O2 insertion into a Au(i)-H bond occurs through an oxidative addition/recombination mechanism, showing peculiar differences with respect to Pd(ii)-H, for which O2 insertion takes place through a hydrogen abstraction mechanism in the triplet potential energy surface with a pure spin transition state. We demonstrate that the spin-forbidden Au(i)-hydride O2 insertion reaction can only be described accurately by inclusion of spin orbit coupling (SOC) effects. We further find that a new mechanism involving two O2 molecules is also feasible, and this result, together with the unexpectedly high experimental entropic activation parameter, suggests the possibility that a third species could be involved in the rate determining step of the reaction. Finally, we show that the O2 oxidative addition into a Au(i)-alkyl (CH3) bond also occurs but the following recombination process using O2 is unfeasible and the metastable intermediate Au(iii) species will revert to reactants, thus accounting for the experimental inertness of Au-alkyl complexes toward oxygen, as frequently observed in catalytic applications. We believe that this study can pave the way for further theoretical and experimental investigations in the field of Au(i)/Au(iii) oxidation reactions, including ligand, additive and solvent effects. © The Royal Society of Chemistry.

Dioxygen insertion into the gold(I)-hydride bond: spin orbit coupling effects in the spotlight for oxidative addition

ZUCCACCIA, Daniele;
2016-01-01

Abstract

O2 insertion into a Au(i)-H bond occurs through an oxidative addition/recombination mechanism, showing peculiar differences with respect to Pd(ii)-H, for which O2 insertion takes place through a hydrogen abstraction mechanism in the triplet potential energy surface with a pure spin transition state. We demonstrate that the spin-forbidden Au(i)-hydride O2 insertion reaction can only be described accurately by inclusion of spin orbit coupling (SOC) effects. We further find that a new mechanism involving two O2 molecules is also feasible, and this result, together with the unexpectedly high experimental entropic activation parameter, suggests the possibility that a third species could be involved in the rate determining step of the reaction. Finally, we show that the O2 oxidative addition into a Au(i)-alkyl (CH3) bond also occurs but the following recombination process using O2 is unfeasible and the metastable intermediate Au(iii) species will revert to reactants, thus accounting for the experimental inertness of Au-alkyl complexes toward oxygen, as frequently observed in catalytic applications. We believe that this study can pave the way for further theoretical and experimental investigations in the field of Au(i)/Au(iii) oxidation reactions, including ligand, additive and solvent effects. © The Royal Society of Chemistry.
File in questo prodotto:
File Dimensione Formato  
63_2016_ChemSCi_Au_gaggioli_O2.pdf

accesso aperto

Tipologia: Versione Editoriale (PDF)
Licenza: Creative commons
Dimensione 493.52 kB
Formato Adobe PDF
493.52 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11390/1100962
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 31
  • ???jsp.display-item.citation.isi??? 31
social impact