ISSN:0009-4536    

DOI:10.1002/jccs.199600031

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractTwo‐dimensional planar Schlegel diagrams are used to displace fullerenes and to exhibit cage cluster's vertices, faces and edges as well as cluster's extensions and changes such as isomerization, addition, elimination etc. The Schlegel diagrams also show the possible π bondings and free π radicals to determine symmetry group structures as well as to interact with the corresponding number of electrons in metals. The diagrams also show the possible addition of outside hydrogens and their moveme

ISSN:0009-4536    

DOI:10.1002/jccs.199600032

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractDispersed fluorescence spectra of β2A′ ‐ x̄2A′ transitions are measured on exciting HCO to the vibrational levels (0,0,0), (0,0,1), (0,1,0) and (1,0,0) of β2A′ in a gas cell. Vibrational energies of bound and resonant states are determined for energy up to 17 500 cm−1from the ground vibrational level of the x̄2A′ state. Rotationally resolved spectra of the bands β2A′ ‐ x̄2A′ 203301, 214and 202312were recorded and analyzed. Abnormal intensities in the P, Q and R branches are due to the mechanism of “axis switching”. From the ratios of emission intensity ofa‐ andb‐type transitions, without taking into account the varied lifetimes of rotational states of the upper electronic state, the directions of transition dipole moments of these bands are determined to b

ISSN:0009-4536    

DOI:10.1002/jccs.199600033

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractSodium‐dicyclohexyl‐ 18‐crown‐6 complex cation was used as carrier for the uphill transport of zinc as Zn(SCN)42−complex anion. By using L‐cysteine as a metal ion acceptor in the receiving phase at the optimized pH of 7.6, the amount of zinc transport through the liquid membrane after 90 min was 97.2 ± 1.0%. The selectivity and efficiency of zinc transport from aqueous solutions containing equimolar mixtures of Ag+, Cd2+Co2+, Cu2+, Fe2+, Ni2+, Pb2+, Pd2+, Sr2+, Bi3+, Cr3+and Fe3+ions was investigated. In the presence of NH2OH.HCl as a suitable masking agent in the source phase, the interfering effect of Cu2+and Pb2+ions was diminished

ISSN:0009-4536    

DOI:10.1002/jccs.199600034

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractIn this work, we propose a method to determine trace amounts of Cd in human whole blood samples by electrothermal atomic absorption spectrometry (ETAAS) with the combined chemical modifier including magnesium chloride and sodium hydroxide. Prior to the ETAAS analysis, dissolution of the blood samples is accomplished using a HNO3‐HClO4double closed‐vessel microwave digestion technique followed by drying of the dissolved blood samples by means of an infrared lamp. In using this approach, a MgCl2chemical modifier is added to the digested samples, then they are injected into the graphite furnace for detecting the Cd level via atomic absorption spectrometer. Besides we used a NaOH chemical modifier, which removed the matrix major elements through prior ashing at 1200 ° C for 30 s, and the Cd is subsequently volatilized at 2200 °C and determined by AAS. However, the proposed method can be employed to determine the of Cd level in whole blood samples by the calibration technique and the standard‐additions method. Its validity is confirmed with two certified reference whole blood materials (Seronorm Trace Elements Whole Blood Batch no. 205052 and Batch no. 203056). By using 10 μL injections, a detection limit of 0.052 ng mL−1i

ISSN:0009-4536    

DOI:10.1002/jccs.199600035

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe results of a series of inter‐laboratory cross‐check on the determinations of ppb and sub‐ppb levels of copper and lead in environmental samples are described. Thirteen laboratories participated during a five‐stage comparison. Seven analytical methods and two pre‐concentration procedures were performed on certified and real samples. For controlled and blind standards at higher concentration levels (10 ppb or above) the data reported by different participants show good agreement for both elements regardless of the method chosen. However, for samples having lower concentrations (1‐10 ppb level), the relative standard deviation (R.S.D.) and bias increased. A high degree of scattering on data were demonstrated for a deep ocean water at less than 1 ppb level. The results of the present study give direct comparison between different analytical methods, and also reflect the average aptitude of analytical laboratories in Taiwan on the measurements of copper and lead in environmen

ISSN:0009-4536    

DOI:10.1002/jccs.199600036

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractSix tetraamine ligands, 2,5,8,11‐tetraazadodecane, 2,5,9,12‐tetraazatridecane, 3,7‐dimethyl‐3,7‐diazanonane‐l,9‐diamine, 2,6,9,13‐tetraazatetradecane, 4,7‐dimethyl‐4,7‐diazadecane‐l,10‐diamine, 4‐methy]‐4,7‐diazadecane‐l,10‐diamine, and their nickel(II) complexes have been synthesized. The equilibrium constants and thermodynamic parameters of the high‐spin‐low‐spin conversion of these complexes at various temperatures in 0.10 M NaC1O4have been investigated by spectrophotometric techniques. Influences of the enthalpies of these reactions are attributed to an endothermic contribution due to the breaking of the two Ni‐OH2bonds, an exothermic contribution due to the strengthening of the four in‐plane Ni‐N bonds, an exothermic contribution due to the different ligand field stabilization energies of the square‐planar and the octahedral complexes, an endothermic contribution due to the steric repulsions between theN‐methyl group(s) and methylene groups as well as that between the twoN‐methyl groups of the tetraamine, an exothermic contribution due to the steric repulsions between theN‐methyl group(s) and the coordinated water molecules, and an exothermic contribution due to the inductive effect of theN‐methyl group(s). The important factors influencing the values of the entropies of these reactions are a negative term due to the reduction of spin multiplicity and a large positive term due to the release o

ISSN:0009-4536    

DOI:10.1002/jccs.199600037

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe synthesis, crystal structure and magnetic properties of the non‐transition metals; Cd(II), Zn(II), Hg(II), Mg(II) and the transition metals; Co(II), Ni(II), Cu(II) complexes with 2‐(4‐pyridyl)‐4,4,5,5‐tetra‐methylimidazolinyl‐l‐oxy‐3‐oxide (NITpPy) are presented. The compounds of free radical NITpPy, HgCl2(NITpPy), and Zn(acac)2(NITpPy) crystallize in the same monoclinic system of space group C2/c. The magnetic properties of the temperature‐dependent magnetic susceptibility of NITpPy and its metal complexes are discussed according to the Heisenberg model. A weak ferromagnetic coupling in NITpPy and a weak antiferromagnetic coupling in the metal complex

ISSN:0009-4536    

DOI:10.1002/jccs.199600038

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe monomeric octa‐aza bis‐α‐diimine macrocyclic complex [CoII(C10H20N8)(H2O)](ClO4)2I, undergoes various reactions on the macrocyclic ligand. Reaction of complex I with triethylamine in double molar proportions, followed by slow aerial oxidation, produces a molecular dimeric complex [CoII(C10H14N8)]2, III, and a novel Co(I) complex [CoI(C10H19N8)], IV. Complex III is a staggered cofacial dimer with a cobalt‐cobalt bond length 2.86(1) Å. The macrocyclic ligand of the complex contains an a‐diimine function in each five‐membered chelate ring, and a three‐atom N‐C‐N−delocalized system in each six‐membered chelate ring. Complex IV has the 5‐5‐6‐6 chelate arrangement because one α‐diimine moiety is rearranged to a syn‐anti configuration. In the structure, the two fused six‐membered chelate rings are fully conjugated and the two fused five‐membered rings are saturated. However, when complex I reacts with excess triethylamine under the similar conditions, a dimeric complex of another type, [CoII(C10Hl6N8)]2, II, was generated, in which one N‐N bond of the macrocyclic ligand is broken. Complex IV can be isolated also from the reaction of complex I with excess hydrazine, followed by slow aerial oxidation. When hydrazine in double molar proportions was used, complex [CoI(C10H17N8)(NHNH)] V, which contains a coordinated diazene ligand, was obtained. Only one six‐membered chelate ring of complex V is deprotonated and oxidized to form a three‐atom N‐C‐N−delocalized system. The structures of octa‐aza complexes I‐V are determined by X‐ray crystallography: I, orthorhombic, C mca, a = 11.646(4), b = 17.049(3), c = 10.706(3) Å, Z = 4, R = 0.045, Rw= 0.047, based on 1024 reflections withI>2σ(I); II, monoclinic, P 21/c, a = 9.814(3), b = 22.583(6). c = 14.632(9) Å, β = 98.90(5)°, Z = 4, R = 0.085, Rw= 0.101, based on 2033 reflections withI>2σ(I); III, tetragonal, P 4/nmm, a = 15.614(3), c = 6.498(2) Å, Z = 4, R = 0.081, Rw= 0.115, based on 340 reflections withI>2σ(I); IV, orthorhombic, P bca, a = 8.484(1), b = 16.662(3), c = 18.760(2) Å, Z = 8, R = 0.029, Rw= 0.024, based on 1441 reflections withI>2σ(I); V, monoclinic, P 21/m, a = 7.892(3), b = 11.713(6), c = 9.326(4) Å, β = 108.03(3

ISSN:0009-4536    

DOI:10.1002/jccs.199600039

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0009-4536    

DOI:10.1002/jccs.199600040

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY