Rudolf Haider

The electronic structure of cyclazines

The electronic structure of cyclopenta[h]cycl[4.2.2]azine (1) has been investigated by means of photoelectron spectroscopy and by polarized electronic absorption spectroscopy in stretched polyethylene sheets at 77 K. The measured transitions have been assigned to transitions calculated by a number of semi-empirical methods. The analysis of the results implies that the essential features of the electronic structure of 1 are well described in terms of those of a planar [14]annulene, perturbed by single-bond cross-links.

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 ).

Interaction of walsh orbitals in rotanes. Photoelectron spectroscopic investigation

He I photoelectron spectroscopic investigations of bicyclopropylidene (4), [3]rotane (5), and [4]rotane (6) reveal considerably larger resonance integrals for (4) and (5) compared with values reported for bicyclopropyl and tricyclopropyl derivatives.

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.