Electronic and Geometric Structure of the Cluster Compound Au₅₅[P(C₆H₅)₃]₁₂C_l6. A Computational Study

Abstract

Relativistic density functional calculations have been carried out on the model cluster Au 55 (PH 3 ) 12 Cl 6 assuming a cuboctahedral or an icosahedral Au 55 metal core to model the experimentally suggested cluster compound assigned as Au 55 [P(C 6 H 5 ) 3 ] 12 Cl 6 . Besides the overall shape of the metal core, the study focused on the unresolved issue at which sites the chlorine ligands are attached. The calculations reproduce characteristic interatomic distances within ∼ 2 pm, with the exception of the Au-Cl bonds. Chlorine ligands were calculated to prefer higher coordinated sites whereas the previously postulated on-top coordination at the center of the Au (100) facets of a cuboctahedron was found to be unstable. In fact, the present model results suggest an ensemble of several higher coordinated sites. The often assumed cuboctahedral shape of the metal cluster core was determined to be slightly less stable than an approximately icosahedral shape. The calculations allow a rationalization of the difficulties faced in experiments that attempted to discriminate cluster isomers.

Growth of block copolymer stabilized metal nanoparticles probed simultaneously byin situXAS and UV–Vis spectroscopy

“…Pt 55 is a magic cluster with the closing of a second geometrical shell. A cuboctahedron structure of 55 atoms has an average coordination number of 7.8, while the icosahedrons structure with 55 atoms have 8.5 as average coordination (Genest et al, 2009). In the third stage, Pt-Pt coordination increases to its bulk value of 11 until 60 min through a slower process similar to the Au case.…”

Size-dependent properties of transition metal clusters: from molecules to crystals and surfaces – computational studies with the program ParaGauss

“…sizes can range from just a few to several millions atoms. 16,[19][20][21][22][23][24] In such combined studies the experimentally examined systems need to be as close as possible to the models used in the corresponding computational studies. [2][3][4][5][6][7] The thermodynamic instability due to their high surface energies represents another peculiarity of TM nanoparticles, which are therefore often stabilized by protective ligands or their deposition on support materials.…”

“…Often enough, synergy effects resulting from joint experimental and computational studies turn out to be essential for gaining insights at the atomic level. 16,[19][20][21][22][23][24] In such combined studies the experimentally examined systems need to be as close as possible to the models used in the corresponding computational studies. With regard to nanocatalysis 6,[25][26][27] this requirement can impose considerable problems as the catalytically active species employed in industrial processes often are significantly larger than the computational models for which accurate calculations are feasible, 24,25 e.g., by means of Kohn-Sham (KS) density functional theory (DFT).…”