CarboniumIn chemistry, a carbonium ion is any cation that has a pentacoordinated carbon atom. The name carbonium may also be used for the simplest member of the class, properly called methanium (), where the carbon atom is covalently bonded to five hydrogen atoms. The next simplest carbonium ions after methanium have two carbon atoms. Ethynium, or protonated acetylene , and ethenium are usually classified in other families. The ethanium ion has been studied as an extremely rarefied gas by infrared spectroscopy.
EthaniumIn chemistry, ethanium or protonated ethane is a highly reactive positive ion with formula C2H7+. It can be described as a molecule of ethane (C2H6) with one extra proton (hydrogen nucleus), that gives it a +1 electric charge. Ethanium is one of the simplest carbonium ions (after methanium CH5+). It was first detected as a rarefied gas in 1960 by S. Wexler and N. Jesse. It easily dissociates into ethenium C2H5+ and molecular hydrogen H2. Ethanium was first detected by infrared spectroscopy among the ions produced by electrical discharges in rarefied methane or ethane gas.
MéthyliumIn organic chemistry, methenium (also called methylium, carbenium, methyl cation, or protonated methylene) is a cation with the formula CH3+. It can be viewed as a methylene radical (:CH2) with an added proton (H+), or as a methyl radical (•CH3) with one electron removed. It is a carbocation and an enium ion, making it the simplest of the carbenium ions. Experiments and calculations generally agree that the methenium ion is planar, with threefold symmetry. The carbon atom is a prototypical (and exact) example of sp2 hybridization.
EtheniumIn chemistry, ethenium, protonated ethylene or ethyl cation is a positive ion with the formula C2H5+. It can be viewed as a molecule of ethylene (C2H4) with one added proton (H+), or a molecule of ethane (C2H6) minus one hydride ion (H-). It is a carbocation; more specifically, a nonclassical carbocation. Ethenium has been observed in rarefied gases subjected to radiation. Another preparation method is to react certain proton donors such as H3+, HeH+, N2H+, and N2OH+ with ethane at ambient temperature and pressures below 1 mmHg.
Onium ionIn chemistry, an onium ion is a cation formally obtained by the protonation of mononuclear parent hydride of a pnictogen (group 15 of the periodic table), chalcogen (group 16), or halogen (group 17). The oldest-known onium ion, and the namesake for the class, is ammonium, , the protonated derivative of ammonia, . The name onium is also used for cations that would result from the substitution of hydrogen atoms in those ions by other groups, such as organic groups, or halogens; such as tetraphenylphosphonium, .
CarbocationUn carbocation, parfois appelé ion carbonium ou ion carbenium (en fonction de sa structure), est un ion dérivé d'un composé organique, qui possède une charge électrique positive sur un ou plusieurs atomes de carbone. Les carbocations sont des intermédiaires de réaction. On parle de carbocation primaire, secondaire ou tertiaire selon que l'on a sur le carbone chargé respectivement un, deux ou trois groupements autres que l'hydrogène.
AmmoniumL'ion ammonium de formule brute NH4+ est un ion polyatomique de charge électrique positive. Ce cation polyatomique possède une structure tétraédrique, l'atome d'azote N occupant le centre et les quatre atomes d'hydrogène occupant les sommets équivalents du tétraèdre. Il est obtenu par protonation de l'ammoniac () ; il est parfois présenté comme une molécule d'ammoniac ionisée. L'ion ammonium est présent dans de nombreux produits nettoyants et désinfectants, à commencer par l'ammoniaque.
