摘要:

AbstractA newly developed self‐consistent‐field molecular orbital theory is described and tested. The intermediate neglect of differential overlap (INDO) approximation is used, and all interaction integrals are differentiated according to their dependence upon2sand2pAO's. The bonding parameter βlis reformulated so that the model is calibrated to only one specific molecular property, namely, the ionization energy of Hi. We expect that this model will not be biased toward any special families of molec

ISSN:0009-4536    

DOI:10.1002/jccs.198500060

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractIn the photolysis of acetone at 265nmat 27°C the quantum yield of biacetyl has been determined to be 0.34 and the primary decomposition yield is evaluated to be about 0.68. The fraction of triplet acetone decomposed into methyl and acetyl radicals is estimated to be 0.14 at 313nm. The acetyl radicals undergo reaction to form biacetyl 50 times faster than decomposition to methyl radicals and carbon monoxide

ISSN:0009-4536    

DOI:10.1002/jccs.198500061

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe spin transition of high‐spin (sT2⇄)low‐spin (1A1) of (dithiocyanato) (N‐phenyl‐2‐pyridinaldimine) iron (II) complexes can be altered by substituents on the phenyl ring. Mössbauer spectra at 78Kfor the 4‐substituted derivatives (with the exception of the 4‐OH‐substituted derivative) indicate that the fraction of low‐spin states increases with decreasing substituent electron‐withdrawing ability, as measured by the Hammet σ constant (4‐OCH3<4‐CH3CONH 4‐C6H5<4‐CH3<4‐H<4‐Cl<4‐NO2). In addition, the effect of methyl‐substitution at the ortho‐, meta‐ or paraposition of the phenyl ring on the spin transition was examined. Mössbauer spectra of these methyl‐substituted co

ISSN:0009-4536    

DOI:10.1002/jccs.198500062

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractDetermination of trace amount of vanadium in water was studied by flow injection analysis. Catalytic spectrophotometric detection was performed with bromate oxidation ofo‐phenylenediamine and by addition of tiron as an activator and also as a masking agent. Vanadium can be determined with sample rate of ca. 60–70 samples/hour with in a range of 0.01ppmto 0.5ppmV and with r.s.d. 0.555% for 0.1ppmV and 0.37% for 0.3ppmV. Interference by Fe(III) can be reduced by using 0.3% NH4F as a carrier solut

ISSN:0009-4536    

DOI:10.1002/jccs.198500063

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractSpeciation of Cr(III) and Cr(VI) can be attained by flow injection analysis with amperometric detection. Cr(VI) is reduced in an acidic medium to Cr(III) with a glassy carbon electrode at —0.1V vs.Ag/AgCl and the current is recorded. Cr(III) is oxidised on‐line to Cr(VI) with alkaline hydrogen peroxide solution. From the difference of the total chromium and Cr(VI), the amount of Cr(III) was obtained. A linear calibration curve for Cr(VI) was obtained for the concentration ranges 0.01‐5.0ppmof Cr(VI) and we have calculated the limit of determination to be about 0.5ppb.We have studied the degree of reproducibility obtained using the solid electrodes under various conditions. The influence of flow rate, coil length, interfenences and the extent of reaction were st

ISSN:0009-4536    

DOI:10.1002/jccs.198500064

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0009-4536    

DOI:10.1002/jccs.198500065

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractPolarographic techniques have been used to investigate the complexing behaviour of chromium (III)‐ethylenediamine‐tartrate in aqueous solution. These complexes are reduced irreversibly at the dropping mercury electrode. The stability constants have been calculated by the method of Sundaresan and Sundaram. The values of the kinetic parameters; standard rate constant(Ks), transfer coefficient (α) and activation energy(Q)have also been calculated in each

ISSN:0009-4536    

DOI:10.1002/jccs.198500066

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractA series of binucleating Uganda with fully conjugated π‐systems have been synthesized. Homobinuclear copper(II) complexes of the form [(Cu(dien)ClO4)2L]‐(ClO4)2, wheredienis diethylenetriamine and L is binucleating ligand, were prepared. Mononuclear complexes, with structure similar to that of the preceeding compounds, [Cu(dien)L′(ClO4)](ClO4) were synthesized as reference compounds. The infrared spectra, elctronic spectra and magnetic properties were studied. The inductive effect, steric effect and the effect of the length of the conjugated π‐system on the magnetic exchange interaction between the two copper ions are discussed. The electrochemical properties of these complexes were investigated by cyclic voltammetry. The copper ions showed the cooperative phenomena and a quasi‐reversible sequential transfer of two electrons at the sam

ISSN:0009-4536    

DOI:10.1002/jccs.198500067

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe rate for the substitution reaction of Co(edta)−with ethylenediamine was greatly enhanced by the presence of an excess of Co(II) ion in solution. The rate constant is (13±2)M−‐sec−1at μi=0.10MLiClO4, pH=11.1, [en]=0.10MandT=25°C. The mechanism for the reaction is discussed on the basis of the Marcus theory for outer‐sphere processes corrected for electrostatic effects. This catalytic effect was not observed when the Co(II) was present in small amount due to the stability of the Co(edta)−2complex toward substitution. The rate constant for direct substitution of Co(edta)−under the same conditions has also been measured and the value is (3.6

ISSN:0009-4536    

DOI:10.1002/jccs.198500068

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe diffusion coefficients of sulfide ion in 5MNaOH solution with concentrations of (0.02–0.3)Mat temperatures 24–50°Cwere determined using a rotating‐ring‐disc Pt electrode to be (0.5–2.0)×10−5cm2/sec. The reaction order of the sulfide oxidation to sulfur was calculated to be 0.42 which implies one‐electron transfer as the rate‐limiting step and the reaction rate constant was found to bekf=2.57×10

ISSN:0009-4536    

DOI:10.1002/jccs.198500069

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY