Computational Investigation of the Preferred Binding Modes of NO in Group 8 Metal Complexes.

Nitrous oxide (NO) is a potentially important oxidant for green chemistry applications but thus far has shown limited examples as a ligand for transition metal complexes. Given the lack of reported NO complexes, density functional theory was utilized to study the potential binding effects in multiple group 8 metal complexes. NO is found to be a very weakly π-accepting ligand (approximately 1/3 as effective as CO).

A topological isomer of the Au(SR) nanocluster.

Energetically low-lying structural isomers of the much-studied thiolate-protected gold cluster Au25(SR)18- are discovered from extensive (80 ns) molecular dynamics (MD) simulations using the reactive molecular force field ReaxFF and confirmed by density functional theory (DFT). A particularly interesting isomer is found, which is topologically connected to the known crystal structure by a low-barrier collective rotation of the icosahedral Au13 core. The isomerization takes place without breaking of any Au-S bonds.

Theoretical examination of solvent and R group dependence in gold thiolate nanoparticle synthesis.

The growth of gold thiolate nanoparticles can be affected by the solvent and the R group on the ligand. In this work, the difference between methanol and benzene solvents as well as the effect of alkyl (methyl) and aromatic (phenyl) thiols on the reaction energies and barrier heights is investigated theoretically. Density functional theory (DFT) calculations using the BP86 functional and a triple ζ polarized basis set show that the overall reaction favors methylthiol over phenylthiol with reaction energies of -0.

Prediction of nonradical Au(0)-containing precursors in nanoparticle growth processes.

This density functional theory (DFT) investigation examines the formation of nonradical Au(0) species from the reduction of Au(I) species. The Au(I) complexes of interest are AuCl2(-), AuBr2(-), AuI2(-), AuClPH3, and AuCl(H)SCH3(-), which are precursors for gold nanoparticle and cluster formation. Reaction of two of the Au(I) species with a hydride results in ejection of two of the ligands and formation of Au2 with two ligands still attached.

Oxidation of gold clusters by thiols.

The formation of gold-thiolate nanoparticles via oxidation of gold clusters by thiols is examined in this work. Using the BP86 density functional with a triple ζ basis set, the adsorption of methylthiol onto various gold clusters Aun(Z) (n = 1-8, 12, 13, 20; Z = 0, -1, +1) and Au38(4+) is investigated. The rate-limiting step for the reaction of one thiol with the gold cluster is the dissociation of the thiol proton; the resulting hydrogen atom can move around the gold cluster relatively freely.

The golden pathway to thiolate-stabilized nanoparticles: following the formation of gold(I) thiolate from gold(III) chloride.

Pathways for the formation of gold thiolate complexes from gold(III) chloride precursors AuCl(4)(-) and AuCl(3) are examined. This work demonstrates that two distinct reaction pathways are possible; which pathway is accessible in a given reaction may depend on factors such as the residue group R on the incoming thiol. Density functional theory calculations using the BP86 functional and a polarized triple-ζ basis set show that the pathway resulting in gold(III) reduction is favored for R = methyl.

Incremental binding energies of gold(I) and silver(I) thiolate clusters.

Density functional theory is used to find incremental fragmentation energy, overall dissociation energy, and average monomer fragmentation energy of cyclic gold(I) thiolate clusters and anionic chain structures of gold(I) and silver(I) thiolate clusters as a measure of the relative stability of these systems. Two different functionals, BP86 and PBE, and two different basis sets, TZP and QZ4P, are employed. Anionic chains are examined with various residue groups including hydrogen, methyl, and phenyl.