Syntheses and X-ray structures of the bridging and chelating isomers of Os3(CO)10(dmpe)

The substitution chemistry of the activated clusters Os₃(CO)₁₀(MeCN)₂ (1) and Os₃(CO)₁₀(1,5-cod) (2) has been investigated with the bidentate ligand 1,2-bis(dimethylphosphino)ethane (dmpe). Both starting clusters react rapidly with dmpe at room temperature to give the corresponding substitution product Os₃(CO)₁₀(dmpe) (3), whose isomeric composition is shown to depend on the nature of the starting cluster. Whereas the bridged cluster 1,2-Os₃(CO)₁₀(dmpe) (3b) was formed almost exclusively upon reaction with Os₃(CO)₁₀(MeCN)₂, a near statistical mixture of bridging (3b) and chelating (3c) isomers of Os₃(CO)₁₀(dmpe) was found in the reaction employing Os₃(CO)₁₀(1,5-cod). Both dmpe isomers have been characterized in solution by 3iP NMR spectroscopy and their solid-state structures established by X-ray crystallography. The bridged cluster 1,2-Os₃(CO)₁₀(dmpe) crystallizes in the monoclinic space group P2₁/n, a = 9.867(2) Å, b = 17.081(3) Å, c = 14.198(2) Å, β = 95.902(3)°, V = 2380.4(6) ų, Z = 4, and d _calc = 2.793 Mg/m³; R = 0.0435, R _w = 0.0466 for 3519 reflections with I > 2σ(I). The chelated cluster 1,1-Os₃(CO)₁₀(dmpe) crystallizes in the orthorhombic space group C222(1), a = 8.329(3) Å, b = 19.028(6) Å, c = 15.008(5) Å, V = 2379(1) ų, Z = 4, and d _calc = 2.795 Mg/m³; R = 0.0390, R _w = 0.0718 for 2360 reflections with I > 2σ(I).     

Oxidative dehydrogenation of ethane over sufated zirconia supported oxides catalysts

The oxidative dehydrogenation of ethane into ethylene has been investigated on metal oxide-based sulfated zirconia catalysts at temperatures of 400–600°C. It is found that the activity and selectivity toward ethylene depend on the nature of metal oxide and temperature and that Ni and V oxides supported on sulfated zirconia exhibited higher ethylene yields.     

Transport Properties of Ethane, Butanes and Their Binary Mixtures in MFI-Type Zeolite and Zeolite-Membrane Samples

Transport properties of ethane, butane and their binary mixtures in large crystals of silicalite-1, ZSM-5, and an MFI-zeolite membrane as well as agglomerates (pellets) of silicalite zeolites have been investigated by the Zero Length Column (ZLC) method. It was found that in the large crystals of silicalite-1 and ZSM-5, and in the membrane sample desorption of iso-butane was controlled by micropore diffusion, while in the case of pelleted silicalite sample it was controlled by macropore diffusion. The effective thickness of the zeolite membrane can be reasonably evaluated by comparing the diffusivity data obtained from the ZLC and gas permeation measurements. Desorption of ethane and n-butane in the large crystals of silicalite-1 and ZSM-5 and the membrane sample is attributed to both equilibrium effects and micropore diffusion. The diffusivity of ethane is significantly reduced in the presence of iso-butane giving rise to a micropore diffusion-controlled process. Furthermore, diffusion of iso-butane in the zeolite samples is affected by the counter flow of ethane.     

Acylpyrazolone ligands: Synthesis, structures, metal coordination chemistry and applications

This review summarizes the literature on 4-acyl-5-pyrazolone ligands, their synthesis, characterization and coordination chemistry toward main group, transition, lanthanide and actinide metals and relevant applications of their metal complexes.     

Accurate adsorption energies for small molecules on oxide surfaces: CH4/MgO(001) and C2H6/MgO(001)

A hybrid method is applied that combines second order Møller–Plesset perturbation theory (MP2) for cluster models with density functional theory for periodic (slab) models to obtain structures and energies for methane and ethane molecules adsorbed on the MgO(001) surface. Single point calculations are performed to estimate the effect of increasing the cluster size on the MP2 energies and to evaluate the difference between coupled cluster (CCSD(T)) and MP2 energies. The final estimates of the adsorption energies are 12.9 ± 1.3 and 18.9 ± 1.8 kJ/mol for CH₄ and C₂H₆, respectively. © 2016 Wiley Periodicals, Inc.     

Nucleophilic substitution at phosphorus: stereochemistry and mechanisms

This review is devoted to the stereochemistry of nucleophilic substitution reactions at phosphorus. The study of the reactions of phosphoryl group transfer is important for biological and molecular chemistry. The stereochemistry and mechanisms of S_N1(P) monomolecular and S_N2(P) bimolecular nucleophilic substitution reactions of organophosphorus compounds are discussed. It has been shown that hydrolysis of many natural phosphates proceeds according to the monomolecular S_N1(P) mechanism via the formation of metaphosphate intermediate (PO₃^?). S_N2(P) nucleophilic substitution at chiral trivalent or pentavalent phosphorus compounds proceeds via the formation of penta-coordinated transition state or pentacoordinate intermediate.     

含(1-芳乙酰胺基-2-叔胺基)乙烷结构的六氢-1H-1,4-二氮(艹卓)类化合物的合成与镇痛活性

2-或5-取代的六氢-1H-1,4-二氮(艹卓)类化合物(1～3)经单酰化及酰化反应后,合成了16个带有(1-芳乙酰胺基-2-叔氨基)乙烷结构的六氢-1H-1,4-二氮(艹卓)类目标化合物(5～9,11～13,15～17,19～23),经元素分析、IR、MS和¹H NMR确证了其组成和结构。对所有目标化合物都进行了豚鼠回肠试验,初步药理试验表明,16个化合物对受试标本显示不同程度的抑制作用,对抑制率较高的两个化合物5和7测试了IC₅₀值。对在豚鼠回肠试验中显示较强激动作用的4个化合物进行了小鼠扭体法镇痛活性试验,测得了其ED₅₀值。     

Fe-P-O超细非晶态催化剂的制备与表征

共沉淀法;乙烷化学吸附;Fe-P-O超细非晶态催化剂的制备与表征     

Organic peroxide production in the Cl2-ethane-air photoreaction system

HPLC along with FT-IR technique was used to study the formation of organic peroxides in the Cl₂-ethane-air photoreaction system. Ethyl hydroperoxide (CH₃CH₂₁OOH, EHP) and peroxyacetic acid ( CH₃C(O)OOH, PAA) were conformed to be the peroxide product in the reaction system. In addition, methyl hydroperoxide (CH₃OOH, hydroxymethyl hydroperoxide (HOCH₂OOH, HMHP) and two unidentified organic peroxides were detected for the first time. EHP and were the dominant peroxide products. The identification of HMHP showed that Criegee biradical CH₂OO may be formed as an intermediate in the oxidation of ethane. Simulation results showed that photooxidation of ethane may make substantial contribution to source of organic peroxides in the atmosphere.     

Reaction chemistry of tricarbonyl-η-pentadienylmanganese: Straightforward synthesis of stable manganese carbonyl terminal thiolates and a dinuclear bis(ethylenediaminyl) complex

Tricarbonyl-η⁵-pentadienylmanganese reacts with mercaptans RSH, R = Ph, C₆F₅, m-NH₂C₆H₄, p-NH₂C₆H₄, and HSCH₂CH₂ in the presence of ECH₂CH₂E, E = -PPh₂ or -NH₂ to give novel stable terminal thiolate mononuclear complexes fac-Mn(CO)₃(SR)(Ph₂PCH₂CH₂PPh₂-κ²-P,P′) for R = Ph, C₆F₅, m-NH₂C₆H₄, p-NH₂C₆H₄, and HSCH₂CH₂ and fac-Mn(CO)₃(SR)(H₂NCH₂CH₂NH₂-κ²-N,N′) for R = Ph and C₆F₅. Upon reaction of tricarbonyl-η⁵-pentadienylmanganese with ethylenediamine a dinuclear complex [fac-Mn(CO)₃(μ-H₂NCH₂CH₂NH-κ²-N,N′)]₂ was formed wherein the diaminyl ligand functions in the capacity of chelating and bridging ligand.