Experimental and theoretical studies of metal cation-pyridine complexes containing Cu and Ag

Photodissociative experiments were performed on Cu+-C5H5N and Ag+-C5H5N com plexes in the gas phase; The dissociative ligand-to-metal charge-transfer f ragments, pyridine(+), were observed for both complexes. Photodissociation spectra were recorded as a function of laser wavelength. Two continuous, st ructureless bands were investigated in each complex. Because of the low-ene rgy D-2 state of the Cu atom, the Cu+-pyridine dissociative process is more complicated. Several possible mechanisms for this process have been discus sed. The binding energies were determined experimentally to be 65.5 and 45. 2 kcal/mol for Cu+-pyridine and Ag+-pyridine, respectively. M+-C5H5N (M = C u or Ag) complexes also were studied theoretically using the HF, MP2, and B 3LYP methods. All complexes under study show C-2 nu symmetry. The binding e nergies predicted from the theoretical calculations were less than the expe rimental values, which were derived from the onset of the charge-transfer a ppearance combined with the LP (ionization potential). The complexes contai ning Cu+ and Ag+ are characterized predominantly by electrostatic interacti ons.