AB-INITIO MODELING OF (LIF)(2) AND (LIF)(2)(H2O)

Second-order Moller-Plesset perturbation theory (MP2) and correlation consistent basis sets have been employed to investigate energetics and minimum-energy structures for (LIF)(2) and its complex with one water , (LiF)(2)-(H2O). The computed dimerization energy for 2LiF --> (LiF)( 2) of -61.8 kcal/mol [-59.9 kcal/mol with zero-point correction (ZPC)] compares very well with the experimental value of -59 kcal/mol. The c yclic C-1 minimum structure for (LiF)(2)(H2O) is very similar to that of LiF(H2O). The binding energy for (LiF)(2)(H2O) of -16.7 kcal/mol (- 14.6 kcal/mol with ZPC) is nearly 20% smaller than the value of -20.3 kcal/mol (-17.9 kcal/mol with ZPC) for LiF(H2O). A transition state wi th C-2v symmetry is also discussed. A simple electrostatic argument in dicates that this configuration will remain a transition state even wi th an extended substrate present.