Photodissociation Studies of M(Furan)+ (M = Cu, Ag, and Au) and Au(C3H4)+ Complexes

Abstract

The group 11 metal/furan cationic complexes were generated using a laser vaporization technique combined with a supersonic beam expansion in a time-of-flight mass spectrometer. From the viewpoint of the ionization energies, these complexes were treated as Cu+−furan, Ag+−furan, and Au−furan+. The photodissociative ligand-to-metal charge transfer with an exclusive furan cation was observed for Cu and Ag, whereas a simple bond cleavage with furan+ formation was inspected for Au. The photofragment spectra were recorded as a function of the laser wavelength. The continuous and structureless bands were measured in each complex. The thresholds of the fragment appearance determined the upper limits of the ground-state binding energy with 37 kcal/mol for Cu+−furan, 28 kcal/mol for Ag+−furan, and 62 kcal/mol for Au−furan+. An ab initio approach at the MP2 level was employed to optimize the geometries of the furan complexes and the binding energies were obtained using CCSD(T) single point calculations. The measured binding energies in both Cu and Ag complexes approximate to the theoretical predictions. Both the experimental and theoretical measurements yielded the enhanced bond strength for Au complex. In addition, a furan ring opening process leading to Au+−C3H4 production was observed in the reactions of a gold atom with a furan molecule. The binding energy was taken as a reference to discern three possible isomers, i.e., allene, cyclopropene, and propyne, as C3H4 species by means of experimental and theoretical approaches.