Theoretical study on structures and vibrational spectra of M ~+(H_2O)Ar (M = Cu, Ag, Au)

摘要

A theoretical study on the structures and vibrational spectra of M ~+(H_2O)Ar0-1 (M = Cu, Ag, Au) complexes was performed using ab initio method. Geometrical structures, binding energies (BEs), OH stretching vibrational frequencies, and infrared (IR) absorption intensities are investigated in detail for various isomers with Ar atom bound to different binding sites of M~+(H_2O). CCSD(T) calculations predict that BEs are 14.5, 7.5, and 14.4 kcal/mol for Ar atom bound to the noble metal ion in M~+(H_2O)Ar (M = Cu, Ag, Au) complexes, respectively, and the corresponding values have been computed to be 1.5, 1.3, and 2.1 kcal/mol when Ar atom attaches to a H atom of water molecule. The former structure is predicted to be more stable than the latter structure. Moreover, when compared with the M~+(H_2O) species, tagging Ar atom to metal cation yields a minor perturbation on the IR spectra, whereas binding Ar atom to an OH site leads to a large redshift in OH stretching vibrations. The relationships between isomers and vibrational spectra are discussed.