Computer simulation of Na+ and Cl- ions solvation in aqueous mixtures of formamide.

Molecular dynamics computer simulations have been performed for Na+/Cl--water-formamide mixtures over the whole concentration range of the mixed solvent. It is shown that both Na+ cation and Cl- anion are preferentially solvated by formamide even if only small amounts of formamide are present in the mixture. The Walden products for Na+ and Cl- ions in binary mixture are calculated. It is concluded that the attempts of the direct correlation between the Walden product function shape and the specific ion solvation shell structure might not be successful. (C) 2001 Elsevier Science B.V. All rights reserved.