title: Transition metal-stabilized arenium cations: protonation of arenes dihapto-coordinated to pi-basic metal fragments.
abstract: A series of metal complexes was synthesized in which arenes were dihapto-coordinated to pi-basic metal fragments having the general form [TpM(pi-acid)(L)], where Tp = hydridotris(pyrazolyl)borate, M = rhenium, molybdenum, or tungsten, pi-acid = CO or NO(+), and L = 1-methylimidazole, 1-butylimidazole, pyridine, or trimethylphosphine. The arene complexes were shown to be significantly more basic than the analogous pentaammineosmium(II) arene complexes and were protonated by moderate acids to give remarkably stable eta(2) and eta(3) arenium cation complexes. A crystal structure of [TpRe(CO)(MeIm)(5,6-eta(2)-2H-anisolium)](OTf) confirmed the eta(2) coordination of the anisolium ligand, but suggests a weak long-range interaction between the metal and C1 of the anisolium.
authors.affiliation: Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Keane
authors.forename: Mahendra D
authors.initials: MD
authors.lastname: Chordia
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Mocella
authors.forename: Michal
authors.initials: M
authors.lastname: Sabat
authors.forename: Carl O
authors.initials: CO
authors.lastname: Trindle
authors.forename: W Dean
authors.initials: WD
authors.lastname: Harman
mesh_terms: D000840:Anisoles / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D018360:Crystallography, X-Ray; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry; D019216:Metals, Heavy / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry; D010720:Phosphines / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry
chemical_list: D000840:Anisoles; D002412:Cations; D007093:Imidazoles; D019216:Metals, Heavy; D009942:Organometallic Compounds; D010720:Phosphines; D011725:Pyridines; C032555:1-N-butylimidazole; C023666:pyridine; C018100:1-methylimidazole