Photofragmentation Pathways for Gas-Phase Lanthanide Tris(isopropylcyclopentadienyl) Complexes

Abstract

Photofragmentation mechanisms of gas-phase lanthanide tris-(isopropylcyclopentadienyl) complexes, Ln(iCp) 3 , were studied through experimental photoionization time-of-flight mass spectrometry (PI-TOF-MS). A DFTbased time-dependent excited-state molecular dynamics (TDESMD) algorithm, under standard approximations, was used to simulate the photofragmentation process. Two competing reaction pathways, intact ligand stripping and ligand cracking within the metal−ligand complex, were hypothesized based on experimental data. It was evident that intramolecular hydrogen, methyl, and isopropyl abstraction play an important role in the ligand-cracking reaction pathway, leading to metal carbide and metal hydrocarbide products. The TDESMD simulations also produced branching reaction pathways for ligand ejection and ligand cracking and further suggested that both pathways are initiated by ligand-to-metal charge transfer. Although the simulations reproduced several of the proposed reactions and several of the products of cracking observed in the PI-TOF mass spectra, differences between the simulation and experimental results suggest specific directions for improvement in the computational model.

Photoinduced Charge Transfer versus Fragmentation Pathways in Lanthanum Cyclopentadienyl Complexes

“…, ..., (25) Here, f is the index for a fragment, such that 1 ≤ f ≤ f max . I max ( f) (t) is the number of nuclei in a fragment f. I (f) is an index labeling nuclei in a fragment f such that 1…”

Two Series of New Volatile Rare‐Earth Metal Tris(guanidinates) and Tris(amidinates)

“…The high volatility of certain ring‐substituted lanthanide tris(cyclopentadienyl) complexes such as (EtC 5 H 4 ) 3 Ln and ( i PrC 5 H 4 ) 3 Ln makes them potential precursors for metal‐organic chemical vapor deposition (MOCVD), allowing relatively low deposition temperatures . However, a major problem associated with the Cp 3 Ln ‐derived precursors is their very high air sensitivity.…”

Unraveling Photodimerization of Cyclohexasilane from Molecular Dynamics Studies

“…In our previous study, density-functional-theory (DFT)-based time-dependent excited-state molecular dynamics (TDESMD) was used to investigate the photochemistry of small organic molecules , and large metal–organic complexes. − The atomic models were isolated in the gas phase such that the photochemistry should be interpreted as unimolecular reactions. The photochemical processes were mainly characterized as photodissociation, even though minor photoisomerization events were observed for certain fragments in simulations based on organic molecules. , In this work, we perform TDESMD calculations on a pair of CHS monomers in the gas phase to simulate photoinduced reactions.…”