Photoelectron spectroscopic analysis of through-bond interaction via cyclobutane relay orbitals. Evidence for strong relay conjugation in tricyclo[5.5.0.02,8]dodecatetraene
“…A second example concerns the interaction of the π systems in 4 and 5 . In the case of 4 , the relay is the σ system of the central cyclobutane moiety, while in 5 , it is the bicyclo[1.1.1]pentane cage system (Figure a). 1 Measured energy difference of the vertical ionization energies, I v, j , assigned to the ionizations from the in-plane π orbitals (π i - , π i + ) and the distance, d , between the triple bonds. 2 (a) Energy difference between the first two ionization energies of 4 and 5 .…”
Section: Introductionmentioning
confidence: 99%
“…In the case of 4, the relay is the σ system of the central cyclobutane moiety, 4 while in 5, it is the bicyclo[1.1.1]pentane cage system 5 (Figure 2a).…”
The He I photoelectron spectra of
2,6-dimethylenetricyclo[3.3.01,5.03,7]octane,
(stella-2,6-diene) (6), stella-2,6-dione (8), stella-6-en-2-one (10),
distella-2,2‘,6,6‘-triene (7), distella-6,6‘-en-2,2‘-dione
(9), and distella-2,2‘,6‘-dien-6-one (11) have been recorded. The energy
differences between the π ionizations arising from the terminal
π
bonds amount to 0.9 eV (6) and 0.4 eV (7).
An energy difference of 1.1 eV has been found between the 2p
lone-pair ionizations of 8. Using Hartree−Fock SCF
calculations with a 3-21G basis, the geometries of
6−11 have been
calculated. For all six molecules long central σ bonds
(1.58−1.60 Å) were predicted. By means of the
Weinhold
natural bond localization procedure, the interactions between the σ
frame and the π orbitals as well as between the
σ frame and the n orbitals have been probed. It has been
concluded that the large energy splitting between the π
MOs mainly localized at the terminal π bonds in 6 and
7 is mediated by the ribbon orbitals of the twisted
cyclohexane
ring.
“…A second example concerns the interaction of the π systems in 4 and 5 . In the case of 4 , the relay is the σ system of the central cyclobutane moiety, while in 5 , it is the bicyclo[1.1.1]pentane cage system (Figure a). 1 Measured energy difference of the vertical ionization energies, I v, j , assigned to the ionizations from the in-plane π orbitals (π i - , π i + ) and the distance, d , between the triple bonds. 2 (a) Energy difference between the first two ionization energies of 4 and 5 .…”
Section: Introductionmentioning
confidence: 99%
“…In the case of 4, the relay is the σ system of the central cyclobutane moiety, 4 while in 5, it is the bicyclo[1.1.1]pentane cage system 5 (Figure 2a).…”
The He I photoelectron spectra of
2,6-dimethylenetricyclo[3.3.01,5.03,7]octane,
(stella-2,6-diene) (6), stella-2,6-dione (8), stella-6-en-2-one (10),
distella-2,2‘,6,6‘-triene (7), distella-6,6‘-en-2,2‘-dione
(9), and distella-2,2‘,6‘-dien-6-one (11) have been recorded. The energy
differences between the π ionizations arising from the terminal
π
bonds amount to 0.9 eV (6) and 0.4 eV (7).
An energy difference of 1.1 eV has been found between the 2p
lone-pair ionizations of 8. Using Hartree−Fock SCF
calculations with a 3-21G basis, the geometries of
6−11 have been
calculated. For all six molecules long central σ bonds
(1.58−1.60 Å) were predicted. By means of the
Weinhold
natural bond localization procedure, the interactions between the σ
frame and the π orbitals as well as between the
σ frame and the n orbitals have been probed. It has been
concluded that the large energy splitting between the π
MOs mainly localized at the terminal π bonds in 6 and
7 is mediated by the ribbon orbitals of the twisted
cyclohexane
ring.
Als erstes interessierte die Frage, welchen EinfluD der Ersatz der Ethano-Brucke in 4 durch andere Brucken bzw.keine Briicke auf das thermische Verhalten ausiibt. Die von Borden untersuchte Pyrolyse des nicht uberbriicktenChem.
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