Coinage metal amido and thiolate SNS complexes: consequences of catalyst speciation in Cu(<scp>i</scp>)-catalysed carbonyl hydroboration

Ataie, Saeed; Lohoar, Maxwell; Mangin, Loïc; Baker, R. Tom

doi:10.1039/d2cc06077a

Cited by 8 publications

(9 citation statements)

References 41 publications

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“…As mentioned above, the thiolate SNS ligand has demonstrated ligand-assistance in several catalyzed reactions. 19–22 Although other base-free azide–alkyne cycloadditions in water have been reported, 33 we speculated that the thiolate donor may play a proton-shuttle role in converting the π-coordinated alkyne to the Cu alkynyl intermediate. To assess this possibility, we used DFT calculations 34 to probe potential low-energy intermediates.…”

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confidence: 93%

“…We have recently been comparing ‘soft’ thiolate- ( L 1 ) and ‘hard’ amido- ( L 2 ) SNS ligands (Schemes 2 and 3) in ligand-assisted catalysis. 17,18 Working with base metals from Mn to Zn we demonstrated several different bifunctional mechanisms for catalysed hydroboration 19–23 and hydrosilylation 24 of carbonyls, nitriles 25,26 and N-heterocycles. 27 In expanding the catalytic applications of these coordination complexes, we sought to use these ligands to stabilize Cu( i ) and evaluate their activity in CuAAC.…”

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confidence: 99%

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Tetracopper(i) thiolate- and amido-(SNS) complexes and copper-catalyzed azide–alkyne cycloaddition in water

Khanzadeh,

Ataie,

Baker

2023

Dalton Trans.

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confidence: 93%

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confidence: 99%

Tetracopper(i) thiolate- and amido-(SNS) complexes and copper-catalyzed azide–alkyne cycloaddition in water

Khanzadeh,

Ataie,

Baker

2023

Dalton Trans.

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“…Alcohol oxidation is widely carried out traditionally with small organic-based reagents, such as Dess–Martin periodinane and Swern oxidation or metal-based systems, such as pyridinium chlorochromate, pyridinium dichromate, and ruthenium tetroxide. 2–5 However, most of these have various limitations including moisture-sensitive, expensive, and not reusable. Therefore, new oxidation approaches are expected to be carried out selectively with green, cheap, and non-toxic oxidants, such as dioxygen or air in the presence of reusable catalysts.…”

Section: Introductionmentioning

confidence: 99%

A sustainable protocol for selective alcohols oxidation using a novel iron-based metal organic framework (MOF-BASU1)

Yaghubzadeh,

Alavinia,

Ghorbani-Vaghei

2023

RSC Adv.

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“…37 In contrast, no evidence for hydroboration of the imine donor in L2 was observed in the analogous reaction with 18. 38 The examples above highlight the susceptibility of these ligands to dissociate upon bifunctional activation; however, both the copper and zinc complexes feature the [SNS] ligands coordinated in a bidentate fashion to the metal center. Instead, an original design feature of these ligands included a thioether donor in a 6-membered ring which was envisioned to stabilize the metal center and be hemilabile under catalytic conditions.…”

Section: Carbonyl Hydroboration Catalysis and Divergent Mechanismsmentioning

confidence: 99%

Through the Looking Glass: Using the Lens of [SNS]-Pincer Ligands to Examine First-Row Metal Bifunctional Catalysts

Elsby

Baker

2023

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Homogeneous catalysis is at the forefront of global efforts to innovate the synthesis of fine chemicals and achieve carbon-neutrality in energy applications. For decades, the push toward sustainable catalysis has focused on the development of first-row transition metal catalysts to supplant widespread use of precious metals. Metal−ligand cooperativity is an effective strategy to yield high-performing first-row metal molecular catalysts. Despite remarkable progress, state of the art catalysts often employ phosphorus-based ligands which are air-sensitive, potentially toxic, and on occasion offset the cost-savings of the metal. Thus, the development of simple and economical ligands composed of biomimetic donors should be a key focus that cannot be overlooked in the pursuit of sustainable catalyst candidates. This is an Account of our group's efforts to develop first-row transition metal complexes which use [SNS]-pincer ligands for bifunctional catalysis. We have synthesized two potentially tridentate ligands, one bearing an amido and two thioether donors [(S Me NS Me ), L1] and one which includes thiolate, imine, and thioether donors [(SNS Me ), L2], and used them as platforms upon which to explore the reaction pathways of first-row metals. The [SNS] ligand, L1, leads to formation of high-spin paramagnetic metal complexes of the type M(L1) 2 in which the 6-membered ring thioether donor is hemilabile (M = Mn, Fe, Co). This allows Mn(L1) 2 to function as a carbonyl hydroboration catalyst that operates by a novel hydride-free, inner-sphere reaction pathway. Exploring the reactivity of L2 with Fe and Ni revealed unique coordination chemistry and a variety of mono-, di-, tri-, and tetranuclear complexes enabled by bridging thiolates. Further studies showed L2 undergoes selective C aryl −S bond cleavage upon coordination to a metal with electronrich phosphine donors, yielding a new (CNS) 2− pincer ligand. The analogous reaction with L1 afforded a new (CNS Me ) − pincer ligand via both C aryl −S and benzylic C−H bond cleavage. In an attempt to prepare Fe(L2) 2 , we obtained instead an Fe(N 2 S 3 ) complex in which imine C−C bond formation affords a potentially hexadentate redox-active ligand. The Fe(N 2 S 3 ) complex is a selective catalyst for hydroboration of aldehydes and appears to operate through a complicated mechanism. In contrast, a mechanistic study of Mn(L2)(CO) 3 -photocatalyzed dihydroboration of nitriles indicated that both the flexibility of the κ 3 -SNS Me ligand (fac-vs mer-coordination) and ability of Mn to undergo a spin-state change are required to access low energy barriers for this transformation. To effectively compare the reactivity of the thiolate vs amido donor, we prepared two Cu complexes, Cu(L1)(IPr) and Cu(L2)(IPr) [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene],showing that, while both served as carbonyl hydroboration catalysts, only the amido complex was an effective catalyst for carbonyl hydrosilylation. In addition, complexes of the...

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Coinage metal amido and thiolate SNS complexes: consequences of catalyst speciation in Cu(i)-catalysed carbonyl hydroboration

Abstract: Three new IPr-Ag- and -Au-SNS amido and thiolate complexes were synthesized and compared to their previously reported Cu analogues as carbonyl hydroboration catalysts (IPr = bis(2,6-diisopropylphenyl)imidazol-2-ylidene).

Cited by 8 publications

References 41 publications

Tetracopper(i) thiolate- and amido-(SNS) complexes and copper-catalyzed azide–alkyne cycloaddition in water

Tetracopper(i) thiolate- and amido-(SNS) complexes and copper-catalyzed azide–alkyne cycloaddition in water

A sustainable protocol for selective alcohols oxidation using a novel iron-based metal organic framework (MOF-BASU1)

Through the Looking Glass: Using the Lens of [SNS]-Pincer Ligands to Examine First-Row Metal Bifunctional Catalysts

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