Generation of azulene radical cations from arylalkynes

Cooksey, Christopher J.; Courtneidge, John L.; Davies, Alwyn G.; Gregory, Peter S.; Evans, Jeffrey; Rowlands, Christopher C.

doi:10.1039/p29880000807

Cited by 14 publications

(13 citation statements)

References 4 publications

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“…All reactions were catalyzed using [Pd(PPh 3 ) 2 Cl 2 ], triphenylphosphine as a ligand, copper iodide as a co‐catalyst and piperidine as a base and solvent. Compound M1 is known from the literature 57, 58. To the best of our knowledge, the compounds M2 – M5 have been synthesized here for the first time.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Spectral Properties of Novel Poly(disubstituted acetylene)s

Duchoslavová

Sivkova

Hanková

et al. 2011

Macro Chemistry & Physics

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The synthesis of mostly new acetylenes, R1CCR2, (R1 = 4‐t‐butylphenyl; R2 = 4‐t‐butylphenyl; 4‐[(t‐butyl)(diphenyl)silyloxy]phenyl; 1‐naphthyl; 2‐naphthyl; 9‐anthryl) is reported. Their UV‐vis characteristics are discussed in comparison to the results of TD‐DFT calculations. R1CCR2 (except for R2 = 9‐anthryl) give polyacetylenic polymers—[C(R1) = C(R2)]‐n, insoluble if R1 = R2 and well soluble if R1 ≠ R2 in polymerization with TaCl5/SnBu4. Polymerizability increases with increasing monomer triple bond accessibility for the catalyst. The photoluminescence yield of the soluble polymers rises in the R2 order: 1‐naphthyl < 2‐naphthyl < 4‐[(t‐butyl)(diphenyl)silyloxy]phenyl.

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Section: Resultsmentioning

confidence: 99%

Synthesis and Spectral Properties of Novel Poly(disubstituted acetylene)s

Duchoslavová

Sivkova

Hanková

et al. 2011

Macro Chemistry & Physics

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“…In our case the main problem of the conversion of the tolans into the azulenes is the sensitivity of the azulene solutions towards air, which is even higher in the presence of silica gel, resulting in decomposition during purification by chromatography. Conversion of tolans into azulenes by Lewis acids have been reported in the literature,55 but this was not followed in this work because of the general sensitivity of our triarylamine species towards acids.…”

Section: Resultsmentioning

confidence: 99%

Highly Substituted Azulene Dyes as Multifunctional NLO and Electron‐Transfer Compounds

Lambert

Nöll

Zabel

et al. 2003

Chemistry A European J

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Two highly substituted azulene derivatives were synthesised by Pd-mediated dimerisation from the corresponding tolan species. One azulene derivative (2) has donor functionalities (dianisylaminophenyl and dianisylamino) in the 1-, 2-, 3- and 6-positions, while the other (1) has donors (dianisylaminophenyl) in the 2- and 6-positions and acceptors (nitrophenyl) in the 1- and 3-positions. Each azulene derivative shows strong bond length alternation in the solid state, determined by X-ray crystal analysis, and an intense CT band around 450-500 nm in its UV/Vis spectrum. The first-order hyperpolarisability of 1 and of 2 was measured by hyper-Rayleigh scattering and is about that of disperse red DR1. Both azulene derivatives show multiple oxidation processes. The intramolecular adiabatic ET behaviour of the mixed valence radical cations of 1 and of 2 was investigated by UV/Vis/NIR spectroelectrochemistry. The intervalence-CT band of 1(+) could be analysed by the Generalised Mulliken-Hush theory, which yields an electronic coupling V=1140 cm(-1) for the optically induced adiabatic hole transfer.

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“…EPR spectroscopic evidence is reported for 8, 9, 10, 11, 12, 13, 14, 15 and 16 as new examples of recently recognized alternative mechanism of arene mercuration in which collapse of ArH'+Hg(TFA)2'-radical ion pair leads to arylmercury trifluoroacetate ArHg(TFA)'+ [90]. Dialkyl alkylene cations react with their parents to give tetraalkylcyclobutadiene cation [94] but diaryl alkynes on oxidation showed triarylazulene radical cations [95]; the radical anions of diaryl alkynes on the other hand do not rearrange. Reduction of 21 with potassium and small amount of benzo-18-crown-6 in THF gave septet of septet spectra with a(6H) 1.38, a(6H) 0.10 G, g 2.0026, while oxidation gave simple septet spectrum with a(6H) 1.29 G [90].…”

Section: H Systemsmentioning

confidence: 99%

Electron‐transfer Reactions of Aromatic Compounds

Gescheidt¹,

Khan²

2001

Electron Transfer in Chemistry

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Aromatic molecules are inclined to undergo electron-transfer reactions. The additional charges introduced by the electron-transfer process are efficiently stabilized by delocalization. Nevertheless rearrangements of the molecular skeleton or followup reactions can occur. The course of the electron-transfer reactions and the properties of the species thus formed are the subject of this section.In particular, we concentrate on the species formed after an one-electron transfer reaction. Starting from closed-shell diamagnetic precursors, paramagnetic stages, i.e. radical cations or radical anions are formed in this first step. To understand the properties and reactivity of these species, detailed knowledge in terms of charge and spin delocalization and electronic structure is an important prerequisite. This information is preferably derived from electronic and paramagnetic resonance (EPR and electron-nuclear multiple resonance-techniques such as ENDOR or Triple spectroscopy). It has recently been shown that the experimental results can be substantiated by the use of quantum-chemical calculations. In addition to Hartree-Fock-based ab initio procedures, calculations on the density-functional level of theory have been established as rather efficient tools. Therefore, before representing examples of electron-transfer-generated radicals a short survey of the computational methods is given.Another substantial factor directing the kinetic and thermodynamic stability of charged radicals is ion pairing. This phenomenon, although well established for many years, is often not directly distinct in experiments. To establish the importance of ion pairing, or, in other words, supramolecular interactions, a separate introductory chapter is dedicated to these aspects.The references are selected particularly from recent publications, without, however, ignoring some 'classical' contributions. In some sections topics are included which do not strictly represent aromatic molecules but involve interactions of ztype orbitals.

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Generation of azulene radical cations from arylalkynes

Cited by 14 publications

References 4 publications

Synthesis and Spectral Properties of Novel Poly(disubstituted acetylene)s

Synthesis and Spectral Properties of Novel Poly(disubstituted acetylene)s

Highly Substituted Azulene Dyes as Multifunctional NLO and Electron‐Transfer Compounds

Electron‐transfer Reactions of Aromatic Compounds

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