Molecular complexes of methoxyindoles with 1,3,5-trinitrobenzene and tetracyanoethylene.

Association constants for 1:1 molecular complexes formed between 1,3,5-trinitrobenzene and various methoxy-substituted indoles have been determined by chemical-shift measurements in their nuclear magnetic resonance spectra. The values of association constants for the molecular complexes are comparable to those obtained by optical spectroscopy. The effect on the association constants and relative chemical shifts of the acceptor protons of the pure complexes of various donors is considered. The association constants and relative chemical shifts of the complexes determined by different protons on the nidoles in the presence of an excess of 1,3,5-trinitrobenzene are different. The possible structure of the complexes is discussed. The molecular complexes between tetracyanoethylene and various methoxyindoles have also been studied.