EurJIC

Abstract

In an effort to determine the thermochemistry of established organometallic transformation, the well documented reaction of alkynes with a palladacycle was investigated by isothermal titration calorimetry (ITC). Although the mechanism of the insertion of unsaturated substrates into the Pd-C bond of cyclopalladated compounds is known, so far no information is known about their thermochemistry. The enthalpies of the reactions of Ph-C≡C-Ph and MeOC(O)-C≡C(O)COMe with the bisacetonitrilo salt of the N,N -benzylamine palladacycle were determined by ITC in chlorobenzene after having optimized the conditions to ensure that only the double and a single insertion of alkynes were occuring respectively. The reaction energy profile established by DFT for the double insertion process involving Ph-C≡C-Ph confirmed earlier conclusions on the rate determining character of the first insertion. Further computations of reaction enthalpies reveal significant discrepancies between ITC and DFT-D/continuum solvation enthalpies, that are suspected to arise from an unexpected explicit noncovalent interaction of PhCl with the components of the reaction.
 

Reference

Milan R. Milovanović; Mélanie Boucher; Yann Cornaton; Snežana D. Zarić; Michel Pfeffer; Jean-Pierre Djukic

The Thermochemistry of Alkyne Insertion into a Palladacycle outlines the Solvation Conundrum in DFT

EurJIC,  (Publication Date:November 3, 2021). DOI: https://doi.org/10.1002/ejic.202100750
 

Contact

Jean-Pierre Djukic, équipe LCSOM (http://lcsom.u-strasbg.fr), Institut de Chimie (UMR 7177).