Metal Ion Compiexing by Cryptand 222 in Solutions. A Thermodynamic Approach

Cryptand 222 (4,7,13,16,21,24-hexaoxa-l,10-diazabicyclo(8.8.8) hexacosane) is a well known sequestering agent for metal ions in solution. Thermodynamic data concerning the ligand itself and its metal complexes in various solvents enable the understanding of the ability of cryptand 222 to complex preferentially certain cations and of how solvents affect these preferences. Some comments on the possibility of employing the "cryptate assumption" for obtaining individual ion thermodynamic properties are presented.