Insights into the enhanced Ce[triple bond, length as m-dash]N triple bond in the HCe[triple bond, length as m-dash]N molecule.

Herein, an experimental study of the vibrational spectra of HCeN was carried out in solid argon, followed by theoretical investigations of molecular structures and the nature of Ce[triple bond, length as m-dash]N bond. The absorption band at 937.7 cm-1 with the 1.0311 14N/15N isotopic shift ratio is characteristic of Ce[triple bond, length as m-dash]N stretching band for HCeN, showing a 94 cm-1 higher shift relative to that of the diatomic CeN molecule. This large frequency shift indicates a much stronger Ce[triple bond, length as m-dash]N bond in HCeN, which is confirmed by DFT calculations. Qualitative orbital interaction and orbital composition analyses suggest that the addition of the H ligand to the Ce center will activate the 4f valence shell and strengthen the covalent bond between Ce and N, which may contribute to enhance the Ce[triple bond, length as m-dash]N triple bond in the HCeN molecule.