Isomer generation

If we allow the ligands to be chiral, the isomer-generating group 0 becomes 4. The induction from T>2d to 04 is obtained via 4, according to the procedure outlined in Section II-E. The classes of 4 are those of 4, plus each of these multiplied by tmore than once in a single step of the induction. A qualitatively complete... 

This set of rules stops isomer generation whenever one rule is violated. It implicitly restricts the total number of isomers generated also. 

Since there are no symmetry considerations embedded in the isomer generation approaches described above, duplicate isomers may be generated for symmetric parts of a molecule. 

In the case of alkylated SAMP-hydrazones derived from aldehydes, only two stereoisomers are observed, i.e., the (S,R)-(E)- and the (S,S)-( )-isomers. During H-NMR measurements of alkylated SAMP-hydrazones derived from ketones, a slow isomerization of the (S,R)-(Z)- and (5,S)-(Z)-isomers, generated during metalation, to the thermodynamically more stable (SJi)-(E)- and (S,5)-( )-isomers occurs3. 

The reaction seems to be limited to this very special functional group of the ketimines whereas the terminal alkene component can be varied somewhat. The scope of the reaction is rather limited based on the number of isomers generated from symmetrical (two isomers) and unsymmetrical alkenes (up to six isomers) and, as a consequence, the usefulness of this reaction for the synthesis of more complex molecules is uncertain at the moment. A theoretical investigation has been undertaken to elucidate the reaction pathway and the role of the ketimine subunit. It could be shown that the ketimine functionality is important as it acts as a bidentate ligand... 

C2H2Si Isomers Generation by Pulsed Flash Pyrolysis and Matrix-Spectroscopic Identification... 

T. Onaka, M. Kobayashi, Y. Ishii, K. Okumura, and M. Suzuki, Applications of solid-phase extraction to the analysis of the isomers generated in biodesulfurization against methylated dibenzothiophenes,/. Chromatogr. A 904 (2000), 193-202. 

As the debate concerning health effects of saturated products and that of trans isomers generated during hydrogenation continues, interesterification may offer a viable alternative to the refiner. Outside the United States interesterification is used to produce hardened fats without trans isomers. These products are available in Canada and continental Europe. This technology has been available for quite some time, as a patent on the product was granted to Unilever in 1961 (22). The ability to tailor the melting point and functional crystallization characteristics without... 

FIG. 17.10 Fluorescence spectral change of bulk amorphous film 8 excited with 280 nm by photoirradiation (...) closed-ring form isomer 8b, and (--------) open-ring form isomer generated by... 

With the GT Calculator you can perform a variety of standard group theory calculations simply by entering the appropriate structure details for the molecular geometry. In addition, on the various worksheets of the calculator files, it is straightforward to determine more advanced group theoretical results, such as the numbers of isomers generated for a given structure by decoration, or to calculate and decompose the symmetric and antisymmetric powers of permutation representations. 

Lukovits, I. (1999). Isomer Generation Syntactic Rules for Detection of Isomorphism. J.Chem.Inf.ComputScL, 39,563-568. 

Gas-phase properties of a molecule have, by definition, an intrinsic character and they could be modified by the environment. Although the formation and reactions of gaseous ionized phenol 21 (cf. Chart 5) and its cyclohexa-2,4-dienone isomer 22 have been studied in numerous ionization and mass spectrometric studies , thermochemical parameters of these isomers as well as information on other non-conventional isomers, such as the distonic ion 23, were rather scarce. Conventional cations of analogous aromatic systems (X—CeH5) + and their distonic isomers generated by simple 1,2-hydrogen shifts within the ring were demonstrated to be observable gas-phase species . In addition, the mechanism of the CO-loss upon phenol ionization has only recently been unraveled . ... 

Figure 25.9 Time dependence of the population of the light-induced isomers generated at —163 °C for 190h irradiation (during the experiment, the backward reaction scarcely takes place).

Lukovits, 1. (1999) Isomer generation syntactic rules for detection of isomorphism /. Chem. Inf. Comput. Sci., 39, 563—568. 

Typically, if two distinct terminal olefins (A+B, Scheme 2) undergo CM, multiple products result the homodimers of A and B are formed (A +B ) in addition to the desired cross product (AB). In addition, each of these products is typically formed as a mixture of the cis and trans isomers, generating six different products. 

In addition to the most commonly found end-on M-NO binding mode, we consider the existence of stable linkage isomers generated through reversible photoinduced (and eventually thermal) transformations.15 Photoreactivity may also lead to the irreversible delivery of NO from MNO " complexes.16... 

The chemistry of ephedrines is summarized in Figure 9-9. It will be noted that the four isomers generated by the two chiral centers (22) exist as two nonsuperimposable image pairs. The two ephedrines are enantiomers. Epimerization of the a-carbon produces the other pair—the -ephedrines. Each -ephedrine is an enantiomer of the other however,... 

The HDCl of the three DCB isomers generated CIB (partial dechlorination) and benzene (complete dechlorination) as the only detectable products there was no evidence of any aromatic ring reduction. The kinetic patterns were found to be broadly the same for each DCB isomer. Let us consider first the dependence of HDCl rate on DCB partial pressure (P[)cb), which exhibits a maximum (see... 

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