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A Reexamination of the Walsh‐ and Förster—Coulson—Moffitt‐ (F.C.M.) Orbital Concept, and its Relevance for the Interpretation of PE Spectra
Author(s) -
Honegger Evi,
Heilbronner Edgar,
Schmelzer Andreas,
JianQi Wang
Publication year - 1982
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198200003
Subject(s) - chemistry , natural bond orbital , molecular orbital theory , slater type orbital , molecular orbital diagram , molecular orbital , localized molecular orbitals , antibonding molecular orbital , atomic orbital , linear combination of atomic orbitals , valence bond theory , basis set , non bonding orbital , computational chemistry , physics , quantum mechanics , molecule , electron , density functional theory , organic chemistry
Contrary to what is often believed, the description of the bonding orbitals of cyclopropane in terms of the so‐called Walsh‐orbitals or F.C.M.‐ (bent‐bond) ‐orbitals is not equivalent. These two sets of orbitals transform into each other only if their antibonding counterparts are taken into account. The bent‐bond orbitals can be obtained directly from the set of occupied canonical SCF orbitals of cyclopropane via a unitary transformation into localized orbitals. In contrast, the bonding Walsh‐orbitals are not contained in the occupied manifold of the canonical orbitals, because of their non‐equivalence to the F.C.M.‐ orbitals. This is the reason why the anti‐bonding Walsh‐orbitals have to be taken into consideration if one wants to draw valid conclusions, e.g., about the photoelectron spectra of compounds containing the cyclopropane moiety.