Solvation of lanthanide salts. Anhydrous neodymium perchlorate in methanol

Solvation of neodymium perchlorate in nonaqueous methanol was investigated using the sound velocity method at 298 K. The total solvation number in the most diluted solutions is congruent to 25. It was found that the concentration dependence of the sound velocity (and, consequently, that of the compressibility) is not linear, indicating inclusion of the perchlorate ions into the solvation shell of the lanthanide cation and a resulting decrease in the solvation number. Additional conductivity measurements confirmed this conclusion, although the dielectric relaxation experiments did not give a definite answer concerning the relaxation of solvated ion pairs. A discussion based on spectroscopic results is given.