Charge-transfer complexes. Part X. A nuclear magnetic resonance study of the interaction of N-methylquinolinium and tropylium cations with anion and solvent

Abstract

Sensitivity to changes in solvent and concentration of the chemical shifts of N-methylquinolinium iodide and perchlorate is in the order 2-ring > 1-Me ≈ 4-ring > 3-ring with the iodide giving much larger shifts on increasing concentration than the perchlorate. Internal shifts of the 2-ring and 1-Me and 2-ring and 4-ring protons correlate well with the solvent polarity parameter E_T for protic solvents. Aprotic solvents give a separate and less satisfactory correlation. Association constants derived from the chemical shift data are compared with those derived by a spectrophotometric method.