Substituent effects in photoelectron spectra of monofunctional aliphatic compounds

Carlier, P.; Hernández, R Vigoa; Masclet, P.; Mouvier, G.

doi:10.1016/0368-2048(74)85068-1

Cited by 10 publications

(1 citation statement)

References 2 publications

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“…A fairly good linear relationship (Figure , r 2 = 0.934) is also found between the bromination rate coefficients of the alkenes and their first ionization energies as taken from their PE spectra . An analogous relationship 47 has previously been observed for acyclic alkenes with linear n- alkyl substituents and attributed to the absence of any steric control in the bromination rates.…”

Section: Computational Studiessupporting

confidence: 77%

Reactivities of Methylenetriangulanes and Spirocyclopropanated Bicyclopropylidenes toward Bromine. Relative Stabilities of Spirocyclopropanated versus Methyl-Substituted Bromonium Ions

et al. 2002

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The bromine additions to methylenecyclopropane (1), bicyclopropylidene (2), and spirocyclopropanated methylenecyclopropanes and bicyclopropylidenes 3-6 in methanol at 25 degrees C proceed essentially with the same rate as those to the corresponding oligomethyl-substituted ethylenes. An increasing number of spiroannelated three-membered rings enhances the rate of bromination and stabilizes the intermediate cyclopropyl bromonium cations against ring opening in the course of bromine addition. Calculations at the B3LYP/6-311G(d,p) level show that unsymmetrical bromonium ions are the intermediates, and that they are stabilized by the spiroannelation with cyclopropane rings. The bromonium ion derived from 1 is less stable by 6.3 kcal mol-1 than that from isobutene. One or two spirocyclopropane rings as in 3 and 4 stabilize the corresponding bromonium ion by 9.6 and 16.4 kcal mol-1, respectively, while one or two alpha-cyclopropyl substituents as in ethenylcyclopropane (7) and 1,1-dicyclopropylethene (8) stabilize the corresponding bromonium ions by 13 and 29 kcal mol-1, respectively. The experimental bromination rates of all the studied alkenes correlate reasonably well (r2 = 0.93) with calculated relative energies of the corresponding bromonium ions. The correlation is even better within the series of methylenecyclopropanes 1, 3, and 4 (r2 = 0.974) and bicyclopropylidenes 2, 5, and 6 (r2 = 0.999). The experimental bromination rates also correlate fairly well with the first ionization energies of the corresponding alkenes 1-12 (with r2 = 0.963) and 13-19 (with r2 = 0.991). The calculated preferred nucleophilic attack of a water molecule at both the C1' and C1 atoms of representative bromonium ions conforms well to the experimentally observed product distribution.

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Section: Computational Studiessupporting

confidence: 77%

Reactivities of Methylenetriangulanes and Spirocyclopropanated Bicyclopropylidenes toward Bromine. Relative Stabilities of Spirocyclopropanated versus Methyl-Substituted Bromonium Ions

et al. 2002

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Synthesis and PE Spectra of 1‐Ethynyl‐ and 1,4‐Diethynylbicyclo[2.2.2]octane, and of Related 1,4‐Dihalobicyclo[2.2.2]octanes

et al. 1987

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The assignment of the PE spectra of 1-substituted and of 1,Cdisubstituted bicyclo[2.2.2]octanes or related cage-molecules can present serious difficulties, which have to be kept in mind when attempting a rationalization of such an assignment in terms of qualitative concepts. As long as the molecules consist only of first and second row atoms, the usual ab initio or semiempirical models provide a rather safe basis as we shall see by discussing in detail the PE spectra of l-ethynylbicyclo[2.2.2]octane (1) and of 1,4-diethynylbicyclo[2.2.2]octane (2). However, the problem becomes more involved when the substituents are heavy atoms, e.g., halogen atoms. Thus a recent investigation of the He(Ia) PE spectra of symmetrical 1 ,4-dihalonorbonanes2) has shown that the assignment of such spectra is anything but straightforward. Extensive mixing between the substituent and parent-molecule orbitals does no longer allow a unique classification of the observed PE bands as e.g. dominantly n; ' or D-' bands.Schrtne I

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Photoelectron spectroscopy of biologically active molecules. 17. unsaturated steroids

Klasinc̆

McGlynn

Paša‐Tolić

et al. 2009

Int. J. Quantum Chem.

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The assignment of the He1 photoelectron ( PE) spectra of the unsaturated steroids: estr4ene-3,17dione (1); estr-5( lO)ene-3,17dione (2); pregn-5ene-3,20-dione (3); 208-hydroxypregn4ene-3-one (4); 1 1~, 2 1 d i h y d r o x~~n e -3 , 2 0 -d i o n e (5); androst4ene-3,17dione (6); androsta-l,qdiene-3,17dione (7); androst-5en-l'l-one (8); and androst-5ene-3,17-dione (9) is attempted. This attempt is vested in an analysis of features, the results of quantum chemical calculations ( MNDO) , and correlative studies. A simple empirical method for the prediction of double-bond ioniiation energies of alkenes is described and applied. 1.Although the experimental values are readily obtained (e.g., by PE spectroscopy, multiphoton ionization, and mass spectrometry), the number of possible molecules increases so rapidly with the number of C-atoms that most of the larger molecules will never be either synthesized or isolated.2. The existing data suggest that a large range of I( xcc) values will be spanned by molecules with the same number of C-atoms but with different locations of the double bond.

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Substituent effects in photoelectron spectra of monofunctional aliphatic compounds

Cited by 10 publications

References 2 publications

Reactivities of Methylenetriangulanes and Spirocyclopropanated Bicyclopropylidenes toward Bromine. Relative Stabilities of Spirocyclopropanated versus Methyl-Substituted Bromonium Ions

Reactivities of Methylenetriangulanes and Spirocyclopropanated Bicyclopropylidenes toward Bromine. Relative Stabilities of Spirocyclopropanated versus Methyl-Substituted Bromonium Ions

Synthesis and PE Spectra of 1‐Ethynyl‐ and 1,4‐Diethynylbicyclo[2.2.2]octane, and of Related 1,4‐Dihalobicyclo[2.2.2]octanes

Photoelectron spectroscopy of biologically active molecules. 17. unsaturated steroids

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