Insights into the enhanced CeN triple bond in the HCeN molecule

Abstract

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 CeN bond. The absorption band at 937.7 cm⁻¹ with the 1.0311 ¹⁴N/¹⁵N isotopic shift ratio is characteristic of CeN 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 CeN 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 CeN triple bond in the HCeN molecule.