Onium connection
In chemistry, an onium compound or an onium ion is a cation that is formally formed by protonation of the hydride of a pnictogen ( group 15 in the periodic table), chalcogen ( group 16 ) or a halogen ( group 17 ). The longest known onium ion and namesake of this group is ammonium , NH 4 + , the protonated derivative of ammonia , NH 3 .
The term onium is also used for cations that would result from the substitution of a hydrogen atom by another group (e.g. organyl radicals or halogens ), such as tetraphenylphosphonium , (C 6 H 5 ) 4 P + . The substituting group can also be di- or trivalent, whereby z. B. Ions such as the iminium ion and nitrilium result.
classification
Onium compounds are inversely analogous to ate complexes . Lewis bases form onium ions when the central atom forms another bond and becomes a cation. Lewis acids form ate ions when the central atom receives electrons by entering into another bond and thus becomes an anion.
Onium ions have a charge of +1. A molecule with two or more onium subgroups is called a double onium ion , a triple onium ion , and so on. Compounds that consist of an onium cation and an anion are called onium salts .
Simple onium ions
A number of simple onium ions, i.e. hydrides without substituents, are listed below.
Group 15 (nitrogen group) onium cations
- Ammonium , ( IUPAC name: Azanium) NH 4 + (protonated ammonia , IUPAC name: Azan)
- Phosphonium , PH 4 + (protonated monophosphine )
- Arsonium, AsH 4 + (protonated monoarsane )
- Stibonium , SbH 4 + (protonated stiban )
- Bismutonium , BiH 4 + (protonated bismuthane )
Group 16 (chalcogen) onium cations
- Oxonium , H 3 O + (protonated water )
- Sulfonium , H 3 S + (protonated sulfane )
- Selenonium , H 3 Se + (protonated selan )
- Telluronium , H 3 Te + (protonated monotellane )
Group 17 (halogen) onium cations, halonium ions , H 2 X + (protonated hydrogen halides )
- Fluoronium , H 2 F + (protonated hydrogen fluoride )
- Chloronium , H 2 Cl + (protonated hydrogen chloride )
- Bromonium , H 2 Br + (protonated hydrogen bromide )
- Iodonium , H 2 I + (protonated hydrogen iodide )
Pseudo- halogen onium cations
- Aminodiazonium, H 2 N 3 + (protonated hydrogen azide )
- Hydrocyanonium, H 2 CN + (protonated hydrogen cyanide )
Group 14 (carbon group) onium cations
- Methanium, CH 5 + (protonated methane , sometimes also called methonium, but the latter has different meanings)
- Other alkanium cations: C n H (2n + 3) +
- Ethanium , C 2 H 7 + (protonated ethane )
-
Propanium , C 3 H 9 + ( propane , protonated on any carbon)
- Propylium or propan-1-ylium (propane, protonated at the terminal carbon atom)
- Propan-2-ylium (propane, protonated on the middle carbon atom)
-
Butanium , C 4 H 11 + ( butane , protonated on any carbon)
-
n-butanium ( n-butane , protonated on any carbon)
- n-Butylium or n-Butan-1-ylium (n-Butane, protonated at the terminal carbon atom)
- n-Butan-2-ylium (n-butane, protonated on the middle carbon atom)
-
Isobutanium ( isobutane , protonated on any carbon)
- Isobutylium or Isobutan-1-ylium (isobutane protonated at one end)
- Isobutan-2-ylium (isobutane protonated at the middle carbon)
-
n-butanium ( n-butane , protonated on any carbon)
- Octonium , C 8 H 19 + (protonated octane )
- Silanium (sometimes also Silonium ), SiH 5 + (Protonated Silane ) (Shouldn't be called Siliconium.)
- More silanium cations, Si n H (2n + 3) +
- Disilanium , Si 2 H 7 + (protonated disilane )
- Germonium , GeH 5 + (protonated German )
- Stannonium , SnH 3 + (protonated SnH 2 ; non-protonated stannane SnH 4 )
- Plumbonium , PbH 3 + (protonated lead hydride , PbH 2 )
Group 13 (boron group) onium cations
Hydrogen onium cations
- Hydrogenonium , better known as trihydrogen cation , H 3 + (protonated [molecular] or [diatomic] hydrogen ).
Group 18 (noble gas) onium cations
- Hydrohelium , better known as helium hydride ion , HeH + (protonated helium ). (Abundant in outer space).
- Kryptonium KrH + (protonated krypton )
- Xenonium XeH + (protonated xenon )
Onium ions with monovalent substitution
- primary ammonium cations, RH 3 N + or RNH 3 + (protonated, primary amine )
- Hydroxylammonium , NH 3 OH + (protonated hydroxylamine )
- Methylammonium , CH 3 NH 3 + (protonated methylamine )
- Ethylammonium , C 2 H 5 NH 3 + (protonated ethylamine )
- Hydrazinium or Diazanium , NH 2 NH 3 + (protonated hydrazine )
- Secondary ammonium cations, R 2 NH 2 + (protonated, secondary amine )
- Dimethylammonium (sometimes also Dimethylaminium ), (CH 3 ) 2 NH 2 + (protonated dimethylamine )
- Diethylammonium (sometimes also Diethylaminium ), (C 2 H 5 ) 2 NH 2 + (protonated diethylamine )
- Ethylmethylammonium , C 2 H 5 CH 3 NH 2 + (protonated ethylmethylamine )
- Diethanolammonium (sometimes also Diethanolaminium ), (C 2 H 4 OH) 2 NH 2 + (protonated diethanolamine )
- Tertiary ammonium cations, R 3 NH + (protonated, tertiary amine )
- Trimethylammonium (CH 3 ) 3 NH + (protonated trimethylamine )
- Triethylammonium (C 2 H 5 ) 3 NH + (protonated triethylamine )
-
Quaternary ammonium cations , R 4 N + or NR 4 +
- Tetramethylammonium , (CH 3 ) 4 N +
- Tetraethylammonium , (C 2 H 5 ) 4 N +
- Tetrapropylammonium , (C 3 H 7 ) 4 N +
- Tetrabutylammonium , (C 4 H 9 ) 4 N + , also abbreviated to Bu 4 N +
- Trimethylammonium compounds , (CH 3 ) 3 RN +
- Didecyldimethylammonium , (C 10 H 21 ) 2 (CH 3 ) 2 N +
- Pentamethylhydrazinium , N (CH 3 ) 2 N (CH 3 ) 3 +
- Quaternary phosphonium cations, R 4 P + or PR 4 +
- Tetraphenylphosphonium , (C 6 H 5 ) 4 P +
- secondary sulfonium cations, R 2 SH + (protonated sulfides )
- Dimethylsulfonium , (CH 3 ) 2 SH + (protonated dimethyl sulfide )
- Tertiary sulfonium cations R 3 S +
- Trimethylsulfonium , (CH 3 ) 3 S +
- Secondary fluronium cations R 2 F +
- Dichlorofluoronium , Cl 2 F +
Onium cations with polyvalent substituents
- secondary ammonium cations with a double bonded substituent, R = NH 2 +
- Quaternary ammonium cations with one double bonded substituent and two single bonded substituents, R = NR 2 +
- Quaternary ammonium cations with two double-bonded substituents, R = N = R +
- Nitronium , NO 2 +
- µ-nitrido bis (triphenylphosphine) chloride , ((C 6 H 5 ) 3 P) 2 N +
- tertiary ammonium cations with a triple bonded substituent, R≡NH +
- tertiary ammonium cations with two partially double bonded substituents, R = -NH + = -R
- Pyridinium , C 5 H 5 NH + (protonated pyridine )
- Quaternary ammonium cations with a triply bonded substituent and a singly bonded substituent, R≡NR +
- tertiary oxonium cation with a triple bonded substituent, R≡O +
- Nitrosonium , N≡O +
- tertiary oxonium cations with two partially double-bonded substituents, R = -O + = -R
- Pyrylium , C 5 H 5 O +
- tertiary sulfonium cations with triply bonded substituents, R≡S +
- Thionitrosyl , N≡S +
Doppelonium dications
- Hydrazinium - dication , + H 3 NNH 3 + (double protonated hydrazine )
- Diazenium dication , + H 2 N = NH 2 + (double protonated diazen )
- Diazonium -dication, + HN≡NH + (double protonated nitrogen )
Unusual onium cations
- Borenium cation, R 2 B + (protonated borylene )
- Carbenium cation, R 3 C + (protonated carbenes )
- Silylium cation, R 3 Si + (protonated silylene )
- Nitrenium cation, R 2 N + (protonated nitrene )
- Mercurinium cation, R 3 Hg + (protonated organomercury compound; formed as an intermediate in oxymercurations )
Web links
- Entry on onium compounds . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.O04291 Version: 2.3.3.
- Overview on chem.qmul.ac.uk (English)
Individual evidence
- ↑ a b Entry on onium compounds . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.O04291 Version: 2.3.3.
- ↑ a b George A. Olah (1998), Onium Ions . John Wiley & Sons, 509 pages. ISBN 9780471148777
- Jump up ↑ Advanced Organic Chemistry: Reactions and mechanisms , Maya Shankar Singh, 2007, Dorling Kindersley, ISBN 978-81-317-1107-1 .
- ↑ Entry on carbonium ion . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.C00839 Version: 2.3.3.
- ↑ chem.qmul.ac.uk