Abstract
La(C2H2) and La(C4H6) are observed from the reaction of laser-vaporized La atoms with ethylene molecules by photoionization time-of-flight mass spectrometry and characterized by mass-analyzed threshold ionization spectroscopy. La(C2H2) is identified as a metallacyclopropene and La(C4H6) as a metallacyclopentene. The three-membered ring is formed by concerted H2 elimination and the five-membered cycle by dehydrogenation and C-C bond coupling. Both metallacycles prefer a doublet ground state with a La 6s-based unpaired electron. Ionization of the neutral doublet state of either complex produces a singlet ion state by removing the La-based electron. The ionization allows accurate measurements of the adiabatic ionization energy of the neutral doublet state and metal-ligand and ligand-based vibrational frequencies of the neutral and ionic states. Although the La atom is in a formal oxidation state of +2, the ionization energies of these metal-hydrocarbon cycles are lower than that of the neutral La atom. Deuteration has a small effect on the ionization energies of the two cyclic radicals but distinctive effects on their vibrational frequencies.
Original language | English |
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Pages (from-to) | 4482-4489 |
Number of pages | 8 |
Journal | Journal of Physical Chemistry A |
Volume | 120 |
Issue number | 26 |
DOIs | |
State | Published - Jul 7 2016 |
Bibliographical note
Publisher Copyright:© 2016 American Chemical Society.
Funding
Funders | Funder number |
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National Science Foundation (NSF) | 1362102 |
ASJC Scopus subject areas
- Physical and Theoretical Chemistry