title: Heteroatom-free arene-cobalt and arene-iron catalysts for hydrogenations.
abstract: 75 years after the discovery of hydroformylation, cobalt catalysts are now undergoing a renaissance in hydrogenation reactions. We have evaluated arene metalates in which the low-valent metal species is--conceptually different from heteroatom-based ligands--stabilized by π coordination to hydrocarbons. Potassium bis(anthracene)cobaltate 1 and -ferrate 2 can be viewed as synthetic precursors of quasi-"naked" anionic metal species; their aggregation is effectively impeded by (labile) coordination to the various π acceptors present in the hydrogenation reactions of unsaturated molecules (alkenes, arenes, carbonyl compounds). Kinetic studies, NMR spectroscopy, and poisoning studies of alkene hydrogenations support the formation of a homogeneous catalyst derived from 1 which is stabilized by the coordination of alkenes. This catalyst concept complements the use of complexes with heteroatom donor ligands for reductive processes.
authors.affiliation: Fakultät für Chemie, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg (Germany).
authors.forename: Dominik
authors.initials: D
authors.lastname: Gärtner
authors.forename: Alice
authors.initials: A
authors.lastname: Welther
authors.forename: Babak Rezaei
authors.initials: BR
authors.lastname: Rad
authors.forename: Robert
authors.initials: R
authors.lastname: Wolf
authors.forename: Axel
authors.initials: A
authors.lastname: Jacobi von Wangelin
mesh_terms: D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D006865:Hydrogenation; D007501:Iron / Q000737:chemistry*; D008024:Ligands
chemical_list: D008024:Ligands; D003035:Cobalt; D007501:Iron
keywords: arene complexes; cobalt; homogeneous catalysis; hydrogenations; iron