Nuclear magnetic resonance investigation of iminium ion intermediates. Part VI. A hydrogen-1 and carbon-13 structural and dynamic study of various substituted iminium salts

Abstract

¹ H an ¹³C chemical shifts and ¹J(¹³C–H) of various substituted iminium salts and parent compounds are presented and correlated with the substituent parameters σ_I and σ_R and the energies of electronic transitions λ_π→π*. A ¹³C dynamic study shows that the rotation about the C–N bond is generally slow with respect to the n.m.r. time-scale and T₁(¹³C) measurements are applied to a qualitative description of the molecular motion of iminium salts. The results are discussed in terms of ion-pair constitution.