Electron spin resonance and ENDOR investigation of the ion pairs of 4,4′-dicyanobenzophenone ketyl with alkali-metal cations

Abstract

E.s.r. and ¹H-ENDOR/TRIPLE resonance experiments on ion pairs in solution formed by 4,4′-dicyanobenzophenone ketyl and a few alkali-metal cations (⁷Li, ²³Na, ³⁹K and ¹³³Cs) are reported. Spectral data for the electrolytically generated ketyl (tetra-n-butylammonium counterion) are also given. The ¹³C hyperfine interactions (carbonyl group) as a function of the counterions have been measured by e.s.r. techniques on the labelled radical. All h.f.s. data and their temperature variations are interpreted in the frame of an adequate ion-pair model and the conclusions are supported by MO calculations (McLachlan, INDO and MINDO/3).