title: Gold surfaces and nanoparticles are protected by Au(0)-thiyl species and are destroyed when Au(I)-thiolates form.
abstract: The synthetic chemistry and spectroscopy of sulfur-protected gold surfaces and nanoparticles is analyzed, indicating that the electronic structure of the interface is Au(0)-thiyl, with Au(I)-thiolates identified as high-energy excited surface states. Density-functional theory indicates that it is the noble character of gold and nanoparticle surfaces that destabilizes Au(I)-thiolates. Bonding results from large van der Waals forces, influenced by covalent bonding induced through s-d hybridization and charge polarization effects that perturbatively mix in some Au(I)-thiolate character. A simple method for quantifying these contributions is presented, revealing that a driving force for nanoparticle growth is nobleization, minimizing Au(I)-thiolate involvement. Predictions that Brust-Schiffrin reactions involve thiolate anion intermediates are verified spectroscopically, establishing a key feature needed to understand nanoparticle growth. Mixing of preprepared Au(I) and thiolate reactants always produces Au(I)-thiolate thin films or compounds rather than monolayers. Smooth links to O, Se, Te, C, and N linker chemistry are established.
authors.affiliation: International Centre for Quantum and Molecular Structures, College of Sciences, Shanghai University, Shanghai 200444, China; School of Mathematical and Physical Sciences, The University of Technology Sydney, Sydney NSW 2007, Australia; reimers@shu.edu.cn jeffrey.reimers@uts.edu.au noel.hush@sydney.edu.au.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Reimers
authors.affiliation: School of Mathematical and Physical Sciences, The University of Technology Sydney, Sydney NSW 2007, Australia;
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ford
authors.affiliation: Department of Chemistry, Technical University of Denmark, Kongens Lyngby 2800, Denmark;
authors.forename: Arnab
authors.initials: A
authors.lastname: Halder
authors.affiliation: Department of Chemistry, Technical University of Denmark, Kongens Lyngby 2800, Denmark;
authors.forename: Jens
authors.initials: J
authors.lastname: Ulstrup
authors.affiliation: School of Chemistry F11, The University of Sydney, Sydney NSW 2006, Australia; School of Molecular Bioscience, The University of Sydney, Sydney NSW 2006, Australia reimers@shu.edu.cn jeffrey.reimers@uts.edu.au noel.hush@sydney.edu.au.
authors.forename: Noel S
authors.initials: NS
authors.lastname: Hush
keywords: electronic structure; gold–sulfur bonding; mechanism; nanoparticle; synthesis