Engaging dual donor sites within an N-heterocyclic olefin phosphine ligand

Lui, Melanie W.; Shynkaruk, Olena; Oakley, Meagan S.; Sinelnikov, Regina; McDonald, Robert; Ferguson, Michael J.; Meldrum, A.; Kłobukowski, Mariusz; Rivard, Eric

doi:10.1039/c7dt00398f

Cited by 9 publications

(7 citation statements)

References 56 publications

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“…129b was also employed for the preparation of copper(I) and gold(I) iodide complexes, which were found to display luminescence in the solid state. Attempts to prepare heterobimetallic complexes with this mixed donor ligand were unsuccesful . It should be mentioned that another unusual NHO system with a cationic phosphonium moiety in the backbone and its AuCl complex were reported by Weigand.…”

Section: N-heterocyclic Carbene Adducts Of Group 14 Elementsmentioning

confidence: 99%

“…Attempts to prepare heterobimetallic complexes with this mixed donor ligand were unsuccesful. 208 It should be mentioned that another unusual NHO system with a cationic phosphonium moiety in the backbone and its AuCl complex were reported by Weigand. Upon metal coordination, the expected elongation of the exocyclic CCH 2 bond was confirmed by X-ray diffraction analyses. 209 Harder presented an anionic NHO ligand that was serendipitously synthesized by the reaction of the dimeric amidiniate calcium hydride complex 132 with [(IMe)CH 2 ] (115).…”

Section: Chemical Reviewsmentioning

confidence: 99%

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N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

2019

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N-Heterocyclic carbenes (NHC) are nowadays ubiquitous and indispensable in many research fields, and it is not possible to imagine modern transition metal and main group element chemistry without the plethora of available NHCs with tailor-made electronic and steric properties. While their suitability to act as strong ligands toward transition metals has led to numerous applications of NHC complexes in homogeneous catalysis, their strong σ-donating and adaptable π-accepting abilities have also contributed to an impressive vitalization of main group chemistry with the isolation and characterization of NHC adducts of almost any element. Formally, NHC coordination to Lewis acids affords a transfer of nucleophilicity from the carbene carbon atom to the attached exocyclic moiety, and low-valent and lowcoordinate adducts of the p-block elements with available lone pairs and/or polarized carbon-element π-bonds are able to act themselves as Lewis basic donor ligands toward transition metals. Accordingly, the availability of a large number of novel NHC adducts has not only produced new varieties of already existing ligand classes but has also allowed establishment of numerous complexes with unusual and often unprecedented element−metal bonds. This review aims at summarizing this development comprehensively and covers the usage of N-heterocyclic carbene adducts of the p-block elements as ligands in transition metal chemistry.

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Section: N-heterocyclic Carbene Adducts Of Group 14 Elementsmentioning

confidence: 99%

Section: Chemical Reviewsmentioning

confidence: 99%

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

2019

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“…Following an analogous procedure as reported by Beller, the cationic phosphines [IPrCH 2 –PR 2 ] + (R = i Pr and Ph) were prepared as their chloride salts and then deprotonated to yield the isolable N -heterocyclic olefin-phosphine (NHOP) donors (IPrCH)PR 2 (R = i Pr, Ph) as air-sensitive solids . As summarized in Scheme , these NHOPs can preferentially bind the Lewis acids BH 3 and AuCl through phosphorus rather than the terminal NHO carbon atom; however the remaining carbon donor site can be coaxed to interact with excess AuCl to yield the bis(adduct) IPrCH(AuCl)–PPh 2 (AuCl), featuring (IPrCH)PPh 2 as a four-electron donor ligand . In relation to possible future catalysis based on N -heterocyclic olefin scaffolds, the palladium complex {(IPrCH)P i Pr 2 }PdCl(cinnamyl) was also prepared and displayed preferential P–Pd ligation with the NHOP .…”

Section: Anionic N-heterocyclic Vinylene Ligands and Phosphine- And A...mentioning

confidence: 99%

Pushing Chemical Boundaries with N-Heterocyclic Olefins (NHOs): From Catalysis to Main Group Element Chemistry

2017

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N-Heterocyclic olefins (NHOs) have gone from the topic of a few scattered (but important) reports in the early 1990s to very recently being a ligand/reagent of choice in the far-reaching research fields of organocatalysis, olefin and heterocycle polymerization, and low oxidation state main group element chemistry. NHOs are formally derived by appending an alkylidene (CR) unit onto an N-heterocyclic carbene (NHC), and their pronounced ylidic character leads to high nucleophilicity and soft Lewis basic character at the ligating carbon atom. These olefinic donors can also be structurally derived from imidazole, triazole, and thiazole-based heterocyclic carbenes and, as a result, have highly tunable electronic and steric properties. In this Account, we will focus on various synthetic routes to imidazole-2-ylidene derived NHOs (sometimes referred to as deoxy-Breslow intermediates) followed by a discussion of the electron-donor ability of this structurally tunable ligand group. It should be mentioned that NHOs have a close structural analogy with Breslow-type intermediates, N-heterocyclic ketene aminals, and β-azolium ylides; while these latter species play important roles in advancing synthetic organic chemistry, discussion in this Account will be confined mostly to imidazole-2-ylidene derived NHOs. In addition, we will cover selected examples from the literature where NHOs and their anionic counterparts, N-heterocyclic vinylenes, are used to access reactive main group species not attainable using traditional ligands. Added motivation for these studies comes from the emerging number of low coordinate main group element based compounds that display reactivity once reserved for precious metal complexes (such as H-H and C-H bond activation). Moreover, NHOs are versatile precursors to new mixed element (P/C and N/C), and potentially bidentate, ligand constructs of great potential in catalysis, where various metal oxidation states and coordination environments need to be stabilized during a catalytic cycle. The most active area of recent growth for NHOs is their use as nucleophiles to promote efficient organocatalytic transformations, including transesterification, carbonyl reduction, and the conversion of CO into value added products. Polyesters have also been generated through the NHO-promoted ring-opening polymerization of lactones, and the highly tunable nature of NHO organocatalysts allows for the rapid screening and enhancement of catalytic performance. Therefore, the growing utility of NHOs in the realm of organic and polymer chemistry can be viewed as evidence of the widespread impact of N-heterocyclic olefins on the chemical community. It is hoped that through this Account others will join this flourishing research domain and that the rapid recent growth of NHO chemistry is sustained for the foreseeable future.

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“…This procedure afforded the expected phosphine ( Me IPrCH)PPh 2 ( 5 ) along with insoluble ZnCl 2 as a byproduct (eq ). Compound 5 is analogous to the phosphine-ligand (IPrCH)PPh 2 (IPrCH = [(HCNDipp) 2 CH] − ) reported previously by the Rivard group; notably, (IPrCH)PPh 2 was shown to bind 2 equiv of gold(I) chloride, through coordination to both carbon (IPr C H-) and phosphorus (- P Ph 2 ) centers …”

Section: Results and Discussionmentioning

confidence: 99%

Zinc-Mediated Transmetalation as a Route to Anionic N-Heterocyclic Olefin Complexes in the p-Block

2021

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Anionic N-heterocyclic olefins (aNHOs) are suited well for the stabilization of low-coordinate inorganic complexes, due to their steric tunability and strong σand π-electron donating abilities. In this study, the new two-coordinate zinc complex ( Me IPrCH) 2 Zn ( Me IPrCH = [(MeCNDipp) 2 CCH] − , Dipp = 2,6diisopropylphenyl) is shown to participate in a broad range of metathesis reactions with main group element-based halides and hydrides. In the case of the group 14 halides, Cl 2 E•dioxane (E = Ge and Sn), transmetalation occurs to form dinuclear propellane-shaped cations, [( Me IPrCHE) 2 (μ-Cl)] + , while the aNHO-capped phosphine ligand Me IPrCH-PPh 2 is obtained when ( Me IPrCH) 2 Zn is combined with ClPPh 2 . Lastly, ZnH 2 elimination drives transmetalation between ( Me IPrCH) 2 Zn and hydroboranes and hydroalumanes, leading to Lewis acidic aNHO-supported -boryl and -alane products.

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Engaging dual donor sites within an N-heterocyclic olefin phosphine ligand

Cited by 9 publications

References 56 publications

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry

Pushing Chemical Boundaries with N-Heterocyclic Olefins (NHOs): From Catalysis to Main Group Element Chemistry

Zinc-Mediated Transmetalation as a Route to Anionic N-Heterocyclic Olefin Complexes in the p-Block

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