Formation of Gold(III) Alkyls from Gold Alkoxide Complexes

Chambrier, Isabelle; Roşca, Dragoş‐Adrian; Fernández‐Cestau, Julio; Hughes, David L.; Budzelaar, Peter H. M.; Bochmann, Manfred

doi:10.1021/acs.organomet.7b00077

Cited by 16 publications

(18 citation statements)

References 46 publications

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“…CD 2 Cl 2 was stored in the glovebox over activated 4 Å molecular sieves. (C^N py^C )AuCl (1a), 25 (C^N pz^C )AuCl (1b), 14b (C^N^C)AuMe (7), 26 (C^N^C)Au(p-C 6 H 4 F) (8), 26 (C^N^C)AuOC 6 H 5 (10), 24 and AdSH (0.018 g, 0.105 mmol), which were then dissolved in 5 mL of dry dichloromethane (5 mL).…”

Section: Methodsmentioning

confidence: 99%

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Carbon–sulfur bond formation by reductive elimination of gold(iii) thiolates

et al. 2018

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Whereas the reaction of the gold(iii) pincer complex (C^N^C)AuCl with 1-adamantyl thiol (AdSH) in the presence of base affords (C^N^C)AuSAd, the same reaction in the absence of base leads to formation of aryl thioethers as the products of reductive elimination of the Au-C and Au-S ligands (C^N^C = dianion of 2-6-diphenylpyridine or 2-6-diphenylpyrazine). Although high chemical stability is usually taken as a characteristic of pincer complexes, results show that thiols are capable of cleaving one of the pincer Au-C bonds. This reaction is not simply a function of S-H acidity, since no cleavage takes place with other more acidic X-H compounds, such as carbazole, amides, phenols and malonates. The reductive C-S elimination follows a second-order rate law, -d[1a]/dt = k[1a][AdSH]. Reductive elimination is enabled by displacement of the N-donor by thiol; this provides the conformational flexibility necessary for C-S bond formation to occur. Alternatively, reductive C-S bond formation can be induced by reaction of pre-formed thiolates (C^N^C)AuSR with a strong Brønsted acid, followed by addition of SMe2 as base. On the other hand, treatment of (C^N^C)AuR (R = Me, aryl, alkynyl) with thiols under similar conditions leads to selective C-C rather than C-S bond formation. The reaction of (C^N^C)AuSAd with H+ in the absence of a donor ligand affords the thiolato-bridged complex [{(C^N-CH)Au(μ-SAd)}2]2+ which was crystallographically characterised.

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Section: Methodsmentioning

confidence: 99%

“…For example, addition of HAB 2 to the phenolate 13 24 gave the ether complex 14, without Au-C cleavage.…”

Section: Scheme 3 Reductive C-s Elimination Pathway Induced By Thiolsmentioning

confidence: 99%

Carbon–sulfur bond formation by reductive elimination of gold(iii) thiolates

et al. 2018

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“…sponding Au(III) methoxide complex, (C^N^C)AuÀ OMe, which also readily performs OAT. [5] A notable feature of these computations is that a relatively large activation barrier for this process was computed. [5] In contrast to the known Au(III)À OH case, OAT has been reported unsuccessful for IPr-Au(I)À OH, suggesting that Au(III)À OH may be more suited for the reaction.…”

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confidence: 99%

“…[5] A notable feature of these computations is that a relatively large activation barrier for this process was computed. [5] In contrast to the known Au(III)À OH case, OAT has been reported unsuccessful for IPr-Au(I)À OH, suggesting that Au(III)À OH may be more suited for the reaction. [6] This is noteworthy as in the reaction no change in formal oxidation state takes place and both the Au(I) [7] and Au(III) [8] hydride complexes are known.…”

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Synthesis of a Sterically Encumbered Pincer Au(III)−OH Complex

et al. 2021

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We report the synthesis and crystallographic characterization of a novel Au(III)À OH complex featuring a N^N^N-pincer ligand. Reactivity studies towards oxygen atom transfer (OAT), a type of reactivity previously reported for a Au(III)À OH complex, indicate that this complex provides both a sterically encumbered Au atom and a sterically poorly accessible OH group leading to no reactivity with a series of phosphines. The steric encumbrance sets this example apart from the known examples of Au(III)À OH (pincer) complexes, which commonly feature planar ligands that provide little control over steric accessibility of the Au and O atoms in these complexes. Implications for the mechanism of OAT from AuÀ OH complexes are briefly discussed.Only few examples of structurally defined Au(III) hydroxide complexes have been reported featuring pincer-type ligands, [1] and for most, little is known regarding their reactivity (Figure 1). [2] A notable feature of all reported complexes thus far is that the ligands are planar and therefore provide comparable steric environments. AuÀ OH complexes in general, both Au(I) and Au(III), can be used as synthons to introduce for example anionic ligands, such as a hydride, aryls, and N-heterocycles by ligand exchange. [2c,3] Among the Au(III)À OH complexes an exceptionally wellstudied example is the (C^N^C)AuÀ OH complex from the Bochmann group, which not only serves as a synthon, but also undergoes oxygen atom transfer (OAT) with various phosphines to form the corresponding phosphine oxides and Au(III)À H (Figure 2). [4] Based on a series of experiments, the Bochmann group proposed a concerted mechanism for OAT in which there is planar attack of the phosphine directly onto the oxygen leading to both P=O bond formation and proton reduction giving a AuÀ H (Figure 2). The possibility of an initial AuÀ P interaction was judged unlikely based on DFT calculations [4] and further corroborated by a computational study on the corre-[a

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“…1 H NMR spectra (300.13 MHz) were referenced to the residual protons of the deuterated solvent used. 13 C{ 1 H} NMR spectra (75.47 MHz) were referenced to the D-coupled13 C resonances of the NMR solvent.…”

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confidence: 99%