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  • 1
    Electronic Resource
    Electronic Resource
    Protonenresonanz-Spekroskopie ungesättigter Ringsysteme, XXIX1). Einfache Synthese von Benzocycloocten durch Protonierung von Biphenylen-Dianion (1984)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1069-1076 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Proton Resonance Spectroscopy of Unsaturated Ringsystems, XXIX. Simple Synthesis of Benzocyclooctene by Protonation of Biphenylene DianionBiphenylene dianion (1) reacts with H2O to give 4a,8b-dihydrobiphenylene (3) that opens thermally to give benzocyclooctene (4) (yield 〉 80%). At 0°C 3 has a half life of 1 min. The activation parameters of the rearrangement 3 → 4 are δH* = 78.8 ± 5.0 kJ/mol and δS* = - 7.3 ± 8.7 j/mol K. 3 reacts with maleic anhydride to give a Diels-Alder adduct, whose structure has been determined by X-ray analysis.
    Notes: Biphenylen-Dianion (1) reagiert mit H2O zu 4a,8b-Dihydrobiphenylen (3). das thermisch zu Benzocylcoocten (4) öffnet (Ausb. 〉 80%). Bei 0°C besitzt 3 eine Halbwertszeit von 1 min. Die Aktivierungsparameter der Umlagerung 3 → 4 betragen δH* = 78.8 ± 5.0 kJ/mol und δS* = - 7.3 ± 8.7 J/mol K. 3 liefert mit Maleinsäureanhydrid ein Diels-Alder-Addukt, dessen Struktur röntgenographisch bestimmt wurde.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19841170321
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  • 2
    Electronic Resource
    Electronic Resource
    Protonenresonanz-Spektroskopie ungesättigter Ringsysteme, XXVII. Der Benzolkern als Sonde für die π-Elektronenstruktur von Annulenen; Teil IV: Dehydrobenzoannulene (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 71-83 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Proton Resonance Spectroscopy of Unsaturated Ring Systems, XXVII. The Benzene Nucleus as a Probe for the π-Electronic Structure of Annulenes; Part IV: DehydrobenzoannulenesThe 1H NMR Spectra of 6,9-dimethyl-7-monodehydrobenzo[12]annulene (1), 7,9-bisdehydrobenzo[14]annulene (2a), 6,11-dimethyl-7,9-bisdehydrobenzo[14]annulene (2a), 6,11-dimethyl-7,9-bisdehydrobenzo[16]annulene (3), and 9,11-bisdehydrobenzo[18]annulene (4) have been analyzed with respect to chemical shifts and H,H coupling constants. The electronic ground state properties of the annulene rings have been investigated using the Q-value method2). On the basis of the chemical shifts it was found that, compared to the free bisdehydroannulenes, the diatropic behaviour of 2a and 4 is reduced by ca. 70-80%, whereas the paratropic nature of 3 is diminished by less than 50%. Strong π-bond fixation exists in the annulene rings of 1-4.The conformations of the systems are discussed.
    Notes: Die 1H-NMR-Spektren von 6,9-Dimethyl-7-monodehydrobenzo[12]annulen (1), 7,9-Bisdehydrobenzo[14]annulen (2), 6,11-Dimethyl-7,9-bisdehydrobenzo[14]annulen (2a), 6,11-Dimethyl-7,9-bisdehydrobenzo[16]annulen (3) und 9,11-Bisdehydrobenzo[18]annulen (4) wurden hinsichtlich chemischer Verschiebungen und H,H-Kopplungskonstanten analysiert. Die elektronischen Eigenschaften des Grundzustandes der Annulenringe wurden mit Hilfe der Q-Wert-Methode2) untersucht. Aus den chemischen Verschiebungen wurde abgeleitet, daß das diatrope verhalten von 2a und 4 im Vergleich zu dem der freien Bisdehydroannulene um ca. 70-80% reduziert ist, während das paratrope Verhalten von 3 um weniger als 50% abgenommen hat. In den Annulenringen von 1-4 liegt eine starke π-Bindungsfixierung vor. Die Konformationen der Systeme werden diskutiert.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120107
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  • 3
    Electronic Resource
    Electronic Resource
    Carbon-13, 1H coupling constants for benzene and the tropylium ion13C, 1H Spin-Spin Coupling, Part II; for Part I see Ref. 3. (1978)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 11 (1978), S. 97-102 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 13C, 1H spin-spin coupling constants for benzene and tropylium fluoroborate have been measured from the 13C NMR spectra of [D5]benzene and the [D6]tropylium ion using a new experimental technique which employs highly deuterated compounds and 2D-decoupling. For benzene the new data are in good agreement with earlier results. For the tropylium ion we find 1J = 166.79, 2J ≃ 0, 3J = 9.99 and 4J = (-)0.64 Hz. Secondary isotope effects for 13C chemical shifts, including one over four bonds, are reported.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270110208
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  • 4
    Electronic Resource
    Electronic Resource
    Protonenresonanz-Spektroskopie ungesättigter Ringsysteme, XXVI.Der Benzolkern als Sonde für die π-Elektronenstruktur von Annulenen; Teil III: Dibenzoannulene und Dibenzoannulen-Ionen (1978)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1978 (1978), S. 165-175 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Proton Resonance Spectroscopy of Unsaturated Ring Systems, XXVI1).  -  The Benzene Nucleus as a Probe for the π-Electronic Structure of Annulenes; Part III: Dibenzoannulenes and Dibenzoannulene IonsThe Q-value method for the classification of cyclic π-systems [D. Cremer and H. Günther, Liebigs Ann. Chem. 763, 87 (1972)] is applied to dibenzoannulenes and dibenzoannuleneions. For this purpose the 1H NMR spectra of 1,2,5,6-dibenzocycloocta-1,5-diene-3,7-diyne (1), 1,2,5,6-dibenzocyclooctenediide (5) 1,2,3,4-dibenzocyclooctene (6), and 1,2,3,4-dibenzocyclooctenediide (7) have been completely analyzed. Antiaromatic (4n) character is found for 1. The problems associated with the interpretation of proton resonance frequencies in dehydroannulenes are discussed.
    Notes: Die Q-Wert-Methode zur Klassifizierung cyclischer π-Systeme [D. Cremer und H. Günther, Liebigs Ann. Chem. 763, 87 (1972)] wird auf Dibenzoannulene und Dibenzoannulen-Ionen angewandt. Dazu wurden die 1H-NMR-Spektren von 1,2,5,6-Dibenzocycloocta-1,5-dien-3,7-diin (1), 1,2,5,6-Dibenzocyclooctendiid (5), 1,2,3,4-Dibenzocycloocten (6) und 1,2,3,4-Dibenzocyclooctendiid (7) komplett analysiert. Für 1 wurde antiaromatischer (4n) Charakter gefunden. Die Problematik der Interpretation von Protonenresonanzfrequenzen bei Dehydroannulenen wird diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197819780119
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  • 5
    Electronic Resource
    Electronic Resource
    3J(HH)—Pμ,ν correlation for planar 7-membered cyclic π-systems - structural effects on 3J(HH)Proton Magnetic Resonance Spectra of Unsaturated Ring Systems, Part XXIV; for Part XXIII see Ref. 47. (1977)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 9 (1977), S. 420-425 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that sterically unperturbed vicinal HH coupling constants in planar 7-membered π-systems correlate linearly with the HMO π-bond order: 3J(HH) = 20.91Pμ,ν-3.85 (r.m.s. error 0.26 Hz, correlation coefficient =0.988). Systematic deviations from this relationship which most probably originate from valence angle changes are found for fused π-systems containing rings of different size. Model calculations using the CNDO/2 method as well as finite perturbation theory and INDO wave functions support the experimental findings. An improvement of existing 3J(HH)—Pμ,ν correlations for planar 6-membered rings is possible if CNDO/2 π-bond orders are used instead of HMO or PPP-SCF data.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270090711
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  • 6
    Electronic Resource
    Electronic Resource
    Protonenresonanz-Spektroskopie ungesättigter Ringsysteme, XXX. Benzo[c]-1,7-methano[12]annulen und sein Dianion (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 2942-2955 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Proton Resonance Spectroscopy of Unsaturated Ringsystems, XXX. Benzo[c]-1,7-methano[12]annulene and Its DianionThe 400-MHz 1H NMR spectra of benzo[c]-1,7-methano[12]annulene (1) and its dianion have been analyzed in terms of chemical shifts and H,H spin-spin coupling constants using two-dimensional methods and iterative calculations. Bond orders and CC bond lengths have been estimated from the 3J values and the effect of benzoannulation on the paratropic and diatropic behaviour of 1 and 12-, respectively, is derived from the chemical shifts in comparison with those obtained for the parent systems 1,7-methano[12]annulene (2) and its dianion (22-). In the hydrocarbon, paratropism is reduced by approx. 40-50%, while in the dianion the reduction of diatropism amounts to approx. 10%. The Q value of both systems is characteristic of week [4n]-π-character for 2 and strong [4n + 2]-π-character for 22-. In addition, the results of the 1H NMR analysis of 9,10-dimethyl 1,7-methano[12]annulene-9,10-dicarboxylate (3) are given and discussed with respect to the structure of this compound. The bond fixation present in 3 differs from that in the benzo-annulated systems.
    Notes: Die 400-MHz-1H-NMR-Spektren von Benzo[c]-1,7-methano[12]annulen (1) und seinem Dianion wurden hinsichtlich chemischer Verschiebungen und H,H-Spin-Spin-Kopplungskonstanten mit Hilfe zweidimensionaler Methoden und iterativer Berechnungen analysiert. Bindungsordnungen und CC-Bindungslängen wurden auf der Basis der 3J-Werte abgeschätzt. Der Effekt der Benzoanellierung für die paratropen bzw. diatropen Eigenschaften von 1 bzw. 12- ergibt sich durch einen Vergleich der chemischen Verschiebungen mit denen der Stammsysteme 1,7-Methano[12]annulen (2) und seinem Dianion (22-). Im Kohlenwasserstoff ist der paratrope Charakter um ca. 40-50% reduziert, während die Reduktion des diamagnetischen Verhaltens im Dianion ca. 10% beträgt. Der Q-Wert für beide Systeme ist charakteristisch für schwachen [4n]-π-Charakter in 2 und starken [4n + 2]-π-Charakter in 22-. Zusätzlich werden die Ergebnisse der Analyse des 1H-NMR-Spektrums von 9,10-Di-methyl-1,7-methano[12]annulen-9,10-dicarboxylat (3) angegeben und im Hinblick auf die Struktur der Verbindung diskutiert. Die in 3 vorliegende Bindungsfixierung weicht von der in den benzoanellierten Systemen ab.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861191005
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