Pyridylidene Amide Ru Complex for Selective Oxidation in Organic Synthesis

Bertini, Simone; Henryon, Dorothée; Edmunds, Andrew; Albrecht, Martin

doi:10.1021/acs.orglett.2c00177

Cited by 10 publications

(12 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ligand design is based on a phenoxy-substituted pyridylidene-amine (PYE). PYEs are an underexplored class of ligands − with unique properties originating from their donor flexibility, represented by either a zwitterionic or a neutral quinoidal limiting resonance structure ( A and B in Figure b). ,, This modularity allows this ligand class to toggle between a π-basic ( A ) and a π-acidic donor site ( B ), with obvious benefits to redox events, as demonstrated by the outstanding performance of such systems in oxidation and reduction catalysis. ,− Here we demonstrate accessibility to an unusual underligated PYE iridium(III) complex and its extraordinary activity and cost efficiency in FA dehydrogenation.…”

mentioning

confidence: 74%

A Low-Coordinate Iridium Complex with a Donor-Flexible O,N-Ligand for Highly Efficient Formic Acid Dehydrogenation

Lentz

Albrecht

2022

ACS Catal.

View full text Add to dashboard Cite

Formic acid is one of the most promising hydrogen carriers. Here, we report on a highly productive iridium-based catalyst for formic acid dehydrogenation, which is based on an underligated iridium(III) center containing a donor-flexible pyridylidene-amine ligand containing a chelating phenolate. This complex reaches temperature-dependent turnover frequencies from 2000 (40 °C) to 280000 h–1 (100 °C) and up to 3 million turnover numbers, thus outperforming state-of-the-art systems. The high efficiency together with the remarkably low cost and easy accessibility of the complex (<$100/g) are attractive features for industrial applications.

show abstract

mentioning

confidence: 74%

A Low-Coordinate Iridium Complex with a Donor-Flexible O,N-Ligand for Highly Efficient Formic Acid Dehydrogenation

Lentz

Albrecht

2022

ACS Catal.

View full text Add to dashboard Cite

show abstract

“…Supporting Information Available: Detailed synthetic procedures and analytical data ( 1 H, 13 C, 19 F, 31 P NMR, elemental analysis and HRMS) of 1-12.…”

Section: Methodsmentioning

confidence: 99%

“…[8,9] More recently, our group extended the PYA library with the implementation of highly versatile and modular pincer-type pyridine bis-PYA ligands that coordinate to both noble and base metals in various oxidation states. Some of these complexes have been used for catalytic redox reactions, for example, transfer hydrogenation, [10] CÀ F bond activation, [8] and the oxidation of water, [7] alcohols, [11] alkenes, [12] sulfides, [13] in some cases with extraordinary performance. [12] Here, we describe a new addition to the PYE family, namely a bis-PYE system with the two PYE units linked through a phenyl-NH-phenyl linker.…”

Section: Introductionmentioning

confidence: 99%

Sterically and Electronically Flexible Pyridylidene Amine Dinitrogen Ligands at Palladium: Hemilabile cis/trans Coordination and Application in Dehydrogenation Catalysis

Lentz

Streit

Knörr

et al. 2022

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

Ligand design is crucial for the development of new catalysts and materials with new properties. Herein, the synthesis and unique hemilabile coordination properties of new bis‐pyridylidene amine (bis‐PYE) ligands to palladium, and preliminary catalytic activity of these complexes in formic acid dehydrogenation are described. The synthetic pathway to form cationic complexes [Pd(bis‐PYE)Cl(L)]X with a cis‐coordinated N,N‐bidentate bis‐PYE ligand is flexible and provides access to a diversity of PdII complexes with different ancillary ligands (L=pyridine, DMAP, PPh3, Cl, P(OMe)3). The 1H NMR chemical shift of the trans‐positioned PYE N−CH3 unit is identified as a convenient and diagnostic handle to probe the donor properties of these ancillary ligands and demonstrates the electronic flexibility of the PYE ligand sites. In the presence of a base, the originally cis‐coordinated bis‐PYE ligand adopts a N,N,N‐tridentate coordination mode with the two PYE units in mutual trans position. This cis–trans isomerization is reverted in presence of an acid, demonstrating a unique structural and steric flexibility of the bis‐PYE ligand at palladium in addition to its electronic adaptability. The palladium complexes are active in formic acid dehydrogenation to H2 and CO2. The catalytic performance is directly dependent on the ligand bonding mode, the nature of the ancillary ligand, the counteranion, and additives. The most active system features a bidentate bis‐PYE ligand, PPh3 as ancillary ligand and accomplishes turnover frequencies up to 525 h−1 in the first hour and turnover numbers of nearly 1000, which is the highest activity reported for palladium‐based catalysts to date.

show abstract

“…Complex 22 is also an active oxidation catalyst to a broader range of substrates, including thioethers to sulfones, alkynes to carboxylic acids, and alkenes to carboxylic acids and aldehydes (Figure A) . In substrates containing both thioether and alkene functional groups, the sulfone is selectively and completely formed before the alkene is oxidized to an aldehydethe controlling factor is the reaction time.…”

Section: Oxidation and Reduction Catalysismentioning

confidence: 99%

“…In substrates containing both thioether and alkene functional groups, the sulfone is selectively and completely formed before the alkene is oxidized to an aldehydethe controlling factor is the reaction time. The substrate tolerance of this oxidation process is remarkably high, as shown by full conversion of a range of multisubstituted substrates containing esters, ethers, heterocycles, amines, nitriles, and halogenated groups. , Notably, biomass-derived methyl oleate is also oxidized to nonanal through oxidative CC cleavage, albeit only to 85% conversion at 65 °C.…”

Section: Oxidation and Reduction Catalysismentioning

confidence: 99%

Pyridylidene Amines and Amides: Donor-Flexible Ligands for Catalysis

Race

Albrecht

2023

ACS Catal.

Self Cite

View full text Add to dashboard Cite

Ligands with flexible donor properties exhibit the unique ability to transition within the continuum of neutral (L-type) and anionic (X-type) metal bonding in response to their local electronic environment. This flexibility stabilizes transition-metal complexes in unparalleled ways and facilitates catalytic turnovers, especially when the catalytic cycle features the active metal center in different oxidation states. Pyridylidene amines (PYEs) and pyridylidene amides (PYAs) are examples of nitrogenbased donor-flexible ligands. In the past decade, the application of PYE and PYA ligands in transition-metal catalysis has been growing, to now include reactions such as hydrogen transfer reactions, water oxidation, and CO 2 utilization, among many others. Here we provide an overview of these powerful ligands, including their synthesis, their donor properties, and in particular their catalytic application�highlighting the key ligand features that impart high activity, as well as the wide potential of this rather underexplored ligand system for diverse catalytic applications.

show abstract

Pyridylidene Amide Ru Complex for Selective Oxidation in Organic Synthesis

Cited by 10 publications

References 37 publications

A Low-Coordinate Iridium Complex with a Donor-Flexible O,N-Ligand for Highly Efficient Formic Acid Dehydrogenation

A Low-Coordinate Iridium Complex with a Donor-Flexible O,N-Ligand for Highly Efficient Formic Acid Dehydrogenation

Sterically and Electronically Flexible Pyridylidene Amine Dinitrogen Ligands at Palladium: Hemilabile cis/trans Coordination and Application in Dehydrogenation Catalysis

Pyridylidene Amines and Amides: Donor-Flexible Ligands for Catalysis

Contact Info

Product

Resources

About