NUCLEAR MAGNETIC RESONANCE STUDIES OF DIQUAT PARAQUAT AND THEIR CHARGE-TRANSFER COMPLEXES

The proton magnetic resonance spectra of two quaternary pyridinium salts, diquat (I) and paraquat (II), in D2O solution have been reported. A complete analysis of the spectra has been carried out, and the coupling constants and the chemical shifts for various protons are reported. These studies have indicated a strong tendency for ion association of these cations with electron-donating anions. Iodide and ferrocyanide ions form charge-transfer-type complexes with diquat and paraquat, while ferricyanide ions form an outer-sphere-type ion pair. The association constant for the ion association has been measured using nuclear magnetic resonance and absorption spectrophotometry. The results obtained by the two methods are in good agreement. © 1969, American Chemical Society. All rights reserved.