Abstract: This research has recorded the linewidth of ~(35)Cl of Sr(ClO_4)_2 and Ba(ClO_4)_2 at 0.5 mol·L~(-1) in acetonitrile and ethanol. In terms of nuclear quadrupole moment relaxation mechanism and together with the results for Mg(ClO_4)_2 and Ca(ClO_4)_2 in literature contact type of ion pair for perchlorate salts of alkali earth metals was argued. The linewidth of ~(35)Cl at fixed concentration of Sr (ClO_4)_2 and Ba(ClO_4)_2 in acetonitrile or ethanol as bulk solvent was measured as a function of [B]/[M~(2+)]. where B represents H_2O or DMF. The trend of the plot and the reason for that were explained and the solvation number for Sr~(2+) were estimated. Mole conductivities of salts were also measured and explained for supporting of contact ion pair.

Key words: Relaxation rate, Electric field gradient, Ion pair, Ionic solvation, Perchlorate salts