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The molecular structures, stabilities, and electronic properties of the bare and complex (with group IA/IIA metals) Os32+/0/2− clusters have been investigated systematically using the density-functional theory (DFT) B3LYP method. It is found that the non-linear structures in their heptet states are energetically favored for these bare and complex osmium trimers, i.e. (7A′, Cs), (7A2, C2v) and (7A″, Cs) for bare Os32+/0/2− respectively, and as (7A′, Cs) and (7B1, 7B2, C2v) for isoelectronic (as compared to Os32−) pyramidal Os3M−/0 and bipyramidal Os3M20/2+ (M = Li, Na, K and Be, Mg, Ca) complexes. The detailed molecular orbital (MO) were analyzed. The ground-states of bare Os32+/0/2− clusters were observed to possess the multiple (partial σ- and partial δ-) aromaticity. The Os32− motif structure was perfectly preserved in these pyramidal and bipyramidal all-metal complexes, which also possess corresponding d-orbital aromatic character.

The fully halogenated or hydrogenated B

The fully halogenated or hydrogenated B12X12²- (X = H, F, Cl, Br and I) clusters are confirmed to be icosahedral.Onthe other hand, the bare B12 cluster is shown to have a planar structure.Aprevious study showed that a transformation from an icosahedron to a plane happens when 5 to 7 iodine atoms are remained [P. Farràs et al., Chem. - Eur. J. 18, 13208–13212 (2012)]. Later, the transition was confirmed to be seven iodine atoms based on an infrared spectroscopy study [M. R. Fagiania et al., Chem. Phys. Lett. 625, 48–52 (2015)]. In this study, we investigated the effects of different halogen atoms on the opening of the B12 icosahedral cage by means of density functional theory calculations.We found that the halogen elements do not have significant effects on the geometries of the clusters. The computed infrared (IR) spectra show similar representative peaks for all halogen doped clusters. Interestingly, we found a blue-shift in the IR spectra with the increase in the mass of the halogen atoms. Further, we compared the Gibbs free energies at different temperatures for different halogen atoms. The results show that the Gibbs free energy differences between open and close structures of B12X7- become larger when heavier halogen atoms are presented. This interesting finding was subsequently investigated by the energy decomposition analysis.

The structures, stabilities, and bonding features of neutral M(η5-P5)2 (M = Fe, Ru, and Os) and cationic M(η5-P5)+ have been investigated using density functional theory (DFT) (hybrid B3LYP and pure BP86 methods). The eclipsed (D5h) structure has been predicted to be the global minimum for this triad bis(pentaphospholyl) metallocenes, and the staggered (D5d) structure to be the rotational transition state. The distances between the metal and cyclo-P5 center in bis(pentaphospholyl) metallocenes are longer than in the corresponding M(η5-P5)+ by 0.28-0.38 Å. The M(η5-P5)+ complexes may be tighter binding with the shorter metal-ring distances, the possible reason is that there being stronger metal-ring π interactions in M(η5-P5)+ than in M(η5-P5)2, even though latter satisfies the 18-electron rule. The electron densities are found to accumulate at the metal centers, this novel situation may have an impact on the mechanism of some potential catalysis reactions.

Poly (styrene-co-acrylonitrile) supported TiCl4 was prepared and characterized. IR analysis shows that the absorption of the acronitrile group shifted from 2233cm-1 to 2277cm-1 after its coordination to TiCl4. It is found that this catalyst shows a much higher catalytic activity than that of TiCl4 in the preparation of sydiopolystyrene, especially, it can be used to prepare a styrene rich poly (styrene-co-ethylene), the resulted poly (styrene-co-ethylene) is a crystalline polymer shown a Tm much lower than that of a homo sydiopolystyrene. The molecular simulation result shows that the coordinated metal in the polymer catalyst is more cationic, probably due to an electron withdraw group coordinated to the central metal. This result can help us to understand that the polymer catalyst is more active and there is less cocatalyst MAO was used in the polymerisation process. Based on the results both of the experiment and the molecular simulation, we can give a conclusion that the polymer backbone stabilized the central metal Ti and make it difficulty to be reduced to a TiII complex, and the later shows no activity in the polymerisation. The stabilization is from the coordination of the polymer backbone and not due to an electron donor ligand which is in a normal metallocene.

This paper is basic on a new production small-scale mining road header. It researches the characters of the hydraulic system and mainly concerns on its constant power systems mathematical models, analysis of stability of working condition, the simulation and modulation using the software of AMESim.

Recently, silver nanoparticles(NPs)-based photocatalysts have attracted more attention due to their enhanced visible light photocatalytic activity. In this work, a new Ag@Ag3PO4photocatalyst have been prepared by precipitation replacement and reduction methods. The products were characterized by XRD and SEM. The photocatalytic activities was evaluated using 2-naphthol and methyl orange degradations under visible light irradiation (λ > 400 nm). The degradation rates of 2-naphthol and methyl orange with initial concentration of 15 mg•L-1reached 80% and 99% respectively by using 0.6 g•L-1Ag@Ag3PO4. The photocatalytic mechanism was discussed.

The structures and stabilities of a series of pyramidal MB7 (M = Li, Na, K, Rb, Cs) species were studied by using ab initio (MP2/6-311+G*) and density functional theory (B3LYP/6-311+G* and B3PW91/6...

The structures and stabilities of a series of pyramidal MB7 (M = Li, Na, K, Rb, Cs) species were studied by using ab initio (MP2/6-311+G*) and density functional theory (B3LYP/6-311+G* and B3PW91/6...