Electronic absorption spectra of radical and dianions of azobenzene derivatives

Kalyanaraman, V.; Dua, S. S.; Rao, C. N. R.; George, M. V.

doi:10.1016/s0040-4039(00)75595-x

Cited by 10 publications

(10 citation statements)

References 5 publications

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“…Examination of Table 1 reveals that the starting nitrones are characterized by an absorption maximum around 298-353 nm, whereas the corresponding radical anions showed a red shifted absomtion maximum around 320-450 nm: the corresponding dianions, however, showed an absorption maximum around 280-295 nm. These observations are in tune with the spectral data reported for the radical anions and dianions derived from azobenzene and nitroaromatics through their reaction with lithium in THF (17)(18)(19)). An interesting observation was that the radical anions 2a-d, 27a,b, 35, and 50 and the dianions 3a-d, 28a,b, and 36 were quenched by oxygen, as evidenced by the disappearance of their absorption bands, on bubbling oxygen gas through their solutions in acetonitrile.…”

Section: Cyclic Voltammetric Studiessupporting

confidence: 87%

Electron transfer reactions. Reaction of nitrones with potassium

Ashok¹,

Scaria²,

Kamat³

et al. 1987

Can. J. Chem.

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KONDA ASHOK, PALLIKKAPARAMBIL M. SCARIA, PRASHANT V. KAMAT, and MANAPURATHU V. GEORGE. Can. J. Chem. 65, (1987).Treatment of nitrones ( l a -d , 26a,b, 34, 49) with potassium in tetrahydrofuran (THF) gives rise to radical anion (2a-d, 27a,b, 35, 50) and dianion intermediates (3a-d, 28a,b, 36) through electron transfer reactions. These intermediates undergo further transformations to give a variety of products. Thus, the aldehydonitrones ( l a -d ) give the corresponding aldehydes (1Oa-c), carboxylic acids (25a-c), and azobenzenes (19a,d), whereas the ketonitrones (26a,b) give deoxygenation products (31a,b). The nitrone 34 gave a mixture of products consisting of benzoic acid (25a), dibenzyl(48), the dimeric product 38, and tetraphenylpyrazine (46), whereas 49 did not give any isolable product. Cyclic voltammetric studies have been employed to measure the reduction potentials for both one-electron and two-electron transfer processes, leading to the radical anions and dianions respectively. These intermediates have been characterized through their electronic spectra and they were quenched by oxygen. Pulse radiolysis of the nitrones [Traduit par la revue]

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Section: Cyclic Voltammetric Studiessupporting

confidence: 87%

Electron transfer reactions. Reaction of nitrones with potassium

Ashok¹,

Scaria²,

Kamat³

et al. 1987

Can. J. Chem.

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“…The UV/vis spectrum of dark green has an obvious absorption at 404 nm (ε = 5.35 × 10 2 M –1 cm –1 ) and a broad feature at 628 nm (ε = 1.73 × 10 2 M –1 cm –1 ) in THF (see Supporting Information Figure S3), which can be ascribed to the presence of the electron in the lowest antibonding orbital . Similarly, The azobenzenyl radical compound Na(PhNNPh) shows absorptions at 433 and 628 nm, while the dianion shows only one bond at 379 nm . These results imply that 2 is a Mg(II) complex, in which the azobenzenyl ligand serves as a radical monoanion.…”

Section: Resultsmentioning

confidence: 98%

“…However, the 1 H NMR spectrum keeps silence in the range from −100 to 100 ppm. The electron paramagnetic resonance (EPR) spectrum (Figure 1 unpaired electron coupled two 14 N nuclei (I = 1). The 14 N coupling constant is ∼7.6 G, which is larger than that of free (PhNNPh) •− .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The UV/vis spectrum of dark green has an obvious absorption at 404 nm (ε = 5.35 × 10 2 M −1 cm −1 ) and a broad feature at 628 nm (ε = 1.73 × 10 2 M −1 cm −1 ) in THF (see Supporting Information Figure S3), which can be ascribed to the presence of the electron in the lowest antibonding orbital. 14 Similarly, The azobenzenyl radical compound Na(PhNNPh) shows absorptions at 433 and 628 nm, 14 while the dianion shows only one bond at 379 nm. 14 These results imply that 2 is a Mg(II) complex, in which the azobenzenyl ligand serves as a radical monoanion.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

See 1 more Smart Citation

An Azobenzenyl Anion Radical Complex of Magnesium: Synthesis, Structure, and Reactivity Studies

Ren

2016

Inorg. Chem.

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Azobenzenyl anion radical complex of magnesium [HC(C(Me)N-2,6-PrCH)]Mg(PhNNPh) (THF) (2) was obtained for the first time through the reaction of [HC(C(Me)N-2,6-PrCH)]MgBr (1) with potassium graphite in the presence of azobenzene. Complex 2 is a useful electron-transfer reagent as shown by the reactivity with diphenyl disulfide, diphenyl diselenide, oxygen, sulfur, and MeSiN yielding the magnesium thiolate [HC(C(Me)N-2,6-PrCH)]Mg(SPh)(THF) (3), magnesium selenolate [HC(C(Me)N-2,6-PrCH)]Mg(SePh)(THF) (4), peroxido complex {[HC(C(Me)N-2,6-PrCH)]Mg(THF)}(μ-η-η-O) (5), persulfido complex {[HC(C(Me)N-2,6-PrCH)]Mg(THF)}(μ-η-η-S) (6), and azido complex [HC(C(Me)N-2,6-PrCH)]MgN (7), respectively. Furthermore, treatment of 2 with MeSiCHN results in a rearrangement product {[HC(C(Me)N-2,6-PrCH)]Mg[CNN(SiMe)]} (8).

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“…The UV-Vis spectrum (Figure 114) of 23 has an obvious absorption at 465 nm (ε = 600 M -1 cm -1 ) and two broad feature at 579 (ε = 625 M -1 cm -1 ) and 731(ε = 586 M -1 cm -1 ) nm in THF, which can be ascribed to the presence of the electron in the lowest antibonding orbital. [86] Similarly, the azobenzene radical compounds (nacnac)Mg(PhNNPh) [81f] and Na(PhNNPh) [86] have bands at 404, 628 nm and 433, 628 nm, respectively. with no discernable hyperfine interactions to the central metal ion or the nitrogen atoms (Figure 115a).…”

Section: One Electron Reduction Of Azobenzenementioning

confidence: 99%

A Dinuclear Dihydride Complex for Bimetallic Reductive Activation and Transformation of a Range of Inert Substrates

Duan¹

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Electronic absorption spectra of radical and dianions of azobenzene derivatives

Cited by 10 publications

References 5 publications

Electron transfer reactions. Reaction of nitrones with potassium

Electron transfer reactions. Reaction of nitrones with potassium

An Azobenzenyl Anion Radical Complex of Magnesium: Synthesis, Structure, and Reactivity Studies

A Dinuclear Dihydride Complex for Bimetallic Reductive Activation and Transformation of a Range of Inert Substrates

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