摘要:

AbstractA single MoFe3S4cubane‐like cluster compound has been synthesized through spontaneous self‐assembly of simple inorganic salts with organosulfur ligand for the first time. (Et4N)‐(MoFe3S4(Et2NCSS)5] CH3CN(1) is quite stable in air. The crystal of 1 is monoclinic with space groupP2/c,a=22.897 (3)Å,b= 12.399 (2)Å,c=20.928 (4)Å, β=97.15 (1)°, andZ=4. A full matrix least‐squares refinement with 6725 unique reflections for all nonhydrogen atoms givesR=0.068.The anion of 1 is the first isolated single MoFe3S4cubane cluster with core oxidation state [MoFe3S4]4+. The distance between the two 6‐coordinate metal atoms (Mo, Fe) is 2.624 Å, which is the shortest M‐M' bond observed for Mo‐Fe‐S clusters so far and the only one shorter than similar distances in FeMo‐cofactor.The bond orders of this anion were calculated by EHMO method and the results coincide with the general rule. The structural feature and the unusual stability of 1 can be attributed to the bidentate chelating effect of Et2NCSS‐, which leads to high coordination of metal atoms and

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040202

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe1H NMR spectra recorded during the thermolysis of lauroyl peroxide and of 3,5,5‐trimethylhexanoyl peroxide in ODCB containing 2‐iodopropane show CIDNP multiplet effect. It was observed that the relative concentrations of 1‐iodoundecane and 2‐iodopropane, both polarized and normal species, changed with time. The relaxation timeT1of the α‐protons in 1‐iodoundecane and vinyl protons of CH2in 1‐undecene, enhancement factor of the protons of polarized species and the rate constant of decomposition for lauroyl peroxide have been determined. The mechanism of the decomposition of the entitled peroxides is discussed in terms of the radic

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040203

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe phase equilibria as well as the properties and crystal structures of the compounds formed in both Li2SO4‐MgSO4and Li2SO4‐Li4SiO4systems have been studied by means of x‐ray diffraction technique (at high and room temperatures) as well as by the thermal analyses (DTA, DSC, TGA,etc.).In Li2SO4‐MgSO4system there exists a compound Mg4Li2(SO4)5formed by peritectic reaction at 840°C and decomposed at 105°C into the Li2SO4‐base solid solution and MgSO4· Mg4Li2(SO4)5and Li2SO4‐base solid solution conduct an eutectic reaction at 663°C with the composition of eutectic point lying in 22 mol% MgSO4. The solubility of MgSO4in Li2SO4is a little smaller than 10 mol% while at the same time the Li2SO4phase transition temperature decreases from 574 to 560°C On the other hand, no noticeable solid solubility of Li2SO4in MgSO4has been observed. The reaction\documentclass{article}\pagestyle{empty}\usepackage{amssymb,amsmath}\begin{document}$$ 4{{\rm MgSO}}_4 + {{\rm Li}}_2 {{\rm SO}}_4 \underrightarrow {105^\circ {{\rm C}}}{{\rm Mg}}_4 {{\rm Li}}_2 ({{\rm SO}}_4)_5 $$\end{document}is an endothermal one and its heat of formation is 2.57 kJ/mol. The activation energy of the reaction calculated by thermal peak displacement method at various heating rates is 173.5 kJ/mol (1.80 ev). The crystal Mg4Li2(SO4)5belongs to orthorhombic system with lattice parameters at 180°C:a= 8.577,b=8.741,c= 11.918 Å. The space group seems to be eitherP222 orPmmm. Assuming that there are two formula units in a unit cell, the density calculated is then 2.20 g/cm3very close to that of Li2SO4or MgSO4.Meanwhile, in Li2SO4‐Li4SiO4system a new phase Li8‐2x(SiO4)8‐x(SO4)xis formed by peritectic reaction at 953°C with a range of compositionx=0.96 −0.58. The crystal belongs to ortho‐rhombic system with lattice parameters atx=0.8:a= 5.002,b= 6.173 andc=10.608Å. The density observed is 2.31 g/cm3and there are 2 formula units in an unit cell. It is shown from the measurements of piezoelectric and laser SHG coefficients of the crystal that the crystal posseses a symmetrical center with the space group belonging toPmmn. The lattice parameterchas a maximum atx=0.8. In the air Li8‐2x(SiO4)2‐x(SO4)xcan absorb 7.6 wt% water vapour and other gases which can only be desorbed by heating it at a temperature above 350°C. Neither absorption nor desorbtion can change its crystal structure, a characteristic similar to that of zeolite molecular sieve. The dewater activation energy of Li8‐2x(SiO4)2‐x(SO4)xis 171.5 kJ/mol.Li8‐2x(SiO4)2‐x(SO4)xand Li4SO4bring about an eutectic reaction at 823°C with its eutectic composition being 12 mol% Li4SiO4. No observable solubility of Li4SiO4in Li3SO4has been noticed. The solubility of Li2SO4in Li4SiO4is approximately equal to 5 mol%. With Li2SO4being dissolved in, the phase transition temperature of Li4SiO4is decreased.After being fused, the specimens Li3SO4‐MgSO4and Li2SO4‐Li4SiO4are cooled at a rate of 10°C/min, their meta

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040204

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe electrocatalytic reduction of carbon dioxide in aqueous solution using Co [p‐N(CH3)3) TPPI under pressure (4∼22 kg · cm−2) was carried out on solid‐state metal electrodes such as In, Sn, Pb and Pb‐Hg. The reduction products were mainly carbon monoxide and a small amounts of formic acid. The effects of the pressure of carbon dioxide, electrolytes, catalyst concentration, electrode materials and potentials on the reduction of carbon dioxide were studied. The optimum voltage for maximum current efficiency of reduction products was at −1.2Vvs.SCE for all four kinds of metal electrodes. High current efficiencies (>90%) were obtained with lead and amalgamated lead electrodes in an aqueous solution of NaHCO3containing 7.4 × 10×5mol

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040205

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractVarious silatrane compounds were studied by means of15N NMR spectroscopy. The quantum chemical calculations of some of the compounds were carried out using CNDO/2 method. The following correlations were obtained,i.e.,15N chemical shifts vary linearly with Taft's polar substituent constants (s) of the substituents R on the silicon atoms, and also with the net charge densities on the nitrogen atoms. From both experimental and theoretical aspects, it could be concluded that the SiN dative bonds in a series of silatrane compounds actually exist.

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040206

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractIn a supporting electrolyte containing 6 × 10−5M Alizarin red S, 0.2 M NH3‐NH4Cl, at pH 8.2‐8.6, three adsorptive complex waves of germanium‐Alizarin red S have been obtained by single‐sweep polarograph. The most sensitive one among them is atEp=−1.130 V (SCE). The compositions of the complexes and the mechanism of electrode processes were studi

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040207

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe title compound has been prepared. Using1H NMR,13C NMR and selected decoupling method, the compound is shown in the keto‐form. DNMR method was used to investigated the exchange between NH in the title compound and water in DMSO‐d6. The rate process was calculated by complete line shape analysis method and activation parameters ΔH≠, ΔG≠and ΔS≠were found to be 8.4±0.5 kcalmol−1, 16.9±0.2 kcalmol−1and −26.9±1.5 ca

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040208

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractSeveral quaternary phosphonium salts have been used as the site materials for construction of carbonate ion electrodes. Among them the electrode based on hexadecyltriphenylphosphonium salt showed best performance characteristics. The Nerstian response range of the electrode is from 1 × 10−2down to 6.3 × 10−7mol · dm−3with a detection limit of 1.8 × 10−7mol · dm3. The selectivity order of ions can be altered by the introduction of trifluoroacetyl‐tert‐butylbenzene as a solvent mediator. The strong solvatoin of the primary ion of interest in the membrane phase by the solvent mediator favors the improvement of the selectivity of the pr

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040209

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractDSIP and its fourteen analogs as well as three short peptides were synthesized by solid phase method. The design of the analogs was based on the consideration of the introduction ofD‐amino acid into the molecules to inhibit the enzymatic hydrolysis and the introduction of amino acids with a hydrophobic side chain. The modification was placed on the position of 1, 3, 4, 5, 8 and 9,e.g. D‐ Trp1, Tyr1, Tyr1Phe5,D‐Trp1Phe8, Trp3,4,D‐Trp1,3,4Phe8,D‐Trp3,4Phe8D‐Glu9,D‐pF‐Phe3,4Phe8D‐Glu9, Phe5, Glu5Asp9, Tyr6Asp9, Asp9and Ala7‐DSIP as well as Trp‐Ala‐Gly‐Gly‐Asp, Trp‐Ala‐Gly‐Gly‐Glu and Trp‐Gly‐Glu. DSIP and Phe5‐DSIP were also prepared by pentafluorophenyl ester method. The purity of the synthetic peptides was checked by amino acid analysis, elemental analysis, thin layer chromatography and paper electrophoresis. The biological assay showed that the analogs ofD‐Trp1, Tyr1, Tyr1Phe5and Ala7‐DSIP as well as three short peptides were inactive whereas Phe5‐DSIP sh

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040210

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractQuantum chemical calculations and studies have been made on the different spin states of unsaturated carbenes X2CC: and X2CCC: (XH, Li, F). The geometries and relative stabilities of these carbenes with various groups X have been outlined. The ground states of unsaturated carbenes are all singlet. The energy splittings between the ground states and first excited states ΔE(1A1‐3B1) are generally within the value of 60 kcal/mol and change greatly with the electronegativities of groups X, but little with the sizes of the cumulidenes. The equilibrium conformations of1A1and3B1are

ISSN:0256-7660    

DOI:10.1002/cjoc.19860040211

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY