Bonding interactions in Ag+(O2)n and Ag2+(O2)n clusters:: experiment and theory

Equilibrium methods were used to measure binding energies and entropies for the attachment of up to four O-2 ligands to ground-state Ag+(S-1, 4d(10)) and for the attachment of up to three O-2 ligands to ground-state Ag-2(+)((2)Sigma(g), 4d(20) sigma(5s)(1)). Bond dissociation energies (BDEs) of the first three O-2 ligands from Ag+(02) are 6.9, 7.4, and 5.5 kcal/mol for n = 1-3, respectively, with the BDE of the fourth ligand estimated to be 4.8 kcal/mol. BDEs of the first and second O-2 ligands from Age(+)(O-2)(n) are 4.5 and 4.2 kcal/mol, respectively, with the BDE of the third ligand estimated to be 3.5 kcal/mol. All of the observed attachments of O-2 ligands to both the monomer and dimer Ag core ions were within the first solvation shell. Theoretical calculations at the DFT-B3LYP level were done on all of the observed Ag+ and Ag-2(+) clusters in order to determine the vibrational frequencies and geometries and to examine the origin of the bonding and its variation with core ion coordination. Comparisons are made with the Cu+(H-2) and Cu-2(+)(H-2)(n) systems. (C) 2003 Elsevier B.V All rights reserved.