Proton Magnetic Resonance in Some Triarylaminium Salt Free Radicals

Abstract

Abstract The static magnetic susceptibilities from 77 to 300 K and the proton NMR spectra from 1.5 to 77 K have been measured on powder samples of tris-p-chlorophenylaminium perchlorate and chloroantimonate, and tris-p-tolylaminium perchlorate and chloroantimonate. The Weiss constants have been determined to be −2.0, −40, −0.5, and −10 K respectively. A broad maximum which indicates an antiferromagnetic interaction has been observed in the electron susceptibilities of the chloroantimonates obtained from the paramagnetic shift. The magnetic behavior is interpreted assuming the linear-chain model. On the other hand, the perchlorates obeyed the Curie-Weiss law down to 1.5 K. The isotropic hyperfine coupling constants of these four aminium salts have been estimated from the proton NMR spectra, from which the cations of these crystalline aminium salts can be expected to have similar configurations.