Oxatriquinane (oxoniaperhydrotriquinacene) is an alkyl

oxonium ion In chemistry, an oxonium ion is any cation containing an oxygen atom that has three chemical bond, bonds and 1+ formal charge. The simplest oxonium ion is the hydronium ion (). Alkyloxonium Hydronium is one of a series of oxonium ions with the fo ...

with formula (CH₂CH₂CH)₃O⁺. It has a

cyclononane Cyclononane is an alicyclic hydrocarbon consisting of a ring of nine carbon atoms. Its molecular formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical c ...

backbone, with a tricoordinated

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

connected to

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

1, 4, and 7, forming three fused pentagonal rings. In contrast to most trialkyloxonium ions, oxatriquinane hydrolyzes slowly.

History

Oxatriquinane was first described in 2008. Its five-step synthesis starts from 1,4,7-cyclononatriene. Its C–O bond lengths are 1.54 Å. The C−O−C angles are acute.

Reactions

Oxonium ions normally are strong

alkylating agent Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting ...

s and are hydrolytically sensitive. Oxatriquinane does not react with boiling water or with alcohols, thiols, halide ions, or amines, although it does react with stronger

nucleophile In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are ...

s such as hydroxide, cyanide, and azide. The ability of the oxygen to enter into a fourth covalent bond has been of some theoretical interest and was achieved using

carborane acid Carborane acids (X, Y, Z = H, Alk, F, Cl, Br, CF3) are a class of superacids, some of which are estimated to be at least one million times stronger than 100% pure sulfuric acid in terms of their Hammett acidity function values (''H''0 ≤ −18 ...

. As illustrated by the structures of most

metal oxide An oxide () is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of −2) of oxygen, an O2− ion with oxygen in the oxidation state o ...

s, oxygen compounds routinely have bonds to >3 elements in other classes of compounds.

Analogs

Related species include

oxatriquinacene Oxatriquinacene is an organic cation with formula . It is an oxonium ion, with a tricoordinated oxygen atom with +1 charge connected to carbons 1,4, and 7 of a cyclononatriene ring, forming three fused pentagonal cycles. The compound may pos ...

, the tri-unsaturated

analog Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog ...

, which is of interest as a possible precursor to oxaacepentalene, a neutral aromatic species. 1,4,7-Tri-''tert''-butyloxatriquinane has also been synthesized. This compound contains significant amounts of intramolecular steric strain, resulting in further bond elongation to give C–O bond lengths of 1.622 Å, the longest recorded in any species. File:Oxatriquinacene.svg, Oxatriquinacene File:Oxaacepentalene.svg, Oxaacepentalene

Notes

:1. Triquinane is more often used in the natural product literature to refer to three angularly fused cyclopentane rings sharing a common quaternary carbon in the center, a structure which contains one more carbon atom at the periphery. Moreover, substitution by O⁺ is more properly designated by the prefix oxonia. Nevertheless, the authors who first prepared the cation called it oxatriquinane, and the name has been perpetuated in the literature. A semisystematic name in line with standard nomenclature would be 2a¹-oxonia-1,2,3,4,5,6-hexahydrotriquinacene.

References

{{reflist, 2 Oxonium compounds Oxygen heterocycles