title: Probing the electronic structure and chemical bonding of the "staple" motifs of thiolate gold nanoparticles: Au(SCH3)2- and Au2(SCH3)3-.
abstract: Thiolate-protected gold nanoparticles have been found recently to be coordinated by the so-called "staple" bonding motifs, consisting of quasi-linear [RS-Au-SR] and V-shaped [RS-Au-(SR)-Au-SR] units, which carry a negative charge formally. Using photoelectron spectroscopy (PES) in conjunction with ab initio calculations, we have investigated the electronic structure and chemical bonding of the simplest staples with R = CH(3): Au(SCH(3))(2)(-) and Au(2)(SCH(3))(3)(-), which were produced by electrospray ionization. PES data of the two Au-thiolate complexes are obtained both at room temperature (RT) and 20 K. The temperature-dependent study reveals significant spectral broadening at RT, in agreement with theoretical predictions of multiple conformations due to the different orientations of the -SCH(3) groups. The Au-S bonds in Au(n)(SCH(3))(n+1)(-) (n = 1, 2) are shown to be covalent via a variety of chemical bonding analyses. The strong Au-thiolate bonding and the stability of the Au-thiolate complexes are consistent with their ubiquity as staples for gold nanoparticles and on gold surfaces.
authors.affiliation: Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Chuan-Gang
authors.initials: CG
authors.lastname: Ning
authors.forename: Xiao-Gen
authors.initials: XG
authors.lastname: Xiong
authors.forename: Yi-Lei
authors.initials: YL
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang