Infrared Spectra and DFT Calcula­tions of Planar and Bridged Methyl­idene Intermediates in Reactions of Laser-Ablated Yttrium and Lanthanum Atoms with Di-, Tri-, and Tetrahalomethanes

Abstract

Reactions of laser-ablated Y and La atoms with di-, tri-, and tetrahalomethanes in excess argon were investigated and the products were identified from their infrared matrix spectra, isotopic shifts, and comparison with frequencies computed by density functional theory. These DFT calculations also show that the primary products are planar and bridged methylidenes depending on the number of halogen atoms with no trace of insertion and products, parallel to the previous Sc results. While the C–M bond in the planar configuration has a considerable amount of -character, the observed bridged Y and La methylidene structures are indicative of strong electron donation to the empty d-orbtals on the metal center. These identified products reconfirm that the electronic structures of group 3 metals (d¹s²) do not allow formation of the higher oxidation-state product in reaction with halomethanes. The preference of a group 3 metal product with more M–F bonds over those with more M–Cl bonds is also investigated.

Laser-ablated Y and La atoms react with di-, tri-, and tetrahalomethanes in excess argon to give primary products identified from their infrared matrix spectra, isotopic shifts, and comparison with frequencies computed by density functional theory. These DFT calculations also show that these lowest energy products are planar or bridged methylidenes depending on the number of halogen atoms.

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