Chlorine–benzene complexes—the reliability of density functionals for non-covalent radical complexes

A K Croft,H M Howard-Jones

doi:10.1039/b704966h

Abstract

The structure of the chlorine atom-benzene complex has been a topic of significant controversy for more than 50 years. We have reexamined the structure of this complex with new density functional methods especially designed for non-covalent complexes, and compared the structures and energetics to those obtained using standard DFT and high accuracy composite methods. We find that the popular B3LYP functional fails to identify stationary points revealed by other functionals, and that the eta(1)-sigma complex appears to be more stable than the eta(1)-pi complex, contrary to other recent work, highlighting the careful selection of methods required in non-covalent radical systems.

Highlights

Scale factors were determined from a least squares fit to a series of 20 small molecules for which the ZPE has already been experimentally determined
Energies of the π-complexes in Hartrees calculated for different DFT methods, with zero point correction energies and counterpoise corrected energies
PBEPBE -459.9662324 -232.0171272 0.097593 -692.0067246 0.097890 n/i zpe -

Summary

Introduction

Chlorine-Benzene Complexes – The Reliability of Density Functionals for Non-Covalent Radical Complexes Calculation of ZPE correction term for BH&HLYP/6-311+G(d, p) Calculation of ZPE correction term for B3PW91/6-311+G(d, p) Calculation of ZPE correction term for MPW1K/6-311+G(3df, 2p) Calculation of ZPE correction term for MPWB1K/6-311+G(3df, 2p)

Results

Conclusion