On the electronic structures of cyclobutadiene and trimethylenemethane

Worley, S. D.; Webb, Thomas R.; Gibson, Dorothy H.; Ong, Tek-Sing

doi:10.1016/s0022-328x(00)92004-7

Cited by 20 publications

(4 citation statements)

References 33 publications

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“…Thus it is in essential agreement with the predicted value of 8.65 eV (ab initio) calculated by Buenker and Peyerimhoff,16 and the LNDO/S value of 8.19 eV obtained by Schweig and his co-workers32 for the ionization energy of 4. More recently Worley et al 33 have derived an estimate of 8.29 eV for the first ionization energy of 4 from a study of the photoelectron spectrum of its tricarbonyl complex, a value in complete agreement with the one obtained above.…”

Section: Resultssupporting

confidence: 75%

“…If we accept this assignment, then the energy gap between the two 7r bands, i.e., those correlated with the two orbitals which are dominated by the in-phase and out-of-phase combination of the two double-bond basis functions, is approximately 3.9 eV in 6, 3.3 eV in 8,26 and 3.5 eV in 9. Extrapolating the values observed for the ionization energies of the tricarbonyl complex of the parent compound 4, Worley et al 33 predict that the second ionization energy of free 4 should be 11.95 eV, which leads to a value of 3.7 eV for the energy gap between the two it bands of 4. Assuming that the influence of the substituting alkyl groups has only a small effect on the difference of the two it ionization energies, a value of 3.6 ± 0.2 eV seems a reasonably safe estimate.…”

Section: Resultsmentioning

confidence: 98%

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A photoelectron spectroscopic investigation of tetra-tert-butyltetrahedrane and of tetra-tert-butylcyclobutadiene

Heilbronner¹,

Jones²,

Krebs³

et al. 1980

J. Am. Chem. Soc.

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 98%

A photoelectron spectroscopic investigation of tetra-tert-butyltetrahedrane and of tetra-tert-butylcyclobutadiene

Heilbronner¹,

Jones²,

Krebs³

et al. 1980

J. Am. Chem. Soc.

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“…14 Photoelectron spectroscopy of CBD, based on the photolysis or pyrolysis of a suitable precursor, thus drew a lot of interest, but the difficulties of generating the molecule cleanly as well as its high reactivity hampered the experiments. Earlier studies extrapolated an IE of 8.29 eV from the values of related molecules 15 or reported broad bands without assignable vibrational structure, which only permitted the extraction of a band maximum of 8.24 eV. 16 The exception is a 118.2 nm (10.49 eV) photoelectron spectrum of CBD generated by pyrolysis of tricyclopentan-3-one, which was reported by Kohn and Chen (KC).…”

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confidence: 96%

Threshold Photoelectron Spectrum of Cyclobutadiene: Comparison with Time-Dependent Wavepacket Simulations

Bosse

Mant

Schleier

et al. 2021

J. Phys. Chem. Lett.

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The C 4 H 4 isomer cyclobutadiene (CBD) is the prime model for antiaromaticity and thus a molecule of considerable interest in chemistry. Because it is highly reactive, it can only be studied under isolated conditions. Its electronic structure is characterized by a pseudo-Jahn−Teller effect in the neutral and a E ⊗ β Jahn−Teller effect in the cation. As a result, recording photoelectron spectra as well as describing them theoretically has been challenging. Here we present the photoion mass-selected threshold photoelectron spectrum of cyclobutadiene together with a simulation based on time-dependent wavepacket dynamics that includes vibronic coupling in the ion, taking into account eight vibrational modes in the cation. Excellent agreement between theory and experiment is found, and the ionization energy is revised to 8.06 ± 0.02 eV.

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“…is also gratefully acknowledged. The anomalous greater basicity of trimethylphosphine than trimethylamine relative to borane1 was used to advantage in the preparation of a new borane-derived base, trimethylphosphine-((dimethylamino)methyl)borane (2) (eq 1). The Me3P + Me3N-BH2CH2NMe2 -1 Me3N + Me3P-BH2CH2NMe2 (1) 2 known amine analogue, 1, is prepared from the reaction of feri-butyllithium and bis(trimethylamine)dihydroboron(l+) chloride.2 After 12 h in hexane solution, the reaction with 1:1 to 1.5:1 stoichiometry yields nearly 50% of product which is separated as a clear, colorless liquid, mp -31 to -33 °C, by fractional condensation in a -35 °C trap.…”

mentioning

confidence: 99%

Electronic structures of some .eta.3-allyl transition-metal complexes

Worley¹,

Gibson²,

Hsu³

1981

Inorg. Chem.

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In recent years there has been much interest in the electronic structures of transition-metal carbonyl i r complexes of hydrocarbons in these laborat~ries~-~ and in others6 A primary thrust of the work in these laboratories has been to demonstrate that the ultraviolet photoelectron spectra (UPS) of the stable complexes of intriguing labile transients such as cyclobutadiene can be used in estimating the T ionization energies of the In fact, recent UPS studies by Heilbronner and co-workers' on tetra-tert-butylcyclobutadiene have supported our predictions for the i r electronic structure of the parent cyclobutadiene. This note will address UPS of several transition-metal complexes of and the electronic structure of another interesting transient species-the allyl radical. Results and DiscussionThe low-ionization-energy regions of the photoelectron spectra of four q3-allyl transition-metal carbonyl complexes are shown in Figure 1. The resolution in the region above 12 eV for these spectra was not sufficient to render definitive assignments for the ionization bands corresponding to removal of electrons from a-bonding orbitals. However, assignment of the bands in the region below 12 eV for these complexes would appear to be straightforward.The spectrum of q3-allylmanganese tetracarbonyl, A, exhibits four resolved band components below 12 eV. The I1and I2 components at 8.05 and 8.48 eV, respectively, must correspond to ionization of orbitals primarily confined to the transition metal Mn; ample precedent for such an assignment exists in the literatures2" Thus, the I, and I4 components at 9.03 and 11.13 eV can be assigned to ionization of the perturbed i r orbitals on the allyl ligand. Using a very elaborate photoelectron spectrometer, Houle and Beauchamp were able to obtain the spectrum of the allyl radical.8 They report a(1) (aa 9 io 11 1216 7 a o io 11 12 IOGIZAIIOS ESERGY (eV) Figure 1. Photoelectron spectra of some $-allyl transition-metal complexes. The excitation source was the H e I resonance line.first ionization potential of 8.13 eV for this radical which, of course, must refer to ionization of the highest occupied x orbital which is primarily nonbonding in character. Thus, it is evident that this i r orbital is perturbed significantly (stabilized by ca. 0.9 eV) by the bonding interaction with the manganese tetracarbonyl moiety. In fact, the 0.9-eV perturbation is almost exactly the same as that (0.89 f 0.07 eV)u observed for the highest occupied x orbital of a number of hydrocarbons when these systems are coordinated to an iron tricarbonyl moiety. While this may seem fortuitous, a similar observation has been reported for the molybdenum, chromium, and iron carbonyl complexes of norb~rnadiene.~ It is interesting that such a divergent series of transition-metal carbonyl complexes has similar perturbation energy for the x HOMO; however, there would seem to be no theoretical justification for this experimental observation. Because of overlapping bands due to decomposition products of 3-butenyl nitrite used to genera...

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On the electronic structures of cyclobutadiene and trimethylenemethane

Cited by 20 publications

References 33 publications

A photoelectron spectroscopic investigation of tetra-tert-butyltetrahedrane and of tetra-tert-butylcyclobutadiene

A photoelectron spectroscopic investigation of tetra-tert-butyltetrahedrane and of tetra-tert-butylcyclobutadiene

Threshold Photoelectron Spectrum of Cyclobutadiene: Comparison with Time-Dependent Wavepacket Simulations

Electronic structures of some .eta.3-allyl transition-metal complexes

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