High-spin electronic states of lanthanide-arene complexes: Nd(benzene) and Nd(naphthalene)

摘要

Neodymium (Nd) complexes of benzene and naphthalene were synthesized in a laser-ablation supersonic molecular beam source. High-resolution electron spectra of these complexes were obtained using pulsed-field ionization zero electron kinetic energy (ZEKE) spectroscopy. Second-order Moller-Plesset perturbation calculations were employed to aid spectral and electronic-state assignments. The adiabatic ionization energies were measured to be 38 081 (5)cm ~(-1) for Nd(benzene) and 37 815 (5)cm ~(-1) for Nd(naphthalene). For the Nd(benzene) complex, the observed frequencies of 831 and 286cm ~(-1) were assigned to C-H out-of-plane bending and Nd ~+-C _6H _6 stretching modes in the 6A 1 ion state and 256cm ~(-1) to the Nd-C 6H 6 stretching mode in the 7A 1 neutral state. To confirm these assignments, the ZEKE spectrum of the deuterated species was recorded, and the corresponding vibrational frequencies were measured to be 710 and 277cm ~(-1) in the ion state and 236cm ~(-1) in the neutral state. For the Nd(naphthalene) complex, the observed vibrational modes were C 10H 8 bending (394cm ~(-1)), Nd ~+-C 10H 8 stretching (286 and 271cm ~(-1)), Nd +-C 10H 8 bending (80cm ~(-1)), and C 10H 8 twisting (105cm ~(-1)) in the 6A ′ ion state and metal-ligand bending (60cm -1) and ligand twisting (55cm ~(-1)) in the 7A ′ neutral state. The formation of the ground state of the Nd(benzene) complex requires 4f → 5d and 6s → 5d electron excitation of the Nd atom, whereas the formation of the ground state of Nd(naphthalene) involves the 6s → 5d electron promotion.