4-Substituted quinuclidinium perchlorates in the determination of polar substituent effects

Ceppi, Eros; Eckhardt, W.; Grob, C. A.

doi:10.1016/s0040-4039(01)86991-4

Cited by 24 publications

(14 citation statements)

References 3 publications

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“…Their efficiency with aryl bromides shows a stronger reductive effect than 20 since the inductive effect of the N-substituents of 21-23 is donating. 24 We also computationally optimized the electron transfer reaction 27 involving these initiators and found lower barriers for 21-23, derived from 8-10, than 20, derived from 7 which is in accordance with our experimental results (Table 3). However, none of these DKP donors was able to promote the coupling reaction of chlorobenzenes or fluorobenzenes to benzene.…”

Section: Scheme 2 Schemesupporting

confidence: 87%

“…The phenyl substituent of 20 decreases the reductive capacity due to its withdrawing inductive effect. 24 Computational optimization [25][26] of the structure of 20 shows there is no co-planarity of the two arene rings with the centre ring, and thus little or no electron delocalisation by resonance ( Figure 3). We also checked the spin density of 20…”

Section: Scheme 2 Schemementioning

confidence: 99%

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A study of diketopiperazines as electron-donor initiators in transition metal-free haloarene–arene coupling

et al. 2017

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Section: Scheme 2 Schemesupporting

confidence: 87%

Section: Scheme 2 Schemementioning

confidence: 99%

A study of diketopiperazines as electron-donor initiators in transition metal-free haloarene–arene coupling

et al. 2017

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“…This orientational selectivity results from the greater electronegativity of chlorine, which makes I in ICl poorer in electron density and thus a better site for accepting -electron density from the moreover, as shown in Figure 5, the CT transition energies calculated at the MPW1PW91 level in both the gas phase and in CCl 4 medium decrease with increasing number of Me groups in a manner similar to the experimental h CT . This is in compliance with the long known concept of the inductive effect, according to which the þI effect [33] of the methyl group should increase the p-donor ability of the aromatic ring, thereby lowering the CT transition energy.…”

Section: 5supporting

confidence: 86%

Calculation of the charge transfer transition energy of the mesitylene–ICl complex byab initioand TDDFT methods: Comparison with other methylbenzene–ICl complexes

Tiwary¹,

Mukherjee

2009

Molecular Physics

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Of the four plausible isomeric structures of the mesitylene-ICl charge transfer (CT) complex, the most feasible one was determined by a detailed ab initio and DFT study at the HF, B3LYP and MPW1PW91 levels using the 6-31þþG(d,p) basis set. Potential energy surface scans followed by frequency calculation and full optimization revealed that the I-Cl bond, with its I atom oriented towards the aromatic ring, stands vertically above an unsubstituted C-atom, being inclined at about 6 to the C 3 -axis. Complexation increases the I-Cl bond length. Correction for basis set superposition error through a counterpoise calculation yields a binding energy close to the experimental value. The electronic CT transition energy (h CT ) with this ground-state structure as input was calculated in vacuo by the CIS method and in carbon tetrachloride medium by the TDDFT method under the polarizable continuum model. In a similar way the values of h CT were calculated for complexes of ICl with p-xylene, durene and hexamethylbenzene. Throughout the series of methylbenzene complexes, the TDDFTcalculated values of h CT were less than the experimental values and such underestimation may be attributed to the inherent difficulties of DFT to take into account long-range interactions. However, the trend of the variation of h CT with the number and position of methyl groups in the series was reasonably similar to the trend followed by the experimental CT transition energies.

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“…[65] However, some more or less rough estimations regarding the order of the I effect are possible. A method of getting polar substituent constants based on the determination of the pK a values by titration with sodium hydroxide of correspondingly 4-substituted 1-azabicyclo[2.2.2]octanes (quinuclidines) perchlorates has been published by Ceppi et al [84] Possibly this is not the most advanced method but it provides some numbers that can be compared. According to these data the -I effect of the substituents increases in the order:…”

mentioning

confidence: 99%

Molecular Aspects of Radical Polymerizations—The Propagation Frequency

Tauer

Hernández

2010

Macromol. Rapid Commun.

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The product of the propagation rate constant and monomer concentration is a central issue of radical polymerization. Both quantities are strongly interrelated as the determination of a reliable value of the propagation rate constant requires exact knowledge of the monomer concentration. Even for homogeneous polymerization conditions, exact knowledge of the monomer concentration at the reaction site from the molecular perspective is not trivial. For emulsion polymerizations the situation is additionally complicated by mass transfer events and colloid-chemical effects. Molecular modeling appears as an attractive alternative or complement to the deterministic kinetic description of radical polymerizations.

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4-Substituted quinuclidinium perchlorates in the determination of polar substituent effects

Cited by 24 publications

References 3 publications

A study of diketopiperazines as electron-donor initiators in transition metal-free haloarene–arene coupling

A study of diketopiperazines as electron-donor initiators in transition metal-free haloarene–arene coupling

Calculation of the charge transfer transition energy of the mesitylene–ICl complex byab initioand TDDFT methods: Comparison with other methylbenzene–ICl complexes

Molecular Aspects of Radical Polymerizations—The Propagation Frequency

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