Transition states electronic structure

The Ti ion attracts the p electron pair of the monomer and forms a s bond, while the counterion attracts the electron-deficient centre of the monomer. Thus the monomer, is inserted into a transition state ring structure shown below ... 

The preceding discussion of the relationships between excited state electronic structure and photochemical reactivity focused primarily upon coordination compounds containing cP or low-spin cP transition metals. These relationships are generally applicable, however, to complexes of other d transition elements, the lanthanides and the actinides. A brief survey of the photochemical reactions of these latter systems is presented below. 

X-Ray absorption data in combination with atomic theory and solid-state band-structure theory can yield detailed information about the ground-state electronic structure of solids on an energy scale on the order of meV. This holds particularly true for correlated narrow-band systems, such as the rare-earth and transition-metal compounds. In broad-band materials, such as the... 

Non-additivity of substituent effects has been proposed as a criterion for the operation of the RSR so the linearity argues against its applicability in this system. In a description of transition states by structure-reactivity coefficients (Jencks and Jencks, 1977), two alternative types of behaviour were discussed. In Hammond -type reactions the more endothermic reactions have later transition states, whereas anti-Hammond behaviour is characterized by an adjustment of the transition-state structure to take advantage of favourable substituent effects. These results illustrate that different systems can display quite different behaviour in linear free energy correlations. Thus, in alkene protonations, such correlations cover vast ranges in reactivity with only modest changes in sensitivities, while in solvolytic reactions the selectivity p varies depending on the electron supply at the electron-deficient centre (Johnson, 1978). 

The primary objective of this paper is to illustrate by specific examples from our past and current research how electrical property measurements can be of value in deducing information regarding the solid-state electronic structure and in studying intermolecular orbital interactions in such transition metal complex systems. To facilitate this discussion, a brief description of electrical conductivity and some other electrical properties is included. For a more detailed account as well as for a description of the various experimental techniques which are used to determine these properties, the reader is referred to any of several excellent books on the subject (12,13). 

The electronic absorption spectrum of bare N2O has been summarized and interpreted in recent tabulations I5i ground state electronic structure of NNO relevant to this discussion can be written as nf ctn 3 ) The lower energy part of the excitation spectrum is dominated by spin triplet and spin singlet 712 - 713(71- 71 ) transitions. The only dipole allowed excitation of this group is to the state with a vertical transition energy... 

Elimination from 2-benzyl-1,1,1-trifluoropropane with potassium /-butoxide undoubtedly occurs through a carbanion-like E2 transition state. The structure of this substrate (14, Table 3, p. 192) is closely related to the pentahaloethanes known to react by the carbanion mechanism. The lesser tendency of the beta methyl and beta benzyl groups to withdraw electrons than the beta halogens accounts for a reduction in carbanion stability and a change to a concerted elimination. 

Stark measurements of intervalence transitions (IT) associated with mixed-valence species can yield information about its ground state electronic structure. IT within valence-localized (Robin and Day Class II) complexes is accompanied by a nonzero dipole moment change. For the example shown in Equation (9), A/. v is large (ca. 21 D), confirming that a Class II description is appropriate. ... 

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