Spiro[4.4]nonatetraene and spiro[4.4]nona-1,3,7-triene.  Synthesis and properties.  Effects of spiroconjugation

Semmelhack, M. F.; Foos, J.; Katz, Stephanie A.

doi:10.1021/ja00803a021

Cited by 91 publications

(36 citation statements)

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“…2, a due to a transition to the corresponding singlet state. The latter assignment follows that given previously [5] [6] for the UV-absorption spectra.…”

supporting

confidence: 80%

“…After the synthesis of 1 had been achieved [4], this prediction was confirmed experimentally [5]. In fact, the EA spectrum of 1 (l max 276 and 218 nm) permitted a first tentative assessment of the magnitude of the above MO splitting due to spiroconjugation (1.23 eV).…”

Section: Dedicated To Edgar Heilbronner On the Occasion Of His 80th Bmentioning

confidence: 53%

“…Based on symmetry considerations, they noted that spiroconjugation for molecules like 1 results in a splitting of the cyclopentadiene HOMOs, whereas it leaves the LUMOs degenerate. As a consequence, the first electronic absorption (EA) band of cyclopentadiene was predicted to be split into a lower-and a higher-lying component of very different absorptivity in 1.After the synthesis of 1 had been achieved [4], this prediction was confirmed experimentally [5]. In fact, the EA spectrum of 1 (l max 276 and 218 nm) permitted a first tentative assessment of the magnitude of the above MO splitting due to spiroconjugation (1.23 eV).…”

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confidence: 81%

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Spiro[4.4]nonatetraene and its Positive and Negative Radical Ions: Molectronic Structure Investigations

Haselbach

Allan

Bally

et al. 2001

HCA

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Dedicated to Edgar Heilbronner on the occasion of his 80th birthdayThe electronic structure of spiro [4.4]nonatetraene 1 as well as that of its radical anion and cation were studied by different spectroscopies. The electron-energy-loss spectrum in the gas phase revealed the lowest triplet state at 2.98 eV and a group of three overlapping triplet states in the 4.5 ± 5.0 eV range, as well as a number of valence and Rydberg singlet excited states. Electron-impact excitation functions of pure vibrational and triplet states identified various states of the negative ion, in particular the ground state with an attachment energy of 0.8 eV, an excited state corresponding to a temporary electron attachment to the 2b 1 MO at an attachment energy of 2.7 eV, and a core excited state at 4.0 eV. Electronic-absorption spectroscopy in cryogenic matrices revealed several states of the positive ion, in particular a richly structured first band at 1.27 eV, and the first electronic transition of the radical anion. Vibrations of the ground state of the cation were probed by IR spectroscopy in a cryogenic matrix. The results are discussed on the basis of density-functional and CASSCF/ CASPT2 quantum-chemical calculations. In their various forms, the calculations successfully rationalized the triplet and the singlet (valence and Rydberg) excitation energies of the neutral molecule, the excitation energies of the radical cation, its IR spectrum, the vibrations excited in the first electronic absorption band, and the energies of the ground and the first excited states of the anion. The difference of the anion excitation energies in the gas and condensed phases was rationalized by a calculation of the Jahn-Teller distortion of the anion ground state. Contrary to expectations based on a single-configuration model for the electronic states of 1, it is found that the gap between the first two excited states is different in the singlet and the triplet manifold. This finding can be traced to the different importance of configuration interaction in the two multiplicity manifolds.1. Introduction. ± Spiroconjugation, a concept first introduced in 1967 [1] [2], results in many interesting spectroscopic and chemical properties. As a consequence, spiroconjugated compounds have often been studied experimentally and theoretically, and they find applications in technology (e.g., as materials for organic light-emitting diodes [3] or nonlinear optical materials).

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“…2, a due to a transition to the corresponding singlet state. The latter assignment follows that given previously [5] [6] for the UV-absorption spectra.…”

supporting

confidence: 80%

Section: Dedicated To Edgar Heilbronner On the Occasion Of His 80th Bmentioning

confidence: 53%

mentioning

confidence: 81%

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Spiro[4.4]nonatetraene and its Positive and Negative Radical Ions: Molectronic Structure Investigations

Haselbach

Allan

Bally

et al. 2001

HCA

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“…In connection with an ongoing study of the synthesis and chemistry of novel, substituted pentacyclo [5.4.0.0E,6.0a,l°.05,9]undecanes (PCUs; Marchand, 1989), the Diels-Alder cycloaddition of spirocyclic diene (1) (Semmelhack, Foos & Katz, 1973) to p-benzoquinone has been investigated. Thus, when an equimolar toluene solution of the diene and dienophile was stirred at ambient temperature for 16 h, the corresponding cycloadduct (2) was produced in 61% yield.…”

Section: Introductionmentioning

confidence: 99%

Structure of an unusual octacyclic cage compound

Watson¹,

Kashyap²,

Marchand³

et al. 1990

Acta Crystallogr C

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“…3 Most often, bis(carbamates) serve as precursors to azo compounds and the latter, in turn, to a host of theoretically interesting materials, reactive intermediates, and precursors to natural products. 2, 4 While hydrolytic methods can also be used, the trichloroethoxy group is most often cleaved reductively, usually with Zinc-Acetic Acid, 5 or with a Zinc/Copper Couple in the presence of a proton donating solvent, 2b,4 or via an electroreductive process. 6 The presence of a proton donor leads to the formation of an intermediate hydrazo compound, which requires further oxidation to generate the azo linkage.…”

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confidence: 99%