Mechanism of Nucleation of Gold(I) Thiolate Oligomers into Gold–Thiolate Nanoclusters

Abstract

The mechanism of reductive synthesis of gold–thiolate nanoclusters from gold­(I)–thiolate oligomers under boron hydride (BH4 –) reduction is studied based on ab initio molecular dynamics (AIMD) simulations and density functional theory (DFT) calculations. The AIMD simulations show that the interaction between BH4 – and the gold­(I)–thiolate oligomers leads to formation of active intermediates containing an Au–H or an Au–H–Au moiety, instead of direct formation of HSR and Au–Au bonds. The active intermediates interact with the gold­(I)–thiolate oligomers or other active intermediates to form Au–Au bonds and 2e– building blocks. In the present studies, the pathways of formation of 2e– building blocks from the active intermediate species are proposed and verified by the DFT calculations, which indicate that the hydride on Au–H and Au–H–Au moieties acts as a nucleophilic agent to attack gold atoms and lead to formation of new Au–Au bonds. The newly discovered nucleation mechanism is applied to understand the formation of 2e– cluster Au15(SR)13 and 4e– cluster Au16(SR)12.

Structure Effects of Ligands in Gold–Ligand Complexes for Controlled Formation of Gold Nanoclusters

“…We compared the stability of the Au 4 (SR) 4 complexes in Figure b–e by calculating the dissociation energy by hydride ( E diss ), average monomer fragmentation energy ( E avg ), and average ligand stabilization energy (ALSE) (Figure f–h and Table S4), as used in previous reports (details in Methods). − The energy values are derived as follows E normald normali normals normals = E [ A u 4 false( normalS normalR false) 3 − ] + E [ H S R ] − E [ A u 4 ( S R ) 4 ] − E [ normalH − ] E a v g = false{ E [ A u 4 ( S R ) 4 ] − 4 E [ normalA normalu false( normalS normalR false) ] false} / 4 …”

“…E diss quantifies the energy associated with a reaction in which certain metallic Au–Au bonds, which are crucial for Au NC formation, are generated by the dissociation of the Au–S part in the Au complex when a hydride anion exists. , E avg provides an insight into the comparative stability of the Au 4 (SR) 4 complex relative to the Au–SR unit . The ALSE reflects the stabilization energy when –H is substituted with a specific ligand in the Au 4 SH 4 complex .…”

Ion mobility–tandem mass spectrometry of bulky tert‐butyl thiol ligated gold nanoparticles

“…Gold nanoparticles (AuNPs) have become one of the "hot topics" in recent decades because of their interesting physical and chemical properties. [1][2][3][4][5][6] These AuNPs have a specific number of gold atoms and protecting-thiolate ligands. AuNPs have gained much interest in recent years due to their applications in imaging, 7 catalytic activity, 8-11 biosensing, 12 drug delivery, 13-18 solar cells, 19-21 super capacitors, 22 and rechargeable Li batteries.…”

“…Gold nanoparticles (AuNPs) have become one of the “hot topics” in recent decades because of their interesting physical and chemical properties 1–6 . These AuNPs have a specific number of gold atoms and protecting‐thiolate ligands.…”

Effects of Diglyme on Au Nanocluster Formation: Mechanism, 1H NMR, and Bonding

“…With the growth of experimental research on ligand-protected gold nanoparticle synthesis, − ,− the mechanisms involved in this process have also been investigated using quantum chemistry calculations. − A plausible reaction pathway from Au­(III) chloride to Au­(I) thiolate via the addition of thiols was first proposed by Barngrover and Aikens using the density functional theory (DFT) method in 2011, and the involved reaction pathways were demonstrated to be thermodynamically favorable . Later, solvent effects and R group effects on the Au­(III) to Au­(I) reaction were examined theoretically .…”