Аннотация:The complexation of NH4+, Li+, Na+, K+, and Ca2+ (as their SCN- salts) with benzo-15-crown-5 and benzo-12-crown-4 was studied at 298 K. Equil. consts. and heats and entropies of complexation were calcd. from calorimetric titrn. data. The Ca2+ and Na+ complexes are more stable than those of Li+, K+, and NH4+. The benzo-15-crown-5 ligand forms more stable complexes and also forms mostly 1:1 complexes. Benzo-12-crown-4 forms less stable complexes and tends to form 1:2 (metal:crown) complexes.