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Induction , resonance , and hybridization modulate electron density at the proton, as the result of local electron c

Induction , resonance , and hybridization modulate electron density at the proton, as the result of local electron currents around the nucleus;. precession of electrons attached to substituent.

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Induction , resonance , and hybridization modulate electron density at the proton, as the result of local electron c

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  1. Induction, resonance, and hybridization modulate electron density at the proton, as the result of local electron currents around the nucleus; precession of electrons attached to substituent Purely magnetic effects of substituents also can have major effects on proton shielding if the group has a non-spherical shape generating a non-local field; Non-spherical electron density distributions generatediamagnetic anisotropy

  2. Diamagnetic anisotropy of aromatic rings change of sign at an angle of 54º44from the plane of the ring; it is the zero value of the expression3cos2q-1, the magic angle in NMR;

  3. Diamagnetic anisotropy of triple and double bonds shielded shielded

  4. Diamagnetic anisotropy of C-C single bonds The larger non-local shielding effect is seen when the C-C bond is perpendicular to B0; less shielded more shielded

  5. Heq Hax

  6. Empirical Correlations for methylene of the type Y-CH2-X by adding Di to the chemical shift of methane; d = 0.23 + DX + DY

  7. substituent constants Zi are added to the chemical shift of ethene; d = 5.28 + Zgem + Zcis+ Ztrans

  8. substituent constants Si are added to the chemical shift of benzene; d = 7.27 + ∑Si

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