Electron Paramagnetic Resonance of Gamma Irradiated [(CH3)4N]InCl4 and [(CH3)4N]2CdCl4 Single Crystals

Abstract

Gamma irradiated [(CH<inf>3</inf>)<inf>4</inf>N]InCl<inf>4</inf> and [(CH<inf>3</inf>)<inf>4</inf>N]<inf>2</inf>CdCl<inf>4</inf> single crystals were investigated by electron paramagnetic resonance at ambient temperature, and it has been found that both compounds indicate the existence of (CH<inf>3</inf>)<inf>3</inf>N·+ radicals. The g factors were found to be isotropic, and the hyperfine constant for H atoms was measured as 2.86 mT and is isotropic for this radical in these substances. The hyperfine coupling constant of the N nucleus with the hole in (CH<inf>3</inf>)<inf>3</inf>N·+ in [(CH<inf>3</inf>)<inf>4</inf>N]InCl<inf>4</inf> was found to be anisotropic with the A<inf>zz</inf> = 2.92, A<inf>yy</inf> = 1.62 and A<inf>xx</inf>=1.40 mT. From these, it has been revealed that the C<inf>3v</inf>-axis of (CH<inf>3</inf>)<inf>3</inf>N·+ radical performs rotational or jumping reorientational motions around a fixed axis, in addition to the rotations of protons in CH<inf>3</inf> groups and the rotational motions of CH<inf>3</inf> groups around the C<inf>3v</inf>-axis of the radical. The g, and the hyperfine coupling factors of the N nucleus were isotropic in (CH<inf>3</inf>)<inf>3</inf>N·+ in [(CH<inf>3</inf>)<inf>4</inf>N]<inf>2</inf>CdCl<inf>4</inf>. This indicates the motional behaviour of the radical in this compound is as in a liquid. This isotropic behaviour of the hyperfine coupling constants was found to be same until the attainable lowest temperature of 113 K in our laboratory. © 2003 Elsevier Science Ltd. All rights reserved.