Anions Dewar structure

In the coordinated anionic polymerizations with Group I—III metal alkyls alone, monomer coordination involves overlap of the olefinic jr-electrons with vacant sp3 hybrid orbitals. Since this interaction is very weak it is most effective with easily polarized monomers. In the coordination polymerizations with Ziegler type catalysts, stronger monomer coordination is obtained by overlap of jr-electrons with vacant -orbitals of the transition metal component. The complexes have structures of the type proposed by Dewar (199b) and by Chatt and Duncanson (200) and applied to Ziegler type catalysts by Cossee (201) (Fig. 6). The olefin yr-electrons overlap with the orbital of... 

The rate-determining step of the DISPl mechanism, the protonation of the radical anion, largely depends on its electronic structure. As a guideline, LUMO energies of the parent hydrocarbon may be used [39,161]. The attempt to correlate rate constants with highest local charge densities failed [162]. Therefore, Eberson suggested the application of the Dewar-Zimmermann rules [163]. 

Ohorodnyk calculated the geometric and electronic structure of the 7-nor-bomenyl anion 231, radical 232 and cation 19. As early as 1947 Coulson and Dewar had attempted to compare the energies of isomeric ions in which the atom positions are different are quite intenable. So the earlier published calculations by the Hiickel... 

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