Der Einfluss von Substituenten in Stellung 4 auf das n‐Ionisationspotential des Chinuclidins

Bieri, Gerhard; Heilbronner, E.

doi:10.1002/hlca.19740570307

Cited by 28 publications

(8 citation statements)

References 26 publications

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“…Hammett σ values are usually used in such analyses for aromatic compounds. For other compounds, e.g., quinuclidines, [27] IPs were found to correlate well with Taft's σ values and, as we have recently shown for 1-substituted 1H-benzotriazoles, [1] IPs related to all occupied π MOs (π 1 -π 5 ) and the two n N orbitals of the parent 1H-benzotriazole unit correlate well with inductive substituent parameters σ I and F. For some substituents, for which no σ I or F parameters are known, these could be determined from their IPs by correlation analysis.…”

Section: Linear Free Energy Correlation Analysis Of Ionisation Energiesmentioning

confidence: 99%

Photoelectron Spectra and Electronic Structures of Substituted Pyrimidines

et al. 2005

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The electronic structures of pyrimidine (1) and its substituted derivatives 2−15 have been investigated by ultraviolet photoelectron spectroscopy and quantum chemical methods. The ionisation potentials corresponding to the π MOs π1‐π3 and the two nN orbitals of the pyrimidine unit could be determined and assigned for 1−15. Multiple linear regression analyses of the IPs related to these orbitals with different substituent constants indicated that Hammett σp values performed well for all these IPs, whereas the resonance parameters R and R+ were satisfactory for π and poor for nN ionisations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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Section: Linear Free Energy Correlation Analysis Of Ionisation Energiesmentioning

confidence: 99%

Photoelectron Spectra and Electronic Structures of Substituted Pyrimidines

et al. 2005

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“…Sie beweisen eindeutig, dass der Tetrahydropyrazin-Ring von I1 in der Halbsessel-Konformation VII vorliegt, mit der H3C-C (6)-Gruppe in pseudoaquatorialer Lage. Die Formylierung von I1 mit HCOOH erfolgte in Anlehnung an [4]. Das reine, kristallisierte 111 liegt in wasseriger Losung nach seinem lH-NMR.-Spektrum (Fig.…”

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“…Das reine, kristallisierte 111 liegt in wasseriger Losung nach seinem lH-NMR.-Spektrum (Fig. 3) als Mischung von zwei Rotameren IIIa und IIIb vor, ahnlich wie alle anderen, bis jetzt beschriebenen 5-Acyl-tetrahydropterine [5] [I], einschliesslich des (6R, S)-6,7-cis-Dimethyl-5-formyl-tetrahydropterins [4]. In DMSO-Losung dagegen liegt nur ein Rotamer, wahrscheinlich IIIa, vor (Fig.…”

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Über Pterinchemie. 77. Mitteilung)Das (6R,S)‐5‐Formyl‐6‐methyl‐5,6,7,8‐tetrahydropterin: Synthese, chemische und physikalisch‐chemische Eigenschaften

Ganguly

Bieri

Viscontini

1981

Helvetica Chimica Acta

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(6R,S)‐5‐Formyl‐6‐methyl‐5,6,7,8‐tetrahydropterine: Synthesis, Chemical and Physico‐chemical Properties (6R, S)‐5‐Formyl‐6‐methyl‐5,6,7,8‐tetrahydropterine (III), a model substance for the biologically important 6‐substituted 5‐formyl‐5,6,7,8‐tetrahydropterines, was obtained for the first time by formylation of the corresponding tetrahydropterine with formic acid. Compound III, analogously to the other known 5‐acyltetrahydropterines, exists in solution (except in DMSO) as a mixture of two rotamers IIIa and IIIb. The two H‐C(7) in III have the same chemical shift and the same coupling constant to H‐C(6), giving rise to a A,A',X,C‐system. Conformational analysis of III, based on its 1H‐NMR,‐spectrum, shows that the methyl group is pseudo‐axial and the formyl group pseudo‐equatorial. Moreover, the H(X)‐C(6) bond lies nearly in the plane bisecting the C(6)‐C(7)‐H(A), C(6)‐C(7)‐H(A') dihedral angle; the C(6) and C(7) lie outside the N(5)‐C(4a)‐C(8a) plane and the tetrahydropyrazine cycle must be extremely strained, according to Dreiding models.

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“…This has led to assignment of a new o t value for I (12). Also, 1, X = 1 deviates below the correlation line for 1 by two standard deviations (10). Thus the deviations of F and I are systematic in the gas phase.…”

Section: B Deviationsmentioning

confidence: 98%

“…In correlations of IP with Hammett substituent constants, however, nitro compounds do not deviate (2). Nor does X = NO, (o, = 0.70) deviate from the line (IP = 0.9520,~~ + 8.07; correlation coefficient, r = 0.968; standard deviation of points from the line 0.07 eV) for series 1 (X = C,H,, OH, OOCCH,, C1, Br, I, CN, NO,, CECH, H, CH,, C,H,, i-C3H7, and tert-C,H,) (10). Therefore, the deviation is not inherent to the gas phase.…”

Section: B Deviationsmentioning

confidence: 99%

Linear free energy relationships. VIII. Ionization potentials of aliphatic compounds

Gibson¹

1977

Can. J. Chem.

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. Can J. Chem. 55,2637Chem. 55, (1977. Ionization potentials (IP) of HX, CH3X, C2H5X, and i-C3H,X, where X is a substituent with non-bonded electrons, are directly proportional to ionization potentials of 4-substituted quinuclidines. This is taken as evidence that in general the energy required to remove an electron from a substituent X, as is the case in HX, CH3X, C,H5X, and i-C3H7X, is directly proportional to the energy required to remove an electron from a site remote from the substituent, as in the quinuclidines in which an electron is lost from the ring nitrogen. Furthermore, the 1P's of the HX-i-C3H7X series are directly proportional to inductive substituent constants, o,, providing a valuable correlation between gas and solution phase behavior.HARRY W. GIBSON. Can. J. Chem. 55,2637(1977. Les potentiels d'ionisation (IP) de HX, CH3X, C2H,X et i-C3H7X, ou X est un substituant comportant des electrons non-lies, sont directement proportionnels aux potentiels d'ionisation des quinuclidines substitues en position 4. On considere cette correlation comme une indication que, d'une facon gtnerale, I'energie requise pour enlever un electron d'un substituant X, comme dans le cas de HX, CH3X, C2H5X et i-C3H7X, est directement proportionnelle a l'energie requise pour enlever un electron d'un site eloigne du substituant comme dans les quinuclidines dans lesquelles un electron est perdu par I'azote du cycle. De plus, les potentiels d'ionisation de la serie HX CC3H7X sont directenient proportionnels aux constantes inductives des substituants, o,, fournissant une correlation tres utile entre le comportemellt en phase gazeuse et en solution.[Traduit par le journal] Molecular orbital energy levels are determining factors both for chemical reactivity and many physical properties, especially spectral and electrical properties. Our previous work using linear free energy relationships (1-7), including the Hammett equation (8), was aimed at quantitatively relating these energy levels to molecular structure (1-4,6,7) and in turn to electrical properties (5) of aromatic compounds. In the first paper of this series it was shown that the ionization potentials (IP) of substituted benzenes are linearly related to the sums of the Hammett substituent constants. To understand and predict the properties of aliphatic series a similar linear free energy relationship would be most helpful. A . Linear Free Energy RelationshipsA number of correlations of ionization potentials of aliphatic compounds with Taft or inductive substituent constants have appeared (9). However, the substituents were restricted to hydrogen or alkyl groups. The only exception is the study of some quinuclidines (1) (lo), in which sitbstituents with non-bonded electrons were examined. It was our objective to deter-'References 1-7 comprise parts I-VII of this series. mine if the ionization potentials of simple alkanes substituted with groups bearing nonbonded electrons could be correlated with the ionization potentials of series 1 and more generally with substituent const...

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Der Einfluss von Substituenten in Stellung 4 auf das n‐Ionisationspotential des Chinuclidins

Cited by 28 publications

References 26 publications

Photoelectron Spectra and Electronic Structures of Substituted Pyrimidines

Photoelectron Spectra and Electronic Structures of Substituted Pyrimidines

Über Pterinchemie. 77. Mitteilung)Das (6R,S)‐5‐Formyl‐6‐methyl‐5,6,7,8‐tetrahydropterin: Synthese, chemische und physikalisch‐chemische Eigenschaften

Linear free energy relationships. VIII. Ionization potentials of aliphatic compounds

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