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Showing 1 to 10 of 10 for “"Rotational Barriers"”.
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Part I. Hindered Rotation in 9-Arylfluorenes. Resolution of the Mechanistic Question. Part Ii. Rotational Barriers of Allyl Anions in Solution
Made available in DSpace on 2014-12-13T20:10:45Z (GMT). No. of bitstreams: 1 8004287.pdf: 2874738 bytes, checksum: 70ef38a709147ca8c03e8f6a98596931 (MD5) Previous issue date: 1979
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Synthesis of Insecticidal Mono- and Diacylhydrazines for Disruption of K+ Voltage-Gated Channels, and Elucidation of Regiochemistry and Conformational Isomerism by NMR Spectroscopy and Computation
… against An. gambiae, NMR spectroscopy revealed rotational isomerisms of two types: chiral helicity (M)/(P) and acyl (E)/(Z)-isomerism due to hindered rotation. Variable temperature NMR allowed the measurement of N-N bond rotational barriers, as well as estimate the barrier of (E)/(Z) …
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The acetanilide crystal structures: packing and conformational similarities
… is observed. Para-substituents affect the rotational barriers; whilst such correlation was not discernible for meta-substituents. Ortho substitution frequently produces intramolecular hydrogen bonding outweighing any other substituent effects. Although the experimental conformations deviate …
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Thermochemistry of fluorinated aldehydes and corresponding radicals;thermochemistry and kinetics of diethyl ether and ethyl oxirane relative to reactions under atmospheric and combustion conditions
… computed frequencies and geometries. Rotational barriers are determined and hindered internal rotational contributions for S*298K and Cp(T) are calculated using the rigid rotor harmonic oscillator approximation, with direct integration over energy levels of intramolecular rotation …
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Synthesis and Evaluation of Densely-Functionalized Troponoids
… DFT and experimental techniques to assess the rotational barriers of a series of benzenoid and troponoid scaffolds, as well as by studying the atropselective bromination of a methoxytropolone. During the course of these studies, <sup>1</sup>H- and <sup>13</sup>C-NMR experiments unveiled several …
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Synthesis, Properties, and Reactivity of Pentafluorophenyl Substituted Cyclopentadienes and Their Transition Metal Complexes
… In addition, dynamic Cp-C6F5 and Cp-M rotational barriers are measured by variable temperature NMR spectroscopy. Finally, ethylene polymerizations and ethylene/1-hexene copolymerizations are conducted using C6F5- and C6H5-substituted zirconocene dichlorides as catalysts. Contrary to …
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Studies on the Synthesis, Function, and Properties of Troponoids
… generate novel tropolone probes for studying the rotational barriers of ketones appended to tropolones. These novel structures were subjected to variable temperature nuclear magnetic resonance spectroscopy, and various racemization studies to quantify the enhancement in rotational energy barriers …
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The study of the asymmetric synthesis of lignans
… lignans and analogs were synthesized and the barriers to rotation about the phenyl-naphthalene bonds were measured. The barriers to rotation ranged from 16.9 to 21.5 kcal/mol, which translated to half-lives for individual rotamers of less than 15 min at room temperature. The experimental …
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Kinetics of HO2 abstraction of H atoms from hydrocarbons and thermochemical properties of urethane monomers and radicals
… H Atoms From Hydrocarbons Structures, internal rotational barriers and ideal gas thermochemical properties, [Delta]H_{f98} for representative series of transition states for abstraction of H atoms from primary, secondary and tertiary hydrocarbons by the HO_2 radical, TC-HOOH (1), TCC-HOOH (2), …
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Effects of non-planar distortions in porphyrin compounds on their properties and functionality
… to explain the unusual experimentally observed rotational behavior of aryl substituents on porphyrins. Meso aryl rotational barriers might be expected to be much higher in dodecaaryl porphyrins than in tetraaryl porphyrins due to the great difference in peripheral crowding, and those NMR studies …