Synthesis and characterization of tetraphenylammonium salts

The phenyl (Ph) group is a representative substituent in the field of organic chemistry as benzene (the parent molecule) is of fundamental importance. Simple Ph-substituted compounds of common chemical elements are well known. However, extensive structural characterization of tetraphenylammonium (Ph₄N⁺) salts has not been reported. Herein, the synthesis of Ph₄N⁺ salts and their characterization data including the ¹H and ¹³C nuclear magnetic resonance (NMR) spectra and the single-crystal X-ray structure have been presented. An intermolecular radical coupling reaction between an aryl radical and a triarylammoniumyl radical cation was conducted to synthesize the target moieties. The Ph₄N⁺ salts described herein are the simplest tetraarylammonium (Ar₄N⁺) salts known. The results reported herein can potentially help access the otherwise inaccessible non-bridged Ar₄N⁺ salts, a new class of rigid and sterically hindered organic cations.