Correlation of Experimental and Calculated Reaction Enthalpies with Ligand Donor Strengths

Calorimetric studies on the formation of [(YPhos)AuCl] complexes confirmed the high binding strength of these ligands. The reaction enthalpies are shown to be easily obtained by calculations and correlate with the phosphine donor properties thus representing an interesting problem-specific descriptor for ligands in gold catalysis.

Abstract

Ylide-functionalized phosphines (YPhos) have recently proven to be strongly donating ligands that enable high catalyst activities in gold(I)-mediated transformations. We now report on a calorimetric study dealing with the [Au(YPhos)Cl] system and assess YPhos-Au bond dissociation enthalpies (BDE). Comparison with other commonly used phosphines confirmed the high binding strengths of the YPhos ligands. Furthermore, the values of the reaction enthalpies were shown to correlate with the electronic properties of the ligands measured via the Tolman electronic parameter or the calculated molecular electrostatic potential at phosphorus. Notably, the reaction enthalpies can conveniently be derived by computational methods, thus making these easy-to-obtain descriptors for ligand donor property quantification.

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