Experimental and theoretical studies on gold(iii) carbonyl complexes: reductive C,H- and C,C bond formation

Abstract

The reactivity of cationic (C^C)gold(III) carbonyl complexes was investigated. While the in situ-formed IPrAu(bph)CO+ complex (bph = biphenyl-2,2’-diyl) does not undergo a migratory insertion of CO into the neighboring gold-carbon...

Migratory Insertion of CO into a Au–C Bond

“…This observation is of fundamental interest, and may underpin the development of future carbonylation reactions by providing another “Pd-like” mechanistic step for Au­(I)/Au­(III) catalysis. During the course of this work, Hashmi and co-workers reported that an in situ formed CO-bound IPr aurafluoroene complex does not undergo migratory insertion of CO, with intermolecular attack of nucleophiles onto the CO moiety occurring instead . This observation contrasts the results presented here and highlights the significance of our findings.…”

“…For 5 , reductive elimination of biphenylene occurred instead (32% yield), whereas 3 remained intact. We note both the similarity between and inactivity toward reaction with CO of 5 and the complexes employed by Hashmi et al in their study on the reactivity of Au­(III) carbonyl complexes . Pleasingly, the analogous experiment using the MeDalPhos ligated Au­(III) complex, 6 , resulted in the formation of 4 in 57% yield, along with trace quantities (<5%) of 2a .…”

“…18a In this study, we demonstrate the hitherto unknown migratory insertion of CO into a Au−C bond by exploring the aforementioned auracycles (Scheme 1B). This observation is of fundamental interest, and may underpin the development of 19 This observation contrasts the results presented here and highlights the significance of our findings. Despite the challenging nature of the Au(I)/Au(III) couple, 20 several small bite angle (approx.…”

“…9b,e To ascertain the feasibility of related C−C oxidative additions, a 1,2-dichlorobenzene solution of 1 was reacted with biphenylene (2a) at 70 °C under static vacuum (Scheme 2A). 21 This resulted in approximately 20% conversion to a new species where the chemical shift of the ligand 19 F reporter nuclei had shifted downfield (δ F = −114.5 ppm vs −117.8 ppm for 1), as expected for Au(III) complex 3. Mass spectrometry provided further support for the formation of 3 {m/z 541.0786 for [M− NTf 2 ] + (calcd.…”

“…We note both the similarity between and inactivity toward reaction with CO of 5 and the complexes employed by Hashmi et al in their study on the reactivity of Au(III) carbonyl complexes. 19 Pleasingly, the analogous experiment using the MeDalPhos ligated Au(III) complex, 6, resulted in the formation of 4 in 57% yield, 25 along with trace quantities (<5%) of 2a. Only a 9% yield of 4 was obtained using a balloon pressure of CO (1 atm), which indicates the process is relatively challenging.…”