On the Accuracy of DFT Methods in Reproducing Ligand Substitution Energies for Transition Metal Complexes in Solution: The Role of Dispersive Interactions

Authors

  • Dr. Heiko Jacobsen,

    Corresponding author
    1. KemKom, 1215 Ursulines Avenue, New Orleans, Louisiana 70116 (USA)
    • KemKom, 1215 Ursulines Avenue, New Orleans, Louisiana 70116 (USA)
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  • Prof. Dr. Luigi Cavallo

    Corresponding author
    1. KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Kingdom of Saudi Arabia)
    • KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Kingdom of Saudi Arabia)
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Abstract

The performance of a series of density functionals when tested on the prediction of the phosphane substitution energy of transition metal complexes is evaluated. The complexes Fe[BOND]BDA and Ru[BOND]COD (BDA=benzylideneacetone, COD=cyclooctadiene) serve as reference systems, and calculated values are compared with the experimental values in THF as obtained from calorimetry. Results clearly indicate that functionals specifically developed to include dispersion interactions usually outperform other functionals when BDA or COD substitution is considered. However, when phosphanes of different sizes are compared, functionals including dispersion interactions, at odd with experimental evidence, predict that larger phosphanes bind more strongly than smaller phosphanes, while functionals not including dispersion interaction reproduce the experimental trends with reasonable accuracy. In case of the DFT-D functionals, inclusion of a cut-off distance on the dispersive term resolves this issue, and results in a rather robust behavior whatever ligand substitution reaction is considered.

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