Photodissociation and theoretical studies of the Au+-(C5H5N) complex

Laser vaporization combined with a supersonic molecular beam was employed to generate and study the Au(C5H5N)(+) complex for the first time. On the basis of the ionization energies (IE) between gold and pyridine, the Au(C5H5N)(+) species is viewed as being a Au+-C5H5N species. Photodissociative charge transfer was observed with exclusive C5H5N+ (pyridine) formation. The photofragmentation spectrum of Au+-(C5H5N) was scanned by monitoring the pyridine fragments. A structureless continuum spectrum was observed and the onset of C5H5N+ appearance indicates the upper limit on the Au+C5H5N bond strength to be 59.6 kcal mol(-1). Ab initio calculations at the MP2 level were employed to optimize the geometries of the gold complexes and binding energies were obtained using CCSD(T) single point calculations. Besides from the C-2v structure observed in Cu+ and Ag+ complexes, the theoretical results yielded a second isomer with C-1 symmetry which is 24 kcal mol(-1) less stable in energy than the C-2v isomer.