Photofragment Spectroscopy of π Complexes: Au⁺(C₂H₄) and Pt⁺(C₂H₄)

Abstract

Photodissociation spectra of the classic π complexes Au+(C2H4) and Pt+(C2H4) in the gas phase are reported, providing upper limits to metal−ligand bond strengths of 28 800 cm-1 (344 kJ mol-1) and 19 200 cm-1 (230 kJ mol-1), respectively. The spectrum of Au+(C2H4) features an extended progression in the metal−ligand stretch with a frequency of 176 cm-1, which drops to 160 cm-1 in Au+(C2D4). Hybrid density functional theory (DFT) calculations at the B3LYP level indicate that both complexes adopt a metallocyclopropane structure. The effect of basis set size and flexibility on the metal−ligand dissociation energy is explored. In addition, excited electronic states of both complexes have been investigated by using TD-DFT calculations.