Studies on the Proton Magnetic Resonance Spectra in Aromatic Systems. XX. Major Factors of the Paramagnetic Shift Parameter of Alkyl Pyridine Derivatives by Tris (dipivalomethanato)-europium

Abstract

The induced paramagnetic shift parameters, S values, due to tris (dipivalomethanato)-europium were examined in alkyl pyridine derivatives from the view points of steric, electronic and solvent effects. 1. The log S values are linearly related with ΔΔ E_R, σ^* and 1-1/ε, and expressed by the following type of equation. S=A.e^-B×k, k=ΔΔ E_R, σ^* or 1-1/ε 2. The three kinds of intercepts are linearly related with each other and decrease regularly from α to γ, whereas a plot of three kinds of slopes, referring to the perturbed state is zig-zag. 3. The S values are expressed by the sum of the contributions of Δ E_steric, Δ E_elect, and Δ E_solv.