Canonical variational transition-state comparative study for M+(= Li+, Na+ and K+)+ H2O →[M ·(H2O)]+ association reactions

Abstract

The Canonical variational transition-state theory (CVTST) has been used in order to study the association reactions of three alkali-metal ions (Li⁺, Na⁺, K⁺) with a water molecule. Generalized transition states (GTS) are obtained by finding the maxima in the free enthalpy along the reaction path in the complete analytic potential-energy surfaces which include all inter- and intra-molecular geometrical parameters. The differences in the positions and energies of the GTS for the three reactions are observed to result mainly from differences in the entropic term –TΔS. The effect of temperature on these reactions is explained by carefully analysing the slopes for enthalpic ΔH and entropic –TΔS profiles along the reaction coordinate.