The Thermochemistry of London Dispersion‐Driven Transition Metal Reactions: Getting the ‘Right Answer for the Right Reason’

Reliable thermochemical measurements and theoretical predictions for reactions involving large transition metal complexes in which long‐range intramolecular London dispersion interactions contribute significantly to their stabilization are still a challenge, particularly for reactions in solution. A...

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Bibliographic Details
Published in:ChemistryOpen (Weinheim) 2014-10, Vol.3 (5), p.177-189
Main Authors: Hansen, Andreas, Bannwarth, Christoph, Grimme, Stefan, Petrović, Predrag, Werlé, Christophe, Djukic, Jean-Pierre
Format: Article
Language:English
Subjects:
Continuum modeling
Coordination compounds
Density
density functional theory
Dispersions
Energy measurement
Enthalpy
Error correction
isothermal titration calorimetry
local coupled cluster
London dispersion interactions
Mathematical models
Solvation
Thermochemistry
Titration calorimetry
Transition metal compounds
transition metal reactions
Transition metals
Vapor phases
Wave functions
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Summary:Reliable thermochemical measurements and theoretical predictions for reactions involving large transition metal complexes in which long‐range intramolecular London dispersion interactions contribute significantly to their stabilization are still a challenge, particularly for reactions in solution. As an illustrative and chemically important example, two reactions are investigated where a large dipalladium complex is quenched by bulky phosphane ligands (triphenylphosphane and tricyclohexylphosphane). Reaction enthalpies and Gibbs free energies were measured by isotherm titration calorimetry (ITC) and theoretically ‘back‐corrected’ to yield 0 K gas‐phase reaction energies (ΔE). It is shown that the Gibbs free solvation energy calculated with continuum models represents the largest source of error in theoretical thermochemistry protocols. The (‘back‐corrected’) experimental reaction energies were used to benchmark (dispersion‐corrected) density functional and wave function theory methods. Particularly, we investigated whether the atom‐pairwise D3 dispersion correction is also accurate for transition metal chemistry, and how accurately recently developed local coupled‐cluster methods describe the important long‐range electron correlation contributions. Both, modern dispersion‐corrected density functions (e.g., PW6B95‐D3(BJ) or B3LYP‐NL), as well as the now possible DLPNO‐CCSD(T) calculations, are within the ‘experimental’ gas phase reference value. The remaining uncertainties of 2–3 kcal mol−1 can be essentially attributed to the solvation models. Hence, the future for accurate theoretical thermochemistry of large transition metal reactions in solution is very promising. Reliable thermochemistry: This joint experimental and theoretical work focusses on how to make reliable thermochemical predictions for large transition metal complexes stabilized by London dispersion interactions. A comprehensive treatment is presented of dispersion in a real case of coordination chemistry in solution with a thorough focus on the theoretical methodology that is much improved with respect to common practice in the field.
ISSN:2191-1363
2191-1363
DOI:10.1002/open.201402017