Peter Bischof

The electronic structure of benzvalene : Photoelectronspectroscopic studies

Abstract The photoelectron(PE)spectrum of tricyclo[3.1.0.02,6] hex-2-ene(benzvalene 1) has been recorded. The first four bands in the PE spectrum of 1 can be assigned to transitions to 2B2, 2A1, 2A2 and 2B1 states of 11. This assignment is discussed in terms of the results of semiempirical and ab initio calculations on 1. Furthermore the highest occupied MOs of 1 are derived qualitatively from an interaction diagram between a distorted bicyclobutane and an ethylene moiety.

Evidence for through-bond interaction between mutually perpendicular PI systems

Abstract Comparison of the photoelectron (PE) spectra of tetravinylmethane ( 1 ) and trans, trans, trans-1,2,3,4-tetravinylcyclobutane ( 2 ) indicates that through-bond interaction in 2 is comparable in magnitude to the through-space spiro interaction in 1 . A similar result is obtained by comparison of the UV absorption spectra of 9,9′-spirobifluorene ( 3 ) and 8b,8c,16b,16c -tetrahydrocyclobuta[1,3-1:2,4-1′]diphenanthrene ( 4 ).

Pyrolyses of azoalkanes. photoelectron spectra of some hydrocarbon radicals

Abstract The pyrolyses of azocyclobutane (=1)and azocyclopropylmethane (=2) have been used to generate C 4 H 7 radicals. The photoelectron spectra at various temperatures are presented and the results compared with the data obtained by pyrolyses of the corresponding methylnitrites.

The photoelectron spectrum of 7b-methyl-7bH-cyclopent[cd]indene

The He1 photoelectron (p.e.) spectrum of 7b-methyl-7bH-cyclopent[cd]indene (1) has been recorded. The first four bands are assigned to ionization events from π-orbitals related to the perimeter of [10]annulene. This assignment is based on model calculations using the HMO and the MIND0/3 model. The p.e. spectrum of (1) is compared with that of 1,6-methano[10]annulene (3). The rearrangement of (1) to its 2aH isomer (4) is also discussed.

Reversal in the sequence of the two highest occupied molecular orbitals in the series pyrazine, 2,6-dimethylpyrazine, and tetramethylpyrazine

Comparison between the photoelectron spectra of pyrazine (1), 2,6-dimethylpyrazine (2), and tetramethylpyrazine (3) indicates that in (3) the HOMO is π(b2g) while in (1) and (2) it is n+, suggesting a different behaviour towards electrophilic attack on (3) compared with (1) and (2).