Sensitivity of Structural and Electronic Properties of Gold-Thiolate Nanoclusters to the Atomic Composition: A Comparative X-ray Study of Au19(SR)13 and Au25(SR)18

With the recent Successful synthesis of an increasing number of atomically precise thiolate gold nanoclusters (NCs.), there are growing demands for a,. better understanding of their atomic structures and structure property relationships in response to composition change. Herein, we present X-ray. experimental results on structural and electronic properties of a recently synthesized gold-thiolate: nanocluster, Au-19(SR)(13) in comparison with the structurally well-known:Au-25(SR)(18) reference. The atomic structure of Au-19(SR)(13) was first probed with extended X-ray absorption fine structure.(EXAFS). A multishell EXAFS fitting method (consisting of one Au-S and three Au-Au shells) allowed for a detailed structural comparison of the two nanoclusters, which revealed a Sizable increase of the bond distances between the surface surface and surface staple Au atoms upon the decrease of Au atoms in the nanocluster. X-ray photoemission experiments and ab initio calculations further demonstrated the sensitive change of electronic properties of the nanoclusters when the cluster composition was varied, that is, the Au-19(SR)(13) nanocluster,has a differently shaped and positively. shifted Au 5d band relative to Au-25(SR)(18). These experimental findings highlight the sensitivity of the local structure and electronic properties or thiolate-gold nanoclusters to even a:small change of the metal: core from Au-13 to Au-11.