Complexation and transfer free energies of metal-ion dibenzocryptates

Abstract

Stability constants of dibenzocryptand-222 and alkali-metal and silver cations in N,N-dimethylformamide, dimethyl sulphoxide, acetonitrile, propylene carbonate and nitromethane and derived free energies of complexing at 298 K are reported. The results obtained in the five dipolar aprotic solvents lend support to the linear correlation previously reported between the single-ion thermodynamic parameters of transfer among the dipolar aprotic solvents based on the Ph₄AsPh₄B convention and the differences between the thermodynamic parameters for the complexation reaction of metal-ion cryptates in these solvents.

The transfer free energies of dibenzocryptand-222 and metal-ion dibenzocryptates from water to nitromethane are reported. The results obtained show the enhancement in the molar transfer constants of metal dibenzocryptates with respect to metal cryptates and to the uncomplexed cations in transfers from water to nitromethane.