TY - JOUR
A1 - Christl, Manfred
A1 - Reich, H. J.
A1 - Roberts, J. D.
T1 - Nuclear Magnetic Resonance Spectroscopy. Carbon-13 Chemical Shifts of Methylcyclopentanes, Cyclopentanols, and Cyclopentyl Acetates
N2 - No abstract available
KW - Organische Chemie
Y1 - 1971
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-57862
ER -
TY - JOUR
A1 - Christl, Manfred
A1 - Roberts, J. D.
T1 - Nuclear Magnetic Resonance Spectroscopy : Carbon-13 Chemical Shifts of Small Peptides as a Function of pH
N2 - No abstract available
KW - Organische Chemie
Y1 - 1972
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-57885
ER -
TY - JOUR
A1 - Christl, Manfred
A1 - Roberts, John D.
T1 - Carbon-13 Nuclear Magnetic Resonance Spectroscopy : Conformational Analysis of Methyl-Substituted Cycloheptanes, Cycloheptanols, and Cycloheptanones
N2 - The 130 chemical shifts were determined of the carbons in 12 cycloheptanes, 21 cycloheptanols, and 8 cycloheptanones. In some cyc1oheptanols and cyc1oheptanones, the assignments have been obtained unambiguously by the synthesis of deuterated derivatives and the use of paramagnetic-shift reagents. Substituent effects for the different types of groups have been calculated. The most informative data about the cyc10heptane conformations were provided by the relatively well understood I' effects. The results are generally in,good agreement with predictions based on the twist-chair form, which has been predicted by Hendrickson to be the most stable conformation. Pairs of cis-trans isomers are found to have rather characteristic differences in their 130 spectra. This fact was used to assign the resonances found for cis-trans mixtures of methyl-substituted cyc1oheptanols to specific isomers.
Y1 - 1972
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-41663
ER -
TY - JOUR
A1 - Christl, Manfred
A1 - Warren, J. D.
A1 - Hawkins, B. L.
A1 - Roberts, J. D.
T1 - \(^{13}\)C and \(^{15}\)N Nuclear Magnetic Resonance Spectroscopy of Nitrile Oxides and Related Reaction Products : Unexpected \(^{13}\)C and \(^{15}\)N Nuclear Magnetic Resonance Parameters of 2,4,6-Trimethylbenzonitrile Oxide
N2 - No abstract available
KW - Organische Chemie
Y1 - 1973
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-57894
ER -
TY - JOUR
A1 - Brüntrup, Gisela
A1 - Christl, Manfred
T1 - Darstellung und Thermolyse der Hexamethyldewarbenzol-Cycloaddukte aromatischer Nitriloxide und des Diphenylnitrilimins
N2 - No abstract available
Y1 - 1973
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30257
ER -
TY - JOUR
A1 - Christl, Manfred
A1 - Brüntrup, Gisela
T1 - Diimine Reduction and Ozonolysis of Benzvalene
N2 - Via reduction of benzvalene (1) with diirnine tricyclo[3.1.0.02•6]hexane is obtained in good yield. The procedure renders 3, which has already been synthesized by Lemal and Shim, accessible much easier and in larger quantities. IH and 13C n.m.r. spectroscopic data are discussed. Both the thermal and the AgBF4-catalyzed rearrangernent of 3 yield 1,3-cyclohexadiene (8). - The ozonolysis of 1 with subsequent LiAIH4-reduction results in cis-I,3- bis(hydroxyrnethyl)cyclobutane (13a).
N2 - Durch Reduktion von Benzvalen (1) mit Diimin wird das Tricyc1o[3.1.0.02•6]hexan (3) in guter Ausbeute erhalten. Das Verfahren macht das bereits von Lemal und Shim dargestellte 3 erheblich leichter und in größeren Mengen zugänglich. IH- und 13C-NMR-spektroskopische Daten werden diskutiert. Sowohl die thermische als auch die AgBF4-katalysierte Umlagerung von 3 führt zu 1,3-Cyclohexadien (8). - Die Ozonolyse von 1 mit anschließender LiAlH4-Reduktion ergibt das cis-l,3-Bis(hydroxymethyl)cyclobutan (13a).
KW - Organische Chemie
Y1 - 1974
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-57953
ER -
TY - JOUR
A1 - Christl, Manfred
A1 - Heinemann, U.
A1 - Kristof, W.
T1 - Thermal Rearrangement of Some Endo-Endo'-Bridged Bicyclo[1.1.0]butanes
N2 - No abstract available
KW - Organische Chemie
Y1 - 1975
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-57967
ER -
TY - JOUR
A1 - Christl, Manfred
T1 - Carbon-13 Chemical Shifts and 13C-15N Coupling Constants of 3,4-Dihydroisoquinoline-15N, its 15N-Oxide and their Conjugate Acids
N2 - No abstract available
Y1 - 1975
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30071
ER -
TY - JOUR
A1 - Volz, H.
A1 - Shin, J.-H.
A1 - Prinzbach, H.
A1 - Babsch, H.
A1 - Christl, Manfred
T1 - Stability of Tricyclo[4.1.0.0\(^{2,7}\)]heptenyl-Cations
N2 - No abstract available
KW - Organische Chemie
Y1 - 1978
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58001
ER -
TY - JOUR
A1 - Christl, Manfred
A1 - Herbert, R.
T1 - Unusual Carbon Shielding Effects of Cyclopropanes and Double Bonds in Strained Bicyclo[3.1.0]hexanes and Cyclopentenes
N2 - Carbon-13 shieldings and one-bond \(^{13}\)C-H coupling constants of bicydo[2.1.1]hexane, bicydo[2.l.l]hex- 2-ene, tricydo[3.1.1.0\(^{2.4}\)]heptane and benzvalene are presented and compared. to the data of related. compounds. H a bicydo[3.1.0]hexane system is part of a rigid skeleton, the cydopropane ring exerts spedfk: 'Y substituent eflects of two ldnds. In the case of the bicyclobexane boat form an upfield shift of the C-3 signal is observed and in tbe esse of the chair form a downfield shift of 15-20 ppm. Compared to the corresponding cydopentanes the double bond in strained cydopentenes causes downfield shifts of the C-4 absorption. 1bis eftect increases witb increasing strain, reaching 8 45.9 ppm maximum in benzvalene. Hence it is tbe only known bicydo[l.l.O]butane baving 8 reversed order of carbon shieldings. The downfield shifts are e:xplained by means of simple orbital interaction schemes.
KW - Organische Chemie
Y1 - 1979
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58038
ER -
TY - JOUR
A1 - Christl, Manfred
A1 - Lang, R.
T1 - Tricyclo[5.1.0.0\(^{2,8}\)]octa-3,5-diene (Octavalene)
N2 - No abstract available
KW - Organische Chemie
Y1 - 1982
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58124
ER -
TY - JOUR
A1 - Leininger, H.
A1 - Lanzendörfer, F.
A1 - Christl, Manfred
T1 - Über die Reduktion des Benzvalenozonids zum cis-1,3-Cyclobutandimethanol mit LiAlH\(_4\)
N2 - No abstract available
KW - Organische Chemie
Y1 - 1983
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58130
ER -
TY - JOUR
A1 - Christl, Manfred
A1 - Leininger, Hartmut
A1 - Mattauch, Brigitte
T1 - The 13C NMR Spectra of Some Tricyclo[2.2.0.02,6]hexane Derivatives : Unexpected High Field Absorptions Due to Additive gamma-anti Subsituent Effects
N2 - By means of the BC NMR spectra of tricyclo{2.2.0~rfJ6Jhexane and thirteen of its derivatives the effects of substituents in endo-3- and endo-5-positions on the HC chemical shifts have been determined. The y-anti effects are at least as Jarge as in monosubstituted cyc1obutanes, where the shielding values of second-row hetero substituents exceed those in unstrained systems by far, and higher-row and carbon substituents still cause substantial upfield shifts. In the title system the y-anti effect of a substituent in the endo-3- and endo-5-position are operative additively, and thus shift the absorption of C-J upfieJd by a maximum of 27 ppm with respect to the unsubstituted hydrocarbon.
Y1 - 1983
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-41620
SN - x
ER -
TY - JOUR
A1 - Lanzendörfer, Franz
A1 - Christl, Manfred
T1 - 3,4-Bismethylentricyclo[3.1.0.02,6]hexan - Synthese und Diels-Alder-Addition an Tetracyanethylen
N2 - No abstract available
Y1 - 1983
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30263
ER -
TY - JOUR
A1 - Christl, Manfred
A1 - Leininger, Hartmut
A1 - Brückner, Dieter
T1 - On the Nature of the Bicyclo [3.2.1]octa-3,6-dien-2-yl Anion: A 13C NMR spectroscopic study
N2 - No abstract available
Y1 - 1983
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30060
ER -
TY - JOUR
A1 - Christl, Manfred
A1 - Brunn, Erich
A1 - Lanzendorfer, Franz
T1 - Reactions of Benzvalene with Tetracyanoethylene, 2,3-Dichloro-5,6-dicyano-rho-benzoquinone, Chlorosulfonyl Isocyanate, and Sulfur Dioxide. Evidence for Concerted 1,4-Cycloadditions to a Vinylcyclopropane System
N2 - No abstract available
Y1 - 1984
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-30052
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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 - 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 NH2, NHD and ND2
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 - 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 - 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 - 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 - 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 -