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 - 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 - 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 - 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 - Christl, Manfred T1 - \(^{13}\)-NMR-Spektren von Bicyclo[n.1.0]kohlenwasserstoffen N2 - No abstract available KW - Organische Chemie Y1 - 1975 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-57977 ER - TY - JOUR A1 - Leininger, H. A1 - Kemmer, P. A1 - Beck, K. A1 - Christl, M. T1 - 7-Thiatetracyclo[4.1.0.0\(^{2,4}\).0\(^{3,5}\)]heptan (Benzvalensulfid) - Synthese und Reaktionen N2 - No abstract available KW - Organische Chemie Y1 - 1982 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-58113 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 - 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 - 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 - 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 -