Gas-phase chemistry of metal ion complexes with arenes and fullerenes.

摘要

Fe+ generated by electron ionization (EI) of ferrocene, Fe(C₅H₅)₂, has been attached to benzene, C₆H₆, coronene, C₂₄H₁₂, corannulene, C₂₀H₁₀ and Buclaninsterfullerene, C₆₀, in helium bath gas at 0.35 ± 0.01 Torr and 295 ± 2K within a Selected-Ion Flow Tube (SIFT) tandem mass spectrometer. Rates were measured for reactions of Fe+, C₂₄H₁₂+, C ₂₀H₁₀+, C₆₀+, C ₆H₆Fe+, C₂₄H₁₂Fe +, C₂₀H₁₀Fe+ and C₆₀Fe + with N₂, D₂, CO₂, CH₄, SO₂, C₂H₄, C₂H₄, H ₂O, NH₃, CO, C₆D₆, N₂O and O₂ in the gas-phase.; Comparisons of measured rates indicated that the presence of benzene, coronene, corannulene and fullerene led to enhancements in the reactivity of bare Fe+ by up to five orders of magnitude while C ₂₄H₁₂+, C₂₀H₁₀ + and C₆₀+ were unreactive towards the neutral molecules investigated. Ligation and sequential ligation was the only chemistry observed with most of the ligands investigated. The extent of ligation was employed to determine coordination numbers and these were rationalized in terms of modes of coordination of Fe+ with the differently curved carbonaceous surfaces. Bimolecular oxidation channels were observed to compete with ligation in the reactions with N₂O and O₂ resulting in either neutral or ionized metal oxides and even in oxides of the carbonaceous surfaces.; Oxidation with molecular oxygen of metal cation complexes was also studied for mono- and bis-adducts of benzene of the type M(C₆H₆) _1,2+ with first, second and thirdrow transition metal cations using an Inductively-Coupled Plasma/Selected-Ion Flow Tube (ICP/SIFT) tandem mass spectrometer. Trends in reactivity were identified for the metal-cation adducts across and down the Periodic Table. A multitude of reaction, pathways including oxygen-atom transfer, addition, addition followed by dehydration, were observed. The intrinsic effect of the benzene ligand(s) on the reactivity of the bare metal cations was determined from comparisons with earlier results obtained for the bare metal ions. Oxidation of the benzene ligand itself was observed to be mediated by the transition metal cations V+, Cr+, Fe+, Co+ and Re+ and appeared to result from simultaneous activation of C-H, C-C and O-O bonds. Catalytic oxidation of the benzene ring observed in the presence of Fe+, Cr+ and Co+ was postulated to result in the production of 1,2-dihydroxybenzene (catechol). (Abstract shortened by UMI.)