摘要:

AbstractMINDO/3 method has been used to study the mechanism of the consecutive addition of HCN to aminoacetonitrile. The results obtained for the first three steps show that the reaction is exothermic, and step I is the rate determining step.

ISSN:1001-604X    

DOI:10.1002/cjoc.19930110101

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

年代:1993

数据来源: WILEY

摘要:

AbstractA new series of solid solutions of composition La21.4) were prepared. All the members of the system are of the tetragonal K2NiF4type structure. The tetragonality ratioc/ashows a progressive decrease with increasing y except for the group ofx= 1.4. The room temperature resistivity exhibits a gradual increase withy, which is interpreted by assuming that the single egelectron of Ni3+is present in localized dZ2orbital but the te electron gradually becomes itinerant because it is delocalized into dx2y2orbital leads to a strong Ni3−O2−covalent interaction with increasing the Sr content. Variation of resistance with temperature shows semiconducting properties except for the composition ofx=1.4,y<0.3 which shows a semiconductor‐to‐metal tra

ISSN:1001-604X    

DOI:10.1002/cjoc.19930110102

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

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper reports the use of an electrochemically polymerized Toluidine Blue (TB) film electrode. The film on platinum electrode surface was analyzed with ESCA. The heterogeneous electron transfer processes of myoglobin at the polymerized TB film electrode have been investigated usingin situUV‐visible spectroelectrochemistry. The formal potential (E°') and electron transfer number (n) of myoglobin were calculated asE°' = 0.045 V (vs.NHE) andn= 0.99. The exhaustive reduction and oxidation electrolyses are achieved in 130 s and 110 s respectively, during a potential step between −0.4 V and +0.4V. A formal heterogeneous electron transfer rate constant (Kah) of 1.09 × 10−4cm/s and a transfer coefficient (α) of 0.47 were obtained by cyclic voltabsorptometry, which indicated that myoglobin underwent a quasi‐reversible electrode process at the polymerized TB fil

ISSN:1001-604X    

DOI:10.1002/cjoc.19930110103

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

年代:1993

数据来源: WILEY

摘要:

AbstractReactions of [NH4]2[MS4](M = Mo,W), CuX(X = Br, I) and PPh3in the solid state produced four mixed‐metal sulfur containing clusters {Cu3MS3X}(PPh3)3S(M = Mo, W; X = Br, I), two of which (1: M = Mo, X = I; 2: M = W, X = Br) were structurally determined. Crystals of 1 and 2 are triclinic, space groupP1(1:a= 11.895(3),b= 13.107(1),c= 20.473(2)Å, α = 74.95(6), β = 84.87(8), γ = 64.27(7)°,Z=2,V=2776.1 Å3,Rw= 0.064 for 6443 observed reflections. 2:a= 11.876 (1),b= 13.065 (2),c= 20.325(2)Å, α = 74.95(1), β= 85.39(1), γ = 64.09(1)°,Z= 2,V= 2737.3Å3,Rw= 0.055 for ·5303 observed reflections). The results of the structure determination showed that the central units of the two cubane‐like cluster compounds are composed of four metal atoms and four non‐metal atoms situated at alternate corners. The differences of cubane‐like cluster compounds obtained from solid state reactions and from solution rea

ISSN:1001-604X    

DOI:10.1002/cjoc.19930110104

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

年代:1993

数据来源: WILEY

摘要:

AbstractTris[o‐mercaptophenolato]vanadium(IV) dimer complexes (A)2[V(mp)3NaLL']2(A = Ph4P+, H2mp =o‐mercaptophenol, L = MeCN, L'=EtOH, (1); L' = MeOH, (2)) were prepared by the reaction of anhydrous VC13, and Na2mp in the molar ratio 1:3. Complex (3) (A = Et4N+, L=L' = MeOH) was prepared by the reaction of VC13, Na2mp and Li2S in the molar ratio 1:2:1. The complexes were characterized by X‐ray diffraction crystallography, infrared spectra, magnetic susceptibility, and cyclic voltammetric measurements. Complex 2 crystallizes in the triclinic space groupP1 witha=12.813(6),b= 14.199(4),c= 12.790(5) Å, α = 112.72(2), β = 104.24(4). γ = 88.68(4)°,V= 2073.6 Å3, andZ=1. The structure was refined toR=0.058. Complex 3 crystallizes in the mono‐clinic space groupP21/nwitha=12.359(3),b=17.452(6),c=14.829(13) Å, βequals;96.51(5)°,V=3177.8 Å3, andZ=2. The finalRfactor is 0.067. Both of the anions of 2 and 3 contain two [V(mp)3]2−fragments linked by sodium ions through the μ3‐O bridges with a crystallographic center of symmetry. The V(IV) atom is in a coordination environment intermediate between a trigonal prism a

ISSN:1001-604X    

DOI:10.1002/cjoc.19930110105

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

年代:1993

数据来源: WILEY

摘要:

Abstract[V2(μ‐S2)2(S2CNEt2)4] 2CH3Cl was synthesized by the reaction of NaS2CNEt2, Li2S and VOCl3at room temperature. Crystal data:M= 1061.3, space groupPbca, with the orthorhombic parameters:a=20.123(3),b= 20.485(4)1c=10.911(3)A,V=4497.7Å3,Z=4,Dc=1.57 g/cm3, MoKoradiation (λ=0.71069 Å), μ = 13.2 cm−1,F(000)—2168. FinalR= 0.041 andRw=0.047 for 2288 observed reflections withI>3σ(I). The coordination sphere of each V atom in title compound is a distorted tetragonal prism composed of two bidentate dithiocarbamate and two S21−ligands. The V—V distance is 2.890 Å while the V—S distances fall in the rang

ISSN:1001-604X    

DOI:10.1002/cjoc.19930110106

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

年代:1993

数据来源: WILEY

摘要:

AbstractA series of thirteen arylmercury derivatives of α‐thiopicolinanilide have been synthesized and characterized by elemental analysis, IR,1H NMR and MS. The intramolecular coordination and the substituent effects on the MS and199Hg NMR behaviours have been studied. It has been shown that a linear correlation exists between the199Hg chemical shifts and the Hammett‐Brown constants σ+, and the electron‐donating groups cause the chemical shift to move

ISSN:1001-604X    

DOI:10.1002/cjoc.19930110107

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe negative secondary ion mass spectrometry, in combination with the stereoselective derivatizations with substituted boronic acid RB(OH)2, was used in the analysis of fourteen oligosaccharides. The mass spectra of the derivatives provide information on their linkage positions and isomerism of the individual monosacaccharide units. The results indicated that among the derivatives of the oligosaccharides analyzed, those with 1–4 and 1–6 linkages all presented the ion peaks atm/z287, sometimes one more peak atm/z449. Furthermore, a relationship was found between the linkage positions and the intensity orders of the derivative ions. Finally, the derivatives of the disaccharides with a galactose presented an intense ion peak atm/z347, and those of oligosaccharides with 1–6 linkage to a galactose at terminal presented the ion atm/z317. In the case of oligosaccharides with a fructose residue, characteristic ion ofm/z155 was produced. The conditions of stereoselective derivatizations and mass spectrometry were studied, in order to obtain a better reproducibility of the mass sp

ISSN:1001-604X    

DOI:10.1002/cjoc.19930110108

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe complexation of lanthanide(III) cations with 1,2‐propanediaminetetraacetate (1,2‐PDTA) in aqueous solution has been investigated by10Na,35Cl,2H and11O NMR shift measurements. It has been shown that the contact shifts are dominant for17O,16Cl and2H (only for the heavier lanthanide series) and the pseudocontact shifts are dominant for25Na. It is suggested that the 1,2‐PDTA ligand is bound pentadentately via the two nitrogens and the three carboxylates for the lighter lanthanide complexes, hexdentately via the two nitrogens and the four carboxylates for the heavier ones. The numbers of the water coordinated were determined. The small amount of chloride anion in inner coordination sphere was obs

ISSN:1001-604X    

DOI:10.1002/cjoc.19930110109

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

年代:1993

数据来源: WILEY

摘要:

AbstractA sensitive, selective, rapid, simple, and convenient method for the determination of thorium was developed. The method was based on the color reaction of thorium with DBF‐arsenazo in a strong acidic medium (4 mol/L HCl). The flow‐injection technique was used with an automated flow‐injection analyzer. Beer's law was obeyed in the range of 0–1.4 μg/mL. The relative standard deviations were less

ISSN:1001-604X    

DOI:10.1002/cjoc.19930110110

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

年代:1993

数据来源: WILEY