摘要:

AbstractThe isomeric structures, isomerization and decomposition of silylenoids H2SiMX (MXKF, KC1, LiBr, NaBr and KBr) have been investigated byab initiomolecular orbital theory. These silylenoids have four kinds of very similar equilibrium structures. The three‐membered ring andp‐complex structures should be stable and experimentally detectable. The lifetime of σ‐complex and tetrahedral structures would be very short and experimentally unde

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130602

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractBoth processes of decarboxylation and decarbonylation of a number of acids including RCOCO2H, RH, CH3, CH2F, CF3, CHCH2, Ph, OH have been studied by semi‐empirical MO theory AM1 method to verify the reaction mechanism of each process and the effect of different substituents on them. The calculated results are consistent with the experimental reports and can be summed up as follows: (1) The decarboxylation of these acids to form aldehydes and carbon dioxide is concerted and takes place through a 4‐membered ring transition state in which a partial negative charge develops on the carbon of the α‐carbonyl group, so that the inductive effect of some substituents is favourable for this process. (2) Their decarbonylation into carboxylic acids and carbon monoxide however is the attack of the OH on the carbon of the alkyl portion of the acid, forming a 3‐membered ring transition state. (3) The activation energy of decarbonylation is lower than that of decarboxylation, since oxygen is more nucleophilic than hydrogen and also the strong OH bond need not

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130603

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractMolecular layer of tungstosilicic acid (H4SiW12O40) deposited on freshly‐cleaved highly oriented pyrolytic graphite (HOPG) was observed by scanning tunneling microscopy (STM) in air at room temperature. The molecular dimension (11.5 Å) of H4SiW12O40measured by STM is consistent with known crystallographic parameter. We also imaged the boundary of H4SiW12O40molecular layer on HOPG showing that molecular layer of H4SiW12C40was formed. It has been proved that individual tungstosilicic acid species is imaged. The probable reason for the formation of the molecular layer is also discuss

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130604

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractA new dinucleating Schiff base ligand HL(LC13H17N2O−3) has been synthesised and characterized. The single crystal structure of its complex [L2Cu4O(AcO4)]·2H2O has been determined by X‐ray diffraction methods. The result indicates that every Cu atom has its square pyramidal coordination polyhedron and there is a tetrahedral Cu4O core in the complex molecule. Its active sites where catalytic oxidation of dioxygen occurs have been in

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130605

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractA three electrode‐measurement unit with 33 microdisk electrode‐array (MDA) as working electrode was constructed by lithography. Its electrochemical behavior was observed. The results of the oxidation of ferrocene in CH3CN‐H2O mixed media demonstrate that high quality electrochemical data for the system without supporting electrolyte can be achieved with the MDA unit constructed in the present

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130606

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractIn this paper, we have suggested an iterative procedure of optimization of the linear parameters in an analytic potential energy function for a triatomic molecule, by combining both variational and second order perturbation methods. The most important feature of this procedure is that the objective function is an analytical expression which can be optimized easily. The application to the water molecule is presented.

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130607

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractA homologous series ofn‐butyl‐4‐[4‐((4‐n‐alkoxyl‐tetrafluorophenyl)ethynyl)benzyloxy] benzoates have been synthesized. Their phase transition temperatures have also measured by polarizing textural observation and con

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130608

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe solid state reactions ofp‐nitroacetophenone, acetyl‐ferrocene with indole were catalyzed by anhydrous zinc chloride or aluminum chloride, and gave exclusively the 1:2 condensation products. The solid state condensation of aromatic ketones with l‐phenyl‐3‐methyl‐5‐pyrazolone was also investigated, and the 1.1 and 2.1 condensation products were obtained. The structures of eleven new products were determined by IR, MS,1H NMR and eleme

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130609

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractFullerene C60reacted withp‐azidostyrene derivatives in refluxing chlorobenzene, yielding monoadducts 2a and 2d as well as diadduct 2c with aziridine structure at 6/6‐ring junctions. Experimental results showed that the addition of the second azide to the monoadduct was regioselective. The diadduct, ofCasymmetry in C60moiety, was unstable by opening to be 1,6‐imido[10]annulene stru

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130610

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe fluorescence spectra and photodimerization of anthrylmethyl α,ω‐alkanedioates (A‐Mn‐A; both in organic and in aqueous organic mixed solvents have been studied. In aqueous organic mixed solvents strong intramolecular excimer emission is detected and the quantum yield for the intramolecular photodimerization is significantly greater than those in organic solvents. These observations suggest that hydrophobic interactions force A‐Mn‐A molecule to self‐coil. The ratio of the head‐to‐head to head‐to‐tail products in the intramolecular photodimers of A‐Mn‐A depends on the length of the linking chain. This work presents a successful example of application of hydrophobic interactions to enhancemen

ISSN:1001-604X    

DOI:10.1002/cjoc.19950130611

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY