EVIDENCE FOR RH(II) IN A LICL-KCL EUTECTIC - AN OPTICAL-ABSORPTION INVESTIGATION

Rhodium exists in LiCl-KCl melts at 400-450 degrees C as the RhCl63- s pecies. Spectroscopic data show that an increase of the temperature up to 600 degrees C leads to a reaction of this species with the melt an d to the formation of the stable Rh(II) chlorocomplex. This reaction, which has not been reported previously, is reversible since on cooling to lower temperatures, 400-450 degrees C, reoxidation to the Rh(III) complex is observed. The Rh(ll) complex however persists even at these lower temperatures if the experimental cell is connected to a vacuum line to remove the chlorine formed in the reduction reaction.