title: Photofragmentation of Gas-Phase Lanthanide Cyclopentadienyl Complexes: Experimental and Time-Dependent Excited-State Molecular Dynamics.
abstract: Unimolecular gas-phase laser-photodissociation reaction mechanisms of open-shell lanthanide cyclopentadienyl complexes, Ln(Cp)3and Ln(TMCp)3, are analyzed from experimental and computational perspectives. The most probable pathways for the photoreactions are inferred from photoionization time-of-flight mass spectrometry (PI-TOF-MS), which provides the sequence of reaction intermediates and the distribution of final products. Time-dependent excited-state molecular dynamics (TDESMD) calculations provide insight into the electronic mechanisms for the individual steps of the laser-driven photoreactions for Ln(Cp)3. Computational analysis correctly predicts several key reaction products as well as the observed branching between two reaction pathways: (1) ligand ejection and (2) ligand cracking. Simulations support our previous assertion that both reaction pathways are initiated via a ligand-to-metal charge-transfer (LMCT) process. For the more complex chemistry of the tetramethylcyclopentadienyl complexes Ln(TMCp)3, TMESMD is less tractable, but computational geometry optimization reveals the structures of intermediates deduced from PI-TOF-MS, including several classic "tuck-in" structures and products of Cp ring expansion. The results have important implications for metal-organic catalysis and laser-assisted metal-organic chemical vapor deposition (LCVD) of insulators with high dielectric constants.
authors.affiliation: Department of Chemistry, University of South Dakota , Vermillion, South Dakota 57069, United States.
authors.forename: Jiangchao
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Chemistry, University of South Dakota , Vermillion, South Dakota 57069, United States.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Hochstatter
authors.affiliation: Department of Chemistry, University of South Dakota , Vermillion, South Dakota 57069, United States.
authors.forename: Dmitri
authors.initials: D
authors.lastname: Kilin
authors.affiliation: Department of Chemistry, University of South Dakota , Vermillion, South Dakota 57069, United States.
authors.forename: P Stanley
authors.initials: PS
authors.lastname: May
authors.affiliation: Department of Chemistry, University of South Dakota , Vermillion, South Dakota 57069, United States.
authors.forename: Qingguo
authors.initials: Q
authors.lastname: Meng
authors.affiliation: Department of Chemistry, University of South Dakota , Vermillion, South Dakota 57069, United States.
authors.forename: Mary T
authors.initials: MT
authors.lastname: Berry