Photodissociation and Theoretical Studies of Au+-pyridine and M(thiophene)+ (M=Cu, Ag, Au) Complexes

• Main Authors: Hsu-Chen Hsu, 許旭辰
• Other Authors: Chen-Sheng Yeh
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/82094354333177650197

碩士 === 國立成功大學 === 化學系碩博士班 === 90 === We have successfully produced Au+-pyridine, M(thiophene)+ (M = Cu, Ag, Au) via combination of laser vaporization technique and supersonic molecular beam in a time-of-flight mass spectrometer. From the viewpoint of the ionization energies, these complexes were treated as Au+-pyridine, Cu+-thiophene, Ag+-thiophene and Au-thiophene+. The photodissociative ligand-to-metal charge transfer was observed in all complex ions, except Au-thiophene+ species, proceeding a simple bond cleavage after absorption photon. The photofragment spectra were recorded as a function of the laser wavelength. The continuous and structureless bands were measured in all complexes. The thresholds of the fragment appearance determined the upper limits of the ground-state binding energies with 59.7 kcal/mol for Au+-pyridine, 40 kcal/mol for Cu+-thiophene, 30 kcal/mol for Ag+-thiophene, and 58 kcal/mol for Au-thiophene+. An ab-initio approach at MP2 level was employed to optimize the geometries of all complexes and the binding energies were obtained using CCSD(T) single point calculations. The binding energies measured from both Cu and Ag complexes were consistent with the theoretical predictions. Both Cu and Ag complexes exhibited CS symmetry in structures. However, the theoretical results of both Au+-pyridine and Au-thiophene+ showed the existence of the second isomers. Regarding to Au+-pyridine complex C1 symmetry is 24 kcal/mol less stable than C2V isomer in energy. On the other hand, C1 symmetry is 8.1 kcal/mol more stable than CS isomer in energy for Au-thiophene+.