Advanced

Does DFT-D estimate accurate energies for the binding of ligands to metal complexes?

Ryde, Ulf LU ; Mata, Ricardo A and Grimme, Stefan (2011) In Dalton Transactions 40(Online 19 Aug 2011). p.11176-11183
Abstract
We have studied the homolytic dissociation of a methyl radical from a model of methyl cobalamin. For this reaction, density functional theory with an atom-pairwise dispersion correction (DFT-D) gives a dispersion contribution to the bond dissociation energy (BDE) of 22-51 kJ mol(-1) depending on the functional, i.e. much more than common estimates for the total dispersion interaction energy of the methyl group in typical solvents. We show that this large energy correction results from many rather small (0-2 kJ mol(-1)) interactions that arise between the ligand and the metal and the other ligands when a short metal-ligand bond is formed. The energy terms result mostly from atom pairs connected by two or three bonds, i.e. terms that... (More)
We have studied the homolytic dissociation of a methyl radical from a model of methyl cobalamin. For this reaction, density functional theory with an atom-pairwise dispersion correction (DFT-D) gives a dispersion contribution to the bond dissociation energy (BDE) of 22-51 kJ mol(-1) depending on the functional, i.e. much more than common estimates for the total dispersion interaction energy of the methyl group in typical solvents. We show that this large energy correction results from many rather small (0-2 kJ mol(-1)) interactions that arise between the ligand and the metal and the other ligands when a short metal-ligand bond is formed. The energy terms result mostly from atom pairs connected by two or three bonds, i.e. terms that normally are ignored or scaled down at the molecular mechanics level, and have large contributions from r(-8) terms. The added dispersion energy diminishes the variation in the calculated BDE observed among various generalised-gradient approximation (GGA) functionals, whereas a gap still persists between the results of GGA and hybrid functionals. Model calculations at the local MP2 and CCSD (second-order perturbation theory and coupled cluster theory with single and double excitations) levels are in a similar range as the dispersion interactions estimated by DFT-D (23-29 kJ mol(-1)). However, both the DFT-D and the wavefunction-based results include middle-range correlation effects that vary greatly between different DFT methods owing to their different density-based description in the short-range regime. Therefore, it is not meaningful to discuss which DFT method gives the most accurate estimate of the dispersion contribution to the BDE. Moreover, for a balanced treatment of dispersion during the binding reaction in solution, the dispersion energy of the ligand and the unbound complex with the surroundings needs also to be considered, which decreases the net dispersion contribution to binding by ~20 kJ mol(-1). (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Dalton Transactions
volume
40
issue
Online 19 Aug 2011
pages
11176 - 11183
publisher
Royal Society of Chemistry
external identifiers
  • wos:000296024000015
  • pmid:21853206
  • scopus:80055021247
ISSN
1477-9234
DOI
10.1039/c1dt10867k
language
English
LU publication?
yes
id
447ec855-a930-45fe-b096-810776ecd5ff (old id 2150854)
date added to LUP
2011-08-31 11:02:20
date last changed
2016-09-20 05:34:15
@article{447ec855-a930-45fe-b096-810776ecd5ff,
  abstract     = {We have studied the homolytic dissociation of a methyl radical from a model of methyl cobalamin. For this reaction, density functional theory with an atom-pairwise dispersion correction (DFT-D) gives a dispersion contribution to the bond dissociation energy (BDE) of 22-51 kJ mol(-1) depending on the functional, i.e. much more than common estimates for the total dispersion interaction energy of the methyl group in typical solvents. We show that this large energy correction results from many rather small (0-2 kJ mol(-1)) interactions that arise between the ligand and the metal and the other ligands when a short metal-ligand bond is formed. The energy terms result mostly from atom pairs connected by two or three bonds, i.e. terms that normally are ignored or scaled down at the molecular mechanics level, and have large contributions from r(-8) terms. The added dispersion energy diminishes the variation in the calculated BDE observed among various generalised-gradient approximation (GGA) functionals, whereas a gap still persists between the results of GGA and hybrid functionals. Model calculations at the local MP2 and CCSD (second-order perturbation theory and coupled cluster theory with single and double excitations) levels are in a similar range as the dispersion interactions estimated by DFT-D (23-29 kJ mol(-1)). However, both the DFT-D and the wavefunction-based results include middle-range correlation effects that vary greatly between different DFT methods owing to their different density-based description in the short-range regime. Therefore, it is not meaningful to discuss which DFT method gives the most accurate estimate of the dispersion contribution to the BDE. Moreover, for a balanced treatment of dispersion during the binding reaction in solution, the dispersion energy of the ligand and the unbound complex with the surroundings needs also to be considered, which decreases the net dispersion contribution to binding by ~20 kJ mol(-1).},
  author       = {Ryde, Ulf and Mata, Ricardo A and Grimme, Stefan},
  issn         = {1477-9234},
  language     = {eng},
  number       = {Online 19 Aug 2011},
  pages        = {11176--11183},
  publisher    = {Royal Society of Chemistry},
  series       = {Dalton Transactions},
  title        = {Does DFT-D estimate accurate energies for the binding of ligands to metal complexes?},
  url          = {http://dx.doi.org/10.1039/c1dt10867k},
  volume       = {40},
  year         = {2011},
}