The first isolated examples of intermolecular oxidative addition of alkenyl and alkynyl iodides to AuI are reported. Using a 5,5′‐difluoro‐2,2′‐bipyridyl ligated complex, oxidative addition of geometrically defined alkenyl iodides occurs readily, reversibly and stereospecifically to give alkenyl‐AuIII complexes. Conversely, reversible alkynyl iodide oxidative addition generates bimetallic complexes containing both AuIII and AuI centers. Stoichiometric studies show that both new initiation modes can form the basis for the development of C−C bond forming cross‐couplings.

Acombined theoretical and experimental approach has been used to study the unusual mechanism of oxidative addition of aryl iodides to [bipyAu(C 2 H 4 )] + complexes.T he modular nature of this system allowed asystematic assessment of the effects of complex structure.C omputational comparisons between cationic gold and the isolobal (neutral) Pd 0 and Pt 0 complexes revealed similar mechanistic features,b ut with oxidative addition being significantly favored for the group 10 metals.F urther differences between Au and Pd were seen in experimental studies:s tudying reaction rates as af unction of electronic and steric properties showed that ligands bearing more electron-poor functionality increase the rate of oxidative addition;i nacomplementary way, electron-rich aryl iodides give faster rates.T his divergence in mechanism compared to Pd suggests that Ar À Xo xidative addition with Au can underpin ab road range of new or complementary transformations.Scheme 1. Oxidative addition at transition metal centers.

We describe a AuI complex of a hemi‐labile (C^N) N‐heterocyclic carbene ligand that is able to mediate oxidative addition of aryl iodides. Detailed computational and experimental investigations have been undertaken to verify and rationalize the oxidative addition process. Application of this initiation mode has resulted in the first examples of “exogenous oxidant‐free” AuI/AuIII catalyzed 1,2‐oxyarylations of ethylene and propylene. These demanding yet powerful processes establish these commodity chemicals as nucleophilic‐electrophilic building blocks in catalytic reaction design.

A MeDalPhos-ligated gold(III) metallafluorene complex, generated via C–C oxidative addition of biphenylene, reacts with CO to produce 9-fluorenone. Experimental and computational studies show that this proceeds via a hitherto unknown migratory insertion of CO into a Au(III)–C bond. This process is more energetically challenging compared to other M–C bonds, but once achieved, the product is comparatively stable with respect to retro-carbonylation. Exploiting migratory insertion of CO into Au–C bonds may extend the range of products that are accessible using gold chemistry.

The passage of stock solutions through stainless-steel needles during sample preparation or introduction into the apparatus led to rapid oxidative decay rates due to metal leaching. What practical measures should be taken in this and related systems and what would be the best alternative to stainless-steel needles?Guy Lloyd-Jones answered: For this system, use of glass or polymer seems to work ne. For other systems, this is a difficult question to answer. It will always be a balance of practicality over 'purity'. Just like using glass reaction vessels (which are not always as inert as we would expect), stainless steel needles and cannulae are very convenient, and do not oen interfere with reactions. A few controls should hopefully elucidate if there is any interference, and if so, then other nominally inert materials (e.g. PTFE, ceramic, titanium, etc.) can be used, if required.Jennifer Love continued the discussion of the paper: It's great that you have gured this out. We've seen in other systems that decomposition is a lot more complex than one would think and our problem was that we couldn't isolate and measure our product. Were you able to measure and fully characterise the product 282

responded: Experimentally, the competition reactions were performed in a 4 : 1 mixture of dichloromethane:methanol. In methanol, the reactions both proceed more rapidly and also go more to full completion, while dichloromethane was introduced to ensure the solubility of all products. We therefore ran calculations incorporating a correction for pure methanol and a second set (in the supporting information) with pure dichloromethane. Importantly, the trends are identical with these two approaches, but with higher computed barriers in dichloromethane (consistent with the slower reactions observed experimentally). The increased barriers are due to the more difficult Cl À dissociation step (D to E in the paper). We feel justied in emphasizing the results in methanol as other experimental work has shown similar C-H activation reactions to be promoted upon the addition of just a few equivalents of methanol. This may be due to specic solvation of the Cl À anion as it dissociates. The computed barriers in methanol are also more consistent with most of the reactions proceeding at a reasonable rate at room temperature experimentally. We also found the balance between intramolecular AMLA/CMD and an external CMD process was solvent dependent: in methanol the former is clearly favoured, whereas in dichloromethane external CMD can become competitive, especially for the more electron-withdrawing substituents.

The first isolated examples of intermolecular oxidative addition of alkenyl and alkynyl iodides to AuI are reported. Using a 5,5′‐difluoro‐2,2′‐bipyridyl ligated complex, oxidative addition of geometrically defined alkenyl iodides occurs readily, reversibly and stereospecifically to give alkenyl‐AuIII complexes. Conversely, reversible alkynyl iodide oxidative addition generates bimetallic complexes containing both AuIII and AuI centers. Stoichiometric studies show that both new initiation modes can form the basis for the development of C−C bond forming cross‐couplings.

We describe a Au I complex of a hemi-labile (C^N) N-heterocyclic carbene ligand that is able to mediate oxidative addition of aryl iodides. Detailed computational and experimental investigations have been undertaken to verify and rationalize the oxidative addition process. Application of this initiation mode has resulted in the first examples of "exogenous oxidantfree" Au I /Au III catalyzed 1,2-oxyarylations of ethylene and propylene. These demanding yet powerful processes establish these commodity chemicals as nucleophilicelectrophilic building blocks in catalytic reaction design.