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Theoretical Chemistry Accounts

, Volume 99, Issue 3, pp 151–157 | Cite as

Theoretical studies on the structure of M+BF−4 ion pairs M = Li+, NH+4: the role of electrostatics and electron correlation

  • C. H. Suresh
  • S. R. Gadre
  • S. P. Gejji
Regular article

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 Møller-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.

Key words: Molecular electrostatic potential Ab initio calculations 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • C. H. Suresh
    • 1
  • S. R. Gadre
    • 1
  • S. P. Gejji
    • 1
  1. 1.Department of Chemistry, University of Pune, Pune 411 007, IndiaIN

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