Generalized valence bond study of rotational singlet structures and pi bond energies for systems containing C=C, Si=Si, and C=Si double bonds
Article Abstract:
Generalized valence bond calculations of singlet state rotations around double bonds based on ab initio molecular orbital theory can determine pi bond energies and fluorine substitution effects in double-bond systems. The pi bond energy of the carbon-carbon bond in ethene is 65.4 kcal/mol, and decreases with fluorine substitution. The silicon-silicon bond in disilene has a pi energy of 23.2 kcal/mol, and the carbon-silicon bond in silaethene a pi energy of 31.6 kcal/mol.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
User Contributions:
Comment about this article or add new information about this topic:
Chiral N-(o-aryl)-thiazolidinediones: synthesis from rhodanines and investigation on rotational enantiomers by NMR spectroscopy
Article Abstract:
N-(o-aryl)-rhodanines which are sterically hindered (that is, N-(o-aryl)-2-thioxo-4-thiazolidinones) were synthesized. The N-(o-tolyl) and N-(o-chlorophenyl) derivatives were converted to their dioxo analogs (N-(o-aryl)-2,4-thiazolidine-diones). The compounds were shown through use of 1H and 13C NMR spectroscopy to be chiral in their conformational ground states through detection of the methyl groups or diastereotopic protons at C-5 of the heteroring.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
User Contributions:
Comment about this article or add new information about this topic:
Ab initio conformational analysis of the model tripeptide N-formyl-L-alanyl-L-alanine amide
Article Abstract:
The model tripeptide N-formyl-L-alanyl-L-alanine amide (ALA-ALA) has been studied and two previously unreported energy minima have been described. The ab initio conformational energy minima were found by using ab initio RHF/6-31F gradient geometry refinement. The torsion angles of the ab initio energy minima are not what is found in typical substructures of proteins. Limitations of the dipeptide approximation have been examined.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
User Contributions:
Comment about this article or add new information about this topic:
- Abstracts: Scanning probe studies of single nanostructures. Organic polyvalent iodine compounds. Self-assembly of discrete cyclic nanostructures mediated by transition metals
- Abstracts: Structure and dynamics of hydrated ions. Protein-protein interactions: interface structure, binding thermodynamics, and mutational analysis
- Abstracts: Heme/copper terminal oxidases. Protein structure and the energetics of protein stability. Iron-sulfur proteins with nonredox functions
- Abstracts: Selective hydroboration of alkenes and alkynes in the presence of aldehydes and ketones. The reactivity of the high-energy intermediates formed in the reactions of Group 13 metal atoms and aromatic alkenes
- Abstracts: Chemical kinetics and thermodynamics of tin ionization in H2-O2-N2 flames and the proton affinity of SnO. The decarbonylation of ionized beta-hydroxypyruvic acid: the hydrogen-bridged radical cation (CH2=O...H...O=C-OH)super.+ studied by experiment and theory