Study of the mechanism of redox transformations of sterically hindered N-aryl-o-iminoquinones

Smolyaninov, I. V.; Letichevskaya, N. N.; Kulakov, A. V.; Aref’ev, Ya. B.; Пащенко, К. П.; Берберова, Н. Т.

doi:10.1134/s1023193507100138

Cited by 13 publications

(9 citation statements)

References 48 publications

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“…The additional one electron oxidation wave is observed at 1.45 V. This value is very close to the oxidation potential of sterically hindered o-iminobenzoquinones 22 and is responsible for the oxidation of the imine nitrogen atom in L 0 . Two irreversible anodic processes at E 1/2 1.32 and 1.45 V result in the destruction of 3 and the reversibility of the first anodic redox wave disappears on the reverse scan of the CV.…”

Section: Cyclic Voltammetrysupporting

confidence: 55%

Tin(iv) and lead(iv) complexes with a tetradentate redox-active ligand

et al. 2012

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The coordination chemistry of a tetradentate redox-active ligand, glyoxal-bis(2-hydroxy-3,5-di-tert-butylanil) (H(2)L), was investigated with the diorganotin(IV) and diphenyllead(IV) moieties. Complexes R(2)SnL (R = Me (1), Et (2), (t)Bu (3), Ph (4)) and Ph(2)PbL (5) have been prepared and characterized. The molecular structures of compounds 1, 3, and 5 have been determined by single crystal X-ray diffraction. The diamagnetic octahedral complexes bear a tetradentate O,N,N,O redox-active ligand with a nearly planar core. Complexes 1-5 demonstrate solvatochromism in solution. The CV of complexes 1-5 reveals four one-electron redox processes. The spin density distribution in the chemically generated cations and anions of 1-5 was studied by X-band EPR spectroscopy. The experimental data agree well with the results of DFT calculations of electronic structures for 1, its pyridine adduct 1·Py, cation 1(+) and anion 1(-).

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Section: Cyclic Voltammetrysupporting

confidence: 55%

Tin(iv) and lead(iv) complexes with a tetradentate redox-active ligand

et al. 2012

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“…In order to inhibit axial coordination, we targeted the 2,6-diisopropylphenyl-substituted complex (Diso) 2 Ni (Scheme ). In this case, the preparation of the corresponding aminophenol has not been described, but the compound is readily prepared using the nickel(0) precursor Ni(cod) 2 and the appropriate iminoquinone (eq ). This procedure mirrors the preparation of nickel bis(semiquinone) complexes from Ni(CO) 4 and the corresponding 1,2-benzoquinones. ,, This sterically encumbered bis(iminoquinone) complex does indeed show a simple one-electron oxidation to the monocation (Figure ), though the subsequent oxidation event is irreversible.…”

Section: Resultsmentioning

confidence: 99%

Group 10 Bis(iminosemiquinone) Complexes: Measurement of Singlet–Triplet Gaps and Analysis of the Effects of Metal and Geometry on Electronic Structure

et al. 2018

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Bis(iminosemiquinone) complexes of divalent group 10 metals have been described as having open-shell singlet ground states characteristic of very strong coupling between the two ligand radicals. By using the nonlinear temperature dependence of the chemical shifts of the H NMR spectra, the singlet-triplet gaps in seven of these compounds have been measured, with the nickel compounds having gaps of about 2400 cm and the palladium compounds about 1800 cm. Bis(iminosemiquinone)platinum complexes have singlet-triplet gaps too large to measure by this technique (over 2800 cm, estimated to be about 3000 cm), though bis(3,5-di- tert-butylbenzosemiquinonato)platinum(II) has a measurable singlet-triplet gap of 1850 cm. In combination with near-IR absorption data of the neutral, cationic, and anionic bis(iminosemiquinone) complexes, a simplified two-electron, two-orbital bonding model describing these compounds can be fully parametrized based on experimental data. The identity of the central metal principally affects the difference in energy between metal-ligand π nonbonding and metal-ligand π antibonding orbitals, with the strength of the bonding interactions increasing in the order Pd < Ni < Pt. Twisting the ligands out of planarity (by using a 2,2'-biphenylenediyl linker) has a marked effect on the optical spectra of the compounds but not on their singlet-triplet gaps; this indicates that the effect is not due to changes in bonding interactions but rather due to a decrease in the magnitude of the quantum mechanical exchange interactions in the twisted compared to the flat compounds.

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“…The easy oxidation of (AP-iPr)H 2 (þ0.82 V) makes possible the autooxidation of this ligand by air oxygen [48]. o-Aminophenol (AP-iPr)H 2 inhibits effectively oleic acid oxidation during short time with the formation of two-electron oxidation product -the corresponding o-iminobenzoquinone which is also able to inhibit chain-radical process of oxidation.…”

Section: Discussionmentioning

confidence: 99%

“…The number n DPPH for ascorbic acid and catechol is 2.0 and 2.3 respectively. The sterically hindered o-aminophenols as well as catechols can be oxidized in two-electron stage to the corresponding o-iminobenzoquinones [48]. The total number of electrons in the course of electrochemical experiment for complexes varies from 1.5 to 2.…”

Section: Radical Scavenging Reactions Of the Target Complexes In Deaementioning

confidence: 99%

Radical scavenging activity of sterically hindered catecholate and o-amidophenolate complexes of LSbVPh3 type

Smolyaninov

Antonova

Poddel’sky

et al. 2011

Journal of Organometallic Chemistry

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Study of the mechanism of redox transformations of sterically hindered N-aryl-o-iminoquinones

Cited by 13 publications

References 48 publications

Tin(iv) and lead(iv) complexes with a tetradentate redox-active ligand

Tin(iv) and lead(iv) complexes with a tetradentate redox-active ligand

Group 10 Bis(iminosemiquinone) Complexes: Measurement of Singlet–Triplet Gaps and Analysis of the Effects of Metal and Geometry on Electronic Structure

Radical scavenging activity of sterically hindered catecholate and o-amidophenolate complexes of LSbVPh3 type

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