Redoxaktive Liganden in der Katalyse

Praneeth, V. K. K.; Ringenberg, Mark R.; Ward, Thomas R.

doi:10.1002/ange.201204100

Cited by 83 publications

(8 citation statements)

References 82 publications

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“…In the pioneering studies of such MET-sensitizers [7], the combination of redox-active main group elements acting as earth-abundant non-precious metal catalytic sites [22] combined with radicalstabilizing non-innocent organic ligands [23,24] has been successfully introduced as a new concept for modelling multielectron transfer photoreactions. The accumulation of permanent energy-rich photoproducts following this strategy has also been demonstrated [2].…”

Section: Multielectron Catalysis and Energy Storage In Chemical Bondsmentioning

confidence: 99%

Recent progress in homogeneous multielectron transfer photocatalysis and artificial photosynthetic solar energy conversion

Knör

2015

Coordination Chemistry Reviews

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Section: Multielectron Catalysis and Energy Storage In Chemical Bondsmentioning

confidence: 99%

Recent progress in homogeneous multielectron transfer photocatalysis and artificial photosynthetic solar energy conversion

Knör

2015

Coordination Chemistry Reviews

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“…Pincer ligands are commonly used as ancillary ligands in organometallic chemistry, [18] but they can also act as electron reservoirs by delocalizing excessive (or deficient) electron density. [2] Incorporation of an amido functionality into a pincer motif can be employed to stabilize complexes with aminyl radical ligands. As such, Mindiola, Szilagyi, and coworkers reported the synthesis of [(PNP)NiCl]OTf complex 12 a, which was obtained in 87 % yield by oxidation of the neutral precursor 11 a with FcOTf (Scheme 6).…”

Section: Aminyl Radical Complexesmentioning

confidence: 99%

“…Capture of the generated alkyl radical R 2 C through a rebound mechanism was demonstrated to lead to amino complex 31. However, 26 has a similar affinity for the radical R 2 C and leads to amido complex 30 (Scheme 12). [27] The nonselective CÀH functionalization reactivity of 26 compared to 22 and its putative {[Cl 2 NN]Cu] 2 (m-NAd)} precursor is noteworthy.…”

Section: Nitrene Radical Complexesmentioning

confidence: 99%

“…[1] In particular, ligands that can assist in catalytic transformations by storing and releasing electrons during catalytic turnover have attracted a lot of interest over the past years. [2] Such "redox non-innocent" (redox-active) behavior of ligands has received further attention because of the related ligandcentered redox processes observed in several metalloenzymatic reactions, [2,3] which in fact initiated the study of redoxactive ligands in the first place. Meanwhile it has resulted in the development of a number of efficient and practically useful "bio-inspired" catalytic transformations.…”

Section: Introductionmentioning

confidence: 99%

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Complexes with Nitrogen‐Centered Radical Ligands: Classification, Spectroscopic Features, Reactivity, and Catalytic Applications

et al. 2013

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The electronic structure, spectroscopic features, and (catalytic) reactivity of complexes with nitrogen-centered radical ligands are described. Complexes with aminyl ([M(˙NR2)]), nitrene/imidyl ([M(˙NR)]), and nitridyl radical ligands ([M(˙N)]) are detectable and sometimes even isolable species, and despite their radical nature frequently reveal selective reactivity patterns towards a variety of organic substrates. A classification system for complexes with nitrogen-centered radical ligands based on their electronic structure leads to their description as one-electron-reduced Fischer-type systems, one-electron-oxidized Schrock-type systems, or systems with a (nearly) covalent M-N π bond. Experimental data relevant for the assignment of the radical locus (i.e. metal or ligand) are discussed, and the application of complexes with nitrogen-centered radical ligands in the (catalytic) syntheses of nitrogen-containing organic molecules such as aziridines and amines is demonstrated with recent examples. This Review should contribute to a better understanding of the (catalytic) reactivity of nitrogen-centered radical ligands and the role they play in tuning the reactivity of coordination compounds.

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confidence: 99%

Bio‐Inspired Catalytic Imine Reduction by Rhodium Complexes with Tethered Hantzsch Pyridinium Groups: Evidence for Direct Hydride Transfer from Dihydropyridine to Metal‐Activated Substrate

2013

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Herein, we report a conceptually new approach to the catalytic reduction of unsaturated substrates, demonstrated for imine hydrogenation, based on mimicry of biological processes [1] in which hydride is directly transferred from dihydronicotinamide adenine dinucleotide (phosphate) (NAD(P)H) cofactor to an enzyme-activated substrate. NAD(P)H is Natures hydride carrier. [2, 3] In many (de)hydrogenase enzymes that catalyze direct hydride transfer to/ from NAD(P) + /NAD(P)H, the substrate is polarized and thus activated by binding to a metal ion. [4,5] Classic examples are alcohol dehydrogenases (Zn 2+ active site) [4] and acetohydroxy acid isomeroreductase hydrogenases (with an (Mg 2+ ) 2 or (Mn 2+ ) 2 active site). [5] Our aim in this research was to prepare and test a new design for a homogeneous catalyst in which an unnatural organo-transition-metal center is tethered to an organohydride donor (OHD). The design incorporates the main features of an (de)hydrogenase enzyme and its NAD(P)H cofactor into one molecule. We envisaged that the close proximity of cofacial, linked metal and OHD centers would facilitate both regeneration of the OHD through the intermediacy of metallo-hydride species and the rapid transfer hydride from the OHD to a metal-bound, and thus activated, unsaturated substrate.We targeted a [Cp*Rh III (NN)L] n+ (NN = diimine; L = halido, n = 1; L = solvato co-ligand, n = 2) complex, as these are the most commonly used catalysts for regeneration of NAD(P)H from NAD(P) + . [6] Electrolytic reduction of [Cp*Rh III (NN)L] n+ affords the corresponding Rh I complex, which is rapidly protonated at low pH to give the active hydrido-Rh III species for hydride transfer to NAD(P) + . [6][7][8][9] Conveniently, catalytic regeneration of OHDs using [Cp*Rh III (NN)L] n+ can be driven directly by electricity, by light and a photosensitizer, or by renewable chemical reductants, such as formate. [7][8][9] We employed a Hantzsch

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Redoxaktive Liganden in der Katalyse

Cited by 83 publications

References 82 publications

Recent progress in homogeneous multielectron transfer photocatalysis and artificial photosynthetic solar energy conversion

Recent progress in homogeneous multielectron transfer photocatalysis and artificial photosynthetic solar energy conversion

Complexes with Nitrogen‐Centered Radical Ligands: Classification, Spectroscopic Features, Reactivity, and Catalytic Applications

Bio‐Inspired Catalytic Imine Reduction by Rhodium Complexes with Tethered Hantzsch Pyridinium Groups: Evidence for Direct Hydride Transfer from Dihydropyridine to Metal‐Activated Substrate

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