以交叉分子束及时间切片离子速度成像法研究产物成对相关讯息

A novel experimental technique has been developed to measure the attributes of product pair correlation of bimolecular reactions under the crossed molecular beam condition. The first system that we picked is F + CD4/CHD3 / CH4 reactions. By combining a crossed molecular beam method with a time-sliced ion velocity imaging technique,the product state-resolved pair-correlated differential cross sections were revealed directly from the measurements. Several facets of the product pair correlation have been explored. The dependence on the collisional energy has been elucidated. The pair-correlated angular distributions show strong dependences on the HF/DF vibrational quantum numbers,and weaker yet not negligible dependences on the methyl radical vibrational quantum numbers. For the F + CH4 reaction at collisional energies close to the reaction threshold,the first experimental evidences of a reactive resonance in a polyatomic reaction were discovered. The product pair-correlated information helps us to unravel the complexity of polyatomic reactions and offers the important link between A + BC type of reactions and more general polyatomic reactions.     

A General Procedure for Synthesis of NG-Alkyl,and NG-Aryl-L-Arginines as Potential Nitric Oxide Synthase inhibitors

A general procedure for the synthesis of N^G-alkyl, and N^G-aryl-L -arginines with relatively high overall yield is reported. The key step involved the coupling of protected L -ornithine 4 with isothiourea 7 to give the fully protected N^G-aryl-L -arginine derivative 8 . Subsequent deprotection of 8 in acidic condition provided the final target compound 9 with an overall yield of more than 80%.     

A Cantor set Associated With Sierpinski's Algorithm

W. Sierpiski showed that each x in 0<x1 has a representation1/a₁...a_k is an increasing sequence of positive integers. Weshow that the subset of numbers x for which(a_k) is strictlyincreasing is a Cantor set.     

Organotransition-Metal Complexes of Multidentate Ligands 3. The Unexpected Derivatives of Bis(3,5-Dimethylpyrazol-1-YL)Methanetetracarbonylmolybdenlim(0) and-Tungsten(0) Complexes

Thermolysis of (H₂CPz′₂)M(CO)₄ (H₂CPz′₂ = bis(3,5-dimethylpyrazol-1-yl)methane; M=Mo, W) in 1,2-dimethoxyethane did not give the expected 16-electron complexes, (H₂CPz′₂)M(CO)₃, but gave dinuclear compounds, [(H₂CPz′₂)M(CO)₃]₂, probably containing two linear carbonyl bridges and no metal-metal interactions. The dimers reacted with CH₃CN to give mononuclear compounds, (H₂CPz′₂)M(CO)₃(NCCH₃), identical to the substitution products between (H₂CPz′₂)M(CO)₄ and CH₃CN.     

Synthesis of Lithiophorite in High Alkaline Conditions

Lithiophorite consists of alternatively stacked MnO₆ octahedral sheets and LiAl₂(OH)₆ octahedral sheets. Its applications in laboratories and industries have been hindered by sophisticated operation procedures, long reaction time, or impurities existing in the final product. We proposed a fast and simple method, mixing birnessite, aluminate and lithium hydroxide together (designated it as the BAL method) in high alkaline conditions (pH > 13), and treating it hydrothermally at 423 K for 6 hours to prepare pure lithiophorite. A specific reaction between lithium cations and aluminate anions plays as a key role in the BAL method. Due to this specific reaction, Li_xAl_n(OH)_m^+z complexed cations can form and penetrate into interlayers of birnessite to replace sodium cations. In high alkaline conditions (pH > 12), Li_xAl_n(OH)_m^+z complexed cations become smaller and are soluble. Thus, the higher alkaline Li_xAl_n(OH)_m^+z complexed cations can penetrate into interlayers of birnessite at a higher rate. Furthermore, impurities, such as lithium intercalated gibbsite (LIG), aluminum oxyhydroxides and aluminum hydroxides are not stable in high alkaline conditions. Consequently, pure lithiophorite can be easily obtained within 6 hours in high alkaline conditions.     

Syntheses, X-ray structures, and reactions of ruthenium carbonyl complexes containing 1,1-dithiolates

Treatment of [Ru₂(CO)₄(MeCN)₆][BF₄]₂ or [Ru₂(CO)₄(μ-O₂CMe)₂(MeCN)₂] with uni-negative 1,1-dithiolate anions via potassium dimethyldithiocarbamate, sodium diethyldithiocarbamate, potassium tert-butylthioxanthate, and ammonium O,O′-diethylthiophosphate gives both monomeric and dimeric products of cis-[Ru(CO)₂(η²-(SS))₂] ((SS)⁻=Me₂NCS₂⁻ (1), Et₂NCS₂⁻ (2), ^tBuSCS₂⁻ (3), (EtO)₂PS₂⁻ (4)) and [Ru(CO)(η²-(Me₂NCS₂))(μ,η²-Me₂NCS₂)]₂ (5). The lightly stabilized MeCN ligands of [Ru₂(CO)₄(MeCN)₆][BF₄]₂ are replaced more readily than the bound acetate ligands of [Ru₂(CO)₄(μ-O₂CMe)₂(MeCN)₂] by thiolates to produce cis-[Ru(CO)₂(η²-(SS))₂] with less selectivity. Structures 1 and 5 were determined by X-ray crystallography. Although the two chelating dithiolates are cis to each other in 1, the dithiolates are trans to each other in each of the {Ru(CO)(η²-Me₂NCS₂)₂} fragment of 5. The dimeric product 5 can be prepared alternatively from the decarbonylation reaction of 1 with a suitable amount of Me₃NO in MeCN. However, the dimer [Ru(CO)(η²-Et₂NCS₂)(μ,η²-Et₂NCS₂)]₂ (6), prepared from the reaction of 2 with Me₃NO, has a structure different from 5. The spectral data of 6 probably indicate that the two chelating dithiolates are cis to each other in one {Ru(CO)(η²-Et₂NCS₂)₂}fragment but trans in the other. Both 5 and 6 react readily at ambient temperature with benzyl isocyanide to yield cis-[Ru(CO)(CNCH₂Ph)(η²-(SS))₂] ((SS)=Me₂NCS₂⁻ (7) and Et₂NCS₂⁻ (8)). A dimerization pathway for cis-[Ru(CO)₂(η²-(SS))₂] via decabonylation and isomerization is proposed.     

Normal Components, Kekulé Patterns, and Clar Patterns in Plane Bipartite Graphs

As a general case of molecular graphs of polycyclic alternant hydrocarbons, we consider a plane bipartite graph G with a Kekulé pattern (perfect matching). An edge of G is called nonfixed if it belongs to some, but not all, perfect matchings of G. Several criteria in terms of resonant cells for determining whether G is elementary (i.e., without fixed edges) are reviewed. By applying perfect matching theory developed in plane bipartite graphs, in a unified and simpler way we study the decomposition of plane bipartite graphs with fixed edges into normal components, which is shown useful for resonance theory, in particular, cell and sextet polynomials. Further correspondence between the Kekulé patterns and Clar (resonant) patterns are revealed.