Infrared intensities as a measure of intramolecular interactions. Part XXXVI. Field-induced resonance effects

Propagation of Polar Substituent Effects in 1-(Substituted phenyl)-6,7-dimethoxy-3,4-dihydro- and -1,2,3,4-tetrahydroisoquinolines As Explained by Resonance Polarization Concept

“…This can affect the molecule's reactivity, conformation, solubility, equilibrium between the different potential tautomeric forms, acidbase properties or stacking tendency, and so forth. The analysis of the systematic substituent effects on the 13 C NMR chemical shifts propagating all along the molecule is an effective way to study the changes in electronic states promoted by different phenyl substituents. [1][2][3][4][5] The substituent effects can follow the normal pattern, for instance, electron-withdrawing substituents affecting low-field (high-frequency) 13 C NMR chemical shifts.…”

“…The analysis of the systematic substituent effects on the 13 C NMR chemical shifts propagating all along the molecule is an effective way to study the changes in electronic states promoted by different phenyl substituents. [1][2][3][4][5] The substituent effects can follow the normal pattern, for instance, electron-withdrawing substituents affecting low-field (high-frequency) 13 C NMR chemical shifts. The occurrence of the so-called reverse substituent effect (RSE) is, however, well-established at some sites of, for example, styrenes, chalcones, carboxylic acid derivatives, imines, and hydrazones.…”

Improved Yukawa-Tsuno equation and the substituent effect on pyridine basicity

“…In the meta series, our constrained tetralinear approach accommodates well the increased effect by electron-donating substituents, in relation to the other substituents, 27 originated in the fieldinduced resonance effect. [28][29][30] This effect is considered to be responsible for an observed ! value below theoretical calculations.…”

“…As noted before, 11 our hyperbolic model is consistent with errorfree data for which r 3n and r 3s are different, this difference being related to 3s [see Eqn (41) The behaviour of 3s substituents in the pyridine reactivity has been qualified as unexpected 28 and its origin ascribed 28,29 to the field-induced resonance effect. 30 This effect, which cannot be accounted for separately from pure field effects, should therefore explain the increased reaction constant for 3s substituents relative to 3n substituents, a feature precluded by the bilinear and unilinear models.…”

“…value can be ascribed to indirect meta resonance or field-induced resonance effects (FIRE). [28][29][30] Since 11 ! = !…”