Electronic structure and reactivity of propellanes : Photoelectron spectra of thia[4.4.3]propellanes

The photoelectron spectra of 12-thia[4.4.3]propell-3-ene (), 12-thia[4.4.3]propell-3-ene-12-oxide (2), 12-thia[4.4.3]propella-3,8-diene-12-oxide (3), 12-thia[4.4.3]propella-3,8-diene-12-dioxide (4), 12 thia[4.4.3]propella-2, 4-diene-12-oxide (5), 12-thia(4.4.3]propella-2,4,7,9 tetraene-12-oxide (6) and 12-thia[4.4.3]propella-2,4,7,9 tetraene-12-dioxide (7) have been investigated and the first bands have been interpreted. For compounds 3 and 4 the endo-endo conformation could be excluded. For 6 and 7 the interaction of the two butadiene moieties is of the same order as that of the π-orbitals in norbornadiene. The electronic structure of 3 and 4 allows us to rationalize and to predict the direction of the addition of cations and carbenes.     

Reaction of [3.3.1]propellanes with diaryl diselenides

Russian Journal of Organic Chemistry -     

Construction of [4.3.1]propellanes via molybdenum fischer carbene complexes

Treatment of molybdenum Fischer carbene complexes with 6-methylene-7-octen-1-yne derivatives at 40 degrees C generates substituted tricyclo[4.3.1.0(1,6)]deca-2,4-dienes in good yield. Pentacarbonyl(butylmethoxycarbene)molybdenum(0) afforded the highest cyclization yields (54%), while the analogous chromium carbene complex gave no reaction. The range of dienyne substrates that participate in this reaction is explored and its mechanism is analyzed and discussed.     

The Photoelectron Spectrum of [18]Annulene

The PE. spectrum of [18]annulene has been measured and correlated with MO-calculations. The experimental ionization energies can only be explained by computing the electronic states of the cation, that is by taking into account the electron correlation and reorganization in the ionic states. The results allow a discussion of the structure of the neutral molecule; they are consistent with a D_6hpoint group of symmetry.     

Synthesis of heterocyclic [3.3.3]propellanes via a sequential four-component reaction

A highly chemoselective heteroannulation protocol for the synthesis of unreported polysubstituted heterocyclic [3.3.3]propellanes has been developed by sequential four-component reaction of ninhydrin, malononitrile, primary amines, and dialkyl acetylenedicarboxylates under mild conditions in water. To the best of our knowledge, there are no previous reports for the synthesis of these classes of heterocyclic [3.3.3]propellanes. The merit of this sequential Knoevenagel condensation/enamine formation/Michael addition/cyclization sequence is highlighted by its high atom-economy, excellent yields, the use of water as reaction media, and the efficiency of production without the use of any activator or metal promoters. This synthesis serves as a nice addition to group-assistant-purification (GAP) chemistry in which purification via chromatography and recrystallization can be avoided, and the pure products were obtained simply by washing the crude products with 95% ethanol.     

Photoelectron spectra and quantum-chemical calculation of 5-vinyl- and 5-ethylidenebicyclo[2.2.1]hept-2-ene

The photoelectron spectra of 5-vinyl- and 5-ethylidenebicyclo[2.2.1]-hept-2-ene have been measured, and they have been interpreted with the aid of a quantumchemical calculation by the CNDO/S method. The reactivity of the compounds indicated has been discussed on the basis of the results obtained.Translated from Teoreticneskaya i Éxperimental'naya Khimiya, Vol. 21, No. 4, pp. 472–475, July–August, 1985.     

Photoelectron spectra of cyclopolysilanes

Summary He (I) PE spectra of cyclopentasilane and cyclohexasilane show excellent agreement with STO-3 G + ab initio calculations. The HOMO in both compounds is of (SiSi) 3 p character. First IP's appear at 9.4 and 9.6 eV respectively.

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Photoelektronenspektren von Cyclopolysilanen (Kurze Mitt.)

Zusammenfassung Die He (I) PE-Spektren der Cyclosilane Si₅H₁₀ und Si₆H₁₂ zeigen ausgezeichnete Übereinstimmung mit STO-3 G + ab initio Rechnungen. Beide Ringe besitzen HOMO's mit (SiSi) 3 p Charakter. Die ersten Ionisierungspotentiale liegen bei 9.4 bzw. 9.6 eV.

     

Electronic structure and reactivity of propellanes : The stereochemistry of diels-alder- and related cyclo-additions in the series of [4.4.2] and [4.4.3] propellanes; models and interpretations

The stereochemistry of the products obtained by Diels-Alder addition of 1 to 2-6 and 14 and 15 has been rationalised. In case of the propellanes 2-6 a frontier MO approach substantiated by extended Hückel calculations has been invoked. For 14 and 15 the Coulomb interaction between the polar SO and SO₂ groups and the dienophile is decisive for the observed stereochemistry.     

Photoelectron spectra of vinyl tellurides

The lowest energy band in the photoelectron (PE) spectra of alkyl vinyl tellurides is attributed to-MO with predominant contribution from the p_z-AO of the tellurium atom. The second and fourth lowest energy bands correspond to-MO. An additional-MO is located between these-MO. The introduction of a second vinyl group hardly affects the HOMO. The heterocyclization of divinyl telluride has a large perturbation effect. Nevertheless, divinyl telluride and tellurophene have the same type of orbital structure.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 935–939, April, 1991.     

Photoelectron spectra of 1,4-benzodiazepines

Photoelectron (PE) spectra of 20 biologically active molecules of 1,4-benzodiazepine derivatives have been measured. The spectra in the range of low ionization energies (IE) were interpreted by comparison of MNDO quantum-chemical calculation data with the perturbation theory estimations. The effect of substituents and structural changes in the series studied is felt mainly by the -MOs of ring A; theortho effect is observed in the PE spectra ofortho isomers.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1583–1587, September, 1993.     

Photoelectron spectra of substituted benzenes

Photoelectron spectra of several substituted dimethylanilines, nitrobenzenes, acetophenones and nitrosobenzenes have been studied with a view to examine the electronic effects of substituents on the various φ and n levels. The results are discussed in the light of molecular orbital calculations and electronic absorption spectra. Correlation of substituent effects on the IE's with π-electron densities and Hammett substituent constants has enabled rationalization of all available data on mono- and disubstituted benzenes. The IE's generally increase with the electron-withdrawing power of the substituents.     

Propellanes. Part LXXVIII. Preparation of Several Triaza[3.3.3]propellanes and an Oxadiaza[3.3.3]propellane

3,7,10-Tribenzyl-3,7,10-triaza[3.3.3]propellane ( 4a ), 3,7-dibenzyl-10-phenyl-3,7,10-triaza[3.3.3]propellane ( 4c ), 3,7-dibenzyl-10-(p-tolyl)-3,7,10-triaza[3.3.3]propellane ( 4b ), and 3-oxa-7,10-diaza[3.3.3]propellane ( 6 ) have been prepared.     

Thermolysis of the [a.2.2]propellanes. Mechanisms for the thermolysis of bicyclo[2.2.0]hexanes.

The thermolysis of the [4.2.2]propellene proceeds with good first order kinetics and gives E_a = 46 kcal/mole. The increase in E_a over that for bicyclo[2.2.0]hexane and the [2.2.2]propellane provides evidence tor the mechanism of these thermolyses.     

Propellanes—XXIII : The synthesis of [4.4.3]propellanes containing one cyclohexadiene ring

Several propellanes containing in common a cyclohexane and a cyclohexadiene ring but varying in the structure of the third, 5-membered ring—an ether, a thioether, an anhydride or a methylimide ring—have been prepared.     

Synthesis of 2,4,6,8,9,11-hexaaza[3.3.3]propellanes as a new molecular skeleton for explosives

Azapropellanes are of great interest in many disciplines, including materials science and medicinal chemistry. Various synthetic approaches for azapropellanes have been explored; however, the synthetic study of the polyazapropellane skeleton containing five or more nitrogen atoms is rare. Here, we report a simple yet highly efficient protocol for the synthesis of the hexaaza[3.3.3]propellane skeleton as a building block for high energy materials for the first time. The key reactions include the Boc₂O-assisted cyclization of glycoluril diamine without a column purification step and the first full reduction of all the three carbonyl groups to the methylene groups through a combination of LiAlH₄ and DIBAL-H. All the structures were confirmed by spectroscopic and X-ray analyses.     

Photoelectron spectra of planar sulfur heterocycles

The photoelectron spectra of benzo[b]thiophene (2), benzo[c]thiophene (3), thieno[3,2-b] thiophene (4) and thieno[2,3-b]thiophene (5) together with 2,1,3-benzothiadiazol (6) and benzofurazan (7) have been recorded and the first three bands have been assigned to π-orbitals on the basis of band shapes and semiempirical calculations. The good agreement obtained between measured and calculated ionization potentials suggests that sulfur 3d orbital participation must be very small.     

Photoelectron spectra of the allyl amines

The Hel photoelectron spectra of the three allyl amines show low ionization potential bands arising from nitrogen lone-pair n electrons and ethylenic π-bond electrons. Analysis of the spectra using MINDO/3 calculations and comparisons with ionization data of related molecules shows that π-π interactions are considerable, but n-π interactions are small. The π-π splitting in triallyl amine is consistent with a near-planar C₃ symmetry structure for the gas phase molecule.