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The Conjugative Interaction between π‐Orbitals and Walsh ‐ e ‐Orbitals in Bullvalene and Related Systems
Author(s) -
Bischof P.,
Gleiter R.,
Heilbronner E.,
Hornung V.,
Schröder G.
Publication year - 1970
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19700530712
Subject(s) - slater type orbital , chemistry , natural bond orbital , molecular orbital , molecular orbital theory , linear combination of atomic orbitals , atomic orbital , localized molecular orbitals , molecular orbital diagram , atomic physics , basis set , sto ng basis sets , orbital hybridisation , physics , computational chemistry , quantum mechanics , molecule , electron , density functional theory , organic chemistry
The photoelectron spectra of bullvalene ( 1 ), dihydrobullvalene ( 2 ), tetrahydrobullvalene ( 3 ), hexahydrobullvalene ( 4 ), and homotropylidene ( 5 ) have been recorded. The first bands in these spectra are correlated with orbitals which are linear combinations of the Walsh ‐ e ‐orbitals and of the olefinic π‐orbitals. This assignment is based on a qualitative ZDO‐molecular orbital model as well as on the results of extended Hückel calculations. As anticipated, a large interaction is found between the π‐ and the Walsh ‐ e ‐orbitals in 1 , 2 , and 3 , indicative of a resonance integral β ≈ −2 eV, i.e. of the same order as that between the two double bond π‐orbitals in butadiene (β = − 2.4 eV). In 5 the interaction between π‐ and Walsh ‐ e ‐orbitals is negligible.