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  • 1
    Electronic Resource
    Electronic Resource
    Lösungsmitteleinflüsse auf die NMR-Spektren von Cyclopropan-Derivaten (1967)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 703 (1967), S. 109-115 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es werden die NMR-Spektren der Cyclopropan-Derivate 1-11, deren α-C-Atom eine funktionelle Gruppe abnehmender Elektrophilie enthält, in CDCl3 und C6D6 miteinander verglichen. Hierbei wird eine gleichgerichtete Abnahme der Δδ-Werte (Tab. 1) festgestellt.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19677030113
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  • 2
    Electronic Resource
    Electronic Resource
    Photochemie kleiner Ringe, XXVIII1) Dibenzo[2.4]spirene und deren Umlagerungsprodukte durch Photofragmentierung und Thermolyse von Spiropyrazolen (1974)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1974 (1974), S. 1132-1139 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photochemistry of Small Rings, XXVIII1). - Dibenzo[2.4]spirenes and Their Derivatives via Photofragmentation and Thermolysis of SpiropyrazolesPhotofragmentation of the spiropyrazoles 3 leads to the dibenzo[2.4]spirenes 4 in good to average yields. Thermolysis of 3 at lower temperatures also gives 4. At higher temperature, however, the pentalene derivatives 9 are formed. This rearrangement involves spirenes 4. The vinylcarbene 11 or the diradical 13 are intermediates in the reaction 3 → 4. Rearrangement 4 → 9 can proceed synchronously or via the diradical 15.
    Notes: Die Photofragmentierung der Spiropyrazole 3 ergibt in guten bis mittleren Ausbeuten die Dibenzo[2.4]spirene 4. Die Thermolyse von 3 führt bei tieferen Temperaturen ebenfalls zu 4, bei höheren Temperaturen werden die Pentalen-Derivate 9 gebildet. Bei dieser Umlagerung treten die Spirene 4 als Zwischenprodukte auf. Die Reaktion 3 → 4 dürfte über das Vinylcarben 11 oder das Diradikal 13 als Zwischenstufen verlaufen. Die Umlagerung 4 → 9 kann entweder synchron oder über ein Diradikal 15 formuliert werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197419740709
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  • 3
    Electronic Resource
    Electronic Resource
    Photochemie kleiner Ringe, XVIII1) Addition von Carbena-cyclopentadienen an Benzol (1970)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 734 (1970), S. 141-154 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photochemistry of Small Cyclic Compounds, XVIII1). Addition of Carbenacyclopentadienes to BenzenePhotolysis of 1,4-disubstituted diazocyclopentadienes (12) in benzene leads, via carbenacyclopentadienes (with 4n + 2-π-electrons) as intermediates to 7H-(13) and 5 H-benzocycloheptenes (14). Side reactions of the carbenacyclopentadienes form insertion products (15) and dimerization products (17). Catalytic hydrogenation of 13 and 14 gives the tetrahydro derivatives 19. The photo-fragmentation of 13 und 14 leads to the naphthalene derivatives 18. Thermolysis of 12a in mesitylene gives exclusively the insertion product 22. - The mechanism of the formation of 13 und 14 is discussed. Photochemical sigmatropic 1,3- and/or 1,7-H shifts are proposed as reaction steps.
    Notes: Die Photolyse 1.4-disubstituierter Diazo-cyclopentadiene (12) in Benzol ergibt, über die intermediär entstehenden Carbena-cyclopentadiene (mit 4n + 2 π-Elektronen), die 7 H-(13) und die 5 H-Benzocycloheptene (14). In Nebenreaktionen werden Insertions- (15) und Dimerisierungsprodukte (17) der Carbena-cyclopentadiene gebildet. 13 und 14 lassen sich durch katalytische Hydrierung in die Tetrahydro-Derivate 19 umwandeln. - Die Photofragmentierung von 13 und 14 führt unter Abspaltung von Methylen zu den Naphthalin-Derivaten 18. Die Thermolyse von 12a in Mesitylen ergibt ausschließlich das Insertionsprodukt 22. - Der Bildungsmechanismus von 13 und 14 wird diskutiert, wobei photochemische sigmatrope 1.3 und/der 1.7-H-Verschiebung als Reaktionsschritte vorgeschlagen werden.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19707340115
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  • 4
    Electronic Resource
    Electronic Resource
    Addition von Cycloalken-carbenen mit 6 π-Elektronen an Cyclooctatetraen (1970)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 740 (1970), S. 74-78 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Addition of Cycloalkene-carbenes with 6 π-Electrons to CyclooctatetraenePhotolysis of the diazo-compounds 3 or 6 in cyclo-octatetraene leads by addition to spiro-bicyclo[6,1,0]-nonatrienes 4 or 7. No insertion product was formed by this reactions and no substituent-effect has been observed during the formation of 4.
    Notes: Die Photolyse der Diazo-Verbindungen 3 bzw. 6 in Cyclooctatetraen ergibt unter Addition die Spirobicyclo[6.1.0]nonatriene 4 bzw. 7. Ein Insertionsprodukt konnte in keinem Falle isoliert, ein Substituenteneinfluß bei der Bildung von 4 nicht festgestellt werden.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19707400108
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  • 5
    Electronic Resource
    Electronic Resource
    Über Cycloalken-carbene, VI1) Spiro-Konjugation bei Spiro[2.4]heptatrienenHerrn Prof. Dr. B. Eistert zum 70. Geburtstag gewidmet. (1973)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1973 (1973), S. 214-220 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Cycloalkene Carbenes, VI1). Spiro Conjugation of Spiro[2.4]heptatrienesPhotolysis of diazocyclopentadienes 4 in alkynes or alkenes leads to spiro[2.4]heptatrienes 1 and spiro[2.4]heptadienes 5, respectively. The presence of spiro conjugation in compounds of type 1 can be proved by comparing the UV spectra of 1 and 5.
    Notes: Die Photolyse von Diazocyclopentadienen 4 in Alkinen oder Alkenen ergibt die Spiro[2.4]-heptatriene 1 bzw. die Spiro[2.4]heptadiene 5. Aus dem Vergleich der UV-Spektren von 1 und 5 läßt sich das Auftreten der Spiro-Konjugation bei den Verbindungen 1 nachweisen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197319730207
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  • 6
    Electronic Resource
    Electronic Resource
    Stereochemische Studien an Bicyclen.  -  Einfluß von Verschiebungsreagenzien auf 1H-NMR-Spektren (1973)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1973 (1973), S. 1691-1701 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereochemical Studies on Bicyclic Systems.  -  Effect of Shift Reagents on 1H-NMR SpectraParamagnetic shift reagents like tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium(III) [Eu(tmh)3] give rise to splitting of the resonance signals in the 1H-NMR spectra of bicyclo[3.1.0]hexenes 1-4. The complex spectra of 2-4 are simplified to 1 st order spectra and can thus be analyzed directly. The evaluation of ΔEu values allows unambiguous assignment to the exo- or endo-isomer of 1. In spite of the simplifications, a satisfactory relation exists between ΔEuvalues and 1/R3, and between log ΔEu and log ri.
    Notes: Durch das paramagnetische Verschiebungsreagenz Tris(2,2,6,6-tetramethyl-3,5-heptandionato)europium(III) [Eu(tmh)3] tritt in den 1H-NMR-Spektren der Bicyclo[3.1.0]hexene 1-4 eine Auffächerung der Resonanzsignale ein. Dadurch werden die komplexen Spektren von 2-4 praktisch 1. Ordnung und können direkt analysiert werden. Die Bestimmung der ΔEu-Werte erlaubt eine eindeutige Zuordnung der Stereoisomeren zur exo- oder endo-Form von 1. Trotz der gemachten Vereinfachungen besteht eine befriedigende Beziehung zwischen den ΔEu Werten und 1/R3 sowie zwischen log ΔEu und log ri.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.197319731014
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  • 7
    Electronic Resource
    Electronic Resource
    Supramolecular sensitizer-relay assemblies. An evaluation of binding constants from non-linear stern-volmer plotsDedicated to Professor K. Schaffner on the occasion of his 60th birthday. Electron Transfer Reactions, Part 9. For Part 8, see Ref. 2A. (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 63-73 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A novel technique for determining the binding constants of host-guest complexes, viz. the bis-cationic electron relays methylviologen and octylviologen in the macrocyclic host of novel (bisheteroleptic) crown ether-ruthenium sensitizers, is described. This technique allows the separation of the quenching effects of bound and free electron relays. It can be used to calculate binding constants in non-covalently linked supramolecular systems evaluating the electron transfer process between guest and host. High binding constants comparable to those in many natural enzymes and the photosynthetic reaction centre were found. As an explanation for the behaviour of the sensitizers bound to the bipyridinium cations it is suggested that photoelectron transfer affects the binding between the excited sensitizer and the bound acceptor.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050202
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  • 8
    Electronic Resource
    Electronic Resource
    4,5-Diazafluorenylidene: Preparation, Reactivity, Multiplicity, and Selectivity StudiesDedicated to Professor H. D. Scharf on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1611-1618 
    Details
    ISSN: 0947-3440
    Keywords: Carbenes ; Cycloadditions ; Diazo compounds ; Styrene ; Electrophilic addition ; Nitrogen heterocycles ; Photolysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chemistry of 4,5-diazafluorenylidene (3), generated from the diazo compound 3a by photolysis, has been studied with regard to reactivity, multiplicity and selectivity. Reaction of 3 in 2,3-dimethylbutene gave exclusively ketazine 24. The [1 + 2] cycloaddition with styrenes 5-11 afforded cyclopropanes 16-23 in 25-54% yields and 24 as a side product. In these reactions no diazirine intermediate was involved. Irradiation of 3a in methanol afforded the ether 26 (25% yield). The stereoselectivity of 3 was studied by its addition to (E)- and (Z)-β-methylstyrene. A mixture of the (E)- and (Z)-cyclopropanes 22 and 23, respectively, was detected. Thus for 3, triplet multiplicity was concluded. The results of competition experiments with singlet/triplet scavengers (methanol/dimethylbutadiene) demonstrated that an equilibrium between singlet and triplet manifold of 3 exists at room temperature. Selectivity studies with carbene 3 were carried out by evaluating the competition experiments of the cycloaddition of 3 with differently substituted styrenes. A plot of the krel values from the competition studies versus Hammett σ constants gave ρ = -0.65 indicating that carbene 3 reacts as an electrophile.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970745
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  • 9
    Electronic Resource
    Electronic Resource
    Modellsysteme zur artifiziellen Photosynthese - Synthese und Elektronentransferstudien neuartiger Sensibilisator-Relais-EinheitenHerrn Prof. Dr. C. W. Jefford zum 65. Geburtstag gewidmet. (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 407-413 
    Details
    ISSN: 0947-3440
    Keywords: Artificial photosynthesis ; Electron transfer ; Sensitizer-relais assemblies ; Photophysical properties ; Hydrogen production ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modell Systems for an Artificial Photosynthesis - Synthesis and Electron Transfer Studies of Novel Sensitizer-Relais AssembliesSyntheses and determination of electron transfer rates between sensitizers and electron acceptors for a novel class of bis(4,4′-dimethyl-2,2′-bipyridine)[4,4′-bis(alkoxymethyl)-2,2′-bipyridin]ruthenium(II) complexes 6-8 are described. We report on the formation of supramolecular complexes between the dialkoxybenzene-tethered bisheteroleptic Ru(II)-bipyridine complexes 5, 8 and 1,1′-dimethyl-4,4′-bypiridinium (MV2+) and cyclo-[bis(1,1′-p-xylylene-4,4′-bipyridinium)] (BXV4+), respectively. Evidence for the formation of supramolecular sensitizer-relais assemblies is taken from the viologen radical and hydrogen production rates in sacrificial model systems for artificial photosynthesis.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199519950249
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  • 10
    Electronic Resource
    Electronic Resource
    Zum Mechanismus der Photoreduktion von Wasser mit Ruthenium-trisbipyrazil als Sensibilisator (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 2652-2655 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Mechanism of the Photoreduction of Water with Ruthenium-trisbipyrazil as SensitizerOxidative and reductive primary steps can be differentiated in using Ru(bipy)32+ and Ru(bipz)32+, respectively, as sensitizers in a photochemically induced, Pt-catalyzed sacrificial water reduction. Experimental evidence for the reductive primary step and kinetic data are given for the electron transfer to methylviologen as relay compound.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660833
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