Thermodynamic parameters for the complexation process between metal(I) cations and dibenzocryptand 222 in dipolar, aprotic solvents. Linear correlation between entropies of complexation and entropies of solvation of cations

Abstract

Enthalpies and entropies of complexation of metal(I) cations and dibenzocryptand 222 in N,N-dimethylformamide, dimethyl sulphoxide, propylene carbonate and acetonitrile at 298.15 K are reported. The lower flexibility of dibenzocryptand 222 compared with cryptand 222 results in a decrease in complex stability. In most cases this is controlled by the higher entropy loss observed for the complexation process between metal(I) cations with dibenzocryptand 222 relative to the same process with cryptand 222 in dipolar aprotic solvents. A linear correlation between entropies of metal(I) dibenzocryptates and entropies of solvation of these cations in these solvents is found. These results are discussed in terms of a similar correlation found for cryptand 222 in the dipolar aprotic solvents.