The Molecular and Electronic Structure of NdF₂^-/0

The molecular and electronic structures of NdF₂^- and NdF₂ were elucidated through a combined anion photoelectron spectroscopy and quantum chemistry investigation. The anion photoelectron spectrum of NdF₂^- yielded an experimental vertical detachment energy (VDE) of 1.11 eV, in excellent agreement with the theoretical estimate of 1.106 eV. The calculated adiabatic electron affinity (AEA) of 1.055 eV lies close to the VDE, consistent with the similar optimized structures of the anion and neutral. Geometry optimizations confirm that both NdF₂^- and NdF₂ adopt bent C_2v structures with the anion possessing a ⁴A₂ (4f³6s²) ground state and the neutral possessing a ⁵A₂ (4f³6s¹) ground state. Extensive multireference calculations reveal a dense manifold of low-lying neutral excited states. Moreover, we juxtapose NdF₂^-/0 with its periodic analogue UF₂^-/0, showing similar metal-centered s-electron photodetachment, bent anion/neutral structures, and largely nonbonding 4f/5f electrons. Together, these results demonstrate the collaborative utilization of aPES with relativistic multireference calculations for the electronic structure of f-element molecules.