Closed-Cage Tungsten Oxide Clusters in the Gas Phase

Abstract

During the course of a study on the clustering of W-Se and W-S mixtures in the gas phase using laser desorption ionization (LDI) , stand out as intense peaks in the regular mass spectral pattern of tungsten oxide clusters suggesting unusual stabilities for them. Moreover, these clusters do not fragment in the postsource decay analysis. While trying to understand the precursor material, which produced these clusters, we found the presence of nanoscale forms of tungsten oxide. The structure and thermodynamic parameters of tungsten clusters have been explored using relativistic quantum chemical methods. Our computed results of atomization energy are consistent with the observed LDI mass spectra. The computational results suggest that the clusters observed have closed-cage structure. These distinct W 13 and W 14 clusters were observed for the first time in the gas phase.

Structures and Electronic Properties of Cu3On (n = 1–6) Clusters using ab initio Monte Carlo Simulations

“…25 Also, the B3LYP functional and LANL2DZ basis set have been previously used for studying transition metal oxide clusters. [35][36][37][38][39] Not every configuration of each MC step was optimized. After running the MC simulation, we obtained local minimum energy structures among all of the configurations.…”

Density Functional Calculation of the Structure and Electronic Properties of CunOn (n = 1−8) Clusters

“…Although there are well known deficiencies with the B3LYP functional (particularly for excited states63), there are plenty of studies of transition metal clusters (neutral and charged) for which the B3LYP/LANL2DZ basis set has been used successfully 64–68. For TiO 2 and TiO, Qu and Kroes64 found (in comparison to experiment) vibrational frequencies accurate to about 60 wavenumbers, ionization energies accurate to 0.2 eV, and electron affinities accurate to 0.2 eV.…”

Molybdenum blue nano-rings: an effective catalyst for the partial oxidation of cyclohexane

“…26,27 This suggests that MB could be a good candidate as a catalyst in some challenging selective oxidation reactions. For this reason we have explored whether or not the Mo V -O-Mo VI bridging structure in MB is active for selective redox chemistry 6,[8][9][10][11][12][13] by testing it for the oxy-functionalization of cyclohexane.…”

“…9 There has been particular interest in utilising molybdenum oxide containing catalysts, including the use of heteropolyacids. 10,11,12 In the majority of these reports the molybdenum is usually present as Mo VI species. However, it has been demonstrated that an activating pre-treatment step in an H 2 or a hydrocarbon atmosphere is very important in establishing the activity and selectivity of oxidized molybdenum carbides.…”

“…9,13 We also note that in many previous studies of other molybdenum-based materials, including molybdenum sulfides and molybdenum oxides, there have been reports of a strong blue colouration, thereby suggesting the possible formation of MB-like species during their preparation. [9][10][11][12] Consequently, we reasoned that MB, which exhibits significant electron hopping between Mo V and Mo VI sites via Mo V -O-Mo VI bridging bonds, might represent a material that could be highly active for selective redox chemistry. 6 In particular, we considered that MB should be active for the oxyfunctionalization of alkanes to selective oxidation products such as alcohols, ketones and acids, and additionally that this process should be feasible under mild reaction conditions.…”