Ten-vertex Zintl cluster ions are of interest because of their ability to accommodate interstitial transition ...
Wenjie Chen,Yunfei Li,Yongfan Zhang and Xin Huang~* Department of Chemistry,Fuzhou University,Fuzhou,Fujian,350108,P.R.China and State Key Laboratory of Structural Chemistry,Fuzhou,Fujian,350002,P.R.China,
The HCNH and CNH2 adsorption on different coordination sites of Cu(100) was theoretically studied considering the cluster approach. The present calculations show that the bridge site is the most favorite for CNH2 perpendicularly adsorbed on the Cu(100) surface via the C atom. For HCNH absorbed on the Cu(100) surface=the parallel adsorption mode with the C and N atoms nearly directly above the adjacent top sites of Cu(100) surface is the most favored. Both CNH2 and HCNH are strongly bound to the Cu(100) surface with CNH2 which is lightly stable (2.51 kJ.mol-1)=indicating that both species may be co-adsorbed on the Cu(100) surface.
Extensive DFT calculations are performed to optimize the geometric structures of O-rich tungsten oxide clusters, to simulate the PES spectra, and to analyze the chemical bonding. The ground-state structure of W4O14-is best considered as W4O12(O2-), containing a side-on bound superoxide ligand. The current study indicates that the extra electron in W4O12-is capable of activating dioxygen by non-dissociative electron transfer (W 5d → O2 π*), and the anionic clusters can be viewed as models for reduced defect sites on tungsten oxide surfaces for the chemisorption of O2.
The adsorption of cyanide on the top site of a series of transition metal M(100) (M = Cu, Ag, Au, Ni, Pd, Pt) surfaces via carbon and nitrogen atoms respectively, with the CN axis perpendicular to the surface, has been studied by means of density functional theory and cluster model. Geometry, adsorption energy and vibrational frequencies have been determined, and the present calculations show that the adsorption of CN through C-end on metal surface is more favorable than that via N-end for the same surface. The vibrational frequencies of CN for C-down configuration on surface are blue-shifted with respect to the free CN, which is contrary to the change of vibrational frequencies when CN is adsorbed by N-down structure. Furthermore, the charge transfer from surface to CN causes the increase of surface work function.
A theoretical study was carried out on the adsorption of hydrocyanic acid on small Aun (n ≤ 7) clusters using density functional methods. For HCN adsorption on gold clusters, no dependence was found with respect to the even-odd alternation in relation to the number of gold atoms in the cluster. The HCN molecule is adsorbed at simple adsorption sites (1-fold coordination), perpendicular to the adsorption site. The largest adsorption energy is only about 74.61 kJ·mol-1, which indicates that the HCN molecule does not decompose and the C–N bond retains triple bond, and that the C–H and C–N stretching frequencies are only weakly perturbed. The adsorbed C–N and C–H stretching frequencies are blue- and red-shifted compared with the values of free HCN, respectively.
The niobia-tantala mixed oxides are very efficient as catalysts in numerous processes. Gas-phase clusters as a...
Bocun Zhao,Xianhui Zhang,Yongfan Zhang and Xin Huang Department of Chemistry,Fuzhou University,Fuzhou,Fujian,350108,P.R.China and State Key Laboratory of Structural Chemistry,Fuzhou,Fujian,350108,P.R.China,
