J.W. Buchanan

NOVEL MIXED LIGAND SANDWICH COMPLEXES : COMPETITIVE BINDING OF IRON WITH BENZENE, CORONENE, AND C60

Abstract Organometallic complexes of iron with benzene, coronene and C60 are produced in a molecular beam and studied with time-of-flight mass spectrometry and laser photodissociation. The cation complexes are produced in a pulsed nozzle laser vaporization source using an iron rod coated with a sublimed film of coronene and/or C60. Benzene is seeded in the expansion gas. Masses of the form [Ax–Fe–By]+ are observed when A and B are benzene, coronene, or C60, taken any two at a time. Masses are observed for all combinations where x + y = 1 or 2, indicating the formation of monoligand and sandwich complexes. Mixed-ligand sandwiches form with comparable abundance to homoligand sandwiches. Mass-selected photodissociation probes the relative bonding strengths in these new species.

Photodissociation of exohedral transition metal–C60 complexes

Abstract Laser ablation/vaporization of solid metal samples coated with thin films of C60 is employed in a pulsed-nozzle cluster source to produce various transition metal–C60 complexes. Mass spectra contain species of the form Mx(C60)y, where x = 1–5 and y = 1,2. Mass-selected photodissociation studies investigate the structural and bonding properties of these complexes. Photodissociation shows primarily the elimination of metal in all complexes, demonstrating that the complexes are exohedral. Atomic and molecular desorption of metal are observed in different situations, suggesting that these complexes have metal dispersed to some degree as “films” on the fullerene surface. Some clusters fragment by loss of metal carbides (e.g. C59Fe+, V3C4+), indicating insertion of metal into the fullerene cage wall. Keywords: Clusters; Metallo-fullerenes; Photodissociation

Photodissociation of silver–coronene cluster cations

Abstract Gas phase complexes of coronene and silver are produced in a molecular beam and studied with time-of-flight mass spectrometry and laser photodissociation. The cation complexes are produced in a pulsed nozzle laser vaporization cluster source using a silver rod coated with a sublimed film of coronene. Cluster masses of the form Agx–(cor)y+ are observed for x = 0, 1, 2 and y = 1–3. Mass-selected photodissociation experiments probe the structure and bonding in these new cluster species. These studies demonstrate that silver binds weakly to coronene and that cation clusters of pure coronene have substantial stability.

Ring destruction and carbide formation in niobium-PAH complexes

Abstract Gas phase complexes between niobium atoms and the polycyclic aromatic hydrocarbons (PAHs) pyrene (C16H10) and coronene (C24H12) are produced in a molecular beam using laser vaporization in a pulsed nozzle cluster source. Cation complexes are studied with time-of-flight mass spectrometry and mass-selected photodissociation. Mass distributions and fragmentation patterns for Nbx–(PAH)y complexes are significantly different from those found previously for other Mx–(PAH)y complexes. Masses indicating the formation of metal–hydrocarbons and metal–carbides are prominent. Larger complexes add intact PAH moieties to the strongly bound mono-metal adducts. Niobium is significantly more reactive with PAH species than other transition metals studied to date.