Cation radical cycloadditions and related sigmatropic reactions

Pericyclic reactions of radical cations

The cation radical vinylcyclobutane rearrangement

Adiabatic semi-empirical parametric method for computing electronic-vibrational spectra of complex molecules part 1. Polyenes and diphenylpolyenes

The electronic transitions of the cations of benzene, p‐difluorobenzene (p‐DFB), and 1,3,5‐trifluorobenzene (1,3,5‐TFB) have been measured by mass‐selected ion‐dip spectroscopy which utilizes the dissociation of a parent cation in an excited state. This spectroscopy was successfully applied to the vibrational level selected cation in the ground electronic state which was prepared by 1+1 REMPI (resonant enhanced multiphoton ionization) of the neutral molecule in a supersonic jet. For all the cations, the spectra due to the transition from the ground state to the excited π,π state were observed. Ion‐dip spectra having sharp vibrational structures were found for p‐DFB and 1,3,5‐TFB cations, while a broad spectrum was observed for a benzene cation. It was also found that the vibrational structure of the ion‐dip spectrum of the 1,3,5‐TFB cation is quite different from that of the fluorescence excitation spectrum. The assignments of the ion‐dip spectra and dissociation mechanisms of the excited cations will be ...

Electronic spectra of isolated cations in supersonic jets by mass‐selected ion‐dip spectroscopy. Cations of benzene, p‐difluorobenzene, and 1,3,5‐trifluorobenzene

Matrix photoionization experiments with bicyclooctadiene and cyclooctatriene gave sharp new bands between 400 and 500 nm. Selective photolysis with visible light decreased the longer wavelength absorptions and increased a band system beginning at 447 nm; irradiation at 420-470 nm essentially restored the original spectrum. Photoionization of all-trans-octatetraene directly produced a strong 447-nm band system and a sharp weaker 756-nm band system; the latter origin and vibrational structure are in excellent agreement with the emission spectrum of the gaseous cation. Cyclooctatriene and bicyclooctadiene cations experienced a series of photochemical rearrangements, which initially gave a mixture of trans- and cis-octatetraene cations that were converted to all-trans-octatetraene cation by selective irradiation in the solid argon matrix. 23 references, 4 figures, 3 tables.

Absorption spectra and photochemical rearrangements of C8H10 cations in solid argon. Bicyclo[2.2.2]octa-2,5-diene, cycloocta-1,3,5-triene, and octatetraene

Etude detaillee et comparative des resultats. Interet particulier de l'ouverture du cycle des radicaux cationiques pour donner le cation trans-decapentaene

Absorption spectra and photochemical rearrangements of C10H12 radical cations in solid argon. Dicyclopentadiene, 1,3-bishomocubane, bicyclo[6.2.0]deca-2,4,6-triene, and decapentaene

Ultraviolet absorption spectra of all-trans-octatetraene and -decapentaene in solid argon

Absorption spectra and photochemical rearrangement of octatetraene and decapentaene radical cations in solid argon

Matrix photoionization of argon/fluoro- and difluorobenzene/ CH2Cl2 samples during condensation at 20 K produced new structured bands, which can be assigned to the parent radical cations based on agreement with differences between photoelectron bands.

Joseph T. Lurito

Papers

Absorption spectra and photochemical rearrangements of C8H10 cations in solid argon. Bicyclo[2.2.2]octa-2,5-diene, cycloocta-1,3,5-triene, and octatetraene

Absorption spectra and photochemical rearrangements of C10H12 radical cations in solid argon. Dicyclopentadiene, 1,3-bishomocubane, bicyclo[6.2.0]deca-2,4,6-triene, and decapentaene

Ultraviolet absorption spectra of all-trans-octatetraene and -decapentaene in solid argon

Absorption spectra and photochemical rearrangement of octatetraene and decapentaene radical cations in solid argon

Vibronic absorption spectra of fluorobenzene and difluorobenzene radical cations in solid argon