13 C nuclear magnetic resonance spectra of the reciprocal of macrotetrolide antibiotics with Na + , K + , Rb Rb + , Cs + , NH 4+ and Ba 2+

The ¹³C NMR. spectra of nonaction have been recorded at 22.6 MHz. Additivityrules, chemical shift reagents and spectra of model compounds enabled a full assignment of the lines to be made. A comparison of the spectra of the nonactin complexes with Na⁺, K⁺, Rb⁺, Cs⁺, NH₄⁺ and Ba²⁺ showed that no H-bridges between NH₄⁺ and the nonactin carbonyls exist. This is corroborated by the infrared spectra of the complexes.