Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
Chemical compound
The tropylium ion or cycloheptatrienyl cation is an aromatic species with a formula of [C7H7]+.[4] Its name derives from the molecule tropine from which cycloheptatriene (tropylidene) was first synthesized in 1881. Salts of the tropylium cation can be stable, even with nucleophiles of moderate strength e.g., tropylium tetrafluoroborate and tropylium bromide (see below). Its bromide and chloride salts[5] can be made from cycloheptatriene and bromine or phosphorus pentachloride, respectively.[6]
It is a regular heptagonal, planar, cyclic ion. It has 6 π-electrons (4n + 2, where n = 1), which fulfills Hückel's rule of aromaticity. It can coordinate as a ligand to metal atoms. The structure shown is a composite of seven resonance contributors in which each carbon atom carries part of the positive charge.
^ abcdefg"tropylium | ChemSpider". www.chemspider.com. p. Names. Retrieved 30 December 2018. tropylium
^ abcdef"Tropylium". pubchem.ncbi.nlm.nih.gov. Retrieved 30 December 2018. Chemical Names: Tropylium; Cycloheptatrienylium; Cyc-C 7H+ 7; Cyclohepta-2,4,6-trienylium
^International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 1127. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
^IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "molecule". doi:10.1351/goldbook.M04002
^A mixture of [C7H7]+Cl− and [C7H7]+[PCl− 6] is produced by treatment of tropylidene with phosphorus pentachloride.
^Tropylium fluoborate Organic Syntheses, Coll. Vol. 5, p.1138 (1973); Vol. 43, p.101 (1963). link Archived 2012-08-29 at the Wayback Machine
Salts of the tropyliumcation can be stable, even with nucleophiles of moderate strength e.g., tropylium tetrafluoroborate and tropylium bromide (see...
bridge (-CH2-) with respect to the other atoms; however the related tropyliumcation is. Albert Ladenburg first generated cycloheptatriene in 1881 by the...
(itself named for the molecule atropine). Salts of the tropyliumcation can be stable, e.g. tropylium tetrafluoroborate. It can be made from cycloheptatriene...
non-classical carbocations like the 2-norbornyl cation. According to the IUPAC, a carbocation is any cation containing an even number of electrons in which...
major contributions include recognition of the aromatic nature of the tropyliumcation and the early use of 1H NMR for the characterization of carbocations...
the analogous intermediate in nucleophilic aromatic substitution Tropyliumcation Olah, G. A. (1972). "Stable carbocations. CXVIII. General concept and...
Tropylium tetrafluoroborate is an organic compound with the formula [C7H7]+[BF4]−. Containing the tropyliumcation and the non-coordinating tetrafluoroborate...
fusion of a 6 π-electron cyclopentadienyl anion and a 6 π-electron tropyliumcation: one electron from the seven-membered ring is transferred to the five-membered...
relative cation reactivities are −0.4 for the malachite green cation, +2.6 for the benzenediazonium cation, and +4.5 for the tropyliumcation. In the Mayr–Patz...
of conjugation. Comparison of hydride ion affinities of propyl cation and allyl cation, corrected for inductive effects, results in a considerably lower...
ring, a favorable mode of cleavage is to lose a H-radical to form the tropyliumcation (m/z 91). Alkyl substituted benzenes can fragment via the kinetic controlled...
cycloheptatriene. This leads to an isoelectronic state akin to that of the tropyliumcation, aromatizing the borepin while also allowing it to act as a Lewis acid...
spectrum of toluene [1]. Note parent peak corresponding to molecular mass M = 92 (C7H8+) and highest peak at M-1 = 91 (C7H7+, quasi-stable tropyliumcation)....
homotropenylium cation is one of the most studied homoaromatic compounds. Many homoaromatic cationic compounds use as a basis a cyclopropenyl cation, a tropylium cation...
absorbance. Common carbenium ions are trityl and tropyliumcations. Ionizing radiation can form a radical-cation pair that can then react with a monomer to...
with for instance sesquifulvalene 4, which can be thought of as a tropyliumcation joined to a cyclopentadienyl anion (both stable and aromatic). In this...
becomes a positive cation. Lewis acids form -ate ions when the central atom gains one more bond and becomes a negative anion. boronium cation, BH+4 (protonated...
cleave acetals and some ethers. Many reactive cations have been obtained using fluoroboric acid, e.g. tropylium tetrafluoroborate (C7H7+[BF4]−), triphenylcarbenium...
found in ions as well: the cyclopropenyl cation (2e system), the cyclopentadienyl anion (6e system), the tropylium ion (6e), and the cyclooctatetraene dianion...
carbanions. Carbocations are often named -um. Examples are tropylium and triphenylmethyl cations and the cyclopentadienyl anion. Haloalkanes are a class...
+ 2 C5H6 → 2 NaC5H5 + H2 Aromatization can entail removal of hydride. Tropylium, C 7H+ 7 arises by the aromatization reaction of cycloheptatriene with...
from the external field. For example, in proton NMR the electron-poor tropylium ion has its protons downfield at 9.17 ppm, those of the electron-rich...
referring to the ester linkages in glycerides. Formerly known as 𨤎 yán. 䓬 tropylium 卓 zhuó 'eminent' zhuó European pronunciation 腙 hydrazone 宗 zōng 'faction'...
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