrogen atoms surrounding the central nitrogen atom have been replaced by fluorine. Tetrafluoroammonium ion is isoelectronic with tetrafluoromethane , trifluoramine oxide , tetrafluoroborate anion and the tetrafluoroberyllate anion.

Trimethylsulfonium (systematically named trimethylsulfanium) is an organic cation with the chemical formula (also written as ).

An oxycation, or oxocation, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Their names normally end with the suffix "-ium" or "-yl".

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.

Argonium (also called the argon hydride cation, the hydridoargon(1+) ion, or protonated argon; chemical formula ArH+) is a cation combining a proton and an argon atom. It can be made in an electric discharge, and was the first noble gas molecular ion to be found in interstellar space.

A dication is any cation, of general formula X2+, formed by the removal of two electrons from a neutral species.

chemical compound

thumb|S-Ethylisothiouronium diethylphosphate|S-Ethylisothiouronium diethylphosphate: an example of an isothiuronium compound

Hydrazinium is the cation with the formula . This cation has a methylamine-like structure (). It can be derived from hydrazine by protonation (treatment with a strong acid). Hydrazinium is a weak acid with pKa = 8.1.

Tetrabutylammonium is a quaternary ammonium cation with the formula , also denoted (where Bu = butyl group). It is used in the research laboratory to prepare lipophilic salts of inorganic anions. Relative to tetraethylammonium derivatives, tetrabutylammonium salts are more lipophilic but crystallize less readily. It is useful for phase-transfer catalysis.

chemical compound

REDIRECTKrypton#kryptonium

Methylpyridinium is an ion with the formula . It is the N-methylated derivative of pyridine. It confers no color to its salts. The ion is classified as a quaternary ammonium ion.

The xenonium ion, XeH+, is an onium compound, consisting of protonated xenon. Although the existence of the xenonium salts has not been proven, the isolated XeH+ ion is known. Salts of the fluoroxenonium ion, XeF+, are known to exist, for instance fluoroxenonium pentafluoroplatinate (XeFPtF5), more commonly known as xenon hexafluoroplatinate.

thumb|right|100px|Structure of quaternary arsonium compound arsenobetaine. The arsonium cation is a positively charged polyatomic ion with the chemical formula . An arsonium salt is a salt containing either the arsonium () cation, such as arsonium bromide () and arsonium iodide (), which can be synthesized by reacting arsine with hydrogen bromide or hydrogen iodide. Or more commonly, as organic derivative such as the quaternary arsonium salts (CAS: , hydrate form) and the zwitterionic compound arsenobetaine.

1-Methylnicotinamide (1-MNA, trigonellamide) is a prototypic organic cation. 1-Methylnicotinamide is the methylated amide of nicotinamide (niacinamide, vitamin B3).