Spectroscopic and DFT evidence for a nonclassical radical cation derived from 7-benzhydrylidenenorbornene

Ikeda, Hiroshi; Namai, Hayato; Hirano, Takashi

doi:10.1016/j.tetlet.2005.03.156

Cited by 4 publications

(2 citation statements)

References 15 publications

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“…We also compared the UV/vis absorption spectra of γ-irradiated low-temperature matrices of 4 , 6 , 7 , and 8 with DFT calculations of their radical anions, i.e., the counterparts of the radical cations 4 •+ , 6 •+ , 7 •+ , and 8 •+ . As a result, we were able to deduce the molecular geometry and electronic structure of both the radical cations and radical anions of 4 , 6 , 7 , and 8 , and to demonstrate that their classical and nonclassical natures are controlled topologically 1 7-Benzhydrylidenenorbornene Derivatives ( 4 and 6 − 8 ), the Corresponding Radical Cations ( 4 • + and 6 • + − 8 • + ), the Corresponding Radical Anions ( 4 •- and 6 •- − 8 •- ), and Related Intermediates ( 1 - , 1 • , and 1 + ) …”

Section: Introductionmentioning

confidence: 89%

Spectroscopic and Density Functional Theory Studies of the Molecular Geometry and Electronic Structure of Classical and Nonclassical Radical Ions Derived from 7-Benzhydrylidenenorbornene Analogues

et al. 2007

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A spectroscopic study, using nanosecond time-resolved laser flash photolysis and gamma-irradiation of low-temperature matrices, was undertaken along with a theoretical study using density functional theory (DFT) and time-dependent (TD)-DFT calculations to gain insight into the molecular geometry and electronic structure of radical cations and radical anions of 7-benzhydrylidenenorbornene (4) and its derivatives 6-8. The radical ions 4(.+), 6(.+), 7(.+), 8(.+), 4(.-), 6(.-), 7(.-), and 8(.-) exhibited clear absorption bands in the 350-800 nm region, which were reproduced successfully from the electronic transitions calculated with TD-UB3LYP/cc-pVDZ. Radical cations 4(.+) and 8(.+) are consistent with a bent structure having a delocalized electronic state where the spin and charge are delocalized not only in the benzhydrylidene subunit but also in the residual subunit. In contrast, 6(.+) and 7(.+) have nonbent structures with a localized electronic state where their spin and charge are localized in the benzhydrylidene subunit only. Therefore, 4(.+) and 89(.+) have a nonclassical nature, with 6(.+) and 7(.+) possessing a classical nature. In contrast, in the radical anion system, 7(.-) and 8(.-) are considered nonclassical, and 4(.-) and 6(.-) are classical. Orbital interaction theory and DFT calculations can account fully for the spectroscopic features, molecular geometries, and electronic structures of the radical ions. For example, the shift of the absorption bands and the nonclassical nature of 4(.+) are due to the antibonding character of the highest occupied molecular orbital (HOMO) of 4, and those of 7(.-) arise from the bonding character of the lowest unoccupied molecular orbital (LUMO) of 7. A topological agreement of p-orbitals at C-2, C-3 (or C-5, C-6), and C-7 produces strong electronic coupling with an antibonding or a bonding character in the frontier orbitals. It is the ethylene and butadiene skeleton at C-2-C-3 (or C-5-C-6), with its contrasting topology in the HOMO and LUMO of the neutral precursor, that holds the key to deducing the nonclassical nature of the 7-benzhydrylidenenorbornene-type radical cation and radical anion systems.

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Section: Introductionmentioning

confidence: 89%

Spectroscopic and Density Functional Theory Studies of the Molecular Geometry and Electronic Structure of Classical and Nonclassical Radical Ions Derived from 7-Benzhydrylidenenorbornene Analogues

et al. 2007

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“…DFT calculations often give more satisfactory results. Indeed our experience has shown that charge and spin densities ( q and ρ , respectively) calculated by using the B3LYP method are of sufficiently high quality to explain the reactivity of 2,2′,3,3′‐tetraphenylbicyclopropenyl radical cations [restricted B3LYP/6‐31G(p)], the molecular geometries and electronic structure of the geminally diphenyl‐substituted trimethylenemethane radical cation and 1,4‐diphenylcyclohexane‐1,4‐diyl radical cation ( 5 •+ ) (UB3LYP/cc‐pVDZ), and the classical and nonclassical radical ions derived from 7‐benzhydrylidenenorbornene analogs, in addition to other reactive intermediates of this type …”

Section: Methodsmentioning

confidence: 99%

Density functional theory study of silole‐fused tetramethyleneethane biradicals with orbital interactions

Kano

Mizuno

Ikeda

2011

J of Physical Organic Chem

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The geometries, energy gap between singlet and triplet states (S–T gap), electronic transitions, and molecular orbitals of the diphenyl derivative of the silole‐fused tetramethyleneethane (TME) (3,4‐dimethylenesilole) biradical 7•• were determined by using the density functional theory method at the unrestricted Becke, three‐parameter, Lee–Yang–Parr/cc‐pVDZ level. In a manner similar to that of the parent TME biradical, the S–T gap of 7•• is small. The wavelengths of electronic transitions of 37•• (λET = 450 nm) are calculated to be different from that of 17•• (λET = 673 nm). These differences are attributed to interactions between orbitals of the two allyl radical moieties, especially, the existence of double σ*–π* conjugation, that is, π*–σ*–π* conjugation, that takes place in the silole subunit. Copyright © 2011 John Wiley & Sons, Ltd.

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DFT studies of unique stereoelectronic effects of substituents on divergent reaction pathways of methylenecyclobutanone radical cations

et al. 2012

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Spectroscopic and DFT evidence for a nonclassical radical cation derived from 7-benzhydrylidenenorbornene

Cited by 4 publications

References 15 publications

Spectroscopic and Density Functional Theory Studies of the Molecular Geometry and Electronic Structure of Classical and Nonclassical Radical Ions Derived from 7-Benzhydrylidenenorbornene Analogues

Spectroscopic and Density Functional Theory Studies of the Molecular Geometry and Electronic Structure of Classical and Nonclassical Radical Ions Derived from 7-Benzhydrylidenenorbornene Analogues

Density functional theory study of silole‐fused tetramethyleneethane biradicals with orbital interactions

DFT studies of unique stereoelectronic effects of substituents on divergent reaction pathways of methylenecyclobutanone radical cations

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