Radical-initiated alkene hydroauration as a route to gold(<scp>iii</scp>) alkyls: an experimental and computational study

Pintus, Anna; Bochmann, Manfred

doi:10.1039/c7ra13481a

Cited by 11 publications

(15 citation statements)

References 25 publications

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“…The calculations also showed the increase in radical stability in the order R1 < R2 ≪ R3 (Scheme 82), which explains the facile insertion of allenes. 386 Whereas the previously described bimolecular reaction pathway via Au(II) radicals led to 1,2-insertion products, the hydroauration of arylisocyanides is a 1,1-insertion process. Fernandez-Cestau et al reported the first example of such an insertion, to give the gold(III) iminoformyl complex (C^N^C)-Au−CHNAr (223).…”

Section: Insertions Into Gold−carbon Bondsmentioning

confidence: 99%

“…Calculations showed that this behavior was a function of the exergonic or endergonic character of alkyl radical formation, driven by spin delocalization over the unsaturated substituents. The calculations also showed the increase in radical stability in the order R1 < R2 ≪ R3 (Scheme ), which explains the facile insertion of allenes …”

Section: Catalysis-relevant Reaction Stepsmentioning

confidence: 99%

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Recent Advances in Gold(III) Chemistry: Structure, Bonding, Reactivity, and Role in Homogeneous Catalysis

2020

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Over the last decade the organometallic chemistry of gold(III) has seen remarkable advances. This includes the synthesis of the first examples of several compound classes that have long been hypothesized as being part of catalytic cycles, such as gold(III) alkene, alkyne, CO and hydride complexes, and important catalysis-relevant reaction steps have at last been demonstrated for gold, such as migratory insertion and β-H elimination reactions. Also, reaction pathways that were already known, such as the generation of gold(III) intermediates by oxidative addition and their reductive elimination, are much better understood. A deeper understanding of fundamental organometallic reactivity of gold(III) has also revealed unexpected mechanistic avenues, which can open when the barriers for reactions that for other metals would be regarded as "standard" are too high. This review summarizes and evaluates these developments, together with applications of gold(III) in synthesis and catalysis, with emphasis on the mechanistic insight gained in these investigations.

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Section: Insertions Into Gold−carbon Bondsmentioning

confidence: 99%

Section: Catalysis-relevant Reaction Stepsmentioning

confidence: 99%

Recent Advances in Gold(III) Chemistry: Structure, Bonding, Reactivity, and Role in Homogeneous Catalysis

2020

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“…Additionally, these in situ generated gold(II) radicals react with 1-alkenes leading to gold(III) alkyl complexes. 87 The T-shaped Au(III)-H complex 26 presents a covalent Au−H bond, which does not react with excess of various acids, but addition of NaH produced the regeneration of the starting material and formation of H 2 (g) after 3 days at room temperature (Scheme 24). This result corroborates the protic and not hydridic character of the complex.…”

Section: Gold Hydride Complexesmentioning

confidence: 99%

Main Avenues in Gold Coordination Chemistry

2021

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In this contribution, we provide an overview of the main avenues that have emerged in gold coordination chemistry during the last years. The unique properties of gold have motivated research in gold chemistry, and especially regarding the properties and applications of gold compounds in catalysis, medicine, and materials chemistry. The advances in the synthesis and knowledge of gold coordination compounds have been possible with the design of novel ligands becoming relevant motifs that have allowed the preparation of elusive complexes in this area of research. Strong donor ligands with easily modulable electronic and steric properties, such as stable singlet carbenes or cyclometalated ligands, have been decisive in the stabilization of gold(0) species, gold fluoride complexes, gold hydrides, unprecedented π complexes, or cluster derivatives. These new ligands have been important not only from the fundamental structure and bonding studies but also for the synthesis of sophisticated catalysts to improve activity and selectivity of organic transformations. Moreover, they have enabled the facile oxidative addition from gold(I) to gold(III) and the design of a plethora of complexes with specific properties.

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“…The reactivity of gold(III) hydrides reflects this; whereas B can be deprotonated only by very strong bases, 7 complexes of type A undergo homolytic Au–H bond cleavage and insertion reactions with alkenes and alkynes via bimolecular pathways involving (C^N^C)Au II radical intermediates. 6 , 10 …”

Section: Introductionmentioning

confidence: 99%

Unlocking Structural Diversity in Gold(III) Hydrides: Unexpected Interplay of cis/trans-Influence on Stability, Insertion Chemistry, and NMR Chemical Shifts

et al. 2018

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The synthesis of new families of stable or at least spectroscopically observable gold(III) hydride complexes is reported, including anionic cis-hydrido chloride, hydrido aryl, and cis-dihydride complexes. Reactions between (C^C)AuCl(PR3) and LiHBEt3 afford the first examples of gold(III) phosphino hydrides (C^C)AuH(PR3) (R = Me, Ph, p-tolyl; C^C = 4,4′-di-tert-butylbiphenyl-2,2′-diyl). The X-ray structure of (C^C)AuH(PMe3) was determined. LiHBEt3 reacts with (C^C)AuCl(py) to give [(C^C)Au(H)Cl]−, whereas (C^C)AuH(PR3) undergoes phosphine displacement, generating the dihydride [(C^C)AuH2]−. Monohydrido complexes hydroaurate dimethylacetylene dicarboxylate to give Z-vinyls. (C^N^C)Au pincer complexes give the first examples of gold(III) bridging hydrides. Stability, reactivity and bonding characteristics of Au(III)–H complexes crucially depend on the interplay between cis and trans-influence. Remarkably, these new gold(III) hydrides extend the range of observed NMR hydride shifts from δ −8.5 to +7 ppm. Relativistic DFT calculations show that the origin of this wide chemical shift variability as a function of the ligands depends on the different ordering and energy gap between “shielding” Au(dπ)-based orbitals and “deshielding” σ(Au–H)-type MOs, which are mixed to some extent upon inclusion of spin–orbit (SO) coupling. The resulting 1H hydride shifts correlate linearly with the DFT optimized Au–H distances and Au–H bond covalency. The effect of cis ligands follows a nearly inverse ordering to that of trans ligands. This study appears to be the first systematic delineation of cis ligand influence on M–H NMR shifts and provides the experimental evidence for the dramatic change of the 1H hydride shifts, including the sign change, upon mutual cis and trans ligand alternation.

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Radical-initiated alkene hydroauration as a route to gold(iii) alkyls: an experimental and computational study

Abstract: Gold(iii) hydrides undergo radical-induced insertion reactions with alkenes via gold(ii) intermediates. The success of the reaction depends on the degree of spin delocalisation.

Cited by 11 publications

References 25 publications

Recent Advances in Gold(III) Chemistry: Structure, Bonding, Reactivity, and Role in Homogeneous Catalysis

Recent Advances in Gold(III) Chemistry: Structure, Bonding, Reactivity, and Role in Homogeneous Catalysis

Main Avenues in Gold Coordination Chemistry

Unlocking Structural Diversity in Gold(III) Hydrides: Unexpected Interplay of cis/trans-Influence on Stability, Insertion Chemistry, and NMR Chemical Shifts

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