Ninth paper from a Short-Term Scientific Mission (STSM) (July 25, 2016)

This publication is the result of a collaboration project between two research groups involved in the ECOSTBio action, headed by Paola Belanzoni (University of Perugia, Italy) and Jeremy N. Harvey (University of Leuven, Belgium). This collaboration started thanks to a Short Term Scientific Mission, in which the PhD student Carlo Alberto Gaggioli (University of Perugia, Italy) spent 3 months in Leuven. This work has focused on a computational study, which relies on experimental data published in the literature.

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.

This work has been published in Chemical Science as an Edge Article. Part of this work has been recently awarded through a poster prize for the PhD student Carlo Alberto Gaggioli during the last Summer School in Spin States, held in Groningen (The Netherlands) in July 2016.
160725 160725

STSM reference: COST-STSM-CM1305-24515
STSM Participant: Carlo Alberto Gaggioli

C.A. Gaggioli, L. Belpassi, F. Tarantelli, D. Zuccaccia, J. Harvey, and P. Belanzoni
"Dioxygen insertion into the gold(I)-hydride bond: spin orbit coupling effects in the spotlight for oxidative addition"
Chem. Sci. 2016, [], ASAP- [abstract] #OpenAccess
DOI: 10.1039/C6SC02161A
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