title: Carbenes as catalysts for transformations of organometallic iron complexes.
abstract: Compared with the enormous arsenal of catalysts used to produce organic compounds, complementary species that are able to mediate sophisticated organometallic transformations are virtually nonexistent. We found that stable N-heterocyclic carbenes (NHCs) can mediate unusual organometallic transformations in solution at room temperature. Depending on the choice of NHC initiator, stoichiometric or catalytic reactions of bis(cyclooctatetraene)iron [Fe(COT)2] ensue. The stoichiometric reaction leads to the isolation of a previously unknown mixed-valent species, featuring distinct and directly bonded Fe(0) and Fe(I) centers. In the catalytic process, three iron atoms are fused to afford the tri-iron cluster Fe3(COT)3, which is a hydrocarbon analog of Dewar's classic Fe3(CO)12 complex. The key step in both of these processes is proposed to involve the NHC's ability to induce metal-metal bond formation. These NHC-mediated reactions provide a foundation on which to develop future organometallic transformations that are catalyzed by organic species.
authors.affiliation: Arnold and Mabel Beckman Laboratory of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Lavallo
authors.forename: Robert H
authors.initials: RH
authors.lastname: Grubbs
mesh_terms: D002384:Catalysis; D055598:Chemical Phenomena; D003460:Crystallization; D018360:Crystallography, X-Ray; D005296:Ferrous Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D006571:Heterocyclic Compounds / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008956:Models, Chemical; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013696:Temperature
chemical_list: D005296:Ferrous Compounds; D006571:Heterocyclic Compounds; D008024:Ligands; D009942:Organometallic Compounds; C030011:carbene; D007501:Iron; D008697:Methane