Matrix infrared spectroscopic and electronic structure investigations of the lanthanide metal atom-methyl fluoride reaction products CH_3-LnF and CH_2-LnHF: The formation of single carbon-lanthanide metal bonds

摘要

Lanthanide metal atoms, produced by laser ablation, were condensed with CH_3F in excess Ar at 8 K. New infrared absorption bands are assigned to the first insertion CH_3LnF and oxidative addition methylene lanthanide hydride fluoride CH_2LnHF products on the basis of ~(13)C and deuterium substitution and density functional theory calculations of the vibrational frequencies. It is also possible to observe the cationic species CH_3LnF~+ for some Ln. For Ln = Eu and Yb, only CH3LnF is observed.CH_3LnF in the Ln formal +2 state is predicted to be more stable than CH_2LnHF with the Ln in the formal +3 oxidation state. CH_3-LnF forms a single bond between Ln and C and is a substituted methane. Similar to CH_2-LnF_2, CH _2-LnHF does not form a π-bond between Ln and C and is best described as a LnHF-substituted CH_3 radical, with an unpaired p electron on C weakly interacting with the unpaired f electrons on the Ln. The calculated potential energy surface for the CH_3F+La → CH _3-LaF/CH_2-LaHF shows a number of intermediates and transition states on multiple paths. The reaction mechanism involves the potential formation of LaF and LaHF intermediates.