Theoretical studies on the structure of M+BF?4 ion pairs M?=?Li+, NH+4: the role of electrostatics and electron correlation |
| |
Authors: | C H Suresh S R Gadre S P Gejji |
| |
Institution: | (1) Department of Chemistry, University of Pune, Pune 411 007, India, IN |
| |
Abstract: | A systematic investigation of the M+BF4
− (M = Li or NH4) ion-pair conformers has been carried out using an electrostatic docking model based on the molecular electrostatic potential
topography of the free anion. This method provides a guideline for the subsequent ab initio molecular orbital calculations
at the Hartree-Fock (HF) and second-order M?ller-Plesset perturbation theory (MP2) levels. It has been demonstrated that the
model presented here yields more than 75% of the HF interaction energy when Li+ is the cation involved and more than 90% for the case of NH4
+. Inclusion of MP2 correlation in the HF-optimized geometries leads to stationary point geometries with different numbers
of imaginary frequencies and in some places where the energies of two adjacent conformers are very close, the energy rank
order is altered. The HF lowest-energy minima for the Li+BF4
− and NH4
+BF4
− show a bidentate and tridentate coordinating cation, respectively, whereas at the MP2 level, this ordering is reversed.
Received: 9 September 1997 / Accepted: 5 November 1997 |
| |
Keywords: | : Molecular electrostatic potential Ab initio calculations |
本文献已被 SpringerLink 等数据库收录! |
|