Configuration change in —

The decalin (bicyclo[4.4.0]decane) ring system provides another important system for study of conformational effects in cyclohexane rings. Equilibration of the cis and trans isomers reveals that the trans isomer is favored by about 2.8 kcal/mol. Note that this represents a change in configuration, not conformation. The energy difference can be analyzed by noting that the cis isomer has three more gauche butane interactions that are... 

AU = is the change in configurational energy associated with the process An efficient way to compute AU is... 

Having rationalized that the transition state should be a square-based pyramid, it should be mentioned that there are numerous cases in which the transition state appears to be a trigonal bipyramid. We know that because the substitution occurs with a change in configuration. From the foregoing discussion, we would expect this to occur with first-row transition metals because if 11.48 Dq must be sacrificed, this would be more likely if Dq is smaller (which it is the case for first-row metals). If a trigonal bipyramid transition state forms, there would be more than one product possible. This can be... 

Jay Kochi In principle, yes. However, the problem is quite a bit more complicated than that encountered with phosphines, in which steric effects derive from a coordination to metal with minimal changes in configuration, e.g.,... 

Therefore the change in configurational entropy caused by introducing these defects is... 

A change in configuration, from tram to cis, has been shown to occur upon the coordination of AU with the lanthanide ions (104). This is shown by the shift in the symmetric and asymmetric NH2 stretching vibrations in the complexes. 

Implementation of the recommendations led to a change in configuration of the membership in the pharmacopeial harmonization process. Whereas the British Pharmacopoeia had been an independent member of the Quadripartite Group from its inception, implementation of harmonization of standards and tests for excipient was... 

When the initial compound was irani-stilbene, the nnconsnmmated part was recovered with no change in configuration. When di-stilbene was employed as the initial reactant, the recovered olefin was a mixtnre of trans and cis isomers. Hence, the trans confignration is more favorable for oxidative acetoxylation than the cis confignration. In accordance with this conclnsion, the mechanism shown in Scheme 2.30 is proposed. 

A change in configuration occurs either by the action of ammonia or by the action of nitrosyl bromide. By studying the conversion by the action of ammonia under various conditions, Fischer was able to show conclusively that this reagent behaved optically normally, which result was confirmed by a later experiment upon optically active trimethyl-a-propiobetaine (a-homobetaine),... 

If an electron is localized , abandoning its core has important consequences. An important assumption of (11) is that the a are unchanged if we excite one electron from a state a to a state This change in configuration (see A.II.) within the band does not perturb the other electron states (Koopman theorem ). 

This is profoundly different from what happens in an atom, where a change in configuration involves always a certain amount of energy. 

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