title: The Nature of Bonding between Argon and Mixed Gold-Silver Trimers.
abstract: The controversial nature of chemical bonding between noble gases and noble metals is addressed. Experimental evidence of exceptionally strong Au-Ar bonds in Ar complexes of mixed Au-Ag trimers is presented. IR spectra reveal an enormous influence of the attached Ar atoms on vibrational modes, particularly in Au-rich trimers, where Ar atoms are heavily involved owing to a relativistically enhanced covalency. In Ag-rich trimers, vibrational transitions of the metal framework predominate, indicating a pure electrostatic character of the Ag-Ar bonds. The experimental findings are analyzed by means of DFT calculations, which show how the relativistic differences between Au and Ag are manifested in stronger Au-Ar binding energies. Because of the ability to vary composition and charge distribution, the trimers serve as ideal model systems to study the chemical nature of the bonding of noble gases to closed-shell systems containing gold.
authors.affiliation: Eduard-Zintl-Institut, Technische Universität Darmstadt, Alarich-Weiss-Strasse 8, 64287 Darmstadt (Germany). shayeghi@cluster.pc.chemie.tu-darmstadt.de.
authors.forename: Armin
authors.initials: A
authors.lastname: Shayeghi
authors.affiliation: School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (UK).
authors.forename: Roy L
authors.initials: RL
authors.lastname: Johnston
authors.affiliation: National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada).
authors.forename: David M
authors.initials: DM
authors.lastname: Rayner
authors.affiliation: Eduard-Zintl-Institut, Technische Universität Darmstadt, Alarich-Weiss-Strasse 8, 64287 Darmstadt (Germany).
authors.forename: Rolf
authors.initials: R
authors.lastname: Schäfer
authors.affiliation: Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany). fielicke@physik.tu-berlin.de.
authors.forename: André
authors.initials: A
authors.lastname: Fielicke
keywords: IR spectroscopy; chemical bonding; clusters; noble gases; noble metals