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  • crystal structure
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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis and structure of tetrakis(2,6-dichlorophenoxide) bis(THF) uranium(IV) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 7-10 
    Details
    ISSN: 1572-8854
    Keywords: crystal structure ; uranium (IV) ; dichlorophenoxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The reaction of UCl4 with KO-2,6-Cl2C6H3 in tetrahydrofuran results in the preparation of the title compound. The six-coordinate complex possesses pseudo-octahedral geometry about uranium, with U-O(phenoxide) bond lengths in the range 2.161(11) to 2.178(10) Å and U-O(THF) bond lengths of 2.467(10) and 2.475(11) Å. This complex crystallizes in the monoclinic space group P21/n (a = 11.169(2), b = 11.588(2), c = 35.119(5) Å, β = 92.11(1)°, V = 4542.2(13) Å3, and Z = 4).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009594612946
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and crystal structure of hexakis(N-methylimidazole) iron(II) pyridine-2-sulfonate (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 23-26 
    Details
    ISSN: 1572-8854
    Keywords: iron ; crystal structure ; synthesis ; N-methylimidazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound [Fe(C4H6N2)6][C5H4NSO3]2 crystallized in the monoclinic space group, P21/n with unit cell parameters: a = 13.676(3), b = 8.345(2), c = 18.663(4) Å, β = 106.40(3)° and Z = 2. The title compound consists of a [Fe(C4H6N2)6]+2 hexacoordinated iron(II) cation and two C5H4NSO− 3 anions. In the cation the iron atom is coordinated to six N-methylimidazole imine nitrogen atoms in a distorted octahedral arrangement. The N1,N5,N1i,N5i atoms are coplanar and the iron lies in this plane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009537830693
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  • 3
    Electronic Resource
    Electronic Resource
    Crystal structure of [Cu2(II)(dmpa)2(p-Cl-C6H5COO)2] (Hdmpa = N,N-dimethyl-3-amino-1-propanol) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 35-38 
    Details
    ISSN: 1572-8854
    Keywords: copper(II) ; aminoalcoholato ; hydrogen bonding ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The copper complex, [Cu2(II)(dmpa)2(p-Cl-C6H5COO)2], has been prepared and its structure determined using X-ray crystallography. The dimer is a di-μ2-alkoxo complex which is a five-coordinate copper dimer with unsupported alkoxo bridges. The complex crystallizes in the triclinic space group P-1 with a = 11.384(2), b = 14.636(5), c = 9.609(2) Å, α = 100.07(2), β = 104.33(3), γ = 72.79(2)°, V = 1471.8(7) Å3, and Z = 2. The structure is comprised of discrete binuclear clusters in which the metal atoms are bridged by two alkoxo oxygens of the dmpa− ligands. The Cu-O and Cu-N distances are in good agreement with those found for other copper(II) aminoalcoholato complexes. The Cu···Cu distance is 2.9765(6) Å. In the crystal, every two dimeric coordination molecules are combined together by the recognition through intermolecular hydrogen-bonding interactions between the apical water molecule and the non-coordinated O atom from the p-chlorobenzoato ligand, forminga tetramer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009542031602
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and crystal structure of manganese(III) hydroxyl-containing Schiff base complexes: [Mn(III)(Hvanpa)2]N3 (H2vanpa = 1−(3-hydroxysalicylaldeneamino)-3-hydroxypropane) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 39-42 
    Details
    ISSN: 1572-8854
    Keywords: manganese(III) ; Schiff base ; hydrogen bonding ; crystal structure ; Jahn-Teller distortion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The manganese complex, [Mn(III)(Hvanpa)2]N3 has been prepared and the crystal structure determined using x-ray crystallography. The mononuclear complex has a six-coordinate octahedral geometry. The complex crystallizes in the monoclinic space group P21/c with a = 9.867(1), b = 13.316(2), c = 9.0110(1) Å, β = 107.870(1)°, V = 1126.8(2) Å3, and Z = 2. The Mn-O and Mn-N distances in the equatorial plane are in good agreement with those found for other manganese(III) Schiff base complexes. In the axial direction, the Mn-O distances of 2.274(2) Å is about 0.3 Å longer than those in the equatorial plane due to a Jahn-Teller distortion at the d4 manganese(III) center. In the crystal, each azido ion is linked through hydrogen bonding with two hydrogen atoms from the coordinate hydroxyl groups at the apical site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009594015672
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  • 5
    Electronic Resource
    Electronic Resource
    Preparation, characterization and crystal structure of an intermolecular compound based on H3PMo12O40·nH2O and diethylamine (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 43-48 
    Details
    ISSN: 1572-8854
    Keywords: molybodophosphoric acid ; crystal structure ; diethylamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An intermolecular compound, H3PMo12O40·5(CH3CH2)2NH·H2O, between the heteropolymolybdate α-H3PMo12O40 and the organic substrate diethylamine, has been synthesized and characterized. Light yellow crystals of the title compound were crystallized from a mixed solvent of water and acetonitrile with formula H3PMo12O40·5(CH3CH2)2NH·H2O. Spectroscopic data support the presence of a sizable electronic interaction between the organic substrate and the inorganic anion in the solid state. The single crystal x-ray structure analysis of the title compound revealed that it crystallized in the triclinic system, space group P $$\overline 1$$ with a = 12.0786(13), b = 12.102(5), c = 21.416(3) Å, α = 94.87(2), β = 94.755(9), γ = 113.81(2)°, V = 2830.3(13) Å3, and Z = 2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009546132511
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and crystal structure of K3Sb4BO13 (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 53-53 
    Details
    ISSN: 1572-8854
    Keywords: boroantimonate ; borate ; antimonate ; crystal structure ; 49
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract K3Sb4BO13, Mr = 823.11 g.mol−1, crystallizes in the triclinic system, space group P $$\overline 1$$ , Z = 2. The lattice parameters are a = 7.133(1) Å, b = 7.232(1) Å, c = 13.259(2) Å, α = 82.00 (1)°, β = 99.77(1)° and γ = 117.08(1)°, V = 598.7(2) Å3, Dx = 4.566 Mg m−3. The final R index and weighted Rw index are 0.0251 and 0.0623, respectively. The three-dimensional network of the title compound is constituted by layers (Sb3O9)n, similar to that of hexagonal bronze of Magneli. These layers are linked together, in the c direction, alternatively by edge-sharing pairs of SbO6 octahedra and BO3 triangles. This framework has interconnected tunnels, running approximately along the a and b directions, in which the K+ ions are located.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009598116581
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  • 7
    Electronic Resource
    Electronic Resource
    Crystal structure of a (25R)-2α,3α-epoxy-5α-spirostan-6, 23-dione hemi-ethyl acetate solvate (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 693-697 
    Details
    ISSN: 1572-8854
    Keywords: brassinosteroids ; steroids ; natural products ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound (25R)-2α,3α-epoxy-5α-spirostan-6,23-dione, crystallizes as a hemi-ethyl acetate solvate, having two host molecules of similar conformation per molecule of ethyl acetate, in the asymmetric unit. The O atom of the epoxy group is α-oriented. The presence of the epoxy group disturbs the chair conformation in the ring A of the steroidal nucleus. Ring A has a C5α,C10β half-chair conformation. The six-membered rings B, C, and F have chair conformation as expected. The D ring adopts a C14α-envelope conformation and the E ring is midway between a C22α,O3β half-chair and a C22α-envelope conformations. The A/B, B/C, and C/D ring junctions are trans. Crystal data: C27H38O5·1/2C4H8O2, Monoclinic, space group P21, a = 7.7363(18) b = 28.769(12) c = 12.038(6) Å, β = 90.88(5), V = 2679.0(10) Å3, Z = 4. The packing of the molecules is assumed to be dictated by van der Waals interactions and by intermolecular C—H ··· O hydrogen bonds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012277425969
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  • 8
    Electronic Resource
    Electronic Resource
    X-ray crystal structure of trans-bis(monoethanolamine) bis(saccharinato)nickel(II) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 767-771 
    Details
    ISSN: 1572-8854
    Keywords: saccharin ; monoethanolamine ; nickel(II) complex ; hydrogen bonding ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of trans-bis(monoethanolamine)bis(saccharinato)nickel(II), [Ni(C7H4NO3S)2(C2H7NO)2], has been determined from X-ray diffraction data. The metal complex is monoclinic, with a = 11.0555(5), b = 8.9103(4), c = 11.3890(5) Å, β = 105.0230(10)°, Z = 2, and space group P21/c . The structure consists of individual molecules. Two monoethanolamine molecules and two saccharinate anions coordinate the nickel atom forming a distorted octahedron. The monoethanolamine molecules act as a bidentate ligand and form five-membered trans chelate rings, which constitute the plane of the coordination octahedron, while two saccharinate ions behave as a monodentate ligand occupying the axial positions. Intermolecular hydrogen bonds link the molecules to form a three-dimensional infinite structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1013292406687
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  • 9
    Electronic Resource
    Electronic Resource
    Novel Cu–Te Clusters Synthesised from tBuTeSiMe3: [Cu18Te6(TetBu)6(PPh2Et)7], [Cu19Te6(TetBu)7(PEt3)8], [Cu27Te15(PiPr2Me)12] and [Cu58Te32(PtBu2nBu)14] (2000)
    Springer
    Journal of cluster science 11 (2000), S. 135-151 
    Details
    ISSN: 1572-8862
    Keywords: copper telluride clusters ; copper telluro-tellurolato clusters ; crystal structure ; influence of phosphine ligands ; Frank-Kasper polyhedron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reactions of CuCl and tBuTeSiMe3 in the presence of phosphine ligands result in the formation of four new Cu/Te cluster complexes, [Cu18Te6(TetBu)6(PPh2Et)7], [Cu19Te6(TetBu)7(PEt3)8], [Cu27Te15(PiPr2Me)12] and [Cu58Te32(PtBu2 nBu)14], which have been structurally characterized by single crystal structural analysis. The former two clusters show a layer-type tellurium frameworks in which the copper atoms are asymmetrically spread. The latter two clusters possess a tellurium framework in a body-centered Te14-Frank-Kasper polyhedron or a Te28 polyhedron with four interstitial tellurium atoms and belong to mixed-valence Cu/Te compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009016832159
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  • 10
    Electronic Resource
    Electronic Resource
    Cluster Build-up Reactions using Di-gold Cationic Fragments: Synthesis and Structural Characterization of [Os7(CO)19(Au2dppm)] (2000)
    Springer
    Journal of cluster science 11 (2000), S. 217-226 
    Details
    ISSN: 1572-8862
    Keywords: gold ; osmium ; cluster ; carbonyl ; phosphine ; heteronuclear ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of the di-gold cation [Au2(dppx)]2+ with the heptanuclear cluster dianion [Os7(CO)20]2− affords the mixed metal cluster [Os7(CO)20{Au2(dppx)}] (x=m (1), e (2), b (3)). On standing, in solution, this complex undergoes decarbonylation to give the cluster [Os7(CO)19{Au2(dppx)}] (x=m (4), e (5), b (6)). The complexes have been characterised spectroscopically, and an X-ray structure determination of the dppm derivative shows that it contains a metal core based on an Os7 edge-bridged bicapped tetrahedron with the two μ 3-Au atoms capping adjacent triangular Os3 faces of the central tetrahedron. In an analogous reaction, the carbido anion [Os7(H)C(CO)19]− affords the neutral cluster [Os7C(CO)19{Au2(dppm)}] (7) when treated with [Au2(dppm)]2+ in the presence of base.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009025101208
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  • 11
    Electronic Resource
    Electronic Resource
    Crystal structure of 2,2,3-trimethyl-3-(2′,4′,5′-tricyanophenyl) cyclopentyl-1-acetic acid, methyl ester, C20H21N3O2 (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 589-592 
    Details
    ISSN: 1572-8854
    Keywords: Phenylcyclopentaneacetate derivative ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in space group P21/n, with a = 14.600(2), b = 7.091(2), c = 18.211(5) Å, and β = 103.67(2)°. Owing to the centric space group, both C(1) and C(3) chiral centers are either R or S. The acetate group is equatorial, the H(1) and the methyl group at C(3) are axial and reciprocally trans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011358327087
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  • 12
    Electronic Resource
    Electronic Resource
    The crystal and molecular structure of spiro[1-(S)-Br-3-(S)-H-4-(R)-l-(1′ R,2′ S,5′R)-menthyloxy-5-oxo-6-oxa-bicyclo[3.1.0]hexane-2,3′-(R)-(4′-(R)-diphenylmethoxy-5′-l-(1′ R,2′ S,5′ R)-menthyloxy-butyrolactone)] (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 737-741 
    Details
    ISSN: 1572-8854
    Keywords: crystal structure ; asymmetric synthesis ; spiro-cyclopropane derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystal structure of C41H53O7Br has been determined by single-crystal X-ray diffraction. The compound crystalline in the orthorhombic space group P212121, with a = 11.264(2), b = 12.058(2), c = 29.337(6) Å, Z = 4. The bond angles of cyclopropane moiety in the molecule are approximate to 60° and agree with theoretic values of the internal angles in a cyclopropane, and two chiral menthyloxy groups are located above and under the whole chiral molecule, respectively. The configuration of the pentacyclic lactone is shown as envelope form.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012254312765
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  • 13
    Electronic Resource
    Electronic Resource
    Structural Redetermination of Rh4(CO)12 at 293 and 173 K and Analysis of the Thermal Motion in Relation to the Dynamical Behavior (2000)
    Springer
    Journal of cluster science 11 (2000), S. 39-53 
    Details
    ISSN: 1572-8862
    Keywords: thermal motion ; crystal structure ; rhodium carbonyl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The structure of Rh4(CO)12 (1) has been redetermined at room temperature and at 173 K. Crystallographic data for 1 at 293 K are as follows: C12O12Rh4, space group P21/c, a=9.209(3), b=11.790(7), c=17.721(8) Å, β=90.46(3)°, V=1924.0(16) Å3, Z=4, 5570 reflections to θ=30.0°, and R=0.030. For 1 at 173 K the data are as follows: space group P21/c, a=9.127(3), b=11.672(6), c=17.492(13) Å, β=90.64(5)°, V=1863.3(18) Å3, Z=4, 3782 reflections to θ=26.3°, and R=0.033. There was no detectable phase change on cooling to 173 K. Crystals of 1 are twinned by pseudo-merohedry, but a satisfactory refinement was obtained by assuming a (100) twinning mirror plane. TLS analysis of the anisotropic displacement parameters at both temperatures has been undertaken. Investigation of the mean square displacement difference between the observed and the rigid body displacement parameters reveals there is a signficant internal motion of the carbonyl ligands relative to the metal skeleton. This motion is consistent with a normal mode or modes of C 3 symmetry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009000428525
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  • 14
    Electronic Resource
    Electronic Resource
    A Novel Cluster Consisting of Seven Fused MX6 Octahedra, Li14(THF)8[Ni7Cl17(μ-formamidinate)3(μ-Cl)]2 (2000)
    Springer
    Journal of cluster science 11 (2000), S. 87-94 
    Details
    ISSN: 1572-8862
    Keywords: nickel cluster ; fluorinated formamidine ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract When a THF solution made from equimolar amounts of methyllithium and N,N′-bispentafluorophenyl formamidine, C6F5NC(H)N(H)C6F5, was added to a suspension of NiCl2 in THF and the mixture refluxed for 12 h, a bright yellow-green solution was formed, from which a bright green crystalline compound was obtained in 〉60% yield upon partial evaporation of the solvent. This compound, Li14(THF)8[Ni7Cl17(μ-formamidinate)3(μ-Cl)]2·9.4THF, crystallizes in the tetragonal space group P4 2/mnm (No. 136) with Z=2. The core consists of two Ni7 units bridged by two Cl atoms.
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    URL: http://dx.doi.org/10.1023/A:1009008630342
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  • 15
    Electronic Resource
    Electronic Resource
    Organically Templated Vanadium Oxide Phases: Synthesis and Structures of [H3NCH2CH2NH3][V2O6] and [HN(CH2CH2)3NH][VV2VIV4O14]·H2O (2000)
    Springer
    Journal of cluster science 11 (2000), S. 433-447 
    Details
    ISSN: 1572-8862
    Keywords: crystal structure ; vanadium oxide ; organic template ; mixed valence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The synthesis and crystal structures of [H3NCH2CH2NH3][V2O6] (1) and [HN(CH2CH2)3NH][VV 2VIV 4O14]·H2O (2) are described. The structure of the oxidized compound 1 consists of parallel stacks of vanadium oxide chains of corner sharing {VO4} tetrahedra. The chains are stabilized by extensive hydrogen bonding involving oxide ligands of the chains and ethylenediammonium ions which fill the space between the stacks of chains. The structure of compound 2 consists of vanadium oxide layers separated by doubly protonated 1,4-diazabicyclo[2.2.2]octane and lattice water. The vanadium oxide layers, containing mixed-valence vanadium (VV and VIV) centers, are composed of zigzag ribbons of edge-sharing {VO5} square pyramids interconnected by {VO4} tetrahedra. Crystal data. C2H10N2O6V2 , 1: monoclinic, space group P21/c (No. 14), a=5.5359(5), b=12.9430(12), c=5.6856(5) Å, α=90, β=97.460(2), γ=90°, V=403.93(6) Å3, Z=2. A total of 2506 reflections (θ max=27.89°) was collected, of which 954 were used to resolve the structure. The structure was solved by direct methods and least-squares refinement converged at R=0.0592. C6H16N2O15V6, 2: monoclinic, space group C2 (No. 5), a=19.303(4), b=6.667(2), c=7.579(2) Å, α=90, β=111.31(2), γ=90°, V=908.4(4) Å3, Z=2. A total of 1779 reflections was collected, of which 1591 unique reflections were used for structural elucidation. The structure was solved by direct methods and least-squares refinement converged at R=0.0314.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009051500265
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  • 16
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure studies of tris(2-hydroxy-3-t-butyl-5-methylbenzene)-methane trihydrate and N-benzyl-N-phenyl benzamide (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 255-258 
    Details
    ISSN: 1572-8854
    Keywords: THBMBM ; BPB ; crystal structure ; helical packing ; columnar packing ; mesophase transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structures of the title compounds, tris(2-hydroxy-3-t-butyl-5-methylbenzene)-methane)C34H46O3.3H2O, 3) and N-benzyl-N-phenylbenzamide (C20H17NO, 6), have been investigated by X-ray crystallography. Compound 3 crystallizes in the trigonal space group $$P\bar 3 $$ with cell parameters a = 14.090(5) Å, b = 14.090(5)Å, c = 10.485(5)Å, Z = 2. Compound 6 crystallizes in the monoclinic space group C2/c with cell parameters a = 24.533(4)Å, b = 9.176(4)Å, c = 16.711(5)Å, β = 125.88(2)°, Z = 8. Compound 3 has both intra-and intermolecular hydrogen bonds. It also exhibits a helical columnar arrangement of the molecules and goes into mesophase before melting into an isotropic liquid.
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    URL: http://dx.doi.org/10.1023/A:1009595123416
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  • 17
    Electronic Resource
    Electronic Resource
    Synthesis and crystal structure of 4-(p-methoxyphenyl)-3, 5-bis(4-pyridyl)-1,2,4-triazole (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 429-432 
    Details
    ISSN: 1572-8854
    Keywords: Triazole ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The 4-(p-methoxyphenyl)-3,5-bis(4-pyridyl)-1,2,4-triazole has been synthesized and its crystal structure has been determined by X-ray diffraction methods. It crystallizes in the monoclinic space group P21/n, with a = 12.5832(6) Å, b = 7.0512(5) Å, c = 18.4669(12) Å, β = 96.826(1)°, and Dcalc = 1.345 g cm−1 for Z = 4. In the structure, two pyridyl rings, phenyl ring, and triazole ring do not share a common plane. The most favored orientation of the pyridyl rings in the crystal is that their planes are inclined toward opposite directions with respect to the triazole ring.
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    URL: http://dx.doi.org/10.1023/A:1009542208264
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  • 18
    Electronic Resource
    Electronic Resource
    Crystal structure and spectroscopy of the low-spin iron(II) compound: tris(bipyrimidine)iron(II) bis(triflate), [Fe(bipym)33](CF3SO3)2 (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 441-444 
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    ISSN: 1572-8854
    Keywords: 2,2′-Bipyrimidine ; low-spin ; iron ; crystal structure ; infrared
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound [Fe(bipym)33](CF3SO3)2 (in which bipym = 2,2′-bipyrimidine) crystallizes in the space group P21/c, with a = 13.7641(11), b = 18.7557(19), c = 12.3627(11) Å, β = 103.085(8)° and Z = 4. The low-spin Fe(II) atom is octahedrally surrounded by six nitrogen atoms of three bipyrimidine groups with Fe—N distances that vary from 1.968(4) to 1.975(4) å. In the far-infrared region the Fe—N vibrations are observed at 359 and 372 cm-1.
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    URL: http://dx.doi.org/10.1023/A:1011339214337
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  • 19
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    Electronic Resource
    Crystal structure of a novel bis(guanidiniums) compound incorporated by sulfate anion (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 483-487 
    Details
    ISSN: 1572-8854
    Keywords: Bis(guanidiniums) ; sulfate anion ; hydrogen bond ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystal structure of a novel bis(guanidiniums) compound 1 by sulfate anion and water, C11H20N6OċSO4ċH2O, was measured by X-ray crystallographic analysis with an “imaging plate” method. It possesses space group P21/c, with a = 7.6433(15), b = 19.447(4), c = 12.115(2) Å, β = 107.81(3)°, and φcalc = 1.420 mg/m3 for Z = 4. Crystal data indicate that the architecture network is formed through hydrogen bonds, electrostatic interactions, and arene–arene stacking interaction among the bis(guanidiniums) compound, the sulfate anion and water molecule.
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    URL: http://dx.doi.org/10.1023/A:1011359702042
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  • 20
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    Electronic Resource
    Redetermination of the structure of bis[chloro-2-(2-hydroxy-4,5-dimethylphenylazo)-5,5-dimethyl-4,5,6,7-tetrahydrobenzothiazol-7-on] copper(II) complex (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 505-507 
    Details
    ISSN: 1572-8854
    Keywords: Bis[chloro-2-(2-hydroxy-4,5-dimethylphenylazo)-5,5-dimethyl-4,5,6,7-tetrahydrobenzothiazol-7-on]copper(II) ; thiazolylazo dye ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of C17H18ClCuN3O2S (M = 854.78, monoclinic, P21/c, a = 8.316(2), b = 18.461(4), c = 11.774(2) Å, β = 99.64(3)°, V = 1782.0(7) Å3, Z = 4) is formed by dimeric molecules [C17H18ClCuN3O2S]2 with two monomeric units linked together by two chlorine atoms. The Cu atom is coordinated by two chlorine atoms, an oxygen atom, the azo nitrogen atom attached to the benzene ring, and the nitrogen atom of the thiazole ring, in the form of a distorted tetragonal pyramid.
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    URL: http://dx.doi.org/10.1023/A:1011377120727
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  • 21
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    Electronic Resource
    Synthesis and crystal structure of the perchlorate salt of diprotonated N,N′-bis(1-methylimidazole-2-methyl)1,5-diazacyclooctane (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 531-534 
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    ISSN: 1572-8854
    Keywords: 1,5-Diazacyclooctane (DACO) ; crystal structure ; boat/chair configuration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The diprotonated perchlorate salt of a new 1,5-diazacyclooctane (DACO) mesocycle functionalized by two imidazole pendants, N,N′-bis(1-methylimidazole-2-methyl)-1,5-diazacyclo-octane (C16H28N6Cl2O8), has been synthesized and the structure determined by X-ray diffraction analysis. The title compound crystallizes in the monoclinic system, space group P21/c with a = 11.964(2), b = 13.251(3), c = 14.741(3) Å, β = 106.00(3)°, Mr = 503.34, V = 2246(1) Å3, Z = 4. The crystal structure of the title compound reveals that the DACO ring is also folded up into the “chair/boat” configuration, which is consistent with the configuration in most of the transition metal complexes of DACO and its derivatives. The two imidazole pendants of the compound are in cis position with a dihedral angle of 16.0(4)°.
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    URL: http://dx.doi.org/10.1023/A:1011337722544
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  • 22
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    Electronic Resource
    Structural and spectroscopic characterization of tris (o-phenanthroline)iron(II) disaccharinate monosaccharin hexahydrate (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 539-544 
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    ISSN: 1572-8854
    Keywords: Iron(II) ; o-phenanthroline ; saccharinate ; crystal structure ; spectroscopic properties ; thermal behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of the title compound, for short [Fe(o-phen)3](sac)2·(Hsac)·6H2O, has been determined by X-ray diffraction methods. It crystallizes in the monoclinic space group P21/n with a = 16.3190(1), b = 19.2890(1), c = 17.4490(2) Å, β = 92.586(1)°, V = 5486.95(8) Å3 and, Z = 4. The investigated compound constitutes the first example of a species in which uncoordinated saccharin and saccharinate anions are present in the structure. The crystallographic results reveal the subtle differences between the structure of the neutral molecule and its anion. The complex was also characterized by means of infrared, electronic, and 57Fe-Mössbauer spectroscopy. Its magnetic susceptibility was determined at room temperature and its thermal behavior investigated by means of thermogravimetric and differential thermal analytical techniques.
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    URL: http://dx.doi.org/10.1023/A:1011341823452
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  • 23
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    Electronic Resource
    Synthesis and X-ray structure of [(H3O)(C14H20O5)2][Me2NH2]2 [PMo12O40] · 2C14H20O5 (C14H20O5 = benzo-15-crown-5; Me2NH = dimethylamine) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 577-581 
    Details
    ISSN: 1572-8854
    Keywords: Oxonium ions ; crystal structure ; molybdophosphate ; crown ether
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [(H3O)(C14H20O5)2][Me2NH2]2 [PMo12O40] · 2C14H20O5 1 was synthesized from benzo-15-crown-5 and H3PMo12O40·24H2O in N,N′-dimethylformamide for the first time. 1 crystallizes in the monoclinic space group C2/c with a = 18.583(4), b = 25.510(5), c = 19.904(4) Å, β = 94.66(3)° D c = 2.124 mg/m3 for Z = 4. Refinement based on 7358 observed reflections led to a R1(wR2) = 0.0378(0.0761). The complex cation, [(H3O)(C14H20O5)2]+, exhibits a sandwich structure by hydrogen-bonding in the mean distance of 2.955 Å. The anion, PMo12O40 3−, is a α-Keggin structure.
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    URL: http://dx.doi.org/10.1023/A:1011354226178
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  • 24
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    Electronic Resource
    Synthesis, spectroscopy, and X-ray structure of the polymer catena-[bis(azido-N)-copper(II)-μ-bis(2-benzimidazolyl)butane] (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 69-72 
    Details
    ISSN: 1572-8854
    Keywords: azido ; crystal structure ; copper(II) ; infrared ; polymeric
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound, catena-[bis(azido-N)-copper(II)-μ(bis(2-benzimidazolyl)butane), [Cu(C18H18N4)(N3)2]n, was obtained from the reaction of the ligand bis(2-benzimidazolyl)butane and Cu(N3)2. The x-ray crystal structure is reported. The compound crystallizes in the monoclinic space group P21/c with a = 8.2524(10), b = 12.765(5), c = 9.1125(15) Å, β = 106.423(12)°, Z = 2. The Cu(II) ions are square-planar coordinated with trans-oriented end-on binding azido ligands. The structure is a polynuclear chain with the benzimidazole bridging at each end. In addition a N(ligand)-H···N(azido) H-bridge [N(ligand)···N(azido) = 2.994(7) Å] is present, resulting in a pseudo 2-dimensional lattice. The characteristic azido infrared vibrations are found at 2060 and 2077 cm−1 (νas(N3)) and 1284 and 1297 cm−1 (ν(N3)).
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    URL: http://dx.doi.org/10.1023/A:1009506418398
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  • 25
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    Electronic Resource
    Synthesis and crystal structure of [Tb4(H2O)2](C2O4)2(C5H6O4)4 (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 633-639 
    Details
    ISSN: 1572-8854
    Keywords: Lanthanide ; oxalate ; glutarate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A terbium complex associating two ligands, oxalate and glutarate, was prepared under hydrothermal conditions at 200°C by treating an aqueous suspension of terbium oxalate decahydrate with glutaric acid and guanidinium carbonate. Its structure was solved by X-ray diffraction on a single crystal. It crystallizes in the monoclinic space group P21 with lattice constants, a = 9.514(1) Å, b = 9.0681(8) Å, c = 19.702(2) Å, and β = 97.90(1)°. The terbium atoms and the oxalate ligands build dense chains which are connected by one side of the carboxylic group of some glutarate ligands, thus forming a sheet at the c level ≅ 0 and 1/2. These sheets are bridged by glutarate groups. The terbium atoms are ninefold coordinate with nine oxygen atoms of the ligands or with one water molecule and eight oxygen atoms of the ligands. Each polyhedron of the terbium atoms share one edge and one face of oxygen atoms with the two neighboring ones. The oxalate ligands are bischelating and bismonodentate. The coordination scheme of glutarate differs: either they are bismonodentate from one side and chelating and monodentate from the other side or they are chelating and monodentate from both sides.
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    URL: http://dx.doi.org/10.1023/A:1011992031111
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  • 26
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    Electronic Resource
    Terbium and holmium trans-2,3-dimethylacrylic acid complexes with 1,10-phenanthroline (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 777-782 
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    ISSN: 1572-8854
    Keywords: terbium complex ; holmium complex ; crystal structure ; trans-2,3-dimethylacrylic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Novel dinuclear complexes, [REL3(phen)]2 (where RE = Tb, Ho; HL = trans-2,3-dimethylacrylic acid; phen = 1,10-phenantheoline), were synthesized and determined by elemental analysis, infrared absorption spectra (IR), thermogravimetric analysis (TGA), and X-ray diffraction. The Tb complex crystallizes in space group P21/n with the cell dimensions a = 12.939(2) Å, b = 13.018(2) Å, c = 15.400(3) Å and β = 94.72(1)°. The Ho complex crystallizes in P (9) with a = 12.406(3) Å, b = 13.280(3) Å, c = 9.823(2) Å, α = 110.80(2)°, β = 103.42(2)°, γ = 63.67(1)°. The Tb atom is nine coordinate and the separation of Tb...Tb* is 3.97 Å. The Ho atom is eight coordinate and the separation of Ho...Ho* is 4.01 Å.
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    URL: http://dx.doi.org/10.1023/A:1013220207596
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  • 27
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    Electronic Resource
    Synthesis and crystal structure of 1-(1′,3′-dimethyl-5′-chloropyrazol-4′-carbonyl′-3-(2′-chlorophenyl)-5-amino-4-cyanopyrazole (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 789-792 
    Details
    ISSN: 1572-8854
    Keywords: crystal structure ; pyrazolide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound 1-(1′,3′-dimethyl-5′-chloropyrazol-4′-carbonyl)-3-(2′-chlorophenyl)-5-amino-4-cyanopyrazole (C16H12Cl2N6O) has been synthesized and characterized by X-ray diffraction: Triclinic, space group P1, with a = 8.6712(8) Å, b = 9.5091(10) Å, c = 11.2170(11) Å α = 71.531(2)°, β = 84.683(2)°, γ = 74.099(2)° Z = 2; V = 843.7(14) Å3. C(10), O(1), C(11), and N(2) atoms are coplanar with the average deviation of 0.0071 Å, which form 11.03° and 43.93° dihedral angles with pyrazole planes (I) and (II), respectively.
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    URL: http://dx.doi.org/10.1023/A:1013224308504
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  • 28
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    Structure, thermal behavior, and IR investigation of bis(3-amino-1,2,4-triazolium)monohydrogen monophosphate (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 805-809 
    Details
    ISSN: 1572-8854
    Keywords: organic phosphate ; crystal structure ; DTA/TG/DSC ; IR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Chemical preparation, calorimetric studies, crystal structure, and IR spectrometric investigation of (C2H5N4)2HPO4, denoted ATZP, are described. The compound crystallizes in the monoclinic system with C2/c space group. Its unit cell dimensions are a = 13.589(2) Å b = 11.105(2) Å c = 15.734(3) Å β = 104.68(2)°, V = 2296.8(7) Å3, and Z = 8. The structure of the title compound consists of a three dimensional network of H-bonds connecting all its components. The IR spectrum of ATZP is reported and discussed on the basis of group theoretical analysis.
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    URL: http://dx.doi.org/10.1023/A:1013280426251
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  • 29
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    Electronic Resource
    Crystal structure of [WI2(CO)2{P(OiPr)3}(η2-EtC2Et)] (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 181-184 
    Details
    ISSN: 1572-8854
    Keywords: tungsten(II) ; diiodo ; dicarbonyl ; triisopropylphosphite ; 3-hexyne ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [WI2(CO)2{P(OiPr)3}(η2-EtC2Et)] crystallizes in the monoclinic space group P21/n, with a = 11.101(12), b = 16.272(18), c = 14.892(17) Å, β = 93.27(1), Z = 4. The geometry can be considered to be pseudo-octahedral, with the 3-hexyne ligand occupying one site, with two iodo-groups, and the P(OiPr)3 ligand completing the equational plane of ligands, with two trans-carbonyl groups occupying the axial sites.
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    URL: http://dx.doi.org/10.1023/A:1009531014474
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  • 30
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    Electronic Resource
    Synthesis, crystal structure and molecular modeling (AM1) of two 5-arylidene derivatives of Meldrum's acid (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 189-194 
    Details
    ISSN: 1572-8854
    Keywords: crystal structure ; AM1 ; x-ray diffraction ; Meldrum's acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis and structural characterization of two 5-Arylidene derivatives of Meldrum's acid (2,2-dimethyl-1,3-dioxane-4,6-dione) are described: 5-(4-Nitrobenciliden)-2,2-dimethyl-1,3-dioxane-4,6-dione (3a), and 5-(4-Methoxybenciliden)-2,2-dimethyl-1,3-dioxane-4,6-dione (3b). The structure of 3a was refined to R1 = 0.0421 for 2148 reflections (with I 〉 2σ (I)). Crystal data for 3a: C13H11NO6, orthorhombic, space group Pbca, a = 16.008(3), b = 6.137(1), c = 25.281(5) Å, V = 2483.6(8) Å3, Z = 8. The structure of 3b was refined to R1 = 0.0496 for 4681 reflections (with I 〉 2σ(I)). Crystal data for 3b: C14H14O5, triclinic, space group P1, a = 9.131(2), b = 9.922(2), c = 14.490(3)Å, α = 85.076(6), β = 84.80(3), γ = 89.37(2)°,V = 1302.4(5) Å3, Z = 4. The results of crystallographic and molecular modeling (AM1) were compared. The molecules in the crystal are held together, in both compounds, by van der Waals forces and C—H···O hydrogen bond interactions.
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    URL: http://dx.doi.org/10.1023/A:1009535215383
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  • 31
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    Separation of rosin acids by molecular recognition: crystal structure of the complex of neoabietic acid with 2-amino-6-methyl-pyridine (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 195-198 
    Details
    ISSN: 1572-8854
    Keywords: neoabietic acid ; amino(methyl)pyridine ; crystal structure ; molecular recognition ; H-bonding ; rosin acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Neoabietic acid has been separated from gum rosin mixture by the aid of molecular recognition using 2-amino-6-methyl-pyridine as recognition reagent. The complex of neoabietic acid with 2-amino-6-methy-pyridine crystallizes from ether solution in the monoclinic, space group P21 with cell parameters of a = 7.370(1), b = 8.692(1), c = 18.365(2) Å, β = 92.53(1)°,V = 1175.3(2) Å3 and Z = 2. X-ray structure analysis shows that an extensive H-bonding network exists between neoabietic acid and amino(methyl)pyridine, which is considered as one of the factors resulting in successfully separating the neoabietic acid from the gum rosin mixture.
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    URL: http://dx.doi.org/10.1023/A:1009587232221
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  • 32
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    Crystal structure of a novel tertiary phosphine coordination complex: dichlorobis(tribenzylphosphine)nickel(II) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 173-176 
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    ISSN: 1572-8854
    Keywords: phosphine ; nickel(II) complexes ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound dichlorobis(tribenzylphosphine)nickel(II), Ni[P(CH2C6H5)3]2Cl2, belongs to a type of tertiary phosphine coordination complex, M(PR3)2X2. There are two molecules in the unit cell which do not appear to interact chemically. Both molecules have a trans-square planar configuration with each nickel atom on a center of symmetry. Three benzyl groups are bonded to each phosphorus atom as rotors in a propeller, and the threefold axis is along the P—Ni bond, which has a mean length of 2.23(1) Å. Crystal data: C42H42Cl2NiP2, Triclinic, space group $$P\bar 1 $$ , a = 10.4892(15) b = 10.5249(12) c = 19.453(2) Å, α = 83.872(8), β = 76.839(9), γ = 62.241(8)°, V = 1850.5(4) Å3, Z = 2. There is an intramolecular hydrogen bond between the C3 and C11 atoms.
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  • 33
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    A dinuclear cyanide-bridged complex, [(DMF)4(H2O)3LuCo(CN)6]·H2O (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 671-675 
    Details
    ISSN: 1572-8854
    Keywords: Synthesis ; crystal structure ; lutetium(III) ; cobalt(III) hexacyanide ; cyanide bridging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of the bimetallic cyanide bridged complex [(DMF)4(H2O)3LuCo(CN)6]·H2O (1) was obtained by single-crystal X-ray diffraction. The central lutetium(III) ion is eight coordinate arranged in a square antiprism while the cobalt(III) ion is six coordinate, oriented octahedrally. Molecules in the crystal lattice are held together by a network of hydrogen bonding. Crystallization of 1 occurs in the centrosymmetric monoclinic space group P21/c (No. 14) with a = 13.875(2), b = 8.8352(9), c = 24.633(2) Å β = 96.392(8)° and Z = 4.
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    URL: http://dx.doi.org/10.1023/A:1011952316999
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  • 34
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    Identification of a new family of diphosphate compounds, AI2BII3(P2O7)2: Structures of Ag2Co3(P2O7)2, Ag2Mn3(P2O7)2, and Na2Cd3(P2O7)2 (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 705-716 
    Details
    ISSN: 1572-8854
    Keywords: mixed metal diphosphates ; AI 2BII 3(P2O7)2 ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Syntheses and single-crystal X-ray structural results are reported for three new mixed diphosphates of the family AI 2BII 3(P2O7)2; Ag2Co3(P2O7)2 (I), Ag2Mn3(P2O7)2 (II), and Na2Cd3(P2O7)2 (III). All crystallize in the triclinic system, space group P1 bar: (I) a = 5.351(4), b = 6.375(4), c = 16.532(4) Å, α = 80.83(6) β = 81.45(4), γ = 72.87(5)°, V = 528.9(6) Å3, Z = 2, D calc = 4.649 mg/m3, R/Rw = 0.0428/0.0548 for 3949 obs. reflns; (II) a = 5.432(7), b = 6.619(6), c = 16.51(3) Å, α = 80.78(8) β = 82.43(9), γ = 72.82(7)°, V = 557.7(13) Å3, Z = 2, D calc = 4.338 mg/m3, R/Rw = 0.0679/0.1303 for 2100 obs. reflns and (III) a = 5.67(3), b = 7.08(4), c = 7.90(4) Å, α = 77.0(2), β = 82.5(2), γ = 67.8(2)°, V = 286(3) Å3, Z = 2, D calc = 4.249 mg/m3, R/Rw = 0.0307/0.0342 for 1945 obs. reflns. (I) and (II) are isostructural but (III) is of a different type. All three structures are characterized by layers of P2O7 groups alternating with layers of mixed metal atoms. Differences are seen in the conglomerate bonding patterns of B atoms and in the irregular geometry of Ag in (I) and (II) compared to the octahedral bonding seen for Na in (III). The differences in structure may be understood in terms of the ratios of the ionic radii of A and B atoms.
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  • 35
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    Crystal structure of diethoxynitrobenzene-p-tert-butylcalix [4]arene⋅2(CH3)2C=O: Evidence of intra- and intermolecular CH/π interactions forced by crystal packing (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 717-720 
    Details
    ISSN: 1572-8854
    Keywords: calix[4]arene ; CH/π interaction ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Diethoxynitrobenzene-p-tert-butylcalix[4]arene⋅2(CH3)2C=O crystallized in the monoclinic system, space group P21/c, with cell dimensions a = 16.1437(2) Å, b = 21.0292(2) Å, c = 18.9685(3) Å and β = 110.308(1)°. The asymmetric unit consists of a diethoxynitrobenzene-p-tert-butylcalix[4]arene molecule and two solvated acetone molecules. Besides the usual CH/π interaction between p-tert-butylcalix[4]arene π cavity and a solvated acetone, this structure shows the intra- and intermolecular CH/π interactions among a nitrobenzene ring, ethylene bridge of the ethoxynitrobenzene side chain and a solvated acetone molecule.
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    URL: http://dx.doi.org/10.1023/A:1012246110948
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  • 36
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    Crystal structure of a 26-membered hexaaza macrocycle bearing hydroxyethyl pendants containing p-xylyl spacers (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 743-747 
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    ISSN: 1572-8854
    Keywords: macrocycle ; hydroxyethyl pendant ; crystal structure ; hydrogen bonds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The new macrocyclic compound bearing hydroxyethyl pendant arms containing p-xylyl spacers, 3,6,9,16,19,22-hexaaza-6,19-bis(2-hydroxyethyl)-tricyclo[22,2,2,211,14] triaconta-1,11,13,24,27,29-hexaene, crystallizes in the monoclinic space group P21/c with a = 8.700(2) Å, b = 18.301(4) Å, c = 11.766(2) Å, β = 108.57(2)°. The two hydroxyethyl pendants are at the opposite sides of the macrocyclic plane. Benzene rings in macrocycle are parallel and exist the π-π weak interaction with distance of 4.28 Å. The crystal packing of the macrocycle is stabilized by the hydrogen bonds.
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  • 37
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    Electronic Resource
    Crystal structure, thermal analysis, and IR spectrometric investigation of bis(tert-butylammonium) sulfate (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 799-804 
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    ISSN: 1572-8854
    Keywords: organic sulfate ; crystal structure ; DTA/TG/DSC ; IR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Chemical preparation, X-ray single crystal, thermal analysis, and IR spectrometric investigation of (C4H12N)2SO4, denoted tBAS, are described. The compound crystallizes in the monoclinic system with C2/c space group. Its unit cell dimensions are a = 11.1585(5) Å, b = 6.2148(4) Å, c = 20.070(1) Å, β = 102.004(4)°, V = 1361.4(1) Å3, and Z = 4. The crystal structure of tBAS can be described as a typical thick layered organization built by all the components of the structure and centered by planes z = 1/4 and 3/4. Connection in these layers are established by N—H···O hydrogen bonds. Thermal analysis shows a reversible weak phase transition.
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  • 38
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    Crystal structure and spectroscopy of bis-[bis(2-benzimidazolyl)propane]copper(II) bis(triflate)monohydrate, a copper complex with a geometry intermediate between tetrahedral and square planar (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 793-797 
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    ISSN: 1572-8854
    Keywords: copper ; bis(benzimidazoles) ; crystal structure ; infrared
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of a mononuclear copper(II) compound with the ligand bis(2-benzimidazolyl)propane (abbreviated as tbz) is reported. The compound [Cu(tbz)2](CF3SO3)2(H2O) crystallizes in the triclinic space group P $$\bar 1$$ , with a = 12.363(6), b = 13.218(9), c = 15.365(8) Å, α = 82.74(5), β = 68.04(4), γ = 65.30(5), and Z = 2. The Cu(II) atom has a geometry intermediate between tetrahedral and square planar, consisting of four nitrogen atoms of two tbz ligands. The Cu—N—Cu angles are about 135°, while the dihedral angle between them amounts to 62° (0° for square planar and 90° for a tetrahedron). Ligand field bands are observed at 10.2 × 103, 13.8 × 103, and 20.3 × 103 cm−1, while the most characteristic infrared vibrations of the triflate anion are observed at 1273, 1260, 1238, 1221, 1171, and 1157 cm−1.
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  • 39
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    Electronic Resource
    Crystal structure and thermal analysis of 1,5-diammonium-2-methyl pentane sulfate monohydrate (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 95-98 
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    ISSN: 1572-8854
    Keywords: organic sulfate ; crystal structure ; DTA/TG/DSC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Chemical preparation, x-ray single crystal, and thermal analysis of C6H18N2SO4·H2O (denoted DMPS) are described. The compound crystallizes in the triclinic system with P $$\overline 1$$ space group. Its unit cell dimensions are a = 5.826(1) Å, b = 10.014(1) Å, c = 11.221(1) Å, α = 66.716(1)°, β = 84.395(1)°, γ = 83.759(1)°, V = 596.7(1) Å3, and Z = 2. The DMPS structure is built up from inorganic chains parallel to the a axis and linked via O(W)-H···O hydrogen bonds. These chains are interconnected by organic groups. Thermal analysis reveals the presence of one water molecule in the structure and shows a reversible weak phase transition.
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  • 40
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    Molecular structure and 1H, 13C NMR assignments of 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 115-118 
    Details
    ISSN: 1572-8854
    Keywords: 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (titmb); crystal structure; hydrogen bonding; 2D NMR ; crystal structure ; hydrogen bonding ; 2D NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The molecule 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (titmb) crystallizes as a monohydrate in the monoclinic space group C2/c with a = 20.888(4), b = 13.220(2), c = 14.385(2) Å, β = 90.36(1)°. Two of three imidazole groups are on one side of the central benzene ring, and the other one is on the opposite side. The crystal packing of titmb is stabilized by O-H--N hydrogen bonding between the water molecule and nitrogen atoms of the imidazole group. The complete 1H and 13C NMR assignments for titmb were carried out by 2D NMR spectral measurements.
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  • 41
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    Crystal structure of 2,6-dimethylpyridinium hydrogen phthalate (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 119-122 
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    ISSN: 1572-8854
    Keywords: phthalic acid ; 2, 6-dimethylpyridine ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new crystal of 2,6-dimethylpyridinium hydrogen phthalate (DPMHP) has been prepared and characterized by x-ray crystallography. DPMHP crystallizes in the monoclinic space group C2/c with a = 26.105(3), b = 8.2250(10), c = 13.8750(10) Å, β = 116.02(1)°, V = 2677.2(5) Å3, and Z = 8. The 2,6-dimethylpyridinium (DPM) is held with the hydrogen phthalate ion (HPI) by intermolecular hydrogen bond of N-H-O. A noncentered hydrogen atom is involved in the short intramolecular hydrogen of O-O [2.398(2) Å] between the neighboring carboxylic groups. The phenyl ring of the HPI appears to be deformed in comparison with the original. The entity of HPI in itself and DMPMHP as a whole are arranged in a rumple pattern. The geometrical arrangement in the crystal structure is characterized by the formation of laminar ribbons of DPMHP.
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  • 42
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    The crystal structures of two reaction products of α-halopyruvamide with nitrogen and sulfur nucleophiles (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 109-113 
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    ISSN: 1572-8854
    Keywords: α-halopyruvamide derivatives ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Two compounds have been prepared during the investigation of the reactivity of α-halopyruvamides. The reaction products: 3-(4-chlorophenyl)imidazo[1,2-a]pyridine-2-carboxamide (1) and 7-carbamoyl-5-phenyl-2,3-dihydro[1,3]thiazolo[4,3-b][1,3]thiazol-4-ium chloride (2) were structurally characterized by x-ray crystallography. Compound 1 crystallizes in the orthorhombic space group Pca21 with a = 28.813(2), b = 9.369(1), and c = 9.361(1) Å. The structure contains two crystallographically different molecules. Compound 2 crystallizes in the monoclinic space group P21/c with the following cell parameters: a = 8.5895(8), b = 22.499(2), c = 7.4133(6) Å, and β = 110.204(1)°.
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  • 43
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    Synthesis and molecular structure of N-[3-(p-bromophenyl)-1,2,4-oxadiazol-5-yl]methylphthalimide. III. (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 131-134 
    Details
    ISSN: 1572-8854
    Keywords: 1,2,4-Oxadiazole ; crystal structure ; phthalimide derivative ; AM1 method ; STO-3G basis set
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis, spectroscopic studies and crystal structure of the title compound is described. The crystallographic studies showed that the p-bromophenyl group is very nearly coplanar with the 1,2,4-oxadiazole ring. The nearly planar phthalimide group makes an angle of about 98° with the bromophenyloxadiazole plane. Semi-empirical (AM1) and ab initio (STO-3G, 6-31G) molecular orbital calculations have been carried out for this compound and a comparison of bond angles, bond lengths and torsion angles has been made with the experimental values, which are remarkably close to each other. This compound crystallizes in the monoclinic space group P21/c with a = 13.6299(2),b = 13.9836(2), c = 8.4817(2) Å, β = 101.9070(10)°, V = 1581.79(5) Å3, and Z = 4.
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  • 44
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    Crystal and molecular structure of augustamine (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 135-138 
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    ISSN: 1572-8854
    Keywords: alkaloid ; tazettine type ; amaryllidaceae ; crystal structure ; molecular mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of augustamine (1), C17H19NO4 an amaryllidaceae alkaloid of the tazettine group has been determined by direct methods from single crystal x-ray diffractometer data and refined by full-matrix least squares. The alkaloid (1) crystallizes in the space group P212121, with cell parameters: a = 7.833(8) b = 11.08(2) å, c = 16.69(6) Å, Z = 4, Dc = 1.381 g/cm−3, R = 7.6% for 1115 observed reflections. The molecule, having a hexacyclic ring system, is very rigid with the ring B in a chair conformation. Molecular mechanics calculations have been made using MM3(2000) force field.
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  • 45
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    Synthesis, crystal structure of a one-dimensional cobalt—azide complex through hydrogen bond (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 159-162 
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    ISSN: 1572-8854
    Keywords: crystal structure ; cobalt (II) complex ; one-dimensional chain ; hydrogen bond
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A one-dimensional chain complex, {[Co(bpm)2(N3)2][Co(bpm)2(H2O)2]} (ClO4)2, (bpm being bis(pyrazol-l-yl)methane), has been synthesized and characterized by X-ray diffraction: triclinic, space group P - 1 with a = 8.805(2) Å, b = 8.902(2) Å, c = 13.621(3) Å, α = 84.27(3)°, β = 84.63(3)°, γ = 80.05(3)°, V = 1043.2(4) Å3, Z = 1. Two cobalt atoms have ideal octahedral environments with different coordination atoms. One cobalt atom is six-coordinated with nitrogen atoms from two bpm ligands and two azide ligands, while the other cobalt atom is coordinated by four nitrogen atoms from bpm and two oxygen atoms from water molecules. The complex forms one-dimensional chain through hydrogen bonds.
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  • 46
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    Electronic Resource
    Syntheses, characterization, and structural analyses of several f-block isothiocyanatonitrato complexes (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 301-309 
    Details
    ISSN: 1572-8854
    Keywords: Synthesis ; crystal structure ; dioxouranium(VI) ; lanthanide(III) ; thiocyanate ; nitrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Reactions of tetra-n-butylammonium thiocyanate with lanthanide and uranyl nitrates yield complexes of the general type [(Bu)4N]x[M(NCS)y(NO3)z]. Samples of [(Bu)4N]2 [UO2(NCS)3( NO3)] (1), [(Bu)4N]3[Yb(NCS)4(NO3)2] (2), and [(Bu)4N]3[Nd(NCS)4(NO3)2rsqb; (3) were prepared from alcohol solutions. Crystallization of 1 occurs in the centrosymmetric monoclinic space group C2/c (No. 15) with a = 17.949(4) Å, b = 16.587(3) Å, c = 16.763(3) Å; β = 99.77(3)°; and Z = 4. The seven-coordinate uranium(VI) ion exhibits a pentagonal bipyramid coordination environment. Crystallization of 2 occurs in the centrosymmetric orthorhombic space group Pnnn (No. 48) with a = 12.530(2) Å, b = 12.9440(10) Å, c = 21.203(2) Å; Z = 2. The eight-coordinate ytterbium(III) ion expresses a dodecahedral coordination environment. Crystallization of 3 occurs in the noncentrosymmetric monoclinic space group Cc (No. 9) with a = 16.556(2) Å, b = 18.130(2) Å, c = 23.984(4) Å; Z = 4. The 10-coordinate neodymium(III) ion exhibits a dodecahedral coordination environment. Characterization includes physical property determinations, conoscopic studies, IR spectroscopic identifications, and UV spectral data. Details of the syntheses along with selected bond distances and angles are presented and discussed.
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  • 47
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    Electronic Resource
    A dimeric pervanadyl (VO2+) complex with a tridentate Schiff base ligand (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 329-333 
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    ISSN: 1572-8854
    Keywords: Pervanadyl complex ; Schiff base ; di(μ-oxo)-bridged dimer ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A di(μ-oxo)-bridged dinuclear complex, [VO2(pamh)]2 was isolated by reacting bis(acetylacetonato)vanadium(IV) and the Schiff base, N-(anisoyl)-N′-(picolinylidene)-hydrazine (Hpamh) in acetonitrile. The complex crystallizes in the space group $$P\bar 1 $$ ;1; (#2) on crystallographic inversion center. Crystal data: a = 8.2202(12) Å, b = 9.8389(19) Å, c = 10.1907(17) Å, α = 68.245(15)°, β = 74.47(2)°, γ = 66.710(19)°, V = 696.0(2) Å3, and Z = 1. The physical properties of the complex and the structural parameters are consistent with the +5 oxidation state of the metal ions. The monomeric VO2(pamh) unit is square-pyramidal. The planar mononegative ligand (pamh−) coordinates the metal ion via the pyridine-N, the imine-N, and the amide-O atoms. One of the oxo groups completes the NNOO basal plane and also participates in the Vndash;Ondash ;V bridge formation. The other oxo group satisfies the fifth apical coordination site. The molecular structure of the dimeric complex, [VO2(pamh)]2 can be described as two edge-shared distorted VO4N2 octahedra.
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  • 48
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    Crystal structure and spectroscopy of a hydrogen-bridged one-dimensional Cu(II) complex containing both octahedral and square pyramidal geometries in the same unit cell (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 351-357 
    Details
    ISSN: 1572-8854
    Keywords: Helical hydrogen-bridged one-dimensional Cu(II) complex ; trans-4-styrylpyridine ; crystal structure ; IR and electronic spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Single crystals of the helical hydrogen-bridged one-dimensional Cu(II) complex, [Cu(stpy)2(CH3COO)2(H2O)2] (1) [Cu(stpy)2(CH3COO)2(H2O)] (2), are prepared and characterized by elemental and thermal analyses, IR, electronic and X-ray crystal structure determination. The crystals are monoclinic, of space group C2/c, with unit cell parameters a = 31.842(7) Å, b = 5.9829(10) Å, c = 30.970(14) Å, β = 111.78(3)°, Z = 4. The asymmetric unit contains two different types of Cu(II) polyhedra, namely, octahedron and square pyramid within the same unit cell. 1 has elongated octahedral geometry with two nitrogen atoms from stpy and two oxygen atoms from synmonodentate acetate ligands, transcoordinated to Cu(II) in the basal plane. The oxygen atoms of the two water molecules occupy the axial positions. 2 has Cu(II) coordination polyhedra similar to 1, except that only one of the apical positions is occupied by a water molecule. The structure consists of two independent linear chains, one involving octahedral (1) and the other involving square-pyramidal (2) polyhedra, held by hydrogen bridges. The Cu–Cu intra- and interchain separations in both 1 and 2 are 5.983 and 8.214 Å. The unit cell packing shows weak π-stacking between adjacent coordinated stpy ligands in the chain, resulting in ladder-type structure. Further, the extended packing reveals helical arrangement of Cu(II) polyhedra in the lattice.
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  • 49
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    Crystal structure of [Yb(L(NO3)2(H2O)2](NO3), L = bromo-N,N,N′,N′-tetraethylmalonamide (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 455-458 
    Details
    ISSN: 1572-8854
    Keywords: Ytterbium ; malonamide ; crystal structure ; extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [Yb(L(NO3)2(H2O)2](NO3), L = bromo-N,N,N′,N′-tetraethylmalonamide crystallizes in the triclinic spacegroup P-1 with cell dimensions a = 9.030(9), b = 12.036(12), c = 12.392(13) Å, α = 84.52(1), β = 77.58(1), γ = 67.21(1)° , dcalc = 1.935 g cm-3 for Z = 2. The ytterbium atom in the complex cation is nine-coordinate being bonded to two oxygen atoms from the malonamide ligand, two nitrate anions, and three water molecules.
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  • 50
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    Electronic Resource
    N-Arylmaleimide derivatives (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 563-571 
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    ISSN: 1572-8854
    Keywords: Maleimide ; crystal structure ; photopolymerization ; monomer ; conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Nine phenyl substituted N-phenylmaleimide monomers for photopolymerization studies have been characterized by x-ray crystallography. Structures for N-(2′-t-butylphenyl)maleimide (1), P21/n, a = 10.197(3) Å, b = 11.904(4) Å, c = 10.496(5) Å, β = 100.61(3)° N-(2′-trifluoromethylphenyl)maleimide (2), P21/c, a = 11.763(8) Å, b = 10.699(9) Å, c = 8.284(5) Å, β = 90.02(5)° N-(2′,6′-diisopropylphenyl)maleimide hemibenzene solvate (3), Pc, a = 16.747(6) Å, b = 8.552(3) Å, c = 12.899(4) Å, β = 105.08(3)° N-(2′,6′-diisopropylphenyl) maleimide (unsolvated) (4), C2/c, a = 28.146(10) Å, b = 8.434(4) Å, c = 12.881(4) Å, β = 92.20(4)° N-(2′-bromo-3′,5′-bis(trifluoromethyl)phenyl) maleimide (5), P21/n, a = 8.7115(16) Å, b = 16.125(3) Å, c = 9.6707(19) Å, β = 99.757(15)° N-(2′-phenylphenyl)maleimide (6), P21/n, a = 8.519(4) Å, b = 13.742(5) Å, c = 11.147(4) Å, β = 92.25(3)° N-(4′-methoxyphenyl)maleimide (7), P21/n, a = 9.320(3) Å, b = 6.621(2) Å, c = 16.059(6) Å, β = 99.58(3)° N-(2′-trifluoromethylphenyl)-2-methylmaleimide (8), Fdd2, a = 43.362(12) Å, b = 8.202(2) Å, c = 12.720(4) Å and N-(2′-trifluoromethylphenyl)-2-methanosuccinimide (9), Cc, a = 7.708(2) Å, b = 22.191(9) Å, c = 7.137(2) Å, β = 115.76(2)° are described. Molecules with bulky 2′-substituents show larger rotations between the mean phenyl and maleimide ring planes, and varying degrees of distortion to the imide group.
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  • 51
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    Oxygen Configuration in the Superconductor (Hg0.7Mo0.3)Sr2(Ca1−xRx)Cu2Oz (R = Nd and Pr) (2000)
    Springer
    Journal of superconductivity 13 (2000), S. 111-119 
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    ISSN: 1572-9605
    Keywords: superconductivity ; Hg-based cuprate ; Hg-1212 (Hg,Mo)Sr2(Ca,R)Cu2O z ; neutron diffraction ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Two series of Hg-based oxides (Hg0.7Mo0.3)Sr2(Ca1−x R x )Cu2O z (R = Nd and Pr, 0.2 ≤ x ≤ 0.7) have been synthesized. Electrical-resistivity measurements show that these compounds are superconductors with maximum onset T c of 107 and 102 K for Nd- and Pr-containing samples, respectively. The neutron powder diffraction experiments on both as-prepared and O2-annealed samples of R = Nd revealed that the O(3) site at the HgOδ sheets are fully occupied and shifted towards the Hg/Mo site to form Mo–O bonds.
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  • 52
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    The consequences of the mutual recognition of measurement standards for international metrology (2000)
    Springer
    Accreditation and quality assurance 5 (2000), S. 409-413 
    Details
    ISSN: 1432-0517
    Keywords: Key words Metrology ; Comparisons ; Chemistry ; Standards
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  After stressing the importance in the modern world of accurate and reproducible measurements, the actions taken by the Bureau International des Poids et Mesures to set up, together with the regional metrology organizations, a series of key comparisons are described. They are the technical foundation of a mutual recognition of national measurement standards arrangement prepared in conjunction with the National Metrology Institutes (NMIs). This arrangement also includes the recognition of calibration and measurement certificates issued by these institutes. Then, the consequences of this arrangement for trade are described. The case of chemical analysis is illustrated by the application of the Kyoto protocol on the reduction of greenhouse gases. But the global workload to be taken up by the International Committee of Weights and Measures, its Consultative Committee for Amount of Substance and the NMIs is huge.
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  • 53
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    Evaluation of Kinetic Data for Crystallization of Tio2 Prepared by Hydrolysis Method (2000)
    Springer
    Journal of thermal analysis and calorimetry 60 (2000), S. 595-604 
    Details
    ISSN: 1572-8943
    Keywords: crystal structure ; DSC ; oxides ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The formation of TiO2 prepared by hydrolysis method was presented. Thermodynamics and kinetics of anatase crystallization reaction were investigated. Differential method of kinetic data evaluation in non-isothermal conditions according toKissinger, Ozawa and Kazeev-Yerofeev was applied. Starting, crystallized and thermally treated powders were determined using X-ray powder diffraction analysis. The characteristic parameters (the activation energy, constant rate and formal kinetic order of reaction) of TiO2 formation were calculated using DSC data.
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  • 54
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    Electronic Resource
    Tosyiate of ethyl 3-amino-2-phenyliodoniocrotonate: Synthesis, crystal structure, and synthesis of heterocyclic compounds based on it (2000)
    Springer
    Chemistry of heterocyclic compounds 36 (2000), S. 672-678 
    Details
    ISSN: 1573-8353
    Keywords: aminocrotonate ester ; pyridinium salts ; phenyliodonium salts ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ethyl 3-aminocrotonate, when reacted with hydroxy(tosyloxy)iodobenzene, forms the tosylate of ethyl 3-amino-2-phenyliodoniocrotonate which crystallizes well in up to 80% yield. X-ray analysis confirms the structure of the phenyliodonium salt, revealing intramolecular and unusual intermolecular hydrogen bonds, stabilizing the compound in the crystalline state. Reaction with pyridine, its 4-substituted derivatives, and 4,4′-bipyridine yields tosylates of 2-pyridinio-substituted ethyl 3-aminocrotonates.1H NMR and IR spectra support formation of an intramolecular hydrogen bond for the E-isomer, and iodonium salts in the case of pyridinium salts for the Z-isomer. The UV spectra of the pyridinium salts show an intramolecular charge transfer band.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02297675
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  • 55
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    Electronic Resource
    Solid-State Supramolecular Chemistry of Porphyrins. Ligand-Bridged Tetraphenylmetalloporphyrin Dimers (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 37 (2000), S. 219-230 
    Details
    ISSN: 1573-1111
    Keywords: porphyrin complexes and clathrates ; coordination oligomers ; supramolecular chemistry ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Eight new crystalline materialsbased on ligand-bridged dimers of either Zn(II)- orCo(II)-tetraphenylporphyrins have been prepared andcharacterized by X-ray diffraction analysis. These supramolecular entities have a ``wheel-and-axle'' typeshape, the elongated bidentate ligands1,3-diaminopropane, 1,4-diaminobutane, 4,4'-bipyridyl, 1,2-bis(4-pyridyl)ethene or1,2-bis(4-pyridyl)ethane coordinating axially on bothsides to the metal centers of the porphyrin species. They vary from one another by the length of the ligandspacer, the distance between the two porphyrincomponents ranging from 9.4 Å to 14.0 Å. Theintermolecular organization in these structures ischaracterized by a similar chain motif in whichadjacent oligomeric units interlock into one another. In spite of the steric constraint imposed by thebridging ligand, this packing preserves the typicalcorrugated stacked arrangement of the porphyrinframeworks which has been commonly observed inclathrates of monomeric tetraarylporphyrins. It alsoinduces in most cases large voids between theinterlocked motifs, causing enclathration of solventmolecules in the crystal lattice. The experimentallyestablished geometries of these oligomers and theircrystal packing modes provide useful information forfurther crystal engineering efforts of polymericmultiporphyrin domains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008118119529
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  • 56
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    Shower Meteoroids: Constraints From Interplanetary Dust Particles And Leonid Meteors (2000)
    Springer
    Earth, moon and planets 88 (2000), S. 35-58 
    Details
    ISSN: 1573-0794
    Keywords: Chemistry ; interplanetary dust particles (IDPs) ; Leonids ; meteor trails ; meteoroids ; meteors ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The cometary Leonid meteoroids represent a size range in between largest carbon-richIDPs and the smallest CI meteorites. Their dustball structure and chemistry offer anopportunity to constrain hierarchical dust accretion inferred from petrologic studies ofaggregate and cluster IDPs. The Leonid shower meteoroids of known ``comet ejection''ages provide an opportunity to study space weathering of cometary dust over periodsof up to several hundred years. The meteors and aggregate and cluster IDPs displaycontinuous thermal modification of organics and volatile element (Na, K-bearing phases), that occur as discrete minerals and amorphous solids each different response during kinetically controlled ablation. Leonid meteoroids are not excessively Na-rich. The occurrences of Leonid meteors can now be accurate predicted and combined withknowledge better models for the settling rates, collections of surviving dust becomea comet nucleus-sampling mission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1013862627781
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  • 57
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    Electronic Resource
    Synthesis, Structure, and Superconductivity of (La1.5Pb0.5−xSrx)CuOz (2000)
    Springer
    Journal of superconductivity 13 (2000), S. 121-128 
    Details
    ISSN: 1572-9605
    Keywords: superconductivity ; crystal structure ; magnetization ; 214
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The substitution of strontium for lead in the material (La1.5Pb0.5−x Sr x )CuO z , x = 0–0.15 has been carried out. A stable and reproducible single phased superconducting materials can be obtained inside an evacuated quartz tube. The X-ray diffraction pattern shows that the superconducting phase can be indexed on the basis of an orthorhombic symmetry (F mmm) for x = 0 and on the basis of tetragonal symmetry (I 4/mmm) for x 〉 0. The transition temperature T c increases as the strontium substitution parameter x increases. We observed the maximal T c around x = 0.15 with 38 K with fairly large Meissner volume fraction of 38% (FC).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007790512982
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  • 58
    Electronic Resource
    Electronic Resource
    Octa(p-hydroxy)octakis(propyloxy)calix[8]arene: The First Crystal Structure of a p-Hydroxy Calixarene (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 36 (2000), S. 259-266 
    Details
    ISSN: 1573-1111
    Keywords: calixarene ; hydroquinone derivative ; crystal structure ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Octa(p-ydroxy)octakis(propyloxy)calix[8]arene.9(pyridine).2(H2O) crystallises in the triclinic space group P-1, a = 14.083(2), b = 14.478(2), c = 15.652(2) Å, α = 70.109(4), β = 74.146(3), γ = 75.572(4)°, V = 2843(1) Å3, Z = 1. Refinement led to a final R1 value of 0.0757 for 4693 reflections. The calixarene sits around a crystallographic centre of inversion and is in the `chair-like' conformation. All p-hydroxyl groups form hydrogen bonds with either pyridine or water molecules leading the extended structure to be composed of infinite ribbons parallel to the [1,0,-1] direction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008018628939
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  • 59
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    A Bridged High-Spin Complex Bis-[Ni(II)( rac-5,5,7,12,12,14-hexamethyl- 1,4,8,11-tetraazacyclotetradecane)]-2,5-pyridinedicarboxylate Diperchlorate Monohydrate (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 38 (2000), S. 45-56 
    Details
    ISSN: 1573-1111
    Keywords: [Ni(rac-Me6[14]aneN4)] ; 2,5-pyridinedicarboxylate ; preparation ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A bridged high-spin complex,bis-[Ni(II)(rac-5,5,7,l2,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)]-2,5-pyridinedicarboxylate diperchlorate monohydrate has been obtained by reaction of [Ni(II)(rac-5,5,7, 12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)](ClO4)2 and 2,5-pyridinedicarboxylic acid in aqueousalkaline (NH4OH) medium. C39H77Cl2N9Ni2O13, chemical formula weight 1068.42, orthorhombic, P212121, a = 11 .423(3) Å,b = 14.770(6) Å, c = 31.608(7) Å,α = β = γ =90.00°, V = 5333(3) Å3, Z = 4, Dcalc = 1.331 g cm-3, μcalc = 0.869 mm-1, F(000) = 2272, T = 293(2), R = 0.0870 for 2686 observed reflections [I 〉 2σ(I)]. The complexincludes two folded [Ni(rac- Me6[14]aneN4)]2+ units havingopposite diastereomeric configuration. They are bridged through a dianion of2,5-pyridinedicarboxylic acid, with one Ni-atom coordinated to the O-atom ofthe 2-carboxylic group and the pyridine N-atom (forming a 5-membered chelatering), and with the second Ni-atom coordinated to both O-atoms of the 5-carboxylic group (forming a 4-membered chelate ring). Hydrogen bonding involving macrocyclic NH groups, both 2- and 5-carboxylic groups, perchlorate anions and water molecules gives rise to the formation of an infinite supramolecular network in the title compound's crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008100726771
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  • 60
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    Synthesis, Structure and Spectroscopy of Clathrate Inclusion Compounds of Cobalt(II), Cadmium(II) and Zinc(II) trans-4-styrylpyridine nitrates as Host with trans-4-styrylpyridine as Guest (2 : 1) (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 38 (2000), S. 233-249 
    Details
    ISSN: 1573-1111
    Keywords: trans-4-styrylpyridine complex ; Werner-type clathrates ; crystal structure ; IR spectra ; electronic spectra and thermal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract New clathrate inclusion compounds with the general formula,MA3X2 β 1/2G (M = Co(II)(1),Cd(II)(2), and Zn(II)(3), X = NO3 - andA and G = trans-4-styrylpyridine), differing from the usualWerner clathrates, MA4X2 β2G, have been prepared and characterized by elemental and thermal analyses,IR and electronic spectroscopy and X-ray crystallography. Tworepresentative compounds [Co(stpy)3(NO3)2] β 1/2stpy (1) and [Cd(stpy)3(NO3)2] β 1/2 stpy (2)are investigated by single crystal X-ray diffraction. Compound (1)crystallizes in the triclinic space group P¯1 with a = 10.966(2),b = 12.802(4), c = 16.063(5) Å α = 83.38(3),β = 71.30(2), γ = 76.88(3) °,Z = 2. The structure is made up of discretemolecules of [Co(stpy)3(NO3)2]. The central Co(II) issurrounded by three stpy nitrogen atoms and four oxygen atoms of twoasymmetrically coordinated bidentate nitrate ligands. One of the oxygensis semicoordinated leading to a distorted octahedral geometry for Co(II).Compound (2) crystallizes in the monoclinic space group P21/nwith a = 15.597(3), b = 18.313(5), c = 16.188(3) Åβ = 115.998(14)° and Z = 4. The structure consists of neutralmolecules of [Cd(stpy)3(NO3)2]. The geometry aroundCd(II) is best described as pentagonal bipyramid with four oxygen atomsfrom symmetrical bidentate nitrate groups and one stpy nitrogen atom inthe equatorial positions. Two other nitrogen atoms from stpy ligands occupythe axial positions. The guest stpy molecules are trapped in the centrosymmetricalcavities in lattices of both 1 and 2. Compound 3is found to beisomorphous with 2. A large splitting of the symmetric and asymmetricNO2 stretching vibrations reveals the presence of bidentate nitrate ligands.Thermogravimetric and DTA studies on the Cd(II) compound, show it to be athermally stable inclusion compound.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008137311908
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  • 61
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    Crystal Structure of a Calix[4]crown Ether-Ester and Molecular Recognition of Alkyl- and Arylalkylamines (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 36 (2000), S. 461-472 
    Details
    ISSN: 1573-1111
    Keywords: calix[4]arene ; calixcrown ; ether ester ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The crystal and molecular structure of3 has been determined by X-ray analysis. Thecrystal data are: triclinic, space group P'1,a = 12.999(2),b = 14.114(3),c = 16.132(3) Å,α = 91.62(2),β = 97.71(1),γ = 91.38(2)°,V = 2930.6(9) Å3,Z = 2,Dm = 1.046 g cm-3.Rotational disorder has been seen in the t-butyl groups whichwere refined isotropically. Least-squares refinementbased on F2, using 4827 observedreflections with I 〉 2σ(I) and 18 restraints,led to R = 0.123. The calix is found in a coneconformation. The crown ether part of the molecule isnot in a fully extended conformation but has foldsin the chain. The calix[4]crown ether-ester exhibitsmolecular recognition properties toward alkylamines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008134703152
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  • 62
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    Triphenylpyrylium Tetrafluoroborate-Sensitized Photochemistry of the Terpenes Sabinene, α-Phellandrene, and α- and γ-Terpinene (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1563-1567 
    Details
    ISSN: 1434-193X
    Keywords: Triplet recombination ; Electron transfer ; Radical ions ; Photochemistry ; Terpenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The triphenypyrylium tetrafluoroborate (TPT)-sensitized reactions of several terpene donor molecules, including sabinene (1), α-phellandrene (4), α-terpinene (5) and γ-terpinene (6) give rise to significantly different products than reactions induced by other electron-transfer sensitizers, such as 1,4-dicyanobenzene (DCB). The divergent reactions require decidedly different key intermediates; the products obtained with TPT can be explained by dissociative recombination of the intermediate radical-radical cation pair in the triplet state, generating donor-derived biradicals.
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  • 63
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    Ring Expansion of 2-Alkylidenedihydroquinazolines to Iminodihydro-1,4-benzodiazepines by Methanesulfonyl and Trifluoromethanesulfonyl Azide (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1577-1587 
    Details
    ISSN: 1434-193X
    Keywords: Azides ; Cleavage reactions ; Cycloadditions ; Nitrogen heterocycles ; Polycycles ; Ring expansion ; Synthetic methods ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---2-Alkyl-1-methylquinazolinium hexafluorophosphates 9 are deprotonated by sodium or potassium hydride to afford solutions of 2-alkylidenedihydroquinazolines 10, which were investigated by NMR spectroscopy. Trapping with methanesulfonyl azide (5a) of 10 in situ or subsequent treatment with trifluoromethanesulfonyl azide (5b) gives mixtures of colourless (15) and intensely yellow N-sulfonylimino-1,4-benzodiazepines 16 along with products due to cleavage of the exocyclic double bond of 10, viz. 11 and 13. The ethylidene compound 10b yields the bicyclic products 18 and 19, apparently by complex sequences of reactions that are triggered by removal of the acidic proton at C-2 of 16b and 16f. The structures of the products are based on spectroscopic evidence and X-ray diffraction analyses performed on 15b, 16d, 16e, and 19.
    Additional Material: 6 Ill.
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  • 64
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    Electronic Resource
    Electrophilic Reactivity of a 2-Azaallenium and of a 2-Azaallylium Ion (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1589-1593 
    Details
    ISSN: 1434-193X
    Keywords: Azaallenium ions ; Azaallylium ions ; Iminium ion ; Kinetics ; Linear Free Energy Relationships ; Ab initio calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The rate constants for the reactions of the 2-azaallenium ion 1b+, the 2-azaallylium ion 2a+ and the iminium ion 3+ with different nucleophiles were determined by 1H NMR spectroscopy. By correlation with the Linear Free Enthalpy Relationship (LFER) lg k20°C = s (E + N), developed by Mayr and Patz, the electrophilicity parameters E(1b+) = -3.7, E(2a+) ≍ -16 and E(3+) = -10.43 were obtained. They show that the relative reactivities of these ions are approximately 1012:1:106. Quantum chemical calculations (ab initio, DFT) of the methyl anion affinities for the ions 1b+,2a+ and3+ are in agreement with the experimental E values. The X-ray structure of 3+·CF3SO3- is reported for the first time; it shows no strong interaction between the cation and the anion.
    Additional Material: 2 Ill.
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  • 65
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    Oxazoline N-Oxide Mediated [3+2] Cycloadditions: Application to a Formal Synthesis of a (+)-β-Methylcarbapenem (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1595-1601 
    Details
    ISSN: 1434-193X
    Keywords: Oxazoline N-oxide ; Cycloadditions ; Cycloadditions ; Lactams ; Thienamycin ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---[3+2] Cycloaddition between a camphor-derived oxazoline N-oxide 9 and the γ,δ-unsaturated enamino ester 11 afforded the single adduct 6. A stereoselective reduction of the enamino ester side chain allowed the control of the absolute configuration of the two additional asymmetric centres. Nitrogen protection and oxidative hydrolysis of the resulting product 13, followed by further functional group manipulations, led to the β-lactam derivative 1, a known precursor of the β-methylthienamycin derivative2a.
    Additional Material: 1 Ill.
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  • 66
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    A New Substitution Pattern in Subphthalocyanines: Regioselective Synthesis and Separation of “ortho” Derivatives (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1603-1607 
    Details
    ISSN: 1434-193X
    Keywords: Boron ; Cyclotrimerizations ; Nitrogen heterocycles ; Macrocycles ; Subphthalocyanines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The regioselective preparation of ortho-substituted subphthalocyanides was achieved employing 3-substituted phthalonitrile derivatives as starting materials. A mechanistic proposal has been outlined.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/99525_s.pdf or from the author.
    Additional Material: 2 Ill.
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  • 67
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    A New Route to 2,7- and 7-Functionalized Labdanes (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1609-1615 
    Details
    ISSN: 1434-193X
    Keywords: Terpenoids ; Natural products ; Total synthesis ; Cyclizations ; Rearrangements ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A new route for the synthesis of 2,7- and 7-functionalized labdanes starts from (R)-carvone (1). 11-Nordrim-7-en-9-one (15) is an appropriate starting material for the total synthesis of hispanone (21), a biologically active furolabdane isolated from the Mediterranean medicinal plant Ballota saxatilis.
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  • 68
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    Preparation of Kingiside from Aucubin (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1623-1626 
    Details
    ISSN: 1434-193X
    Keywords: Iridoid glucoside ; (8S)-Kingiside ; (8S)-Loganin ; (8S)-7-Ketologanin ; Asymmetric synthesis ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The tetraacetyl derivative 8 of the naturally occurring kingiside (8a) was prepared from aucubin (1). Intermediates in the synthesis were (8S)-tetraacetyl loganin (6) and (8S)-tetraacetyl-7-ketologanin (7), whose free (8R)-epimers occur in many different plants (Caprifoliaceae, Loganiaceae). The 13C NMR spectrum allows the structure to be unequivocally identified.
    Additional Material: 1 Tab.
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  • 69
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    Isomeric Tetrakis(dimethylamino)naphthalenes: Syntheses, Structure-Dependence of Basicities, Crystal Structures, and Physical Properties (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1617-1622 
    Details
    ISSN: 1434-193X
    Keywords: Tetrakis(dimethylamino)naphthalenes ; Basicity ; Hydrogen bonds ; Cyclicvoltammetry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---For comparison to the recently described 2,3,6,7-tetrakis(dimethylamino)naphthalene (1) the three isomers 2,3, and 4 were synthesized. The basicities of this group of isomers are strongly dependent upon the different mutual orientations of the pairs of dimethylamino substituents: only the isomers 3 and, partially, 4, both with dimethylamino groups in adjacent peri-positions of the naphthalene, are strong “proton sponges”. For the isomers 1 and 2 with the same number and kind of twofold dimethylamino substituents in neighbouring ortho-positions, however, no significant basicity increase is observed. To explain this difference between the two groups of isomers it is suggested that in the ortho-pairs of 1 and 2 the C-N bonds diverge considerably, leading to an increased N···N distance and consequently to less stable [N···H···N]+ hydrogen bonds in contrast to the parallel C-N bonds in the peri-substituted isomers 3 and 4. X-ray crystal structure analyses of the bases and of some of the salts derived therefrom were solved and are discussed. Cyclic voltammetry indicates that 1 to 4 are strong electron donors, reacting easily to radical cations or dications which with suitable acids have been obtained as salts.
    Additional Material: 3 Ill.
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  • 70
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    Ring Closure Reactions of Disubstituted 4-Penten-1-oxyl Radicals - Towards a Stereoselective Synthesis of allo-Muscarine (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1677-1683 
    Details
    ISSN: 1434-193X
    Keywords: Radicals ; Cyclizations ; Pyridinethione ; Tetrahydrofurans ; Asymmetric synthesis ; Thiazolethione ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The trisubstituted functionalized tetrahydrofurans 10, 11, 16, 18, and 19 were photochemically prepared from 2,3-syn- and 2,3-anti-configuredN-(3-benzoyloxy-5-hexen-2-oxy)thiazole-2(3H)-thione anti-6, pyridinethiones 7, anti-8, and BrCCl3. The formation of tetrahydrofurans was achieved by an efficient and highly regioselective alkoxyl radical cyclization (5-exo-trig). The 2,3-anti substituted intermediates 9 and 12 cyclize stereoselectively whereas a 2,3-syn-configured O-radical affords both possible diastereomeric addition products in equal amounts. The cyclized tetrahydrofuryl methyl radicals were trapped with the bromine atom donor BrCCl3 to afford the bromomethyl-substituted cyclic ethers 10, 11, 18, and 19 in excellent yields. The utility of this reaction was stressed by conversion of one of the newly prepared tetrahydrofurans in a two-step synthesis into (+)-allo-muscarine (+)-20.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/99590_s.pdf or from the author.
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    The Formation of 1,3-Dithiolanes from Aromatic Thioketones and Diazomethane - The Mechanism of the Schönberg Reaction (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1685-1694 
    Details
    ISSN: 1434-193X
    Keywords: Thioketones ; Thiocarbonyl ylides ; Cycloadditions ; Cycloreversions ; Sulfur heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Reactions of diaryl thioketones with diazomethane at room temperature afford 4,4,5,5-tetraaryl-1,3-dithiolanes; the scope of this surprising 2:1 interaction has been studied for decades (Schönberg Reaction). The clue to the mechanism was our observation that the stoichiometry is 1:1 at -78 °C, and 2,5-dihydro-2,2-diaryl-1,3,4-thiadiazoles are formed as primary [2+3] cycloadducts. They lose N2 at -45 °C in first-order reactions generating diaryl thioketone S-methylides which can be intercepted by thioketones (→1,3-dithiolanes), multiple CC bonds, or acids HX. In the absence of trapping reagents, the elusive intermediates either dimerize furnishing 2,2,3,3-tetraaryl-1,4-dithianes or give rise to 2,2-diarylthiiranes by electrocyclization. Beyond thiobenzophenone and diazomethane, our main model reaction, the studies involve fluorene-9-thione, 4,4-dimethoxy- and 4,4-dichlorothiobenzophenone. The ring of 2,5-dihydro-2,2-diphenyl-1,3,4-thiadiazole (8) is opened by LDA at -78 °C and derivatives of anion 12 are obtained. - In summa: The Schönberg reaction consists of two 1,3-dipolar cycloadditions, linked by a 1,3-dipolar cycloreversion.
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    New Boronic-Acid- and Boronate-Substituted Aromatic Compounds as Precursors of Fluoride-Responsive Conjugated Polymer Films (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1703-1710 
    Details
    ISSN: 1434-193X
    Keywords: Conjugation ; Boron ; Sensors ; Cyclic voltammetry ; Polymers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---New electropolymerizable aromatic compounds (i.e. pyrrole, thiophene, aniline) bearing boronic acid and ester substituents have been synthesized and their electrochemical behavior has been investigated. Functionalized polythiophene and polypyrrole films could be anodically generated in acetonitrile, whereas the polyaniline derivative was electroformed in an acidic aqueous solution. The electrochemical responses of some of these materials were changed when fluoride ions were added to the electrolytic solutions. The strongest modifications, caused by binding of fluoride by the immobilized boron, were observed for the polypyrrole derivative in hydroorganic media.
    Additional Material: 5 Ill.
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  • 73
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    Electronic Resource
    The Effect of the Carbon Ligand on the Reaction of Organozinc Reagents in the Synthesis of Substituted 2,5-Dihydrofurans: A Rare Example of An Uncatalysed Allylic-Substitution Reaction Involving Alkyl Zinc Halides (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1711-1718 
    Details
    ISSN: 1434-193X
    Keywords: Heterocycles ; Zinc ; Palladium ; Catalysts ; Sulfur ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Organozinc halides derived from Grignard reagents behave differently in their reaction with ethyl (±±)-(2RS,3SR)-tetrahydro-4-methylene-2-phenyl-3-(phenylsulfonyl)furan-3-carboxylate (3) according to the hybridisation of the carbon ligand. During the development of short multi-component reactions for the synthesis of diverse functionalized ethyl 2,5-dihydrofuran-3-carboxylates it was discovered that aryl and vinyl zinc halides undergo clean reaction with 3 in the presence of Pd(PPh3)4. In contrast, when alkyl zinc halides are reacted with 3 in the presence of Pd(PPh3)4, reductive desulfonation of 3 is observed. Remarkably, in the absence of a transition metal catalyst, the allylic substitution of 3 with alkyl zinc halides proceeds cleanly and in moderate to good yield.
    Additional Material: 2 Ill.
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  • 74
    Electronic Resource
    Electronic Resource
    Stable Heterotopic Noncovalent Resorcin[4]arene Assemblies (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1727-1734 
    Details
    ISSN: 1434-193X
    Keywords: Self-assembly ; Vapor-pressure osmometry ; Resorcin[4]arenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Resorcin[4]arene tetracarboxylic acids 5,6 (A) and resorcin[4]arene tetrapyridines 2,3 (P) self-assemble in chloroform solution to form stable heterotopic AP dimers. Data from NMR titration and dilution experiments, as well as from vapor-pressure osmometry (VPO), indicate that the AP dimer is formed with an association constant greater than 107 M-1. Solid-solution extraction experiments are indicative of the formation of a 2:1 trimer (A2P), while self-associated homotopic species (A2 and A3) can be detected by NMR and VPO. Analysis of the heterotopic noncovalent assembly process over a range of compositions shows that these other species are much less stable than the AP heterodimer, which is the exclusive species at an A/P concentration ratio of 1:1 (〉 99.7% of the total at 10 mM).
    Additional Material: 6 Ill.
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  • 75
    Electronic Resource
    Electronic Resource
    The LiClO4-Mediated Synthesis of β-(Dialkylamino) Sulfoxides and β-(Dialkylamino) Sulfones by Addition of α-Lithiated Salts of Sulfoxides and Sulfones to Aldehydes and (Trimethylsilyl)dialkylamines (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1735-1739 
    Details
    ISSN: 1434-193X
    Keywords: Sulfoxides ; β-Amino sulfones ; Mannich type reaction ; Lithium perchlorate ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The LiClO4-mediated one-pot reaction of aldehydes with (trimethylsilyl)dialkyl amines and the lithium salt of sulfoxides or sulfones, affords the corresponding β-(dialkylamino) sulfoxides and β-(dialkylamino) sulfones in high yields. The aminosulfoxidation reaction of aliphatic or aromatic aldehydes lacks diastereoselectivity, but the diastereomeric sulfoxides can be separated by HPLC or column chromatography for further use.
    Additional Material: 1 Ill.
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  • 76
    Electronic Resource
    Electronic Resource
    Synthesis of Heptano Bridged Pyranoside Derivatives (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1741-1744 
    Details
    ISSN: 1434-193X
    Keywords: Bridged pyranose derivatives ; Ring enlargement ; Carbenes ; Glycosides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Addition of dichlorocarbene to the glycal (±±)-2 followed by cyclopropyl-allyl rearrangement leads to the chloro-2H-pyran (±±)-4. Oxidation of (±±)-4 and reduction of the obtained hydroxypyranone (±±)-5 gave the methyl pyranoside (±±)-6. The relative configuration of (±±)-6 was established by X-ray structural analysis of the corresponding acetate (±±)-7. The synthesis of the optically active starting materials (+)-2 and (-)-2 is also reported.
    Additional Material: 1 Ill.
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  • 77
    Electronic Resource
    Electronic Resource
    Sialyltransferase Inhibitors Based on CMP-Quinic Acid (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1745-1758 
    Details
    ISSN: 1434-193X
    Keywords: CMP-Neu5Ac analogues ; Enzyme inhibitors ; Substrate analogues ; Transition state analogues ; Transferases ; Carbohydrates ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Quinic acid was transformed into phosphitamides 16, 25, and 36, which could be readily linked to 5′-O-unprotected cytidine derivative 17. Ensuing oxidation of the obtained phosphite triesters with tBuO2H and hydrogenolytic de-O-benzylation furnished the corresponding phosphate diesters 18, 26, and 38. Base catalyzed removal of acetyl protecting groups, and methyl ester hydrolysis furnished CMP-Neu5Ac analogues 1d, 1e, and 2. Quinic acid was also transformed into 1,2-unsaturated diallyl α-hydroxymethyl-phosphate derivatives (R)- and (S)-46, which on reaction with cytidine phosphitamide 47 afforded the phosphite triesters. Subsequent oxidation with tBuO2H and then treatment with NEt3 gave phosphate diester derivatives (R)- and (S)-48. Deallylation, acetyl group removal, and methyl ester hydrolysis furnished (R)- and (S)-3, respectively. Treatment of (R)- and (S)-48 with DBU as a base led to acetic acid elimination, thus yielding, after de-O-allylation, acetyl group cleavage, and ester hydrolysis, diene derivative (E)-4. Donor substrate analogues 1d and 1e exhibited good α(2-6)-sialyltransferase inhibition (Ki: 2.0·10-4 and 2.0·10-5 M). However, transition state analogues (R)-, and particularly (S)-3 showed excellent inhibition properties (Ki: 1.6·10-6 and 2.7·10-7 M).
    Additional Material: 1 Tab.
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  • 78
    Electronic Resource
    Electronic Resource
    Synthesis and α-Mannosidase Inhibitory Activity of Three Deoxy Derivatives of Mannostatin A (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1759-1765 
    Details
    ISSN: 1434-193X
    Keywords: Cyclitols ; Aminocyclitols ; Glycosidase inhibitors ; α-Mannosidase inhibitors ; Deoxygenation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Three deoxy derivatives 2-4 of the α-mannosidase inhibitor mannostatin A (1) were synthesized, and their inhibition of Jack bean α-mannosidase was evaluated in order to elucidate the roles of each of the three hydroxyl groups of the inhibitor. The 1- and 2-deoxy derivatives 2 and 3 retained some inhibitory activity, although reduced by a factor of about 100 relative to the parent, whereas it was completely lost with the 3-deoxy derivative 4. Structure and activity relationships are discussed in the light of these findings.
    Additional Material: 1 Tab.
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  • 79
    Electronic Resource
    Electronic Resource
    A Circular Dichroism Approach to the Conformation of 1-Arylethylamino-Substituted 1,3,5-Triazine Derivatives (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1767-1772 
    Details
    ISSN: 1434-193X
    Keywords: Circular dichroism ; Conformation analysis ; s-Triazines ; Chiral auxiliaries ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---CD data of the optically pure 2-[(R)-1-(9-anthryl)ethylamino]-4-chloro-6-[(R)-1-(1-naphthyl)ethylamino]-1,3,5-triazine, 2[(R)-1-(9-anthryl)ethylamino]-4,6-bis[(R)-1-(1-naphthyl)ethylamino]-1,3,5-triazine, 2,4-bis[(R)-1-(9-anthryl)ethylamino]-6-chloro-1,3,5-triazine are presented. The analysis of the CD spectra by means of the nonempirical DeVoe approach has afforded the complete conformational characterisation of the three s-triazine derivatives, allowing us to establish how the conformation of these derivatives depends on the nature of the substituent 1-arylethylamino groups.
    Additional Material: 6 Ill.
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  • 80
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    Electronic Resource
    α,β-Unsaturated Fischer Carbene Complexes vs. 1,3-Dipoles: Reactions with Nitrones and Nitrilimines (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1773-1783 
    Details
    ISSN: 1434-193X
    Keywords: Cycloadditions ; Carbenes ; Nitrones ; Nitrilimines ; Pyrazolines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The reaction of tert-butylalkynyl chromium Fischer carbene complex 1 with nitrones 2 affords β-enamino-ketoaldehydes 4 by the light-promoted rearrangement of the corresponding [3+2] cycloadduct carbene complexes 3. On the other hand, [3+2] cycloaddition of chiral nonracemic Fischer alkenyl carbene complexes 19 with nitrilimines 10 yields enantiomerically pure Δ2-pyrazolines with high regio- and diastereoselectivity.
    Additional Material: 3 Ill.
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  • 81
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    Increasing Enantioselectivities and Reactivities by Stereochemical Tuning: Fenchone-Based Catalysts in Dialkylzinc Additions to Benzaldehyde (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1785-1792 
    Details
    ISSN: 1434-193X
    Keywords: Asymmetric synthesis ; Zinc ; Transition structures ; QM/MM computations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Trimethylsilyl substitutions of the fenchyl alcohols [(1R,2R,4S)-exo-(2-Ar)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol, Ar = 2-methoxyphenyl (1) and Ar = 2-(dimethylaminomethyl)phenyl (2)] yield the chiral ligands 3 [Ar = 2-methoxy-3-(trimethylsilyl)phenyl] and 4 [Ar = 2-(dimethylaminomethyl)3-(trimethylsilyl)phenyl]. Increased reactivities and enantioselectivities in diethylzinc additions to benzaldehyde are obtained from 3 (63% ee R) and 4 (93% ee S), relative to 1 (26% ee S) and 2 (73% ee S). X-ray crystal structures of 3 and of its methylzinc complex 3-Zn reveal out-of-plane bending of the methoxy groups as major geometrical consequences of the trimethylsilyl substitutions. Analyses of QM/MM ONIOM μ-O transition-structure models for 1, 2, 3, and 4 show that trimethylsilyl-induced distortions of methoxy and of dimethylaminomethyl groups explain the observed increased enantioselectivities.
    Additional Material: 10 Ill.
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  • 82
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    Electronic Resource
    Evidence of Formation of an exo-π-Allyl Complex Intermediate in the Pd0-Catalyzed Alkylation of a Bicyclic Allylic Diacetate with Stabilized Carbon Nucleophiles (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1799-1803 
    Details
    ISSN: 1434-193X
    Keywords: Palladium ; exo-π-Allylpalladium complexes ; Allylic alkylation ; Spiro compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The palladium(0)-catalyzed alkylation of 2,3-bis(acetoxymethyl)bicyclo[2.2.1]hepta-2,5-diene 1 with malonate-type enolates as nucleophiles is investigated. A monoalkylated product is formed first, and undergoes (depending on the nucleophile used) a second intramolecular reaction leading to spirocyclopropane-annulated bicyclo[2.2.1]heptene derivatives 5. The formation of endo spirobicyclic cyclopropanes adducts as major isomer is rationalized by assuming formation of an intermediate exo-(π-allyl)palladium complex.
    Additional Material: 2 Ill.
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  • 83
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    Electronic Resource
    Reductions of α,β-Unsaturated Ketones by NaBH4 or NaBH4 + CoCl2: Selectivity Control by Water or by Aqueous Micellar Solutions (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1793-1797 
    Details
    ISSN: 1434-193X
    Keywords: Ketones ; Reductions ; Micelles ; Cobalt ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Operationally simple and environmentally benign procedures have been developed to selectively reduce different α,β-unsaturated ketones, 4,4-dimethylcyclohex-2-ene-1-one (1), isophorone (2), benzylideneacetone (3), chalcone (4) by NaBH4 or by the system NaBH4 + CoCl2. Alternative reaction media to the extensively used MeOH have been explored, and new procedures take advantage of the acceleration and chemoselectivity induced by water or by aqueous micellar solutions. It was possible to selectively and quantitatively afford pure products of 1,2 and of 1,4 reduction as well as the totally reduced compounds (yield and selectivity 〉 90%) by simple changes in the experimental conditions.
    Additional Material: 4 Ill.
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  • 84
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    Electronic Resource
    Conformational Behavior of C-Glycosyl Analogues of Sialyl-α-(2→3)-Galactose (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1805-1813 
    Details
    ISSN: 1434-193X
    Keywords: C-Glycosides ; Conformation analysis ; Molecular dynamics ; Selectins ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The conformational behavior of the C-glycosyl analogue of sialyl-α-(2→3)-galactose, synthesized as a glycosidase inhibitor, has been studied using a combination of NMR spectroscopy (J and NOE data) and molecular dynamics calculations. The obtained results show that the population distribution of conformers with respect to the orientation about the pseudo-glycosidic linkages is mainly controlled by steric interactions. This is in contrast to findings made for O-glycosides. In these natural compounds, the conformational behavior about the glycosidic linkage Φ is mainly governed by the exo-anomeric effect.
    Additional Material: 5 Ill.
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  • 85
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    Electronic Resource
    Enantioselective Preparation of 2,4-Disubstituted Azetidines (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1815-1820 
    Details
    ISSN: 1434-193X
    Keywords: Asymmetric synthesis ; Palladium-catalysed couplings ; Palladacycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Chiral C2-symmetric N-benzylazetidines have been conveniently prepared from optically pure anti-1,3-diols without loss of enantiomeric purity. N-Debenzylation led to the corresponding N-unsubstituted azetidines, which were then subjected to palladium-catalysed coupling reactions with aryl bromides to afford chiral N-arylazetidines. (R,R)-N-Benzyl-2,4-dimethylazetidine has been employed in the synthesis of a new cyclopalladated complex, which can be used, for instance, as a chiral recognition agent for phosphorus ligands.
    Additional Material: 1 Tab.
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  • 86
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    Electronic Resource
    Deoxyhydantocidin: Synthesis by Base-Catalyzed Spiro Cyclization and Interconversion with the 1′-Epimer (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1831-1840 
    Details
    ISSN: 1434-193X
    Keywords: Cyclizations ; Spiro compounds ; Nucleosides ; Isomerizations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Syntheses of the spiro nucleosides 2′-deoxyhydantocidin 3a and its 1′-epimer 3b are described. The newly developed route involves a Horner-Wadsworth-Emmons condensation of the phosphonate 16 with the erythrose derivative 15 affording a mixture of six isomers which was fully assigned by NMR spectroscopy. The mixture was directly converted into the final compounds in an efficient base-catalyzed cyclization reaction. A base-catalyzed interconversion between the two isomers was observed.
    Additional Material: 2 Ill.
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  • 87
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    Electronic Resource
    1-Alkyl- and Azeto[1,2-a][1,5]benzodiazepine Derivatives in the Reaction of o-Phenylenediamine with 3-(Dimethylamino)propiophenones (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1973-1976 
    Details
    ISSN: 1434-193X
    Keywords: Benzodiazepines ; Heterocycles ; Azeto[1,2-a]-1,5-benzodiazepines ; Cyclizations ; Cycloadditions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The reaction of o-phenylenediamine (4) with one, two or three equivalents of p-substituted 3-dimethylaminopropiophenone hydrochlorides 5a-e was studied. 4-Aryl-2,3-dihydro-1H-1,5-benzodiazepine derivatives 6a-e were obtained in good yields, along with the 1:2-adducts 7c-e and the unexpected 1:3-adducts rac-8c-e. The type of adduct formed is determined by the molar ratio of the reactants 4 and 5 and by the nature of the substituent in the para position of the propiophenone 5.
    Additional Material: 1 Ill.
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  • 88
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    Electronic Resource
    Synthesis of Benzotri(benzonorbornadienes) (BTBNDs): Rigid, Cup-Shaped Molecules with High Electron Density within the Cavity (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1965-1971 
    Details
    ISSN: 1434-193X
    Keywords: Cup-shaped PAHs ; Host-guest compounds ; Host-guest chemistry ; Cyclizations ; Semiempirical calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Cyclotrimerisation of benzo-polycyclic bromostannylalkenes 8a-d with Cu(NO3)2·3H2O in THF affords benzotri(benzonorbornadienes) 3a-d as a mixture of the syn and anti isomers. The ratio of syn to anti is close to the 1:3 statistical value in most cases (i.e. in cyclotrimers 3a,b,d), but highly in favour of the anti isomer in 3c, where steric hindrance by the methoxy groups plays an important role in the stereochemistry of the cyclotrimerisation. The substrates for the cyclotrimerisation, i.e. the bromostannyl alkenes 8a-d, were prepared from bromoalkenes 7a-d by treatment with base (LDA) and quenching with trimethyltin chloride. In turn, bromoalkenes 7a-d were prepared from alkenes 5a-d by radical bromination-elimination. The reaction conditions used were designed to minimise Wagner-Meerwein rearrangements that would lead to unwanted bromo isomers. The cup-shaped syn cyclotrimers 3a-d exhibit high electron density within the cavity as determined by AM1 semiempirical calculations of their electrostatic potential surfaces and are valuable substrates for supramolecular chemistry. As an example, it is shown that fullerene C60 is drawn into solution in acetonitrile by complexation with both the syn and anti trimer of benzonorbornadiene 3a.
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  • 89
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    Determination of Pollutant Phenols by Capillary High-Performance Liquid Chromatography with UV Detection (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 367-372 
    Details
    ISSN: 0935-6304
    Keywords: Capillary HPLC ; gradient elution ; temperature programming ; phenolic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---This paper describes a liquid chromatographic method using a reversed phase capillary column coupled to an UV detector for the quantitation of thirteen pollutant phenols. Chromatographic separation was carried out with gradient elution at 25.0 ± 0.1°C. The two major anisocratic elution modes (gradient elution and temperature programming) were evaluated. The detection limit range was 10-81 pg (100 nL injected). The chromatographic method combined with liquid-liquid extraction was applied to analysis of these compounds in river water. Recoveries of 75-103% were achieved for most of them.
    Additional Material: 5 Ill.
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  • 90
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    Use of Capillary Supercritical Fluid Chromatography in the Analysis of Zinc Dialkyldithiophosphates (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 389-392 
    Details
    ISSN: 0935-6304
    Keywords: Capillary SFC ; zinc dialkyldithiophosphates ; lubricating oils ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 5 Ill.
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  • 91
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    Application of Supercritical Fluid Chromatography to the Analysis of Waxes in Objects of Art (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 393-396 
    Details
    ISSN: 0935-6304
    Keywords: Supercritical fluid chromatography (SFC) ; micropacked capillary columns ; waxes ; restoring ; objects of art ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 2 Ill.
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  • 92
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    Identification of Free and Glycosidically Bound Volatiles and Glycosides by Capillary GC and Capillary GC-MS in “Lulo del Chocó” (Solanum topiro) (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 379-385 
    Details
    ISSN: 0935-6304
    Keywords: Aroma ; “lulo del Chocó” ; Solanum topiro ; volatiles ; glycosidically bound volatiles ; glycoside TFA derivatives ; enantioselective gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The volatile constituents of lulo del Chocó (Solanum topiro) fruit pulp obtained by liquid-liquid extraction were analyzed by capillary GC and capillary GC-MS. In total, 30 components were identified with methyl salicylate, hexadecanoic acid, hexanal, guaiacol, ethyl butanoate, and ethyl acetate being the major components. Chirospecific MDGC analysis revealed the predominance of (R)-ethyl-3-hydroxybutanoate (ee 40%) and the presence of racemic mixtures both of δ-octalactone and of δ-decalactone. For γ-hexalactone, γ-octalactone, and γ-decalactone enantiomeric distributions of 22.4 : 77.6, 22.9 : 77.1, and 20.0 : 80.0, (R) : (S), respectively, were determined. Glycosidically bound aroma compounds were identified by capillary GC and capillary GC-MS after isolation of the glycosidic fraction obtained by Amberlite XAD-2 adsorption and methanol elution followed by hydrolysis with a commercial pectinase enzyme. In total 13 bound aroma compounds (aglycones) were identified. These aglycones mainly consisted of compounds exhibiting aromatic structures. Additionally, with the aid of capillary GC and capillary GC-MS (EI and NCI) of trifluoroacetylated derivatives we identified eight glucosides: the novel 3,6-epoxy-7-megastigmen-5,9-diol β-D-glucopyranoside and the hexyl, benzyl, linalyl oxide (furanic), 2-phenylethyl, vomifolyl (isomer 1), (6S,9R)-vomifolyl, and scopoletin β-D-glucopyranosides.
    Additional Material: 1 Ill.
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  • 93
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    System Peaks of Cyclodextrins in Capillary Electrophoresis (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 409-412 
    Details
    ISSN: 0935-6304
    Keywords: Cyclodextrin ; capillary electrophoresis ; system peak ; CHES 1 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using a running buffer containing cyclodextrins (CDs) and 2-[N-cyclohexylamino]-ethanesulfonic acid (CHES), positive system peaks were observed in the analysis of a ganglioside mixture by CE-UV. These system peaks were related to CDs in the running buffer because these peaks were also detected when a plug of solution devoid of CDs but having the same CHES concentration and pH as the running buffer was injected. Neutral CDs were separated owing to the formation of inclusion complexes with the anionic CHES ion. One possible explanation for the positive system peaks is that the anionic CD-CHES inclusion complex is displaced by co-ions with higher UV absorptivity.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 94
    Electronic Resource
    Electronic Resource
    Liquid Chromatography of Unstable Zinc Dithiocarbamates. Application to Rubber Gloves Analysis (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 565-566 
    Details
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; zinc dithiocarbamate ; vulcanization accelerator ; rubber gloves ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 95
    Electronic Resource
    Electronic Resource
    Characteristic Stationary Phase Constants for Two Popular Open-Tubular Column Stationary Phases for Gas Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 603-608 
    Details
    ISSN: 0935-6304
    Keywords: Solvation parameter model ; ystem constants for poly(dimethyldiphenylsiloxane) HP-5 and poly(ethylene glycol) HP-INNOWax stationary phases ; temperature ; molecular interaction ; retention models ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 96
    Electronic Resource
    Electronic Resource
    Determination of Cinnamomi Constituents by High-performance Liquid Chromatography and Capillary Electrophoresis (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 561-564 
    Details
    ISSN: 0935-6304
    Keywords: Retention factors ; Cinnamomi ramulus ; high-performance liquid chromatography ; capillary electrophoresis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 97
    Electronic Resource
    Electronic Resource
    Ion Chromatography of Inorganic Anions on Graphitic Carbon as the Stationary Phase (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 590-594 
    Details
    ISSN: 0935-6304
    Keywords: Ion chromatography ; graphitic carbon stationary phases ; anions ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Inorganic anions could be separated on porous graphitic carbon stationary phases in ion chromatography. Ion exchange between eluent anions and sample anions on the stationary phase was confirmed by the retention behavior and the possibility of indirect photometric detection. The elution order of anions was different from that observed for commercially available anion exchangers. Chloride, nitrate, and sulfate contained in tap water could be determined in 7 min.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 98
    Electronic Resource
    Electronic Resource
    Solid-Phase Microextraction of Pyrethroid Pesticides from Water at Low and Sub-ppt Levels at Different Temperatures (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 485-488 
    Details
    ISSN: 0935-6304
    Keywords: Pyrethroids ; solid-phase microextraction ; water analysis ; temperature ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Synthetic pyrethroids are increasingly being used for insect control on field crops because of their advantageous environmental properties such as short field life, broad spectrum of insecticide activity, and relatively low mammalian toxicity. In the present work, experimental conditions were optimized for trace analysis of pyrethroids in water by using solid-phase microextraction followed by capillary gas chromatography. Effects of temperature, SPME-fiber diameter, and matrix were studied. SPME used off-line with a gas chromatograph electron-capture detection (GC-ECD) showed a linear response over a wide concentration range. Our results showed a strong temperature effect on pyrethroid extraction yield. The detection limit after 5 min of SPME-fiber exposure to the samples changed from 1 ppb (at 30°C) to 0.1 ppt (at 90°C), which is a 10000 increase in pyrethroid detection. The standard deviations of the analyte peak area ratios were typically in the range of 1-7% at 30°C and of 3 to 15% at 90°C. Best conditions for pyrethroids analysis were achieved using high temperature solution and a 100 μm polydimethylsiloxane fiber. No matrix (river water) influence was observed on detection of the investigated pyrethroids.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 99
    Electronic Resource
    Electronic Resource
    Microfabricated Monolith Columns for Liquid Chromatography. Sculpting Supports for Liquid Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 19-26 
    Details
    ISSN: 0935-6304
    Keywords: Microfabrication ; monolith ; electrochromatography ; peptides ; reactive ion etching ; reversed phase ; nanocolumns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monolith columns are generally fabricated by polymerization of monomers within a column. This paper reviews an alternative strategy in which the bed is microfabricated in an inorganic material by ablation. Channels of 1.5 μm width and 10 μm depth were sculpted in quartz by deep reaction ion etching. Using this approach chromatographic beds were constructed in which cubic support structures were created and arranged in rows to mimic particles in a conventional column. Beds ranging from hundreds of thousands to millions of “particles” with volumes of 15 nL to 15 μL were produced. Columns that had been derivatized with an octadecyl silane stationary phase were used to separate both low molecular weight analytes and peptides in the CEC mode. Plate height in the CEC mode was 1.2 μm at maximum efficiency.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    Dynamic Capacity Studies of CIM (Convective Interaction Media)® Monolithic Columns (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 39-43 
    Details
    ISSN: 0935-6304
    Keywords: Monoliths ; CIM® monolithic column ; dynamic binding capacity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The characterization of CIM® DEAE monolithic columns in terms of dynamic binding capacity is presented in this paper. Breakthrough experiments were performed for capacity determination. Bovine serum albumin (BSA) was used as a model protein. It is shown that CIM® monolithic columns have good batch-to-batch reproducibility as well as long-term stability. The experiments performed under different linear velocities demonstrated that the dynamic capacity is unaffected at least up to a linear velocity of 2450 cm/h. Furthermore, the breakthrough curve slope is constant, indicating that the capacity would remain constant at even higher linear velocities. The adsorption isotherm of BSA dissolved in 20 mM Tris-HCl buffer shows a constant capacity of around 30 mg/mL of support down to a concentration of 20 μg/mL. The capacity is substantially influenced by the ionic strength; however, 20% of the maximal capacity is still preserved at 0.3 M NaCl.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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