The interaction of gold clusters with methanol molecules: Ab initio molecular dynamics of Aun+CH3OH and AunCH3OH

Abstract

Two worlds collide: Image analysis methods for quantifying structural variation in cluster molecular dynamics J. Chem. Phys. 140, 064102 (2014); 10.1063/1.4864753The interaction of gold clusters with methanol molecules: Infrared photodissociation of mass-selected Au n + (CH 3 OH) m Molecular dynamics study of the Ag 6 cluster using an ab initio many-body model potential Structural, dynamical, and electronic properties of adducts obtained by adsorbing one methanol molecule onto charged and neutral gold clusters, Au n ϩ -CH 3 OH and Au n -CH 3 OH, are investigated using Car-Parrinello ab initio molecular dynamics as a function of the cluster size n. The absorption process occurs by the formation of a Au à -O coordination bond to one particular gold atom Au à without altering the structure of the underlying cluster. This chemical bond is much stronger for the charged metal clusters Au n ϩ than for the neutral analogs Au n . In the charged case, the C-O stretching vibration of the interacting methanol molecule is found to increase discontinuously as the underlying cluster structure changes from two-dimensional to three-dimensional. The weaker C-O bond in the neutral species however has ''insufficient strength'' to be sensitive to changes in coordination number and cluster structure. This leads to a constant C-O stretching frequency as the size of the cluster increases, including the regime where the Au n cluster changes from planar to three-dimensional.

Theoretical Study of Methanol Decomposition Mediated by Au3+, Au3 and Au3−: Mechanism and Effect of Charge State of Gold on its Catalytic Activity

“…Clearly, the added positive charge enhances the interaction between Au 3 + cluster and methanol. This result is in good agreement with the previous study by Rousseau and Marx [14]. The initial O -H bond scission proceeds via TS 14 - 15 with a barrier as high as 67.5 kcal mol -1 .…”

“…Many previous papers have been devoted to studying the interaction of different charged Au clusters and methanol molecules [13 -16], and some important conclusions have been made. In particular, Rousseau and Marx [14] reported the results of Car -Parrinello molecular dynamics calculations on the methanol -Au cluster systems. They proposed that the Au -O chemical bond is much stronger for the positively charged Au clusters than for neutral Au clusters.…”

Trends in the structure and bonding of noble metal clusters

“…Recently a combined experimental and theoretical study of small anionic 16 and cationic 18,43,44 gold clusters has allowed the assignment of the transition from planar to three-dimensional (3D) structures at n = 14 for Au n − and at n =9 18 or n =7 43,44 for Au n + . Cationic Ag n + clusters with n Ͻ 12 have been studied experimentally and theoretically by Weis and co-workers 17 obtaining 3D structures for n ജ 5, with different geometries than those of gold cations 18 for n Ͼ 5.…”

Infrared Study of OCS Binding and Size-Selective Reactivity with Gold Clusters, Aun+ (n = 1–10)

“…65 The NO stretching frequency of AunNO + complexes exhibits marked odd-even alternation, as the unpaired electron in the l Aun + (n = even) clusters efficiently donates into the NO * orbital, efficiently activating it. 7 Infrared studies of other adsorbates (e.g., CO, 7,66 methane, 67 methanol, [68][69][70] ethanol, 71 and ethene 72 ) on gold clusters suggest alternative binding mechanisms for which odd-even size effects are less clear. All small gold clusters selectively dissociate a single C-H bond in CH4 but, whilst CH4 binding energies to Aun + show a clear size dependence, 73 this is not reflected in the IR-MPD spectra.…”