1,2:3,4:5,6-Tris(bicyclo[2.2.2]octeno)tropylium ion:  an all-hydrocarbon carbocation with extraordinary stability

Komatsu, Kôichi; Akamatsu, Hidekazu; Jinbu, Yasuhisa; Okamoto, Kunio

doi:10.1021/ja00210a072

Cited by 56 publications

(20 citation statements)

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“…19 By the hydride abstraction from 13, tris-BCO-annelated tropylium ion salt 14 + SbF 6 -was readily obtained (Scheme 7), which exhibited an extraordinarily high thermodynamic stability as shown by its pK R + value of 13.0 in 50% acetonitrile. 20 This is among the highest values ever reported for substituted tropylium ions, 21 and the cation 14 + is only half-neutralized even in alkaline water of 0.1 N NaOH.…”

Section: Figurementioning

confidence: 83%

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Synthesis and Properties of Cationic π-Conjugated Systems Stabilized by Bicyclo[2.2.2]octene Units

Komatsu¹,

Nishinaga²

2005

Synlett

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The purpose of this Account is to present the results of our systematic study on the synthesis of a series of cyclic p-conjugated systems with the monocyclic six-membered to eight-membered rings as well as polycyclic aromatic compounds, which are fully surrounded by rigid bicyclic s-frameworks. This structural modification is characteristic in causing elevation of the HOMO levels of neutral p-systems and remarkably stabilizing the corresponding cationic systems by both thermodynamic and kinetic effects. In order to minimize the possible steric strain in p-systems, the relatively strain-free bicyclic system, i.e., bicyclo[2.2.2]octene, was chosen for the structural modification of all the cyclic p-systems, and the successful generation of the cationic species such as radical cation, closed-shell mono-and dications, which are so stable to allow even the X-ray structural analysis, is demonstrated.

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Section: Figurementioning

confidence: 83%

“…22 However, 14 + does react with organolithium reagents at the 7-position and affords the tropylium ion derivatives 15 + , 20 16 + , 23 17 2+ , 23 18 2+ , 23 and 19 2+ (Figure 7) 24 by appropriate ionization methods. The pK R + and reduction potential data of these mono-and dications are given in Table 4.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Properties of Cationic π-Conjugated Systems Stabilized by Bicyclo[2.2.2]octene Units

Komatsu¹,

Nishinaga²

2005

Synlett

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“…dynamic stability (Scheme 7). [22] The stabilization effect of each BCO unit is almost additive, and the pK R ϩ value of When treated with SbF 5 , which has a stronger oxidizing power, these hydrocarbons are transformed into the corre-the tropylium ion 19 having three BCO groups is 13.0 in 50% acetonitrile. This is the highest pK R ϩ value ever responding dications, which can be characterized by 1 H (Table 3) and 13 C NMR (Table 4).…”

Section: With Bcomentioning

confidence: 99%

“…[23] However, 19 does react with organolithium reagents at the 7-position and affords the tropylium ion derivatives 20, [22] 21, [24] 22, [24] Cycloheptatriene, Tropone, and Heptafulvene 23, [24] and 24 [25] after the appropriate ionization method.…”

Section: With Bcomentioning

confidence: 99%

Cyclic π-Conjugated Systems Annelated with Bicycloalkene Frameworks

Komatsu¹

1999

Eur. J. Org. Chem.

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The present article gives an account of the synthesis and chemical properties of the cyclic π‐conjugated hydrocarbons annelated with bicyclic σ‐frameworks. Particular emphasis is placed on π‐systems carrying a positive charge, which is remarkably stabilized by complete annelation with bicyclo[2.2.2]octene. In such systems, not only the kinetic effects but also electronic effects due to σ‐π conjugation affect the properties of the π‐systems. The thermodynamic properties, redox behavior, and the X‐ray crystal structures are discussed.

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“…Selected bond lengths (A) and angles (°) are: Sl-Cl, 1.697(6); CI-C2, 1.394(9); C2-C3,1.389(11); C3-C4, 1.390(11); C4-S1, 1.761(6); C4-C5; 1.421(9); C5-C6, 1.424(9); C6-C7, 1.389(9); C7-C8, 1.418(9); C8-S2, 1.747(6); S2-C5, 1.751(6); C8-C9, 1.436(9); C3-C4-C5-C6, -155.5(8), C7-C8-C9-C10, -149.4(8).…”

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confidence: 99%

Super-Stabilization of π-Conjugated Cations by Annelation to Bicyclic Frameworks

Komatsu

2007

ACS Symposium Series

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As exemplified by the synthesis of the extraordinarily stable tropylium ion, the annelation of cyclic π-conjugated cations with rigid σ-framework, bicyclo[2.2.2]octene, has been found to be an effective method for creation of unusually stable cationic π-conjugated systems. By using this method, detailed X-ray crystallographic studies have been conducted for the monomeric radical-cation salts of hydrocarbons such as cyclooctatetraene and a series of benzenoid condensed aromatics and of sulfur containing compounds such as thiophene, dithiins, and oligothiophenes. Some of these species can be further oxidized to dications, and also undergo intriguing rearrangements to cationic species with novel structures. The results are well interpreted by the use of theoretical calculations. 32

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1,2:3,4:5,6-Tris(bicyclo[2.2.2]octeno)tropylium ion: an all-hydrocarbon carbocation with extraordinary stability

Cited by 56 publications

References 0 publications

Synthesis and Properties of Cationic π-Conjugated Systems Stabilized by Bicyclo[2.2.2]octene Units

Synthesis and Properties of Cationic π-Conjugated Systems Stabilized by Bicyclo[2.2.2]octene Units

Cyclic π-Conjugated Systems Annelated with Bicycloalkene Frameworks

Super-Stabilization of π-Conjugated Cations by Annelation to Bicyclic Frameworks

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