TY  - JOUR
A1  - Christl, Manfred
A1  - Mattauch, B.
T1  - Versuche zur Synthese eines formalen Nitriloxid-Addukts des Benzols. 1,3-Dipolare Cycloadditionen an Bicyclo[2.2.0]hex-5-en-2,3-dicarbonsäureanhydrid, Dewarbenzol und 1,4-Cyclohexadien
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1985
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58216
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Lanzendörfer, U.
A1  - Grötsch, M. M.
A1  - Hegmann, J.
T1  - Primäraddukt, γ-Ketoketen und einige Folgeprodukte der Reaktion von 6-Oxo-5-phenyl-1,3,4-oxadiazin-2-carbonsäure-methylester mit Norbornen
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1985
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58220
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Lang, Reinhard
A1  - Herzog, Clemens
A1  - Stangl, Roland
A1  - Peters, Karl
A1  - Peters, Eva-Maria
A1  - Schnering, Hans Georg von
T1  - Reaktion von Homobenzvalen mit Tetracyanethylen : Bildung eines Tetracyandihydrobarbaralan- und eines Tetracyancyclopropan-Derivats
N2  - In den Reaktionen von Tetracyanethylen (TCNE) und 5,6-Dichlor-2,3-dicyan-p-benzochinon mit Benzvalen haben wir kürzlich die ersten Beispiele für die lange gesuchte einstufige 1,4-Cycloaddition eines Alkens an ein Vinylcyclopropan gcfunden(I~J. Sie ist als [(.,2.+.2s)+ 112J-Prozeß der Dicls-Alder-Addition nahe verwandtllbl. Allerdings entsteht das betreffende TCNE-Addukt, ein Dihydrosemibullvalen-Derivat, nur in einer Ausbeute von wenigen Prozent. Die Hauptprodukte gehen aus einer Zwitterionischen Zwischenstufe hervor, die durch Anlagerung von TCNE an die Benzvalen-n-Bindung resultiert. 

Professor Rolf Huisgen zum 65. Geburtstag gewidmet
KW  - Chemie
KW  - Homobenzvalene
Y1  - 1985
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31839
ER  - 
TY  - JOUR
A1  - Gleiter, Rolf
A1  - Bischof, Peter
A1  - Gubernator, Klaus
A1  - Christl, Manfred
A1  - Schwager, Luis
A1  - Vogel, Pierre
T1  - 2,3-Bis(methylene)bicyclo[2.1.1]hexane and 3,4-Bis(methylene)tricyclo[3.1.0.0\(^{2,6}\)]hexane : Interaction between a π System and a Cyclobutane or Bicyclobutane Moiety
N2  - The He (I) photoelectron spectra of 2-bicyclo[2.1.l]hexene (1), 2,3-bis(methylene)bicyclo[2.1.l]hexane (3), and 3,4-bis(methylene)tricyclo[3.l.O.0\(^{2.6}\)]hexane (4) have been investigated. The assignment given is based on a ZDO model and semiempirical calculations. Tagether with the PE data of benzvalene (2), the reported data allow a comparison between 1-2 and 3-4. This yields a measure of the interactions between 8 cyclobutane or 8 bicyclobutane moiety and a double bond system within a ZDO model. The resonance integral found in the case of 1 and 3 amounts to -1.9 eV, that for 2 and 4, to -2.3 eV. The investigations furthermore reveal that the electronic factors which contribute to the higher reactivity of the bicyclobutane compounds amount to 5 kcal/mol.
KW  - Chemie
Y1  - 1985
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31845
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Lanzendörfer, F.
A1  - Hegmann, J.
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - Cycloadditionen von 6-0xo-l,3,4-oxadiazinen (4,5-Diaza-α-pyronen), 3 : Reaktionen von 6-Oxo-2,5-diaryl-1,3,4-oxadiazinen mit Alkenen
T1  - Cycloadditions of 6-0xo-l,3,4-oxadiazines (4,5-Diaza-α-pyrones), 3 : Reactions of 6-0xo-2,5--diaryl-l,3,4-oxadiazines with Alkenes
N2  - Das bekannte 6-0xo-2,5-diphenyl-6H-l,3,4-oxadiazin (1 a) und die neuen 2,5-Diarylderivate 1 b - g lagern Alkene an, und es entstehen stickstofIfreie Produkte. Im Falle von Cyclopropenen und Cyclobuten bilden sich die a,p-ungesättigten Siebenring-Enollactone 42 -45 bzw. das a,ß-ungesättigte Achtring-Enollacton 47. 42a und d erleiden an basischem Aluminiumoxid die H-Verschiebung zu den ß,y-ungesättigten Siebenring-Enollactonen 46a bzw. d. Bei weiteren Olefinen wurden die 'Y-Ketoketene des Typs 33 als Zwischenprodukte nachgewiesen oder sind aufgrund der Konstitution der Endprodukte wahrscheinlich. Aus 1 a werden mit Norbomen, Norbornadien, Cyc1openten, trans-Cycloocten und Styrol die Sechsring-Enollactone 10, 13, 15, 19 bzw. 21 und 22 erhalten. 10 isomerisiert mit Kalium-tert-butoxid zu 34, und die Methanolyse dieser Enollactone erbringt die diastereomeren Methy]ester 12 bzw. 35. Das y-Ketoketen 16 aus trans-Cycloocten nimmt schneller Wasser und Methanol zu 17 bzw. 18 auf als es zum Enollacton 19 cyclisiert. cis,trans-l,5-Cyc1ooctadien erbringt über die Stufe des nachgewiesenen y-Ketoketens 40 in einer intramolekularen [2 + 2J-Cyc1oaddition den Tricyclus 41. Tetracyclische Verbindungen des Typs 4 gehen aus der Umsetzung von Benzvalen (2) mit 1 hervor. Durch Röntgenstrukturanalysen wurden Konstitution und Konfiguration von 10, 19 und 41 aufgeklärt
N2  - Cycloaddition of the known 6-oxo-2,5-diphenyl-6H-1,3,4-oxadiazine (1 a) and the new 2,5- diaryl derivatives 1 b - g with various alkenes yield nitrogen free products. Using cyclopropenes and cyclobutene, a,~-unsaturated seven-membered enollactones 42-45 and the C't,ßunsaturated eight-membered enollactone 47 are formed, respectively. In the presenee of basic aluminium oxide 42a and d undergo a hydrogen migration to form the ß.y-unsaturated enollactones 46a and d, respectively. With other alkenes, y-ketoketenes 33 have been observed, or are assumed to be intennediates, based on the structure of the isolated products. Tbe six-mernbered enollactones 10, 13, 15, 19, and 21 and 22 have been obtained with norbomene, norbornadiene, cyclopentene, trans-cyclooctene, and styrene. Cornpound 10 isomerizes to 34 on treatment with potassium tert-butoxide. The rnethanolyses of these enollactones result in the formation of the diastereomeric methyl esters 12 and 35. The yketoketene 16 forrned from trans-cyc1ooctene gives acid 17 and ester 18 with water and methanol, respectively. These reactions are faster than the cyc1ization to enollactone 19. From cis,trans-l,5-cyclooctadiene the more short-lived y-ketoketene 40 is formed. which undergoes intramolecular [2 + 2] cycloaddition, giving rise to the tricyclic cyclobutanone derivative 41. Tetracyclic products of type 4 are generated from benzvalene (2) and 1. The structures and configurations of compounds 10, 19, and 41 have been determined by means of X -ray analyses.
KW  - Organische Chemie
Y1  - 1985
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58191
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Herzog, C.
A1  - Brückner, D.
A1  - Lang, R.
T1  - Neue Homobenzvalen-Derivate (Tricylo[4.1.0.0\(^{2,7}\)]hept-3-ene)
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58241
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Lang, R.
A1  - Herzog, C.
T1  - The Synthesis of Octavalene (Tricyclo[5.1.0.0\(^{2,8}\)]octa-3,5-diene) and Several Substituted Octavalenes
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58254
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Mattauch, B.
A1  - Irngartinger, H.
A1  - Goldmann, A.
T1  - Additionen von Benzvalen an Nitriloxide. Eine Synthese für Benzvalen-3-carbonitril
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58269
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Kemmer, P.
A1  - Mattauch, B.
T1  - 1-Methylbenzvalen. Synthese und einige Reaktionen
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58270
ER  - 
TY  - JOUR
A1  - Engels, Bernd
A1  - Peyerimhoff, S. D.
T1  - Theoretical study of the bridging in β-Halo Ethyl
N2  - Large-acale multi-reference configuration interaction (MRD-CI) calculations in a quite flexible AO basis are employed to study the energy hypersurface for the reaction intermediates XC\(_3\)H\(_4\) with X = Cl, Br and F. Particular emphasis is therby placed on determining the equilibrium conformations, the CH\(_2\) rotation barrier and the energy surface for a possible bridging (shuttling motion (1a] of X between the two carbon centers). The absolute minimum in the potential energy surface is found in all three cases for the asymmetric ß-halo radical in general agreement with ESR data at an XCC angle of ca. 110°, a c-c separation somewhat shorter than a single bond and an approximate sp3 type hybridization (\(\alpha _2 \approx \) 135-140°). In FC\(_2\)H\(_4\) the energy difference between the minimum in the symmetric conformation and the absolute minimum is found to be more than 30 kcal so that shuttling seems impossible in agreement with experimental findings. In BrC\(_2\)H\(_4\) the difference between these two potential minima is only between 1-2 kcal, i.e., smaller than the barrier to CH\(_2\), rotation, so that· shuttling is favored, while ClC\(_2\)H\(_4\) takes an intermediate position between these extremes. The use of correlated wavefunctions is found to be quite important for such a study; the results are related to various kinetic studies of these radicals.
KW  - Organische Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58779
ER  - 
TY  - JOUR
A1  - Gleiter, Rolf
A1  - Bischof, Peter
A1  - Christl, Manfred
T1  - Electronic Structure of Octavalene : Photoelectron Spectroscopic Investigations
N2  - The He I photoelectron (PE) spectra of octavalene (5) as weil as its hydrogenated products 6-8 have been investigated. The assignment given is based on an empirical comparison of 5-8 with related compounds, a ZDO model, and semiempirical and ab initio calculations. Within the ZDO model the interaction between the buta.diene moiety and the bicyclobutane fragment of 5 is described by a resonance integral of -2.3 eV. The orbitalsequence of 5 is found tobe 2a\(_2\) (\(\pi\)-\(\sigma\)), 9a\(_1\) (\(\sigma\)), 3b1 (\(\pi\) - \(\sigma\)), 1a\(_2\) (\(\sigma\) + \(\pi\)), 2b\(_1\) (\(\sigma\) + \(\pi\)).
KW  - Chemie
KW  - Octavalen
KW  - Photoelektron
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31588
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Brückner, D.
T1  - Der Einfluß von Phenylgruppen auf die Homokonjugation im Bicyclo[3.2.1]octa-3,6-dien-2-yl-Anion. Eine \(^{13}\)C-NMR-Studie
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58288
ER  - 
TY  - JOUR
A1  - Herzog, C.
A1  - Lang, R.
A1  - Brückner, D.
A1  - Kemmer, P.
A1  - Christl, Manfred
T1  - Norpinene (Bicyclo[3.1.1]hept-2-ene) aus Homobenzvalenen (Tricyclo[4.1.0.0\(^{2,7}\)]hept-3-enen)
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58302
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Herzog, C.
A1  - Kemmer, P.
T1  - Tricyclo[5.1.0.0\(^{2,8}\)]oct-3-en, -oct-4-en und -octan: Darstellung und Thermolyse der Hydroderivate des Octavalens
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58310
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Herzog, C.
A1  - Nusser, R.
T1  - Bicyclo[4.1.1]octa-2,4-dien, -oct-2-en, -oct-3-en und -octan aus Norpinen
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58326
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Herzog, C.
T1  - \(^{13}\)C-NMR-Spektroskopie: Besondere Hochfeldeffekte in Bicyclo[4.1.1]- und Tricyclo[5.1.0.0\(^{2,8}\)]octan-Systemen (1,3-Cycloheptadien-Effekt) und besondere Tieffeldeffekte in Dihalogenbicyclo[2.1.1]hex-2-enen (Cyclopenten-Effekt)
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58334
ER  - 
TY  - RPRT
A1  - Christl, Manfred
T1  - Cycloadditions of 1,3,4-Oxadiazin-6-ones
N2  - No abstract available
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-41677
ER  - 
TY  - JOUR
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
A1  - Davidson, E.R.
T1  - Calculation of hyperfine coupling constants : An ab initio MRD-CI study for nitrogen to analyse the effects of the basis sets and CI parameter
N2  - The hyperfine coupling constant for the nitrogen atom is evaluated by large-scale MRD-CI calculations. A detailed analysis of the charge density at the nucleus and the spin polarization in the ls and 2s shell as a function of various technical parameters is undertaken. Various (s, p) AO basis sets and the inftuence of correlation orbitals is investigated as weil as selection threshold and other properlies in CI calculations. The best value, obtained for the isotropic hyperfine coupling constant in an s, p, d basis, based on theoretical judgment of' best' quantities, is 9·9 MHz compared to 10·4509 MHz.
KW  - Organische Chemie
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58784
ER  - 
TY  - JOUR
A1  - Schreck, Michael
A1  - Christl, Manfred
T1  - Generation and Interception of 1-Oxa-3,4-cyclohexadiene
N2  - No abstract available
KW  - Chemie
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31601
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Schreck, Michael
T1  - 1,2,3,5,8,8a-Hexahydronaphthalin aus 1,2-Cyclohexadien
N2  - Reaktionen von 1,3-Butadien und einigen seiner Methylderivate mit 1a und 1- Methyl-1,2-cyclohexadien 1b sowie den Übergang der [2 + 2]-Cycloaddukte 2 und 3 in das bisher unbekannte 1,2,3,5,8,8a-HexahydronaphthaJin 4a und einige seiner Methylderivate
KW  - Chemie
KW  - Butadien
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31656
ER  - 
TY  - JOUR
A1  - Schreck, Michael
A1  - Christl, Manfred
T1  - Freisetzung und Abfangreaktionen von 1-Oxa-3,4-cyclohexadien
N2  - No abstract available
KW  - Chemie
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31597
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Herzog, C.
T1  - 3-(Phenylsulfonyl)tricyclo[4.1.0.0\(^{2,7}\)]hept-4-en-3-yllithium
N2  - Phenyl(tricyclo[4.1.0.0\^(^{2,7}\)] hept-4-en-3-yl)sulfone 8 has been prepared in two steps from 4,S-dlbromohomobenzvalene (6) and deprotonated to give the title compound 9. The carbon-13 NMR spectrum of 9 reveals a considerable interaction between the allyl anion moiety and the bicyclobutane system.
KW  - Organische Chemie
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58340
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Schreck, M.
T1  - 7-Arylbicyclo[4.2.0]oct-1-ene - Synthese durch [2+2]-Cycloadditionen von 1,2-Cyclohexadien sowie 1-Methyl-1,2-cyclohexadien und thermische Äquilibrierung der exo/endo-Isomeren
T1  - 7-Arylbicyclo[4.2.0]oct-1-eaes - Synthesis by [2+2]Cycloadditions of 1,2-Cyclohexadiene and 1-Methyl-l,l-cyclohexadiene and Thermal Equilibration of the exo/endo Isomers
N2  - Das exo/endo--lsomerenverhältnis Ja: Jb bei der bekannten [2 + 2]-Cycloaddition von Styrol an 1,2-Cyclohexadien (2) wurde als tempcraturabhingiaaefunden. Der Einsatz von (Z)-Dcutcriostyrollicfene den Beweis der Zweistufiakeit dieser Reaktion, und das Diradikal 4 wird als wahrscheinlichste Zwischenstufe anaesehen. Erhitzen von Jb auf 140-170°C führte zur Binstellung des thermodynamischen Gleichgewichts mit Ja (Ja:3b = 93:7), wobei wieder das Diradikal4 als Zwischenstufe fungieren dürfte. Mit Hilfe kinetischer Messungen ermittelte man die Aktivierungsparameter für das System Ja~ 3b. - Aus 2 und den Abfangreagenzien p-Methoxystyrol, 1,1-Diphenylethylen sowie 1-Phenylpropen gingen mit bescheidenen Ausbeuten die Titelverbindungen 6a, b, 7 bzw. 8 hervor. Analoa zu 2 wurde sein l-Methylderivat 13 aus 6,6-Dibrom-1-methylbicyclo[3.1.0]hexan (9) durch Methyllithium freigesetzt. In Gegenwart von Styrol entstand neben den Abfanaprodukten 14a, b auch das Dimere 12 von lJ. - Die 1H-NMR-Spektren der Titelverbindungen belegen eine starre Halbsesselkonformation des Cyclohexentcils mit äquatorial anellienem Cyclobutanring.
N2  - The exofendo ratio of tbe isomers 3a, b formed in the kuown [2 + 2] cycloaddition of styrene to 1 ,2-cyclohexadiene (2) has been found to depend on the tempcrature. The utilization of (Z)deuteriostyrene provided the proof of the stepwise nature of this reaction with thc diradical 4 as the most probable intennediatc. Heating of 3b at l40-170°C established the thermodynamic equilibrium between Ja and Jb (3a:3b = 93:7) and again 4 is assumed to be the intermediatc. By means of kinetic measurements the activation parameten ofthe system 3a ~ Jb have been detcrmined. - From 2 and the trapping reagents p-metboxystyrene, 1,1-diphenylethylene, and 1-phenylpropene the title compounds 6a, b, 7, and 8, respectively, were formed in low yields. In analogy to 2 its 1-methyl derivative 13 has been generated from 6,6-dibromo-l-methylbicyclo[3.t.O]hexane (9) with methyUithium. From the reaction in the presence of styrcne the trappina products 14a, b were isolated in addition to the dimer ll of 13. - The 1H NMR spectra of the title compounds support a rigid halfchair conformation of the cyclohexene moiety with the cyclobutane ring ancllatcd equatorially.
KW  - Organische Chemie
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58352
ER  - 
TY  - JOUR
A1  - Korth, H.-G.
A1  - Müller, W.
A1  - Sustmann, R.
A1  - Christl, Manfred
T1  - Rearrangement of Free Radicals, XII. ESR Spectroscopic Study of the Ring Opening of the Homobenzvalenyl Radical
N2  - Abstraction of an allylic hydrogen atom in homobenzvalene (4) either in solurion by photolyticaßy generated tert-butoxyl radicals or in an adamantane matrix by X-rays produces the homobcnzvalenyl radical (5). which tbennally rearranps · to tbe tropylium ndical (1). In solution tbe activation cnergy for the rate determined step of the reaction sequence was detennined· to be 13.4 ± O.S kcal/mol.
KW  - Organische Chemie
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58376
ER  - 
TY  - JOUR
A1  - Hegmann, J.
A1  - Christl, Manfred
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - Intramolekulare [2+2]-Cycloadditionen von γ-Oxoketenen
N2  - The 1-oxoketenes, which are accessible from methyl 1,3,4-oxadiazin-6-one-2-carboxyIate 1 and cycloalkenes, are shown to undergo an intramolecular [2+2] cycloaddition either on heating or on photolysis to give different sterecisemers of ß-lactones of the 3-oxo-2-oxabicyclo[ 2.2.0]hexane-type.
KW  - Organische Chemie
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58384
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Hegmann, J.
A1  - Reuchlein, H.
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - Überbrückte neungliedrige α,β-ungesättigte Enollactone - Synthese aus 5-Phenyl-1,3,4-oxadiazin-6-on-2-carbonsäure-methylester und Konfigurationsanalyse
N2  - The γ-oxoketenes, which are formed from oxadiazinone Ja and strained cyclopentene der1vat1ves, are shown to undergo a pericyclic ring enlargement to give the title compounds 2a, 2b, and 5. In the case of 5, two configurations, one having a cis and the other a trans Iactone functionality, are in equilibrium.
KW  - Organische Chemie
Y1  - 1987
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58395
ER  - 
TY  - JOUR
A1  - Hegmann, Joachim
A1  - Christl, Manfred
A1  - Peters, Karl
A1  - Peters, Eva-Maria
A1  - Schnering, Hans Georg von
T1  - Die Reaktionskaskade von 6-Oxo-5-phenyl-1,3,4-oxadiazin-2-carbonsäure-methylester und 1,3-Butadienen zu konjugierten und nichtkonjugierten Cyclopentenonen
N2  - Fünfgliedrige Carbocyclen sind Bauelemente zahlreicher NaturstofTe und daher attraktive Syntheseziele. Da bisher kein Syntheseverfahren mit großer Anwendungsbreite bekannt ist, sind neue Methoden willkommen. Wir berichten hier über Umsetzungen des Titelheterocyclus 1 mit l,3-Butadienen 1; diese Reaktionen, obwohl vielstufig, liefern im Eintopfverfahren konjugierte und nichtkonjugierte Cyclopentenone und gestatten auch die Fünfringanellierung.
KW  - Organische Chemie
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58421
ER  - 
TY  - JOUR
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - Study of the 1s and 2s shell contributions to the isotropic hyperfine coupling constant in nitrogen
N2  - The istropic part of the hyperfine coupling constant is investigated by means of multireference configuration interaction calculations employing Gaussian basis sets. A detailed study of the 1s and 2s spin polarisation in the nitrogen atom and the NH molecule shows that the structure of the lower-energy space of the unoccupied orbitals is essential for the results. A contraction of the Gaussian basis is possible without loss of accuracy if enough flexibility is retained to describe the main features of the original space of unoccupied functions. Higher than double excitations are found to be non-negligible for the description of α\(_{iso}\).
KW  - Organische Chemie
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58793
ER  - 
TY  - JOUR
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
A1  - Karna, S.P.
A1  - Grein, F.
T1  - The hyperfine coupling constants of the five lowest states of CH : An ab initio MRD-CI study
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58807
ER  - 
TY  - JOUR
A1  - Freund, S.
A1  - Henneberger, H.
A1  - Christl, Manfred
T1  - Halbkäfigverbindungen aus Diels-Alder-Addukten des Benzvalens mit Cyclopentadien-Derivaten durch Radikalreaktionen mit Thiophenol und Bromtrichlormethan
T1  - Half-Cage Compounds by Radical Reactions with Thiophenol and Bromotrichloromethane from Diels-Alder Adducts of Benzvalene with Cyclopentadiene Derivatives
N2  - In Diels-Alder-Reaktionen wurden aus Benzvalen (1) und Tetrachlorcyclopentadienon- dimethylacetal sowie Tetrachlorfuran die Addukte 2 bzw. 8 und 9 erhalten. Behandlung von 2 mit Natrium und tert-Butylalkohol ergab das chlorfreie Acetal 3, dessen Doppelbindung sich mit Diimin unter Bildung von 4 absättigen ließ. Aus dem bekannten Stammkohlenwasserstoff 5 ging analog 6 hervor, und durch Reaktion seines Anions mit Chlorameisensäure- methylester entstand der Ester 7. - Die Verbindungen l, 3, 5, 7-9 und das bekannte U wurden mit Thiophenol so behandelt, daß Radikalkettenreaktionen abliefen. Bei 8 trat Addition an die Zentralbindung des Bicyclobutan-Systems ein. Dagegen unterlag bei 2, 9, U und zum Teil bei 3, deren Doppelbindung jeweils der BicycJobutan-Einheit benachbart ist, das Primärradikal der 5-Hexen-1-yl- Cyclopentylrneth.yl-Umlagerung, aus der letztlich 15, ll, 13 bzw. 16 resultierten. Zum Teil bei 3 und vollständig bei 5 erfolgte die Addition an die Doppelbindung zu 17 bzw. 18, d.h. ohne Beteiligung der benachbarten Bicyclobutan- Einheit. Durch Aktivierung des Bicyclobutan-Systems mit einer Esterfunktion konnte dessen Passivität aufgehoben werden. So entstanden aus 7 das nichtumgelagerte Produkt 19 und das umgelagerte 20. Ihr Verhältnis hing von der Konzentration an Thiophenol ab. - Analog zur Reaktion 1Z + Thiophenol-13 brachte BromtrichJormethan aus 12 das umlagerte Addukt 21 hervor. - Als Nebenprodukt wurde bei der Umsetzung von 12 mit Thiophenol das Chlorwasserstoff-Addukt 14 des ersteren gefunden. Modellreaktionen für die Bildung von 14 sind die Umsetzungen von 12 mit Essigsäure und von 3 sowie 5 mit +Nitrobenzoesäure zu den Addukten 22, 23 bzw. 24. Seit
N2  - The adducts 2, 8,. and 9 were obtained by Diels-Aider reactions of benzvalene (I) with tetrachlorocyclopentadienone dimethyl acetal and tetracblorofuran. respectively. On treatment of 2 with sodium and tert-butyl alcohol, the chlorine atoms were substituted by hydrogen atoms to give acetal 3, the double bond of · whicb could be hydrogenated by diimine with formation of 4. Analogously, the known parent hydrocarbon 5 afforded 6. Tbe anion of 5 reacted with methyl chloroformate to give the ester 7. - Compounds 2, 3, 5, 7-9, and the known 12 were treated with thiophenol under conditions causing radical chain reactions. Whereas 8 added the reagent across the centrat bond of the bicyclobutane system, the additions to 2, 9, 12 and in part to 3, the double bond of which is adjaceot to the bicyclobutane moiety in each case, were accompanied by a 5-hexen-1-yJcylcopentylmethyl rearrangement of the primary radical resulting in formation of 15, 11, 13, and 16, respectively. In part with 3 and completely with 5, the addition took place at the double bond to give 17 and 18, respectively, i.e. without involvement of the adjacent bicylcobutane moiety. Activation of the bicyclobutane system with an ester functionality led to its participation. Thus, compound 7 gave the nonrearranged product 19 and the rearranged one 20 with their ratio being dependent on the concentration of thiophenol. - In analogy to the reaction 12 + thiophenol-13, tbe rearranged adduct 21 was formed from 12 and bromotrichloromethane. - The hydrogen cbloride adduct 14 was found as a byproduct on treatment of 1l witb thiophenol. Model reactions for the formation of 14 are the additions of acetic acid to 12 an~ 4-nitrobenzoic acid to 3 and 5 leading to the adducts 22, 23, and 24, respectively.
KW  - Organische Chemie
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58435
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Henneberger, H.
A1  - Freund, S.
T1  - Halbkäfigverbindungen aus Polycyclen mit einem Bicyclo[1.1.0]butan-System und dazu benachbarter Azobrücke durch Radikalreaktionen mit Thiophenol und Bromtrichlormethan
T1  - Half-Cage Compounds by Radical Reactions with Thiophenol and Bromotrchloromethane from Polycyclic Compounds with a Bicyclo[1.1.0]butane System and an Adjacent Azo Bridge
N2  - Aus Benzvalen (J) und 3,6-Bis(2-pyridyl)-l,2,4,5-tetrazin wurde das Dihydropyridazin 2c erhalten, das ebenso wie die bekannten Dihydropyridazine 2a, b mit Cyclopropen in die entsprechende Azoverbindung 3 überging. Addition von Thiophenol an 3a, c und 5 lieferte unter Beteiligung des Bicyclobutan-Systems und der Azofunktion die Halbkäfigverbindungen 4a, c bzw. 6. Aus der Umsetzung von 7, in dem die Azobrücke durch zwei BicycJobutan- Systeme flankiert ist, mit Thiophenol sowie Bromtrichlormethan gingen die Halbkäfigverbindungen 8 bzw. 9 hervor. An diesen ~eaktionen wirken beide Bicyclobutan-Systeme und die Azofunktion mit.
N2  - Dihydropyridazine 2c was obtained from benzvalene (1) and 3,6- bis(2-pyridyJ)-1,2,4,5-tetrazine. Like the known dihydropyridazines 2a, b. compound 2c was converted into the corresponding azo compound 3 by treatment with cyclopropene. The addition of thiophenol to 3a, c and S yielded the half-cage compounds 4a, c and 6, respectively. In these processes the bicyclobutane system and the azo functionality are involved. Treatment of 7, in which the azo bridge has two bicyclobutane neighbours, with thiophenol and bromotrichloromethane led to the formation of the half-cage compounds 8 and 9, ~spectively. Both the bicyclobuta_ne systems and the azo functionality are transformed in these reactions.
KW  - Organische Chemie
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58440
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Kraft, A.
T1  - Tricyclo[3.1.1.0\(^{2,6}\)]hexandion (das Valen des o-Benzochinons), Bicyclo[2.1.1]hexan-2,3-dion und Valene eines Chinoxalins, des Phenazins sowie eines Benzophenazins
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58459
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Kraft, A.
T1  - Tricyclo[3.1.1.0\(^{2,6}\)]hexandion (the Valen of o-Benzochinons), Bicyclo[2.1.1]hexan-2,3-dion and Valene of a Chinoxalins, of Phenazins and of a Benzophenazine
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58462
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Freund, S.
A1  - Henneberger, H.
A1  - Kraft, A.
A1  - Hauck, J.
A1  - Irngartinger, H.
T1  - Several Polycyclic Valence Isomers of Dimethyl [14]Annulene-1,8-dicarboxylate. Reactivity of a "Nonconjugated" Bis(bicyclo[1.1.0]butane)
N2  - Diels-Alder reaction of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate (5) with benzvalene (4), norbornene, and norbornadiene afforded the azo compounds 7 and 8. Theseare derivatives of 2,3-diazabicyclo[2.2.2]oct-2-ene as is azo compound 3, which had been obtained previously from 5 and 2 equiv of benzvalene (4). The photochemical extrusion of nitrogen from 3, 7, and 8 has been studied. Whereas 7 and 8 on direct irradiation in benzene gave rise exclusively to the bicyclo[2.2.0]hexane derivatives 9 and 10, respectively, from 3 in addition to the bicyclo[2.2.0]hexane 11, the diolefin 1l was formed. Diolefin 12 has cisdouble bonds in the nine-membered ring and is fixed in a boat conformation in a manner so that the two bicyclobutane systems approach each other very closely. This geometry suggests the unusual ring opening of the intermediate 1,4-cyclohexanediyl diradical from a boat conformation, which arises by inversion of the primarily generated boat conformation. Sensitized photolysis of 3 as weilasthat of ll produced the saturated isomer 13 of 11 and 12. The proximity of the bicyclobutane systems in 1l causes unprecedented reactions leading to cage compounds. When ll was heated at 90 °C, a rearrangement to the pentacyclic product 10 took place. Utilization of tetradeuteriated substrate ll-d4 supported a pathway with two diradical intermediates. Behaving in a convcntional manncr, bicyclobutane 9 and bis(bicyclobutane) 11 took up 1 and 2 equiv of thiophenol most probably in a radical-chain addition to give the thioethers 28 and 19, respectively. In contrast, bis(bicyclobutane) ll was converted by 1 equiv of thiophenol into cagc compound 30 in a process involving both the strained a systems. Heating at 80 °C subjected 30 to a reversible Copc rearrangement, resulting in a 6:1 mixture of 31 and 30. When it was treated with bromine, 11 was transformed to cage compound 38. This addition is believed to proceed via a cationic intermediate. The structure of cage compound 10 was established by a singlc-crystal X-ray analysis of dialcohol 11 prepared from 20 and methyllithium.
KW  - Organische Chemie
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58413
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Nusser, R.
A1  - Herzog, C.
T1  - 4-Bromoctavalen und zwei (Brommethylen)homobenzvalene anstelle eines erwarteten Bromoctabisvalens
N2  - No abstract available.
KW  - Organische Chemie
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58409
ER  - 
TY  - JOUR
A1  - Hegmann, Joachim
A1  - Christl, Manfred
A1  - Peters, Karl
A1  - Peters, Eva-Maria
A1  - Schnering, Hans Georg
T1  - Conjugated and Nonconjugated Cyclopentenones by a Reaction Cascade from Methyl 6-0xo-5-phenyl-1,3,4-oxadiazine-2-carboxylate and 1,3-Butadienes
N2  - No abstract available
Y1  - 1988
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30207
ER  - 
TY  - JOUR
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - Theoretical study of FC\(_2\)H\(_4\)
N2  - Large-scale multireference configuration interaction (MRD-CI) calculations in a quite flexible AO basis are employed to study the energy hypersurface for the reaction intermediate FC\(_2\)H\(_4\) • The reaction F + C\(_2\)H\(_4\) -> FC\(_2\)H\(_4\) as weil as the 1,2 migration of the fluorine atom in FC\(_2\)H\(_4\) is investigated. In addition the rotation around the CC bond in the optimum conformation is studied. The absolute minimum in the potential energy is found for the asymmetric structure but the symmetric structure is also found to be stable with respect to the dissociation, so that a shuttling of the fluorine atom is in principle possible but highly unlikely because ( l) the activation energy is high ( II 5-130 kJ fmol) and the saddle point lies only 4(}-50 kJ jmol below the dissociation Iimit of F + C\(_2\)H\(_4\) and (2) the competitive motion, i.e., rotation around the CC axis, is nearly free (I 1-17 kJ/mol).
KW  - Organische Chemie
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58824
ER  - 
TY  - JOUR
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - The hyperfine coupling constants of the X\(^3\)Σ\(^-\) state of NH : Influence of polarization functions and configuration space on the description of spin polarization
N2  - The hyperfine coupling constants for the \(^3\)Σ\(-\) ground state of the NH molecule are determined by configuration interaction calculations whereby the infl.uence of polarization functions as weil as of the configuration space on the spin polarization mechanism is analysed. The dipolar part Au(N) and Au(H) can be obtained very reliably without much computational effort (A .. (N) == -45·3 MHz and A"(H) = -62·3 MHz). The value for the isotropic contribution a1.., in the best AO basis and MRD-CI treatment is - 64·5 MHz for H and 16·6 MHz for nitrogen compared to the corresponding experimental quantities of -66 MHz and 19 MHz respectively. Their determination depends on a subtle balance of the lu, 2u and 3u shell correlation description, whereby the dominant contribution to a1..,(H) results from the 2u shell. It is shown that the often good agreement of a110 values with experiment in a small basis singledouble configuration interaction treatment results from a cancellation of two errors.
KW  - Organische Chemie
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58832
ER  - 
TY  - JOUR
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - Study of orbital transformations in configurational interaction calculation of hyperfine coupling in nitrogen and CH molecule
N2  - Multi-reference configuration interaction calculations employing various orbital transformations are undertaken to obtain the isotropic hyperfine coupling constant a\(_{iso\) in nitrogen and a\(_{iso\) (H) in the CH molecule. The natural orbital (NO) basis is found to be more effective than the simple RHF-MO basis; the most obvious is a basis of spin natural orbitals (SNO). It is found that a\(_{iso\) is approached from opposite sides in the NO and 2s shell SNO basis if the CI expansion is increased. Both results are within a few percent of the full CI Iimit for the nitrogen atorn (in the given AO basis) and the experimental value for Hin the CH radical. Various features ofthe SNO are discussed.
KW  - Organische Chemie
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58847
ER  - 
TY  - JOUR
A1  - Karna, S.
A1  - Grein, F.
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - The hyperfine coupling constants of \(^{19}\)F\(_2\)
N2  - The isotropic (a\(_{iso}\)) and dipolar (A\(_{dip}\)) hyperfine coupling constants of 19F2 were obtained from MRD-CI wave functions using a variety of basis sets. In series I, increasing numbers of d functions were added to a 5s4p contracted Huzinaga!Dunning basis. In series II, the 5s3p basis set was uncontracted in several steps until 9s5p was reached, to which were added from one to three d-polarization functions. Cl parameters (selectioo threshoids and the number of reference coofiguratioos) were also varied. A study of the R dependence of aiso and Adip was perfonned. The best values obtained at R\(_e\) are 260 G for a\(_{iso}\) and 308 G for A\(_{dip}\)• compared with experimental values of about 280 G for a;10 and 320 G for A\(_{dip}\)·
KW  - Organische Chemie
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58817
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Braun, Martin
T1  - Generation and interception of 1-OXA-2,3-Cyclohexadiene and 1,2,4-Cyclohexatriene
N2  - The cycloadducts 6 and 7 of tricyc1o[4.1.0.0 2 ,7)hepta- 3,4-diene (~) with styrene and 1,3-butadiene rearrange to unusual products on thermolysis, namely the cycloheptatriene derivatives ~ and 10. 1-0xa-3,4-cyclohexadiene (20) is generated smoothly from 6,6-dichloro-3-oxabicyclo[3.1.0]hexane (22) and n-butyllithium. 1-0xa-2,3-cyclohexadiene (11) is formed from 6-exo-bromo-6-endo-fluoro-2-oxabicyclo[ 3.1.0]hexane (30) and methyllithium. In the presence of activated olefins, this reaction provides an efficient route to 28 and 33 - 38, the trapping products of 21. Interestingly, [2+2]-cycloadditions do not take place at the same double bond of 21 as [4+2]-cycloadditions. The reactions of 1,3-cyclopentadiene and indene with bromofluorocarbene afford 6-exo-bromo-6-endo-fluorobicyclo[3.1.0]hex-2-ene (50) and its benzo derivative ~, respectively. On treatment of these compounds with methyl lithium in the presence of styrene, the interception products 53 and 47 of 1,2,4-cyc10- hexatriene (44) and its benzo derivative 43, respectively, are formed in good yields.
KW  - Chemie
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-56566
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Brunn, E.
A1  - Roth, W. R.
A1  - Lennartz, H.-W.
T1  - 7-Methyl- and 7-Phenylcyclohepta-1,3,5-trienes from Benzvalene Via 3,3a,4,5,6,6a-Hexahydro-4,5,6-methenocyclopentapyrazoles and Tetracyclo[4.1.0.0\(^{2,4}\).0\(^{3,5}\)]heptanes
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58471
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Brunn, E.
A1  - Kraft, A.
A1  - Irngartinger, H.
A1  - Huber-Patz, U.
T1  - Nichtbindende Wechselwirkungen in zwei 7-Spirotetracyclo[4.1.0.0\(^{2,4}\).0\(^{3,5}\)]heptanen
T1  - Nonbonded Interactions in two 7-Spirotetracyclo[4.1.0.0\(^{2,4}\).0\(^{3,5}\)]beptanes
N2  - Die Reaktion von Tetrachlordiazocyclopentadien mit Be.nzvalen (2) ergab das Fulven-Derivat 3. Dagegen führten die Umsetzungen von Diazoßuoren und 5-Diazo-10,1 1-dihydro-SH-dibenzo[ a.d]cyclohepten mit 2 zu den erwarteten Spiro-1-pyrazolinen 4 bzw. 5. Die photolytische Abspaltung von Stickstoff aus 4 und 5 lieferte die Spirotetracycloheptane 6 bzw. 7. Die Röntgenstrukturanalyse von 6 beweist einen engen Kontakt zwischen je eineßl Wasserstoffatom der Tetracycloheptan- und der Fluoren-Einheit. Dieser kurze Abstand (2.15 A) ruft Winkelaufweitungen hervor und wird auch als Grund für starke Entschirmungen der betreffenden Protonen und eine formal über sieben Bindungen reichende 0.6-Hz-Kopplung zwischen ihnen angesehen. 7 ist das erste chiralc Tetracyclohcptan. Ursache dafür ist eine nichtebene Konformation des Siebenrings, der bei Raumtemperatur nicht invertiert. Auf der Basis von NOE-Messungen gelang die Zuordnung der tH-NMR-Signale von 6 und 7.
N2  - The reaction or tctrachlorodiazocyclopentadiene with benzvalene (2) gavc, the fulvene derivative 3. In contrast, treatment of diazoßuorene and 5-diazo-1 0,1 1-dihydro·SH -dibenzo[ a,d]cycloheptene with l:afl'orded the expected spiro-1-pyrazolines 4 and 5, respectively. Photolytic extrusion of nitrogen from 4 and S led to the corresponding spirotetracyclobeptanes 6 and 7. The X-ray structure analysis of 6 revealed a close contact between one hydrogen atom cach of the tetracycloheptane and the ßuorene subunits. This short distance (2.15 A) causes an increase in bond angles and is believed to produce strong deshielding of the respective protons and a 0.6-Hz coupling between them, which is formally a long-range coupling across seven bonds. Compound 7 is the first chirat tetracycloheptane. This is due to a nonplanar confonnation of the seven-membered ring, which does not invert at room temperature. On tbe basis of NOE measurements the 1H-NMR signals of 6 and 7 are assigned.
KW  - Organische Chemie
KW  - 5H-Dibenzo[a
KW  - d]cycloheptene
KW  - 10
KW  - 11-dihydro- / 1-Pyrazoline
KW  - Nonbonded Interactions
KW  - Spirotetracyclo[4.1.0.0<sup>2
KW  - 4</sup>.0<sup>3
KW  - 5</sup>]beptanes
KW  - Long-range coupling constants
KW  - mtrogen extruston
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58489
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Braun, Max
T1  - Photocycloadditionen des Benzvalens
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58492
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Braun, Max
T1  - Photocycloadditions of Benzvalene
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58506
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Braun, Martin
T1  - Freisetzung und Abfangreaktionen von 1-Oxa-2,3-cyclohexadien
T1  - Generation and Interception of 1-0xa-2,3-cyclohexadiene
N2  - Umsetzung von 6,6-Dichlor-2-oxabicyclo[3.1.0)hexan (4a) in Styrol mit n-Butyllithium lieferte neben Polystyrol und t-Chlor-1- pbenylhexan (6) in geringer Ausbeute die Tet~hydrocyclobutapyrane 5, die Abfangprodukte des aus 4a generierten t-Oxa-2,3- cyclobexadiens (3). Das unbeständige 6,6-Dibrom-2-oxabicyclo( J.l.O]hexan (4b) wurde bei -60°C erzeugt un~ bei -30°C mit Methyllithium in Gegenwart von Styrol umgesetzt, woraus die Produkte 5 mit 24% Ausbeute hervorgingen. Als bei 20°C beständige Quelle für 3 erwies sich exo-6-Brom-e~o-6-fluor-2-oxabicyclo[ J.t.O]bexan (9), das aus 2,3-Dihydrofuran und Bromßuorcarben mit 25% Ausbeute bereitet wurde. Behandlung von 9 in Styrol, <X-Methylstyrol, 1,3-Butadien, 2,3-Dimet~yl-!,3-butadien, Furan und 2,5-Dimethylfuran mit Methyllithium ergab Abfangprodukte von 3 mit Ausbeuten von 31-80%. Dabei entstanden mit den Styrolen und überwiegend auch mit den l ,3-Butadienen (2 + 2]-Cycloaddukte als Diastereomerengemische, nämlich 5, ll, 13 und 15. Die Furane lieferten ausschließlieb [4 + 2]-Cycloaddukte (17 und 18), die 1,3-Butadiene nur mit einem kleinen Anteil (14 und 16). [2 + 2]- und [4 + 2]-Cycloadditionen zeigen eine unterschiedliche Chemoselektivität. Während erstere die Enolether- Doppelbindung von 3 nutzen, finden letztere an der vom Sauerstoffatom entfernteren Doppelbindung statt. Das als 1 : IGemisch aus exo- und endo-Isomeren anfallende Produkt 5 lieferte beim Erhitzen auf l50°C ein 20:1: 1-Gemiseh aus exo- und endo-5 sowie dem Strukturisomeren 19. Thermolyse· des 2: 1-Gemisches aus 13 und 14 erbrachte ein 2: 1-Gemiscb aus 14 und dem Tetrahydro-1-benzopyran 20.
N2  - The reaction of 6,6-dichJoro-2-oxabicyclo[3.1.0]hexane (4a) in styrene with n-butylJithium gave. mainly polystyrene and 1- chloro-l-phenylhexane (6) but aft'orded the tetrahydrocyclobutapyrans 5, the trapping products of l-oxa-2,3-cyclohexadiene (3) generated froni 4a, only in Jow yield. The unstable 6,6-dibromobicyclo[ 3.1.0]hexane (4b) was generated at -60°C and treated witb methyllithium at -30°C in tbe presence ofstyrene providing the products 5 in 24% yield. Prepared from 2,3-dihydrofuran and bromofluorocarbene in 25% yield, exo-6-bromo-endo-6-ßuoro-2- oxabicyclo[J.t .O]hexane (9) is a stable source for 3. Thus, treatment of9 in styrene, <X-methylstyrene, 1,3-butadiene, 2,3-dimethyl- 1,3-butadiene, furan, and 2,5-dimethylfuran with methyllithium furnished interception products of 3 in 3!-80% yield. [2 + 2] Cycloadducts, i. e. 5, 12, 13, and 15, were fo!l"ed as mixtures or diastereomers with the styrenes and as main products also with the 1,3-butadienes. The furans gave [4 + 2] cycloadducts exclusively (17 and 18), the 1,3-butadienes only to a minor extent (14 and 16). [2 + 2] and [ 4 + 2] Cycloadditions display different chemoselectivity. Wbereas the former utilize the enol ether double· bond, the Iatter take place at tbe double bond more remote from the oxygen. Formed from 3 as a 1: t mixture of diastereomers, the product S gave a 20: 1: 1 mixture of exo-5, endo-5, and the structural isomer 19 on heating at 150°C. Thermolysis of the l: 1 mixture of 13 and 14 furnished a 2:1 mixture of 14 and tbe tetrabydro- 1-benzopyran 20.
KW  - Organische Chemie
KW  - 4
KW  - 4a
KW  - 5
KW  - 8-Tetrahydro-3H-2-benzopyrans
KW  - 3
KW  - 5
KW  - 8
KW  - 8a-Tetrahydro-2H-1-benzopyran
KW  - Allenes
KW  - six-membered
KW  - cyclic / 1-0xa-2
KW  - 3-cyclohexadiene
KW  - 3
KW  - 5
KW  - 6
KW  - 6a-Tetrahydro-2H-cyclobuta[b]pyrans
Y1  - 1989
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58517
ER  - 
TY  - JOUR
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
A1  - Skell, P.S.
T1  - Theoretical study of the potential energy surface governing the stereochemistry in ClC\(_2\)H\(_4\) reactions
N2  - Large-scale multireference configuration interaction calculations in a double·t·type AO basis including polarization functions are carried out for the potential surface of the ClC\(_2\)H\(_4\9 system. The charge distribution for various extreme points of the surface is discussed. The absolute minimum is found for an asymmetric ClC2H4 structure. The symmetrical bridged nuclear conformation is also found to be stable with respect to dissociation into Cl + C\(_2\)H\(_4\)• The activation energy for rotation about the C-C axis is calculated tobe around 18 kJ/mol, which is comparable tothat for the 1,2 migration {around 26 kJ/mol). The stereochemistry is governed by the fact that addition of CI to C\(_2\)H\(_4\) (or dissociation) is a two-step reaction proceeding through a symmetrica1 intermediate. The direct addition pathway possesses a small barrier of about 8 kJ jmol.
KW  - Organische Chemie
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58851
ER  - 
TY  - JOUR
A1  - Kim, E.
A1  - Christl, Manfred
A1  - Kochl, J. K.
T1  - Charge-Transfer Cycloaddition of Homobenzvalene with Tetracyanoethylene
N2  - The transient yellow color observed in the cycloaddition of homobenzvalene (HB) with tetracyanoethylene (TCNE) is associated with the charge-transfer complex [HB, TCNE). The deliberate photoexcitation of [HB,TCNE) affords a mixture of charge-transfer cycloadducts (1, 2, and 3) that differs from that obtained in thermal cycloaddition. The relationship of {HB t TCNE•) radical-ion pair (as the critical reactive intermediate in charge-transfer cycloaddition) to the activation process for thermal cycloaddition is discussed.
KW  - Organische Chemie
KW  - Electron transfer
KW  - photochemical
KW  - Radical-ion pair
KW  - Photochemistry
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58537
ER  - 
TY  - JOUR
A1  - Karna, S.P.
A1  - Grein, F.
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - Ab initio configuration-interaction studies of the ground state potential energy and hyperfine coupling constants of \(^{35}\)Cl\(_2^-\)
N2  - Potential energy and spectroscopic constants for the X\(^2 \sum^+ _\mu\) ground state of a;, were calculated by configuration-interaction (Cl) methods, using large basis sets with polarization and diffuse functions. From these CI wavefunctions, the isotropic (a\(_{iso}\)) and dipolar (A\(_{dip}\)) components of the hyperfine coupling constant were obtained. The effects of various s, p basis sets, polarization and diffuse functions, as well as the influence of reference configurations and configuration selection thresholds were investigated. The best values obtained are 35·31 G for a\(_{iso}\) and 29·440 for A\(_{dip}\)• tobe compared with experimental values of 37 ± 1 G and 32 ± 1 G, respectively. It is shown that the contributions to a1so of the K and L shells are opposite in sign, differing by about 4 G. Upon vibrational averaging, both a\(_{iso}\) and A\(_{dip}\) move towards smaller values as v increases. An adiabatic electron affinity of 2·46eV was obtained for CL\(_2\) , and a vertical electron detachment energy of 3·71 eV for Cl;.
KW  - Organische Chemie
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58869
ER  - 
TY  - JOUR
A1  - Funken, K.
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
A1  - Grein, F.
T1  - Study of the hyperfine coupling constants of the moleculs NH<sub>2</sub>, NHD and ND<sub>2</sub>
N2  - In the present paper we c:alculate tbe magnetic hyperfine couplina constants (hfcc) ai.ID and A11 of the ground states of the isotopes NH2, NHD and ND2 using truncated MR..CI methods. Differences from other theoretical methocls and shortoominp of the truncated Cl approach in calculating tlj10 are studied. Polarization effects wbich detennirae ailo. as weU as a simple model to describe the dipolar hfcc's, are discussed. All results are in. excellent aareement with experimental data. lt is shown that ab initio methods are able to obtain reliable values for otf-diaaonal values of A41 which are difficult to measure experimentaDy.
KW  - Organische Chemie
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58875
ER  - 
TY  - JOUR
A1  - Lang, R.
A1  - Herzog, C.
A1  - Stangl, R.
A1  - Brunn, E.
A1  - Braun, M.
A1  - Christl, Manfred
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - Reaktionen von Homobenzvalenen mit 4-Phenyl-3H-1,2,4-triazol-3,5(4H)-dion, Tetracyanethylen, Chlorsulfonylisocyanat und Schwefeldioxid. Einige konzertierte 1,4-Additionen an eine Vinylcyclopropan-Einheit
T1  - Reactions of Homobenzvalenes wlth 4-Phenyl-3H-1,2,4-trlazole-3,5(4H)-dione, Tetracyanoethylene, Chlorosulfonyl  Isocyanate, and Sulfur Dioxide. Several Concerted 1,4-Additions to a Vinylcyclopropane Subunit
N2  - No abstract available
KW  - Organische Chemie
KW  - 6-Thiatricyclo[3.2.1.o 2.7 ]oct-3-ene 6
KW  - 6-dioxide
KW  - Homo Diels-Alder reactions
KW  - Cyclopropanetetracarbonitrile derivatives
KW  - Barbaralane derivatives
KW  - Urazoles
KW  - polycyclic
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58527
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Reuchlein, H.
T1  - Synthesis and NMR Spectra of 2,3-Dihydro-1,3-methanoindene Derivatives and 1,2,3,5-Tetrahydro-1,3-methanopentalene
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58557
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Lanzendörfer, U.
A1  - Grötsch, M. M.
A1  - Ditterich, E.
A1  - Hegmann, J.
T1  - Cycloadditionen von 1,3,4-0xadiazin-6-onen (4,5-Diaza-alpha-pyronen), 9 - 6-Oxo-5-phenyl-1,3,4-oxadiazin-2-carbonsäure-methylester - Synthese und Reaktionen mit Norbornen, Norbornadien, Cyclopropenen, Cyclobuten und Benzvalen
N2  - No abstract available
KW  - Organische Chemie
KW  - 1
KW  - 3
KW  - 4-0xadiazin-6-ones
KW  - Diels-Alder reactions
KW  - y-Oxoketenes
KW  - ß-Lactones
KW  - bicyclic
KW  - Enol Iactones
KW  - alpha
KW  - ß-unsaturated
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58569
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Reuchlein, H.
T1  - Synthesen und NMR-Spektren von 2,3-Dihydro-1,3-methanoindenderivaten und 1,2,3,5-Tetrahydro-1,3-methanopentalen
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58549
ER  - 
TY  - JOUR
A1  - Irngartinger, H.
A1  - Reimann, W.
A1  - Lang, R.
A1  - Christl, Manfred
T1  - Electron Density Distribution in a Bicyclo[l.l.0]butane
N2  - No abstract available
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31576
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Krimm, Stefan
A1  - Kraft, Arno
T1  - Some Valenes of Benzannelated Five-Membered Heteroarenes - Synthesis and NMR Spectra
N2  - No abstract available
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30026
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Krimm, Stefan
A1  - Kraft, Arno
T1  - Einige Valene von benzanellierten fünfgliedrigen Heteroarenen - Synthesen und NMR-Spektren
N2  - No abstract available
Y1  - 1990
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31559
ER  - 
TY  - JOUR
A1  - Bündgen, P.
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - An MRD-CI study of low-lying electronic states in CaF
N2  - Dipole moments and various spectroscopic constants of some low-lying electronic states of the CaF molecule have been calculated using the multireference single· and double-excitation configuration-interaction (MRD-CI) method. The electronic structure of the highly ionic molecule in various excited states can be explained in tenns of different polarisations of the mainly Cacentered valence electron in the field of the F\(^-\) anion. Plots of natural orbitals occupied by the valence electron in the different states give a qualitative picture of the charge distribution and provide a visualisation of the different polarisations of the valence electron in the various states. Comparisons with the electrostatic polarisation model ofTörring, Ernstand Kändler (TEK model) are made. The unknown A' \(^2 \Delta\) state is predicted to lie about 21200 cm\(^{-1}\) above the ground state.
KW  - Organische Chemie
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58880
ER  - 
TY  - JOUR
A1  - Engels, Bernd
T1  - Estimation of the influence of the configurations neglected within truncated MR-CI wavefunctions on molecular properties
N2  - Reliable prediction of the isotropic hyperfine coupling constant, a\(_{iso}\), is still a difficult task for ab initio calculations. Strong dependence on the method used for its calculation is found. Within a truncated multi-referencc ansatz a\(_{iso}\) is strongly affected by the size ofthe reference space and the nurober of terms in the truncated Cl expansion. In the present paperdifferent effects of the neglected Cl space are discussed. Modified B\(_K\) and A\(_K\) methods are used to estimate the contributions ofthe neglected configurations. lt can be shown that a combination of both methods is able to recover about 90-9 S% of the total error in a\(_{iso}\)· Furthermore, it was found that to obtain about 90% of the B\(_K\) correction only about I 0-20% ofthe configurations within H0 have to be corrected.
KW  - Organische Chemie
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58890
ER  - 
TY  - JOUR
A1  - Peric, M.
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - Ab initio investigation of the vibronic structure of the C\(_2\)H spectrum Calculation of the hyperfine coupling constants for the three lowest lying electronic states
N2  - The hyperfine coupling constants (isotropic hfcc and four Cartesian components of the ani~ tropic tensor) are calculated for all three atoms of C\(_2\)H in its three lowest-lying electronic states at various molecu)ar geometries by means of the ab initio configuration interaction ( MRO.CI) method. The off-diagonal electronic matrix elements involving the two species ofthe A' symmetry are also computed. A diabatic transforrnation is perforrned Jeading to simple geometrical depen· dences of the hyperline coupling constants.
KW  - Organische Chemie
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58901
ER  - 
TY  - JOUR
A1  - Peric, M.
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - Ab initio investigation of the vibronic structure of the C\(_2\)H spectrum Computation of the vibronically-averaged values for the Hyperfine Coupling Constants
N2  - The vibronically averaged values for tbe hyperfine coupling constants in the X\(^2 \sum\)-A\(^2 \Pi\) system of the ethynyl radical are computed by means of tbe ab initio metbod calculations. The results point at tbe importance of taking into account the coupling of a1l tbree electronic states in question ( I\(^2\)A', 2\(^2\)A', and 1\(^2\)A") for a reliable explanation of the available experimental findings. The mean values of the hfcc's for K = 0 and 1 levels in \(^{13}\)C\(_2\)H and \(^{13}\)C\(_2\)D in the energy range up to 6000 cm\(^{-1}\) are predicted.
KW  - Organische Chemie
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58915
ER  - 
TY  - JOUR
A1  - Reuchlein, H.
A1  - Kraft, A.
A1  - Christl, Manfred
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - Reaktionen von Bicyclo[2.1.1]hexenen mit 1,3,4-Oxadiazin-6-onen und dynamische Effekte einem in neungliedrigen, überbrückten, α,β-ungesättigten Enollacton
N2  - No abstract available
KW  - Organische Chemie
KW  - 1
KW  - 3
KW  - 4-0xadiazin-6-ones
KW  - Diels-Alder reactions
KW  - Enol Iactones
KW  - Lactone conformations
KW  - Line-shape analysis
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58577
ER  - 
TY  - JOUR
A1  - Markgraf, J. H.
A1  - Cort, J. R.
A1  - Davis, H. A.
A1  - Lindeman, N. I.
A1  - Myers, C. R.
A1  - Kraft, A.
A1  - Christl, Manfred
T1  - Strained Heterocyclic Systems. 20. Basicities of Bicyclic Quinoxalines
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58584
ER  - 
TY  - JOUR
A1  - Bentley, T. W.
A1  - Christl, Manfred
A1  - Norman, S. J.
T1  - Methanesulfonate/p-Nitrobenzoate and p-Toluenesulfonate/p-Nitrobenzoate Rate Ratios. Solvolyses of 1-Adamantyl and Benzhydryl Substrates
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58599
ER  - 
TY  - JOUR
A1  - Jelinek-Fink, H.
A1  - Christl, Manfred
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - Cycloallene, 7 : Ein Siebenringallen-Dimer: Darstellung aus einem 7,7-Dibromnorcaran-Derivat und Thermolyse
T1  - Cycloallenes, 7 : A Seven-Membered-Ring Allene Dimer: Preparation from a 7,7-Dibromonorcarane Derivative and Thermolysis
N2  - No abstract available
KW  - Organische Chemie
KW  - Bisbenzo[ 4
KW  - 5]cyclohepta[ 1
KW  - 2-α:2'
KW  - 1' -c]naphthalene
KW  - hexahydro-
KW  - 7-Norcaranylidene carbenoid
KW  - substituted
KW  - Cycloallene dimerization
KW  - Tetrakis(arylmethylene)ethane diradical
KW  - 1
KW  - 2-Bismethylenecyclobutanes
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58603
ER  - 
TY  - JOUR
A1  - Gigstad, Kenneth M.
A1  - Ricci JR., John S.
A1  - Markgraf, J. Hodge
A1  - Christl, Manfred
A1  - Kraft, Arno
T1  - Strained Heterocyclic Systems : 18. Structure of 1,2,3-Methylidyne-2,3-dihydro-1H-cyclopenta[b]quinoxaline
N2  - No abstract available
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-41645
SN  - 0108-2701
ER  - 
TY  - JOUR
A1  - Reuter, W.
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - The Reaction of Singlet and Triplet Methylen with Ethene - A Multi-Reference CI Study
N2  - Large-scale multireference configuration interaction (MRD-CI) calculations in a flexible atomic orbital (AO) basis are employed to study the reaction of C\(_2\)H\(_4\) with CH\(_2\) in its firSt triplet and singlet state. The minimum energy path (MEP) of both reactions is calculated, and different mechanisms are discussed. To examine the possible participation of the singlet state in the overall reaction starting from the triplet channel and terminating in the singlet-state c-C\(_3\)H\(_6\), various cuts through both hypersurfaces are calculated. lt is found that favorable interconversion from the trip1et to the singlet surface can only occur at !arge separations of the two fragments of CH2 and C\(_2\)H\(_4\). Experimental data considering the vibrational motion of CH\(_2\) in connection with the relative position of both surfaces are used to obtain an estimate for the overall barrier of the reaction. The height of the barrier is about 6 kcal/mol, while the barrier of the pure triplet reaction is calculated to be 7-9 kcal/mol.
KW  - Organische Chemie
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58923
ER  - 
TY  - JOUR
A1  - Engels, Bernd
A1  - Peric, M.
A1  - Reuter, W.
A1  - Peyerimhoff, S.D.
A1  - Grein, F.
T1  - Study of the hyperfine coupling constants \(^{14}\)N and \(^1\)H) of the NH\(_2\) molecule in the X\(^2\)B\(_1\) ground state and the A\(^2\)A\(_1\) excited state
N2  - The hyperfine coupling constants (hfcc) A\(_{iso}\) and A\(_{ij}\) are calculated for the atoms of NH\(_2\) in its, two lowest-lying electronk states at various molecular geometries by means of the ab initio multireference configuration interaction .method. The vibronically averaged values of the hfccs for the K = 0 and 1 levels in \(^{14}\)N \(^1\)H\(_2\) in the energy range up to 20 000 cm\(^{-1}\) are computed. Polarization elfects which determine A\(_{iso}\) as well as a simple model to describe the dipolar hfccs are discussed. All resrilts are in excellent agreement with experimental data.
KW  - Organische Chemie
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58937
ER  - 
TY  - JOUR
A1  - Peric, M.
A1  - Engels, Bernd
T1  - Ab initio calculations of the vibronically averaged values for the hyperfine coupling constants in NH\(_2\), NHD and ND\(_2\)
N2  - Vibronically averaged values for K =0 and K = 1 bending levels in the energy range between 0 and 25 000 cm\(^{-1}\) are computed for the \(^{14}\)N, H, and D atoms in NH\(_2\), NHD, and ND\(_2\) The pure ab initio electronic potentials, as well as those derived by fitting of experimentally observed band positions are employed. Effects of vibronic coupling and local perturbations of close-lying levels belanging to different electronic states are discussed.
KW  - Organische Chemie
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58941
ER  - 
TY  - JOUR
A1  - Peric, M.
A1  - Engels, Bernd
T1  - Ab initio calculation of the vibronically averaged hyperfine coupling constants in the 1\(^2\)Π\(_u\) electronic state of CH\(_2 ^+\)
N2  - The results of pure ab initio calculations of the hyperfine coupling constants for the 1 \(^2 \pi _u\) electronic state for various isotopomers of CHi in the energy range between 0 and 20 000 cm\(^{-1}\) are presented. Effects of vibronic and spin-orbit coupling are discussed.
KW  - Organische Chemie
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58951
ER  - 
TY  - JOUR
A1  - Kaupp, Martin
A1  - Schleyer, Paul von Rague
T1  - Do Low-Coordinated Group 1-3 cations M\(^n\) \(^+\)L\(_m\) (Mn\(^+\) = K\(^+\), Rb\(^+\), Cs\(^+\), Ca\(^{2+}\), Sr\(^{2+}\), Ba\(^{2+}\), Sc\(^{3+}\), Y\(^{3+}\), La\(^{3+}\); L = NH\(_3\), H\(_2\)0, HF; m = 1-3) with a Formal Noble-Gas Electron Configuration Favor Regular or "Abnormal" Shapes?
N2  - No abstract available
KW  - Anorganische Chemie
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60111
ER  - 
TY  - JOUR
A1  - Stangl, R.
A1  - Jelinek-Fink, H.
A1  - Christl, Manfred
T1  - Darstellung phenylsubstituierter Derivate des Tricyclo[4.1.0.0\(^{2,7}\)]heptans und des 1,2,3,4-Tetrahydro-1,2,3-methenonaphthalins
N2  - No abstract available
KW  - Organische Chemie
KW  - Bicyclo[3.2.0.0<sup>2
KW  - 7</sup>]heptane derivatives
KW  - Norcaranes
KW  - 7
KW  - 7-dibromo
KW  - lH-Cyclopropa[a]naphthalenes
KW  - 1
KW  - 1-dibromo-1a
KW  - 2
KW  - 3
KW  - 7b-tetrahydro-
KW  - Carbene insertion
KW  - Bicyclo[1.1.0]butane derivatives
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58610
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Stangl, R.
A1  - Jelinek-Fink, H.
T1  - Zur Kenntnis der thermischen Umlagerung des Bicyclo[1.1.0]butan-Systems. Eine kinetische Studie des Übergangs von Tricyclo[4.1.0.0\(^{2,7}\)]heptanen in Bicyclo[3.2.0]hept-6-ene
T1  - On the Thermal Rearrangement of the Bicyclo[1.1.0]butane System. A Kinetic Investigation of the Conversion of Tricyclo[4.1.0.0\(^{2,7}\)]heptanes into Bicyclo[3.2.0)hept-6-enes
N2  - No abstract available
KW  - Organische Chemie
KW  - 3-Methenonaphthalenes
KW  - 4-tetrahydro-
KW  - kinetics of thermolysis
KW  - Benzocycloheptene derivatives
KW  - Bicyclo[1.1.0]butanes
KW  - rearrangement
KW  - Tricyclo[4.1.0.0<sup>2.7</sup>]heptanes
KW  - kinetics of thermolysis
KW  - Bicyclo[3.2.0]hept-6-ene derivatives
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58623
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Braun, Martin
A1  - Müller, Germar
T1  - 1,2,4-Cyclohexatriene, an Isobenzene, and Bicyclo[4.4.0)deca-1,3,5,7,8-pentaene, an Isonaphthalene: Generation and Trapping Reactions
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58639
ER  - 
TY  - JOUR
A1  - Hegmann, J.
A1  - Ditterich, E.
A1  - Hüttner, G.
A1  - Christl, Manfred
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - δ-Chlor-δ-lactone aus γ-Oxoketenen
N2  - No abstract available
KW  - Organische Chemie
KW  - 1
KW  - 3
KW  - 4-0xadiazine-2-carboxylate
KW  - methyl 6-oxo-5-phenyl-
KW  - Diels-Alder reactions
KW  - Ketenes
KW  - y-oxo-
KW  - δ-Lactones
KW  - δ-chloro-
KW  - β-Lactones
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58649
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Braun, Martin
A1  - Müller, Germar
T1  - 1,2,4-Cyclohexatrien, ein Isobenzol, und Bicyclo[4.4.0]deca-1,3,5,7,8-pentaen, ein Isonaphthalin : Erzeugung und Abfangreaktionen
N2  - No abstract available
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30249
ER  - 
TY  - JOUR
A1  - Metropoulos, B.
A1  - Engels, Bernd
A1  - Peyerimhoff, S.D.
T1  - On the chemi-ionization reaction O + CH ----> HCO\(^+\)+  e\(^-\). Coollinear O-CH Approach
N2  - We have investigated theoretically the importance of the O(\(^3\)P)+CH(a\(^4\sum^-\)) and the O(\(^3\)P)+CH(X\(^2\Pi\)) channels in the collinear chemi-ionization reaction O+CH->HCO\(^+\) +e\(^-\). We have found that both channels may lead to chemi-ionization via favorable Franck-Condon overlaps with the states ofthe ionic species.
KW  - Organische Chemie
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58963
ER  - 
TY  - JOUR
A1  - Engels, Bernd
T1  - Study of influences of various excitation classes on ab initio calculated isotropic hyperfine coupling constants
N2  - Reliable prediction of the isotropic hyperfine coupling constant A\(_{iso}\) is still a difficult task for ab initio calculations. Strang dependence on the method employed for its ca1culation has been found. Within a CI ansatz A\(_{iso}\) is considerably affected by the excitation classes taken into account within the CI calculation. In the present work the influence of various excitation classes on A\(_{iso}\) is examined. Calculations including all single, double, triple and a large part of the quadruple excitations are performed and the individual effects of the excitation classes are studied. It is found that the surprisingly good agreement found for S-CI treatments is due to large error cancellations. The importance of higher than double excitations arises from their indirect influence on the single excitations.
KW  - Organische Chemie
KW  - Spin density
KW  - Hyperfine coupling constants
KW  - Influence of excitation classes
KW  - Indirect and direct contributions to A<sub>iso</sub>
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58973
ER  - 
TY  - JOUR
A1  - Gittins, C. M.
A1  - Harris, N. A.
A1  - Field, R. W.
A1  - Verges, J.
A1  - Ernst, W. E.
A1  - Bündgen, P.
A1  - Engels, Bernd
T1  - Analysis and Depertubation of the C\(^2\)Π and D\(^2\)Σ\(^+\) states of CaF
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58980
ER  - 
TY  - JOUR
A1  - Staikova, M.
A1  - Engels, Bernd
A1  - Peric, M.
A1  - Peyerimhoff, S. D.
T1  - Ab initio calculation of the vibronically averaged hyperfine coupling constants in the two lowest electronic states of H\(_2\)O\(^+\)
N2  - No abstract available
T2  - Ab initio calculations of the vibronically averaged hyperfine coupling constants in the 1\(^2\)Π\(_u\)(X\(^2\)B\(_1\),A\(^2\)A\(_1\)) state of the water cation
KW  - Organische Chemie
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58998
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Lanzendörfer, U.
A1  - Grötsch, M. M.
A1  - Hegmann, J.
A1  - Ditterich, E.
A1  - Hüttner, G.
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - Cycloadditionen von 6H-1,3,4-0xadiazin-6-onen (4,5-Diaza-α-pyronen), 12 - Dieckmann-Kondensationen ohne Basen
T1  - Cycloadditions of 6H-1,3,4-0xadiazin-6-ones (4,5-Diaza-α-pyrones), 12 - Dieckmann Condensations without Bases
N2  - No abstract available
KW  - Organische Chemie
KW  - 1
KW  - 3
KW  - 4-0xadiazine-2-carboxylate
KW  - methyl 6-oxo-5-phenyl-
KW  - Diels-Alder reactions
KW  - Ketenes
KW  - y-oxo-
KW  - 1
KW  - 2-Cyclopentanedione derivatives
KW  - Adipic acid
KW  - substituted 2-oxo- dimethyl esters
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58665
ER  - 
TY  - JOUR
A1  - Feineis, E.
A1  - Schwarz, H.
A1  - Hegmann, J.
A1  - Christl, Manfred
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - Cycloadditionen von 6H-1,3,4-0xadiazin-6-onen (4,5-Diaza-α-pyronen), 13 - Diels-Alder-Reaktionen mit 6H-1,3,4-Oxadiazin-6-onen als Dienophil
T1  - Cycloaddltions of 6H-1,3,4-0xadiazin-6-ones (4,5-Diaza-α-pyrones), 13 - Diels-Alder Reactions wtth 6H-1,3,4-0xadiazin-6-ones as Dienophile
N2  - No abstract available
KW  - Organische Chemie
KW  - 6H-1
KW  - 3
KW  - 4-0xadiazin-6-ones
KW  - 1
KW  - 2-Bismethylenecyclohexane
KW  - Diels-Alder reactions
KW  - [1
KW  - 3
KW  - 4]0xadiazino[4
KW  - 5-b]isoquinolin-1-one derivatives
KW  - Bicyclo[2.1.l]hexan-5-one
KW  - highly substituted
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58673
ER  - 
TY  - JOUR
A1  - Bentley, T. W.
A1  - Norman, S. J.
A1  - Gerstner, E.
A1  - Kemmer, R.
A1  - Christl, Manfred
T1  - Solvolysis of Tricyclo[3.1.0.0\(^{2,6}\)]hex-3-yl and Bicyclo[2.1.1]hex-2-yl Sulfonates
N2  - No abstract available
KW  - Organische Chemie
KW  - Bicyclo[1.1.0]butylcarbinyl sulfonates
KW  - solvolysis of
KW  - Cyclobutylcarbinyl sulfonates
KW  - Anchimeric assistance in solvolysis
KW  - Rearrangement of carbocations
KW  - Electron demand in ditosylates
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58689
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Müller, H.
T1  - Induktiver Effekt, negative Hyperkonjugation und Gegenion sind nicht die Ursache der besonderen Eigenschaften des Bicyclo[3.2.1]octa-3,6-dien-2-yl-Anions. - Eine NMR-Studie mit phenylsubstituierten Modellen
T1  - Inductive Effect, Negative Hyperconjugation, and Gegenion do not Cause the Unusual Properties of the Bicyclo[3.2.1]octa-3,6-dien-2-yl Anion. An NMR Study with Phenyl-Substituted Models
N2  - No abstract available
KW  - Organische Chemie
KW  - Tricyclo[3.3.1.0 2
KW  - 4]non-7-en-6-ylpotassium
KW  - 6-phenyl
KW  - Homoaromaticity in carbanions
KW  - Bicyclo[3.2.1]oct-3-en-2-yl anions
KW  - phenyl-substituted
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58655
ER  - 
TY  - JOUR
A1  - Epe, Bernd
A1  - Häring, Martin
A1  - Ramaiah, Danaboyina
A1  - Stopper, Helga
A1  - Abou-Elzahab, Mohamed M.
A1  - Adam, Waldemar
A1  - Saha-Möller, Chantu R.
T1  - DNA damage induced by furocoumarin hydroperoxides plus UV (360 nm)
N2  - Wben irradiated at 360 nm, furocoumarins with a hydroperoxide group in a side chain effciently give rise to a type of DNA damage that can best be explained by a photoinduced generation of hydroxyl radicals from the excited pbotosensitizers. The observed DNA damage profiles, i.e. the ratios of single-strand breaks, sites of base loss (AP sites) and base modifications sensitive to fonnamidopyrimidine-DNA glycosylase (FPG protein) and endonuclease m, are similar to the DNA damage profile produced by hydroxyl radicals generated by lonizing radiation or by xanthine and xanthine oxidase in the presence of Fe(III)-EDTA. No such damage is observed with the corresponding furocoumarin alcohols or in the absence of near-UV radiation. The damage caused by the photo-excited hydroperoxides is not influenced by superoxide dismutase (SOD) or catalase or by D2O as solvent. The presence of t-butanol, however, reduces both the formation of single-strand breaks and of base odifications sensitive to FPG protein. The cytotoxicity caused by one of the hydroperoxides in L5178Y mome lymphoma cells is found to be dependent on the near-UV irradiation and to be much higher than that of the corresponding alcohol. Therefore the new type of photoinduced damage occurs inside cells. Intercalating photosensitizers with an attached hydroperoxide group might represent a novel and versatile class of DNA damaging agents, e.g. for phototherapy.
KW  - DNS-Schädigung
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-86870
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Türk, M.
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - Octahydro-1,2,3:4,5,6-dimethenopentalen-2-carbonitril, das erste Derivat eines noch unbekannten (CH)\(_{10}\)-Kohlenwasserstoffs
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58728
ER  - 
TY  - JOUR
A1  - Christl, Manfred
A1  - Türk, M.
A1  - Peters, K.
A1  - Peters, E.-M.
A1  - Schnering, H. G. von
T1  - Octahydro-1,2,3:4,5,6-dimethenopentalene-2-carbonitrile, the First Derivative of a Yet-Unknown (CH)\(_{10}\)-Hydrocarbon
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58731
ER  - 
TY  - JOUR
A1  - Bentley, T. W.
A1  - Christl, Manfred
A1  - Kemmer, R.
A1  - Llewellyn, G.
A1  - Oakley, J. E.
T1  - Kinetic and Spectroscopic Characterisation of Highly Reactive Methanesulfonates. Leaving Group Effects for Solvolyses and Comments on Geminal Electronic Effects Influencing S\(_N\)1 Reactivity
N2  - Highly reactive methanesulfonates (mesylates, ROMs) have been prepared from 1-phenylethanol. cyclohex-2-en-1-ol, diphenylmethanol and p-methoxybenzyl alcohol by treatment with methanesulfonyl chloride and triethylamine in dichloro- or trichloro-methane at - 20 to 0 °C. The mesylates. characterised in solution by \(^1\)H and \(^{13}\)C NMR at -20 °C, were obtained in satisfactory purity (ca. 95%) in cold solutions but they decomposed by reaction with chloride, triethylamine or the parent alcohol. Rate constants for solvolyses in aqueous acetone and aqueous ethanol have been determined by a fast response conductimetric method. Product selectivities for solvolyses of pmethoxybenzyl mesylate in aqueous ethanol and methanol at 0 °C have been determined by HPLC. From additional new or Iiterature kinetic data for solvolyses of corresponding bromides. chlorides and p-nitrobenzoates (OPNB). Br/CI. OMs/Br and OMs/OPNB rate ratios were calculated; the results are consistent with electronic effects stabilising the carbocationic transition states and increasing OMs/Br rate ratios for these SN 1 solvolyses; none of the evidence supports a geminal electronic effect on Br/CI rate ratios (e.g. caused by stabilisation of the initial state in pmethoxybenzyl chloride). Steric effects on ester /halide rate ratios for solvolyses of tertiary substrates are confirmed. Relative rates over a 10\(^{16}\) range for ester and halide leaving groups are evaluated for solvolyses of 1-phenylethyl substrates in 80% ethanol-water. updating previous work by Noyce et al. (1972).
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58748
ER  - 
TY  - JOUR
A1  - Wissing, Elmo
A1  - Kaupp, Martin
A1  - Boersma, Jaap
A1  - Spek, Anthony L.
A1  - Koten, Gerard van
T1  - Alkylation Reactions of Dialkylzinc Compounds with 1,4- Diaza- 1,3-butadienes: Cationic and radical Anionic Organozinc Intermediates. Molecular Structure of the Cationic Organozinc Species [MeZn(t-BuN=CHCH=N-t-Bu)]O\(_3\)SCF\(_3\) and Me\(_2\)Zn(bpy)(bpy = 2,2' -Bipyridine)
N2  - No abstract available
KW  - Anorganische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60008
ER  - 
TY  - JOUR
A1  - Suter, H. U.
A1  - Pleß, V.
A1  - Ernzerhof, M.
A1  - Engels, Bernd
T1  - Difficulties in the Calculation of Electron Spin Resonance Parameters using Density Functional Methods
N2  - Density functional theory is applied to the calculation ofthe isotropic byperfine coupJing constants in some small molecules. Various functionals are tested. The agreement of the calculated values to experimental data and values obtained from sophisticated ab initio methods depends on the functionals used and the system under consideration. With respect to spin density calculations the functional of Lee, Yang and Parr with Becke's excbange functional (BLYP) is found to give good results for tbe heavier center of the CH and the NH molecule, while the spin densities of other molecules such as OH, H\(_2\)CN, H\(_2\)CO\(^+\), NO and O\(_2\) deviate considerably from experimental and/or other theoretical results (30%-60%). In cases where the singly occupied orbital can contribute to the isotropic hyperfine coupling constants, accurate results are obtained. The reason fortbis is analyzed.
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59113
ER  - 
TY  - JOUR
A1  - Mühlhäuser, M.
A1  - Froudakis, G.
A1  - Zdetsis, A.
A1  - Engels, Bernd
A1  - Flytzanis, N.
A1  - Peyerimhoff, S. D.
T1  - Ab initio investigation of the stability of Si\(_3\)C<\(_3\) clusters and their structural and bonding features
N2  - Various structural possibilities for Si\(_3\)C\(_3\) clusters are investigated by ab initio calculations employing basis sets of double- and triple-zeta quality augmented by d polarization functions. Correlation effects are included by a second-order Moeller Piesset perturbation treatment. For the two lowest-lying structures higher-order correlation corrections and multi-reference effects are also included. Bonding features are investigated by two different types of population analyses to obtain insight into the nature of chemical bonding. A total of 17 stationary points were investigated, 14 of which correspond to local minima and three being transition states. The energetically lowest-lying structures are: A "pyramidlike" structure with various multicenter bonds, followed by a es symmetric isomer closely related to the ground state Si6 structure. Planar structures, favoured in small carbon clusters, lie higher in energy and are transition states. The lowest-lying triplet system is found to be the linear nonsymmetric Si - C-C-C-Si -Si structure, which is calculated to lie about 38 kcalfmole above the singlet ground state. A building-up principle based on bonding criteria is suggested for the occurence of the various structural possibilities.
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59060
ER  - 
TY  - JOUR
A1  - Wortmann-Saleh, D.
A1  - Engels, Bernd
A1  - Peyerimhoff, S. D.
T1  - Theoretical Study of the Reaction O(\(^3\)P) + C\(_2\)H\(_4\) and comparison with the \(^3\)CH\(_3\) + C\(_2\)H\(_4\) Reaction
N2  - The minimum energy path for the reaction O(\(^3\)P\(_g\)) + C\(_2\)H\(_4\)(\(^1\)A\(_g\)) has been calculated by optimizing all relevant geometrical parameters along the approach of oxygen to ethene. A barrier of 4.7 kcal/mol in the \(^3\)A"( ... 9a'\(^2\)- 10a'3a") potential energy surface and an energy difference of 14.4 kcal/mol between the product and the fragments is found at the multireference-configuration interaction level. The corresponding values at the lower-level treatment CASSCF are 9 kcal/mol for the barrier and 9 kcal/mol for the depth of the potential; this shows the importance of inclusion of electron correlation. The barrier for CH\(_2\) rotation for the lowestenergy structure (asymmetric OC\(_2\)H\(_4\)) is around 5 kcal/mol. The energy gap to the first excited state \(^3\)A'( ... 9a'l0a'3a'12) is found tobe 3.6 kcal/mol in MRD-CI calculations at the ground-state minimum. Comparison with \(^3\)CH\(_2\) + C\(_2\)H\(_4\) shows that in this system the lowest-energy surface is \(^3\)A', i.e., the state which is the excited state in 0 + C\(_2\)H\(_4\). This difference in energy ordering of \(^3\)A' and \(^3\)A" states results from the fact that the p\(_x\), p\(_y\), p\(_z\) degeneracy of oxygen orbitals is lifted in \(^3\)CH\(_2\)leading to b\(_1\), b\(_2\). and a\(_1\) MOs whereby the lowest b\(_2\) (a") remains doubly occupied; as a consequence, the reaction pattem between the oxygen and \(^3\)CH\(_2\) approach is different, which is also quite apparent in the calculated charge transfer.
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59076
ER  - 
TY  - JOUR
A1  - Staikova, M.
A1  - Peric, M.
A1  - Engels, Bernd
A1  - Peyerimhoff, S. D.
T1  - Ab initio Investigation of the Structure of the X\(^2\)A', A\(^2\)A'' (1\(^2\)Π) Spectral System of HCO: Investigation of the Magnetic Hyperfine Effects
N2  - Results ofan ab initio study ofthe hyperfine structure of the X\(^2\)A', A\(^2\) A" ( 1\(^2 \Pi\)) system ofthe formyl radical are presented. Special attention is paid to the analysis of the interplay between the vibronic and magnetic hyperfine etfects. The results of computations are in very good agreement with the available experimental findings. The values for the hyperfine coupling constants in lower bending Ievels of both electronic species are predicted.
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59089
ER  - 
TY  - JOUR
A1  - Froudakis, G.
A1  - Zdetsis, A.
A1  - Mühlhäuser, M.
A1  - Engels, Bernd
A1  - Peyerimhoff, S. D.
T1  - A comparative ab initio study of the Si\(_2\)C\(_4\), Si\(_3\)C\(_3\), Si\(_4\)C\(_2\) clusters
N2  - Various structural possibilities for the Si\(_2\)C\(_4\) and Si\(_4\)C\(_2\) clusters are investigated by employing a basis set of triple-zeta plus polarization quality; electron correlation is generally accounted for by second-order M0ller-Plesset and, in certain instances, by higher-order perturbation (CASPT2) approaches. The building-up principle recently suggested from an analysis of Si\(_3\)C\(_3\) clusters is found to be fully operative for Si\(_2\)C\(_4\) and Si\(_4\)C\(_2\) clusters. A comparison of the structure and stability of various geometrical arrangements in the series C\(_6\) , Si\(_2\)C\(_4\) , Si\(_3\)C\(_3\) , Si\(_4\)C\(_2\), and Si\(_6\) shows that linear and planar structures become rapidly less stable if carbons are replaced by silicons and that the three-dimensional bipyramidal forms become less favorable as soon as silicons are exchanged by carbons in the parent Si\(_6\) structure. The effects can be rationalized in qualitative terms based on differences in silicon and carbon bonding.
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59097
ER  - 
TY  - JOUR
A1  - Suter, H. U.
A1  - Huang, M.-B.
A1  - Engels, Bernd
T1  - A Multireference Configuration Interaction Study of the Hyperfine Structure of the Molecules CCO, CNN and NCN in their triplet ground states
N2  - The hyperfine structures of the isoelectronic molecules CCO. CNN, and NCN in their triplet ground states (X\(^3 \sum ^-\)) are investigated by means of ab initio methods. The infrared frequencies and geometries are detennined and compared with experiment. Configuration selected multireference configuration interaction calculations in combination with perturbation theory to correct the wave function (MRD-CI/B\(_K\)) employing extended atomic orbital (AO) basis sets yielded very accurate hyperfine properties. The theoretical values for CCO are in excellent agreement with the experimental values determined by Smith and Weltner [J. Chem. Phys. 62,4592 (1975)]. For CNN, the first assignment of Smith and Weltner for the two nitrogen atoms has to be changed. A qualitative discussion of the electronic structure discloses no simple relation between the structure of the singly occupied orbitals and the measured hyperfine coupling constants. Vibrational effects were found to be of little importance.
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59108
ER  - 
TY  - JOUR
A1  - Staikova, M.
A1  - Engels, Bernd
A1  - Peric, M.
T1  - Ab initio investigation of the hyperfine structure in the 1\(^2\)Π\(_u\)(X\(^2\)A\(_1\), A\(^2\)B\(_1\) system of BH\(_2\))
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59000
ER  - 
TY  - JOUR
A1  - Engels, Bernd
T1  - Detailed study of the configuration selected multi-reference configuration interaction method combined with perturbation theory to correct the wave function
N2  - A reliable prediction of the isotropic hyperfine coupling constant A\(_{iso}\) is still a difficult task for ab initio calculations. In previous studies, the configuration selected multireference configuration interaction method in combination with perturbation theory to correct the wave function (MRCI/ B\(_K\)) yielded accurate isotropic hyperfine coupling constants very economically. The present study gives a detailed analysis of the MRCI/ B\(_K\) method based on the X\(^2 \pi\) state of CH as a test case. Furthermore, a comparison to various other methods such as Maller-Ptesset perturbation theory and the coupled cluster approach is made. The success of the MRCI/ B\(_K\) method in predicting isotropic hyperfine coupling constants is explained in terms of the inßuence of higher than double excitations.
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59019
ER  - 
TY  - JOUR
A1  - Suter, H. U.
A1  - Engels, Bernd
T1  - Theoretical investigation of ESR parameters: H\(_2\)CN and H\(_2\)CO\(^+\)
N2  - The hyperfine structure of the two isoelectronic molecules H\(_2\)CN and H\(_2\)CO\(^+\) in their electronic ground state (X\(^2\)B\(_2\)) is studied. The influence of the atomic orbital (AO), basis sets, of the correlation treatment, and of the. equilibrium geometry on the obtained hyperfine propertles 1s - investigated. It is found that the multireference double excitation-configuration interaction (MRD-CI)/ BK treatment in which an MRD-CI wave function is corrected by a modified B\(_K\) method yields equivalent results to quadratic CI [QCISD(T)], coupled cluster single doubles [CCSD(T)), or Brueckner doubled [BD(T)]. Uncertainties in the equilibrium geometries are found to be the major source for discrepancies between theoretically and experimentally determined isotropic hyperfine coupling constants (hfccs). For the heavier centers, the calculated values of the isotropic hfccs agrees nearly perfectly with experimental values (\(\approx\) 1%-2%). The calculated values for the hydrogens are too low, but using the equilibrium structure suggested by Yamamoto and Sato [J. Chem. Phys. 96, 4157 ( 1992)], the best estimate deviates by less than 3%.
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59029
ER  - 
TY  - JOUR
A1  - Mühlhäuser, M.
A1  - Engels, Bernd
A1  - Marian, C. M.
A1  - Peyerimhoff, S. D.
A1  - Bruna, P. J.
A1  - Jansen, M.
T1  - Einfluß der Ladungsverteilung auf die Bindungslängen im P\(_4\)O\(_6\) Gerüst bei Verbindungen des Typs P\(_4\)O\(_6\)X
N2  - No abstract available
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59034
ER  - 
TY  - JOUR
A1  - Huang, M.-B.
A1  - Suter, H. U.
A1  - Engels, Bernd
T1  - Theoretical Study of the Dimethylamino Radical (CH\(_3\))\(_2\)N and its protonated cation (CH\(_3\))\(_2\)NH\(^+\)
N2  - In the present work the dimethylamino radical ( ( CH\(_3\)) \(_2\)N) and its protonated cation ( ( CH\(_3\))\(_2\)NH\(^+\)) are investigated by means of ab initio methods. The geometries of various conformations of both compounds are obtained with UMP2/6·31 G** calculations, while the hyperfine structure and its dependence on the geometry is studied using the MRD-Cl/B\(_K\) method. The two molecules are compared to study the inftuence of the protonation on geometry and hyperfine structure. The effects of the rotational barriers on the hyperfine structures of (CH\(_3\))\(_2\)N, (CH\(_3\)CH\(_2\))\(_2\)N and ( (CH\(_3\))\(_2\)CH)\(_2\)N will be discussed.
KW  - Organische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59047
ER  -