@article{NollGrossShoyamaetal.2023, author = {Noll, Niklas and Groß, Tobias and Shoyama, Kazutaka and Beuerle, Florian and W{\"u}rthner, Frank}, title = {Folding-Induced Promotion of Proton-Coupled Electron Transfers via Proximal Base for Light-Driven Water Oxidation}, series = {Angewandte Chemie International Edition}, volume = {62}, journal = {Angewandte Chemie International Edition}, number = {7}, doi = {10.1002/anie.202217745}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312020}, year = {2023}, abstract = {Proton-coupled electron-transfer (PCET) processes play a key role in biocatalytic energy conversion and storage, for example, photosynthesis or nitrogen fixation. Here, we report a series of bipyridine-containing di- to tetranuclear Ru(bda) macrocycles 2 C-4 C (bda: 2,2′-bipyridine-6,6′-dicarboxylate) to promote O-O bond formation. In photocatalytic water oxidation under neutral conditions, all complexes 2 C-4 C prevail in a folded conformation that support the water nucleophilic attack (WNA) pathway with remarkable turnover frequencies of up to 15.5 s\(^{-1}\) per Ru unit respectively. Single-crystal X-ray analysis revealed an increased tendency for intramolecular π-π stacking and preorganization of the proximal bases close to the active centers for the larger macrocycles. H/D kinetic isotope effect studies and electrochemical data demonstrate the key role of the proximal bipyridines as proton acceptors in lowering the activation barrier for the crucial nucleophilic attack of H\(_{2}\)O in the WNA mechanism.}, language = {en} } @article{ScherpfSchwarzScharfetal.2018, author = {Scherpf, Thorsten and Schwarz, Christopher and Scharf, Lennart T. and Zur, Jana-Alina and Helbig, Andeas and Gessner, Viktoria H.}, title = {Ylide-Functionalized Phosphines: Strong Donor Ligands for Homogeneous Catalysis}, series = {Angewandte Chemie - International Edition}, volume = {57}, journal = {Angewandte Chemie - International Edition}, number = {39}, doi = {10.1002/anie.201805372}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-228551}, pages = {12859-12864}, year = {2018}, abstract = {Phosphines are important ligands in homogenous catalysis and have been crucial for many advances, such as in cross-coupling, hydrofunctionalization, or hydrogenation reactions. Herein we report the synthesis and application of a novel class of phosphines bearing ylide substituents. These phosphines are easily accessible via different synthetic routes from commercially available starting materials. Owing to the extra donation from the ylide group to the phosphorus center the ligands are unusually electron-rich and can thus function as strong electron donors. The donor capacity surpasses that of commonly used phosphines and carbenes and can easily be tuned by changing the substitution pattern at the ylidic carbon atom. The huge potential of ylide-functionalized phosphines in catalysis is demonstrated by their use in gold catalysis. Excellent performance at low catalyst loadings under mild reaction conditions is thus seen in different types of transformations.}, language = {en} } @article{NollKrauseBeuerleetal.2022, author = {Noll, Niklas and Krause, Ana-Maria and Beuerle, Florian and W{\"u}rthner, Frank}, title = {Enzyme-like water preorganization in a synthetic molecular cleft for homogeneous water oxidation catalysis}, series = {Nature Catalysis}, journal = {Nature Catalysis}, edition = {accepted version}, doi = {10.1038/s41929-022-00843-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-302897}, year = {2022}, abstract = {Inspired by the proficiency of natural enzymes, mimicking of nanoenvironments for precise substrate preorganisation is a promising strategy in catalyst design. However, artificial examples of enzyme-like activation of H\(_2\)O molecules for the challenging oxidative water splitting reaction are hardly explored. Here, we introduce a mononuclear Ru(bda) complex (M1, bda: 2,2'-bipyridine-6,6'-dicarboxylate) equipped with a bipyridine-functionalized ligand to preorganize H\(_2\)O molecules in front of the metal center as in enzymatic clefts. The confined pocket of M1 accelerates chemically driven water oxidation at pH 1 by facilitating a water nucleophilic attack pathway with a remarkable turnover frequency of 140 s\(^{-1}\) that is comparable to the oxygen-evolving complex of photosystem II. Single crystal X-ray analysis of M1 under catalytic conditions allowed the observation of a 7th H\(_2\)O ligand directly coordinated to a RuIII center. Via a well-defined hydrogen-bonding network, another H\(_2\)O substrate is preorganized for the crucial O-O bond formation via nucleophilic attack.}, language = {en} } @article{SchindlerMezaChinchaRothetal.2021, author = {Schindler, Dorothee and Meza-Chincha, Anna-Lucia and Roth, Maximilian and W{\"u}rthner, Frank}, title = {Structure-Activity Relationship for Di- up to Tetranuclear Macrocyclic Ruthenium Catalysts in Homogeneous Water Oxidation}, series = {Chemistry—A European Journal}, volume = {27}, journal = {Chemistry—A European Journal}, number = {68}, doi = {10.1002/chem.202100549}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256792}, pages = {16938-16946}, year = {2021}, abstract = {Two di- and tetranuclear Ru(bda) (bda: 2,2′-bipyridine-6,6′-dicarboxylate) macrocyclic complexes were synthesized and their catalytic activities in chemical and photochemical water oxidation investigated in a comparative manner to our previously reported trinuclear congener. Our studies have shown that the catalytic activities of this homologous series of multinuclear Ru(bda) macrocycles in homogeneous water oxidation are dependent on their size, exhibiting highest efficiencies for the largest tetranuclear catalyst. The turnover frequencies (TOFs) have increased from di- to tetranuclear macrocycles not only per catalyst molecule but more importantly also per Ru unit with TOF of 6 \(^{-1}\) to 8.7 \(^{-1}\) and 10.5 s\(^{-1}\) in chemical and 0.6 s\(^{-1}\) to 3.3 \(^{-1}\) and 5.8 \(^{-1}\) in photochemical water oxidation per Ru unit, respectively. Thus, for the first time, a clear structure-activity relationship could be established for this novel class of macrocyclic water oxidation catalysts.}, language = {en} } @article{BudimanWestcottRadiusetal.2021, author = {Budiman, Yudha P. and Westcott, Stephen A. and Radius, Udo and Marder, Todd B.}, title = {Fluorinated Aryl Boronates as Building Blocks in Organic Synthesis}, series = {Advanced Synthesis \& Catalysis}, volume = {363}, journal = {Advanced Synthesis \& Catalysis}, number = {9}, doi = {10.1002/adsc.202001291}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-225908}, pages = {2224 -- 2255}, year = {2021}, abstract = {Organoboron compounds are well known building blocks for many organic reactions. However, under basic conditions, polyfluorinated aryl boronic acid derivatives suffer from instability issues that are accelerated in compounds containing an ortho-fluorine group, which result in the formation of the corresponding protodeboronation products. Therefore, a considerable amount of research has focused on novel methodologies to synthesize these valuable compounds while avoiding the protodeboronation issue. This review summarizes the latest developments in the synthesis of fluorinated aryl boronic acid derivatives and their applications in cross-coupling reactions and other transformations. image}, language = {en} } @article{BudimanFriedrichRadiusetal.2019, author = {Budiman, Yudha P. and Friedrich, Alexandra and Radius, Udo and Marder, Todd B.}, title = {Copper-catalysed Suzuki-Miyaura cross-coupling of highly fluorinated aryl boronate esters with aryl iodides and bromides and fluoroarene-arene π-stacking interactions in the products}, series = {ChemCatChem}, volume = {11}, journal = {ChemCatChem}, number = {21}, doi = {10.1002/cctc.201901220}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204839}, pages = {5387-5396}, year = {2019}, abstract = {A combination of copper iodide and phenanthroline as the ligand is an efficient catalyst for Suzuki-Miyaura cross-coupling of highly fluorinated boronate esters (aryl-Bpin) with aryl iodides and bromides to generate fluorinated biaryls in good to excellent yields. This method represents a nice alternative to traditional cross-coupling methods which require palladium catalysts and stoichiometric amounts of silver oxide. We note that π⋅⋅⋅π stacking interactions dominate the molecular packing in the partly fluorinated biaryl crystals investigated herein. They are present either between the arene and perfluoroarene, or solely between arenes or perfluoroarenes, respectively.}, language = {en} }