Chen J, Hochstatter AM, Kilin D, May PS, Meng Q, Berry MT. Photofragmentation of Gas-Phase Lanthanide Cyclopentadienyl Complexes: Experimental and Time-Dependent Excited-State Molecular Dynamics.
Organometallics 2014;
33:1574-1586. [PMID:
24910492 PMCID:
PMC4045319 DOI:
10.1021/om400953q]
[Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Indexed: 01/07/2023]
Abstract
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Unimolecular
gas-phase laser-photodissociation reaction mechanisms of open-shell
lanthanide cyclopentadienyl complexes, Ln(Cp)3 and 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.
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