Tetrapodal pentadentate ligands occupy five coordination positions in a coordination octahedron, thereby providing the metal ion with a square-pyramidal "coordination cap": In such complexes, all reactivity is focused on a single coordination site. The review highlights recent advances in the coordination chemistry of iron. With a variety of NN(4) ligands, the concept is being used to model non-heme active sites in biomolecules. Tetraphosphane ligands (donor set: NP(4)) undergo, depending on the solvent, remarkably specific P-C bond activation reactions, which may be reversed under suitable conditions.
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Chemocatalytic Conversion of Dinitrogen to Ammonia Mediated by a Tungsten Complex.
Angew Chem Int Ed Engl
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Brest University: Universite de Bretagne Occidentale, Chemistry, FRANCE.
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Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Strasse 2, 24118, Kiel, Germany.
Molybdenum dinitrogen complexes have played a major role as catalytic model systems of nitrogenase. In comparison, analogous tungsten complexes have in most cases found to be catalytically inactive. Herein, a tungsten complex was shown to be supported by a pentadentate tetrapodal (pentaPod) phosphine ligand, under conditions of N fixation, primarily catalyzes the hydrogen evolution reaction (HER), in contrast to its Mo analogue, which catalytically mediates the nitrogen-reduction reaction (N RR).
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April 2022
Institut für Anorganische Chemie, CAU Kiel, Max-Eyth-Str. 2, 24118 Kiel, Germany.
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Institut für Anorganische Chemie, Christian-Albrechts-Universität zu Kiel, Otto-Hahn-Platz 10, 24118, Kiel, Germany.
With [Mo(N )(P PP )] the first Chatt-type complex with one coordination site catalytically converting N to ammonia is presented. Employing SmI as reductant and H O as proton source 26 equivalents of ammonia are generated. Analogous Mo -N complexes supported by a combination of bi- and tridentate phosphine ligands are catalytically inactive under the same conditions.
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