19F nuclear magnetic resonance studies of aromatic compounds. Part III. The transmission of substituent effects across bridged ring systems

Abstract

The synthesis of several series of bridged dinuclear aromatic compounds of the type p-F·C₆H₄·Z·C₆H₄·X-p[Z = all-trans-·CHCH–CHCH·, CCH₂, CH₂, CH(OH), CMe(OH), –O–, or –S–; X = NH₂, OMe, H, F, Cl, or NO₂] is described. The ¹⁹F n.m.r. spectra of these compounds are used to examine the ‘transmission’ of electronic effects, due to the group X, across the bridge Z. A distinction is drawn between ‘transmission effects’ in which electron density may be considered to be transferred from one ring to the other and ‘relay effects’ in which there is probably no net transfer of electron density.