Reactivity and π-facial selectivity of nucleophile addition to the radical cations of 7-benzhydrylidenenorbornene derivatives

Ishii, Hideki; Shiina, Satoshi; Hirano, Takashi; Niwa, Haruki; Ohashi, Mamoru

doi:10.1016/s0040-4039(98)02429-0

Cited by 7 publications

(1 citation statement)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because the substitution of two phenyl groups in 4 induces lowering of the oxidation potential and an increase in the HOMO, phenyl substitutions make it easy to generate and observe the relevant 4 •+ absorption band in the visible region using electron-transfer reactions coupled with UV/vis absorption spectroscopy. The reactivity of 4 •+ was the subject of a study by Hirano and Ohashi . The radical ion 4 •+ was generated by a photoinduced electron transfer (PET) that induced π-facially selective nucleophilic addition of MeOH or H 2 O to yield 5 .…”

Section: Introductionmentioning

confidence: 99%

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

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 99%