Three paramagnetic [RhCl6]4– complexes were detected in X-irradiated solution-grown single crystals: RhCl84- · nV, with n = 2, 1, or 0. All of the complexes had a 4d7 ground state, with the unpaired electron spin being mainly in a 4dz2 orbital. They differed only with respect to the presence of 1, 2 or zero next-nearest cation vacancies. The RhCl84- · 2V complex formed at 77K and partially changed to RhCl84- · 1V at about 190K. At room temperature, the RhCl84- · 0V complex predominated, but traces of the RhCl84- · 1V and RhCl84- · 2V centers remained. A thermally-induced reorientation motion of the 4dz2 molecular orbital was used to explain a temperature-dependence of the RhCl84- · 1V electron spin resonance spectrum.

Electron Spin Resonance of Rhodium-Vacancy Complexes in Solution-Grown NaCl Crystals. H.Vercammen, D.Schoemaker, H.Käss, E.Goovaerts, A.Bouwen, H.Vrielinck, F.Callens: Journal of Applied Physics, 1998, 84[1], 428-32