Electron densitiy

In alkenyl halides, electron donation (( + )-M effect) of the halogen attenuates the inductive effect in the a and increases electron densitiy in the fi position ... 

Model n (c) shows the interaction between a dimer of SiaO and a metal ion. The metal ion decreases the electron densitiy of Si—Ob of SiaOv - as shown in Fig. 4. Therefore, the covalent bond of Si—Ob (Mark C in Fig. 6 (c)) is readily destroyed. As a result, two Si04 - are formed by cooridinating a free oxygen ion (Mark D in Fig. 6(d)), as shown in Model II (d). Further the equilibrium constants, K in eq.(l) of Masson s statistical thermodynamics study was very small[Pg.292]

Mingos, D. M. R, Hawes, J. C. Complementary Spherical Electron Densitiy Model. Vol. 63, pp. 

Thiophene is aromatic. Its electronic structure follows from Fig. 5.2 (see p 53). Thiophene is a n-excessive heterocycle, i.e. the electron densitiy on each ring atom is greater than one. The value of the empirical resonance energy of thiophene is approximately 120 kJ moT the Dewar resonance energy is quoted as 27.2 kJ mol The aromaticity of thiophene is thus less than that of benzene but greater than that of furan. There are two possible explanations to account for the difference between thiophene and furan ... 

It is easy to see from the experimental results how the ring closure is influenced by the electron densitiy on the atom Z. Thus, for example, better yields are obtained with methylallylamine or N-methylacrylamide than with their phenyl homologues [673, 674]. 

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