The reaction graph of the Cope rearrangement in bullvalene

The concept of mode of rearrangement is used to analyse the connectedness of the reaction graph for the Cope rearrangement in bullvalene. © 1994 J.C. Baltzer AG, Science Publishers.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Classification of rearrangement mechanisms and dynamic stereochemistry

We review some aspects of dynamic stereochemistry related to the classification theory of rearrangement mechanisms. This classification is based on the symmetry of the molecular skeleton and has been widely used in connection with nuclear magnetic resonance line shape analysis. It is also related to the Longuet-Higgins approach to nonrigidity and may be used to predict the consequences of various tunneling mechanisms in rotation or vibration spectroscopy. © 1981 Plenum Publishing Corporation.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

The dsd model in heptacoordinate stereochemistry: a comparison with experiment

The diamond-square-diamond or dsd model provides a simple description for heptacoordinate interconversion. We compare it to NMR information. It appears that the model is almost always compatible with experimental facts, at least when the dsd processes do not lead to isomerization. © 1993 J.C. Baltzer AG, Science Publishers.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Contribution à l'étude des phénomènes de transport dans les gaz modérément denses

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Properties of reaction graphs for XeF6

In this study of the automorphism group of some reaction graphs for XeF6 interconversions, there exists a close relation between these groups and the algebraic structure of the modes of rearrangements of this molecule. Two of these groups are of big order (106 and 108). The relation between the present reaction graphs and those for trigonal bipyramids is discussed. In one case, the distance between enantiomers appears to be smaller than the diameter of the graph.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Reaction graphs for square antiprism rearrangements

We obtain the reaction graphs for the rearrangements of the trans family square antiprisms. The automorphism groups of these graphs are analyzed and expressed as products of well-known permutation groups. © 1995 American Chemical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Double cosets and enumeration of permutational isomers of fixed symmetry

When a molecular skeleton with n sites and symmetry group G carries nx ligands of type X, ny of type Y, etc. the resulting isomers are distributed among several symmetries. We show that the numbers υγGB of isomers of symmetry γ obey a system of linear and inhomogeneous equations, as shown by eq 12. The linear coefficients pβγG and the independent terms pβBSn appearing in this system are related to the double-coset structure of G and Sn, respectively, and are easy to calculate by standard group theoretical methods. Unfortunately, the rank of pβγG is smaller than the number of υγGB unknowns. Hence, the system can only be solved if some of the unknowns are calculated independently. However, in practice, some of the υγGB numbers are easy to obtain either because they are vanishing for any ligand partition (phantom subgroups of G) or because they are readily found by inspection, as it is the case when isomers of high symmetry γ have to be enumerated. Therefore, the relations established in this paper do yield an efficient method to enumerate permutational isomers of fixed symmetry. It is remarkable that the calculations required only involve enumeration of double cosets. The present method is applied to the dodecahedrane skeleton. The number of isomers of fixed symmetry and corresponding to the formula C20H20-nXn have been obtained (n = 0, 1, 2, 10). © 1986 American Chemical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Contribution à la chimie des neiges antarctiques. Estimation du dépôt annuel de matière extra-terrestre

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe