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  • Articles  (82)
  • Crystal structure  (71)
  • Immunocytochemistry
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  • Springer  (82)
  • Geosciences  (82)
  • 1
    Electronic Resource
    Electronic Resource
    Discrete stability of the Differential System Method evaluated with geostatistical techniques (1998)
    Springer
    Stochastic environmental research and risk assessment 12 (1998), S. 191-204 
    Details
    ISSN: 1436-3259
    Keywords: Keywords: groundwater flow ; inverse problems ; stability ; geostatistical interpolation ; kriging.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The Differential System Method (DSM) permits identification of the physical parameters of finite-difference groundwater flow models in a confined aquifer when piezometric head and source terms are known at each point of the finite-difference lattice for at least two independent flow situations for which the hydraulic gradients are not parallel. Since piezometric head data are usually few and sparse, interpolation of the measured data onto a regular grid can be performed with geostatistical techniques. We apply kriging to the sparse data of a synthetic aquifer to evaluate the stability of the DSM with respect to uncorrelated measurement errors and interpolation errors. The numerical results show that the DSM is stable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004770050017
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  • 2
    Electronic Resource
    Electronic Resource
    Crystal structure of Pt(S2COEt)2 (1994)
    Springer
    Journal of chemical crystallography 24 (1994), S. 707-710 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; platinum ; xanthate ; square planar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystals of Pt(S2COEt)2 are orthorhombic, Pbca, with (at 20°C)a=7.799(3),b=7.368(6),c=20.588(7) Å.D cale=2.46g cm−3 forZ=4. The platinum atom resides on a crystallographic center of inversion and is bound to the four sulfur atoms of the xanthato ligand in a square planar geometry. The Pt−S distances are 2.313(6) and 2.320(7)Å with an intraligand S−Pt−S angle of 75.1(2)°.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01668235
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  • 3
    Electronic Resource
    Electronic Resource
    Crystal structure of tetrakisdiphenylammonium hexadecachlorotetrabismuthate(III) (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 841-844 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; bismuth chloride complexes ; diphenylammonium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [(C6H5)2NH2]4 +[Bi4Cl16]4− crystallizes in the triclinic space group $$P\bar 1$$ witha=11.835(2),b=12.393(2),c=12.625(3)Å, α=108.37(3), β=108.69(3), γ=96.00(3)° andD c=2.135 g cm−3 forZ=1. The [Bi4Cl16]4− anion is a centrosymmetric cluster of four distorted edge-sharing BiCl6 octahedra. The ranges of the Bi−Cl bonds are 2.484(4)–2.606(3)Å for Bi−Cl(terminal), 2.691(3)–2.956(4)Å for Bi-Cl(µ2), and 2.960(3)–3.120(4)Å for Bi-Cl(µ3). The cations and anions are held in place by weak hydrogen bonds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01671080
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  • 4
    Electronic Resource
    Electronic Resource
    Crystal structure of a bulky cyclic sulfite (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 215-218 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; cyclic sulfite ; pentacycloundecane-8 ; 11-dione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of the cyclic sulfite derived from the reaction of thionyl chloride withendo-8-hydroxy-exo-8-(endo-8′-hydroxypentacyclo[5.4.0.0.2,6.03,10.05,9]undec-exo-8′-yl)pentacyclo-[5.4.0.0.2,6.03,10.05,9]undecane is reported. All bond lengths and angles are consistent with the strained cage geometry. A static disorder of the terminal oxygen was found to be present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01665171
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  • 5
    Electronic Resource
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    Structure of the pinacol formed via sodium-promoted reductive dimerization of 12-methyleneheptacyclo-[6.6.02,6.03,13.04,11.05,9.010,14]tetradecan-7-one (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 417-420 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; pinacol ; reductive dimerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The pinacol resulting from sodium promoted reductive coupling of a methyleneheptacyclo-[6.6.02,6.03,13.04,11.05,9.010,14]tetradecanone possesses a conformation in which equivalent groups on the pinacol carbon are virtually perpendicular to each other. This rotation minimizes steric interactions, thus the geometries of all the fragments in the molecule are within expected values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01665280
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  • 6
    Electronic Resource
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    Crystal and molecular structure of 1-vinyl-3-methyl-imidazolium iodide, C6H9N2I (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 601-603 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; imidazolium ; vinyl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes with two independent molecules in the unit cell. The two molecules arecis-trans isomers. Crystal data: orthorhombic, P212121,a=7.0417(6),b=9.5341(9),c=25.411(2) Å,Z=8. The crystal structure has been solved by automated Patterson methods and refined toR=0.024 for 1843 observed reflections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01667031
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  • 7
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    Molecular structure of 3-(3-oxo-bicyclo[2.2.1]hept-5-en-2-yl)-oxirane-2-carboxylic acid methyl ester (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 81-84 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; epoxy ester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of an epoxy ester is described. The structure has been solved by vector search methods and refined by least squares methods toR 1=0.0372 [I〉2σ(I)]. The structure consists of two independent molecules in the asymmetric unit. These molecules are chemically the same. Crystal data: C11H12O4, triclinic, space group $$P\bar 1$$ ,a=10.324(3),b=10.553(7),c=10.869(5)Å, α=61.77(4), β=88.64(4), γ=88.16(6)°,V=1042.7(9)Å3,Z=4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02018702
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  • 8
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    Crystal structure of a highly hydrated tristrontium phosphate, Sr9(PO4)6·16H2O (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 341-346 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; hydrated phosphate ; layer-type structure ; strontium phosphate ; strontium phosphate hydrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of a highly hydrated tristrontium phosphate, nonastrontium hexakis(phosphate) hexadecahydrate, Sr9(PO4)6·16H2O, has been determined by single crystal X-ray diffraction. The crystals are monoclinic,a=15.203(2),b=6.488(1),c=18.984(7) Å, β=98.42(2)o, space groupP2/c (No. 13),Z=2,V=1852.3 Å3,d c =2.951 Mg·m−3. The structure was refined by full-matrix least-squares techniques toR=0.038,R w =0.051, for 2329 reflections with I≥3σ(I). The structure can be described in terms of a layer-type arrangement parallel to (100). One layer consists of a compact assembly of columns of Sr and PO4 ions in a pseudohexagonal arrangement resembling an apatitic structure. A second layer containing all the water molecules and one PO4 ion that occupies the interstitial space may be referred to as the hydrated layer. The structure has an overall similarity to that of octacalcium phosphate and can be considered as a model for amorphous calcium phosphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01677098
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  • 9
    Electronic Resource
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    Molecular structure of [(tBu)2Al(μ-NHtBu)]2 (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 563-567 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; aluminum ; amide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of [(tBu)2Al(μ-NHtBu)]2 has been determined. The unit cell contains two independent molecules with only slight variation in the orientation of thetert-butyl ligands. Crystal data: Triclinic, $$P\bar 1$$ ,a=9.0138(6),b=10.2944(8),c=15.791(1) Å, α=91.262(6), β=89.822(6), γ=106.141(6)°,V=1407.2(2) Å3,Z=2,R=0.039,R w=0.041.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01668416
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  • 10
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    Crystal structure of 5-(p-methoxyphenylamino)indane and AM1 calculations on N-arylamines derivatives, precursors of phenothiazine drugs (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 735-739 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; diphenyl amines ; AM1 calculations ; phenothiazines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structural determination by X-ray crystallography of the titled N-arylamine 4a, as well as AM1 calculations on a series of derivatives (4b–c, 5a–c), are reported. The compound 4a is monoclinic P21/c with a = 7.656(3), b = 23.655(5), c = 7.686(9) Å, β = 112.59(6)°, V = 1285.2(2) Å3 and Z = 4. This structure has been used as a template for the building of some others derivatives used for AM1 calculations. The results show that the cyclization position on the aromatic rings, which can lead to two regioisomers, depends on the nature of the benzylic substituants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021860410863
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  • 11
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    Synthesis, characterization, and X-ray crystal structure of di-(2,4-imidazolidinedione-5-ethyl)disulfide, C10H14N4O4S2 (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 761-765 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; noncentrosymmetric ; disulfide ; imidazolidinedione ; homocystine hydantoin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Di-(2,4-imidazolidinedione-5-ethyl)disulfide or homocystine hydantoin, C10H14N4O4S2 (I), crystallizes in the non-centrosymmetric space group P21 (No. 4) with two molecules in the unit cell with a = 7.132(1), b = 9.282(2), c = 10.770(2) Å and β = 105.68(1)°. The two imidazolidinedione rings are planar with a dihedral angle of 46.9°. The rings are joined by a diethyl disulfide bridge at chiral centers on the rings. The C-S-S-C torsion angle is −80°(−sc). The absolute stereochemistry of the chiral centers was determined to be (5S, 5′S), η = + 0.92 (11). Important bond distances include: S-S = 2.022(4); S-C (mean) = 1.809(8); and C=O (mean) = 1.224(7) Å. The compound is stabilized by a network of intermolecular carbonyl-to-amine hydrogen bonding and van der Waals cohesive forces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021816628610
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  • 12
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    Crystal structure of a macrocyclic tetraamine isocyanato zinc(II) complex (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 831-834 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; macrocyclic tetraamine ; isocyanato zinc(II) complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex, [Zn(L)(NCO)]Cl · 3H2O (1) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07.12]docosane), has been synthesized and structurally characterized. 1 crystallizes in the monoclinic system, space group P21/n with a = 10.530(3), b = 9.315(2), c = 27.188(3) Å, β = 92.58(1)°, V = 2664.1(9)Å3, and Z = 4. The zinc atom is in a distorted squarepyramidal environment with the four nitrogen atoms of the macrocycle and one nitrogen atom of the isocyanate ligand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021831921283
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  • 13
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    Synthesis and crystal structure of macrocyclic nickel(II) complex bridged by chromate (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 867-870 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; macrocyclic nickel(II) complex ; chromate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A novel compound catena-(μ-CrO4-O,O′)[Ni(L1)Ni(L2)] 3H2O (1) (L1 = 3,5,10,12-tetramethyl-1,4,8,11-tetraazacyclotetradecane and L2 = 2,5,9,12-tetramethyl-1,4,8,11-tetraazacyclotetradecane) has been synthesized for the first time and structurally characterized. 1 crystallizes in the triclinic space group Pī with a = 9.623(1), b = 10.084(1), c = 12.723 (3) Å, α = 66.74(2), β = 75.20(1), γ = 72.02(1)°, V = 1066.2(3) Å3, and Z = 2. The coordination environment around the Ni(II) ions is an axially elongated octahedron with the secondary amines of the isomeric ligands and two oxygen atoms of [CrO4]2−.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022890217250
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  • 14
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    Synthesis, characterization, peripheral studies, and structural analysis of E-4-(N-methylanilino)-3-pentene-2-one, C12H15NO (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 899-903 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; ir/nmr ; β-amino-α ; β-unsaturaled ketone ; noncentrosemmtric ; enamino ketones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystallographic structural refinement of E-4-(N-methylanilino)-3-pentene-2-one (I) has been carried out by means of three-dimensional single-crystal X-ray diffractometry. The title compound crystallizes in space group C2 (No. 5,Z = 4). The lattice constants are a = 21.543(4), b = 6.433(1), c = 8.019(2) Å, and β = 97.82(3)°. Characterizations include physical property determinations and spectrometric identifications employing IR, 1H and 13C NMR, and X-ray powder analyses. The molecules in the crystal lattice are held together by van der Waals forces. Selected bond distances and angles are presented and discussed as well as synthesis and peripheral studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022802619976
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  • 15
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    The structure of N-(1H-benzo[d]imidazol-2-ylmethyl)-N-(2,6-dichlorophenyl)amine (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 145-147 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; benzimidazole ; antimicrobial activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The N-(1H-benzo[d]imidazol-2-ylmethyl)-N-(2,6-dichlorophenyl)amine, C14H11N3Cl2, M r = 292.17, crystallizes in the orthorhombic space group Pbca with unit cell parameters a = 10.707(2), b = 9.615(2), c = 25.944(6) Å. The benzimidazole ring system is planar and makes a dihedral angle of 77.8(1)° with the phenyl ring. The structure is stabilized by an N–H···N hydrogen bond.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022497931783
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  • 16
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    Synthesis and structural characterization of a novel polymeric praseodymium(III) complex with a new flexible double betaine (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 177-183 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; coordination polymer ; praseodymium(III) carboxylate complex ; double betaine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A novel polymeric Pr(III) complex with a new double betaine, namely [{Pr(L1)1.5(H2O)2} n ][ClOli4]3 n ·nH2O (1) (L1 = 1,4-diazoniobicyclo[2,2,2]octane-1,4-dipropionate), has been synthesized and characterized by X-ray analysis. In the title complex, the Pr(III) atom is nine-coordinated by seven oxygen atoms from five L1 ligands and two aqua ligands. Each pair of adjacent praseodymium(III) atoms is linked by a pair of μ3 chelating and bridging carboxylate groups, thus forming an infinite metal···metal chain running parallel to the a direction, and such chains are cross-linked by flexible backbones of L1 ligands into a three-dimensional network with the perchlorate anions and lattice water molecules accommodated in the interstitial space. The title complex crystallizes in the monoclinic space group P21/n with a = 8.085(2), b = 14.316(3), c = 29.775(6) Å, β = 103.04(3)° and Z = 4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022414109261
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  • 17
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    Crystal structures of three substituted pentacyclo[5.4.0.02,6.03,10.05,9]undecanes (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 251-258 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; pentacycloundecane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures of three compounds formed via ultimate nucleophilic attack of unsaturated hydrocarbon fragments are reported. Geometries of the bis(vinyl)-, mono(vinyl), and bis(ethynyl)-substituted PCU species are unexceptional. The crystal structures are dictated by the availability of intermolecular hydrogen bonding.
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    URL: http://dx.doi.org/10.1023/A:1021893001351
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  • 18
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    Molecular structure and absolute configuration of (+)-(1R, 2S, 6R, 7S, 1′R)-5-(1′-phenylethylamino)-endo-tricyclo[5.2.1.02,6]deca-4,8-dien-3-one (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 497-499 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; tricyclodecadienone ; enaminone ; resolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of (+)-(1R, 2S, 6R, 7S, 1′R)-5-(1′-phenylethylamino)-endo-tricyclo[5.2.1.02,6]deca-4,8-dien-3-one is described. Based on the known absolute configuration (R) of the α-phenylethylamine moiety the X-ray analysis revealed the absolute configuration of the title compound. The structure was refined to R 1 = 0.0298 for 1950 reflections (with I 〉 2σ(I)). Crystal data: C18H19NO, monoclinic, space group P21, a = 6.7406(4), b = 9.959(2), c = 11.3123(8)Å, β = 102.969(5), V = 740.0(2)Å3, and Z = 2.
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    URL: http://dx.doi.org/10.1023/A:1021733108852
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  • 19
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    Molecular structure and absolute configuration of (−)-(1R, 2S, 6R, 7S, 2′S)-5-(2′-hydroxymethylpyrrolidin-1′-yl)-endo-tricyclo[5.2.1.02,6]deca-4,8-dien-3-one (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 493-495 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; tricyclodecadienone ; enaminone ; dynamic kinetic resolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of (−)-(1R, 2S, 6R, 7S, 2′S)-5-(2′-hydroxymethyl-pyrrolidin-1′-yl)-endo-tricyclo[5.2.1.02,6]deca-4,8-dien-3-one is described. Knowing the absolute configuration of the prolinol moiety (S) the X-ray diffraction study established the absolute configuration of the title compound. The structure was refined to R 1 = 0.0322 for 1237 reflections (with I 〉 2σ(I)). Crystal data: C15H19NO2, monoclinic, space group P21, a = 6.0757(4), b = 11.3473(5), c = 9.5114(7)Å, β = 104.686(6)°, V = 634.32(7)Å3, and Z = 2.
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    URL: http://dx.doi.org/10.1023/A:1021781024782
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  • 20
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    The crystal structure of 5α,9α-peroxyergosta-7,22-dien-6-one-3β-ol acetate (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 239-241 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; ergosterol peroxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Ergosterol acetate, in pyridine, reacts with hydrogen peroxide and catalytic amounts of FeCl3 to afford the unusual product 5α,9α-peroxyergosta-7,22-dien-6-one-3β-ol acetate. The peroxide, in the title structure, is seen to bridge the C5 and C9 positions of the sterol backbone. Crystal data: C30H44O5, orthorhombic, P212121, a = 6.552(2), b = 11.048(8), c = 37.60(2), V = 2772(3)Å3, Z = 4.
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    URL: http://dx.doi.org/10.1023/A:1022486730643
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  • 21
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    The crystal structure of hexabenzoylhexaazaisowurtzitane (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 593-596 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; cage compound ; hexabenzoylhexaazaisowurtzitane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of an interesting cage compound is described. Crystal data: C48H36N6O6·(CH3)2CO; monoclinic; space group: P2 1 /n; a = 14.948(3) Å, b = 15.079(3) Å, c = 19.539(4)Å, β = 93.93(3)°, V = 4394(2)Å3; and Z = 4.
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    URL: http://dx.doi.org/10.1023/A:1022452707772
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  • 22
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    Structural study of the molecular complex in crystals of brucine with pantolactone (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 121-125 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; brucine ; pantolactone ; molecular complex ; chiral resolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We have determined an X-ray crystal structure, a = 12.482(1), b = 14.349(1), c = 14.342(1) Å, orthorhombic, P212121 for a molecular complex of brucine with pantolactone. The crystal structure is composed of corrugated sheets of brucine molecules containing the guest pantolactone molecules. The conformational twist of the pyrrolidine ring in brucine may probably be important in projecting the amine N2 to provide a strong and specific binding site for a chiral complexation. The pseudo-equatorial orientation of the hydroxyl group of the pantolactone anchors itself for binding via hydrogen bonding. In the crystal packing, the pantolactone molecules form helices and the brucine molecules are attached to these helices by O=H···N hydrogen bonds.
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    Crystal structure of Pt(S2COEt)2 (1994)
    Springer
    Journal of chemical crystallography 24 (1994), S. 711-714 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; platinum ; xanthate ; square planar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystals of Pt(S2COEt)2 are orthorhombic, Pbca, with (at 20°C)a=7.799(3),b=7.368(6),c=20.588(7) Å,D cale=2.46g cm−3 forZ=4. The platinum atom resides on a crystallographic center of inversion and is bound to the four sulfur atoms of the xanthato ligand in a square planar geometry. The Pt−S distances are 2.313(6) and 2.320(7) Å with an intraligand S−Pt−S angle of 75.1(2)°.
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    Highly stereoselective sodium borohydride promoted reduction ofendo-5-acetyl-1,2,3,4-tetrachloro-7,7-dimethoxynorborn-2-ene (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 657-660 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; norbornene ; stereoselective reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Racemicendo-5-acetyl-1,2,3,4-tetrachloro-7,7-dimethoxynorborn-2-ene was stereoselectively reduced by sodium borohydride to give only theS,S orR,R diastereomers. The crystal structure of the product displays no unusual features.
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    Structure of 2-acetoxy-1,2-di(1-adamantyl)ethanone (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 291-294 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; 1,2-di(1-adamantyl)ethene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of 2-acetoxy-1,2-di(1-adamantyl)ethanone is reported. The steric requirements of the two adamantyl groups affect the structure in three ways—a slight elongation of the central bond, a small expansion of the angles about the central bond, and a conformation in which the C(sp2)-connected adamantyl group virtually bisects the large substituents attached to the sp3 carbon.
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    Structure of a PCU-derived pinacol formed via sodiumpromoted reductive dimerization of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione monoethylene ketal (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 517-520 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; pinacol ; reductive dimerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The pinacol resulting from sodium promoted reductive coupling of pentacyclo[5.4.0.02,6.-03,10.05,9]undecane-8,11-dione monoethylene ketal possesses a conformation, dictated by intramolecular hydrogen bonding, that lies midway between eclipsed and staggered. The C−C and C−O distances in the pinacol unit are, respectively, longer and shorter than usual, and all parameters are as expected.
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    Crystal and molecular structure determination, TGA-DTA, and infrared and Raman spectra of rubidium nitroprusside, Rb2[Fe(CN)5NO] (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 325-330 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; rubidium nitroprusside ; IR ; Raman ; thermal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound, Rb2[Fe(CN)5NO], crystallizes in the space group P212121, witha=5.687(1),b=15.956(2),c=12.645(3) Å, andZ=4. Anions are in equivalent C1 sites (one per asymmetric unit) and are slightly distorted octahedra (C4v ideal symmetry). TGA and DTA curves and vibrational (infrared and Raman) spectra of Rb2[Fe(CN)5NO] were obtained. Results are interpreted in view of the crystal structure of the compound and the behavior of related substances.
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    Thermodynamic vs. kinetic control in the Diels-Alder cycloaddition of cyclopentadiene to 2,3-dicyano-p-benzoquinone (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 281-286 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; cyclopentadiene ; 2,3-dicyano-p-benzoquinone ; Diels-Alder reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Diels-Alder cycloaddition of cyclopentadiene (1a) to 2,3-dicyano-p-benzoquinone (2a), when performed in methanol solvent at ambient temperature, proceeds with kinetic control to afford 1α,4α,4aβ,8aβ-tetrahydro-5,8-dioxo-1,4-methanonaphthalene-4a,8a-dicarbonitrile (7, 77% yield). However, when this cycloaddition is performed by refluxing an equimolar solution of1a and2a in benzene for 3 h, the product of thermodynamic control, i.e., 1α,4α,4aα,8aα-tetrahydro-5,8-dioxo-1,4-methanonaphthalene-6,7-dicarbonitrile (3a) is obtained in 64% yield. The structure of3a was confirmed by an analysis of the reduced intramolecular photocyclization product,9.
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    Crystal and molecular structure of (2E,4S,10R)-4-hydroxy-2-undecen-10-olide (nor-patulolide C), C11H18O3 (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 305-308 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; undecen-olid ; nor-patulolide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The stereogeometry and absolute configuration of the title compound has been proved by an X-ray diffraction analysis. Crystal data: monoclinic, P21,a=7.7976(2),b=7.8288(2),c=8.9791(4) Å, β=90.331(4)o, Z=2. The crystal structure has been solved by vector search methods and refined toR=0.042 for 1798 observed reflections.
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    Crystal and molecular structure of diphenylphosphinylacetic acid (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 361-364 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; carboxylic acid ; phosphine oxide ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Diphenylphosphinylacetic acid crystallizes in the monoclinic space groupP2l/n with unit cell dimensionsa=5.6875(7),b=17.049(4),c=13.471(2) Å, β=93.36(1)° and Z=4. The molecular packing consists of hydrogen bonded chains arising from intermolecular interactions between a carboxylic acid hydroxyl group and an oxygen of an adjacent phosphine oxide moiety.
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    Tetracyclo[6.3.0.04,11.05,9]undecane-2,7-dione (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 425-428 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; tetracyclo[6.3.0.04,11.05,9]undecane-2,7-dione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound crystallizes in the triclinic space group, $$P\bar 1$$ , witha=6.7702(4),b=7.0180(4),c=9.1960(7) Å, α=92.457(6), β=96.150(6), γ=93.444(5)°, andZ=2. The structure contains a rather short intramolecular H...H contact of 2.26(4) Å.
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    Crystal structure of strontium potassium arsenate octahydrate (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 741-746 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; hydrated ions ; ionic hydration ; strontium arsenate ; struvites ; struvite-type structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of strontium potassium arsenate octahydrate, SrKAsO4·8H2O, has been determined by single crystal X-ray diffraction. The crystals are tetragonal, a = 7.144(1), c = 23.613(2) Å, space group I41md (No. 109), Z = 4, V = 1205.1(1) Å3, and d c = 2.258 g cm−3. All cations and anions in this compound are completely surrounded by water molecules. Sr2+ and K+ ions are each coordinated to eight water molecules arranged in an approximately square antiprism. The [Sr(H2O)8]2+ polyhedron shares one face of four water molecules with a [K(H2O)8]+ polyhedron forming O4-Sr-O4-K-O4 polyhedra. The O4-Sr-O4-K-O4 units are linked together through a pair of edge-sharing linkages of the outer water molecules, alternating along the a-axis and b-axis. The hydrated cation polyhedra appear to define the host lattice, which accommodates the AsO 4 3- ion in the interstitial space. The environment of the AsO 4 3- ion consists of 16 water molecules; each oxygen atom is the acceptor in hydrogen bonds from four water molecules. The pair distances associated with this environment may be used in investigations of the structure of hydrated 4 n- ions in solutions. Each water molecule is coordinated to one Sr and one K, and hydrogen bonded to two O atoms of two different AsO 4 3- ions. There is no hydrogen bonding between water molecules.
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    Crystal structures of a series of 3,7-bis-(arylazo)-1,3,5,7-tetraazabicyclo[3.3.1]nonanes (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 797-809 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; bicyclononane ; triazene ; bis-triazene ; nitrile substituent ; nitro substituent ; trifluoromethyl substituent ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of a series of 3,7-bis(arylazo)-1,3,5,7-tetraazabicyclo[3.3.1] nonanes (1a–d) have been determined by single crystal X-ray diffraction analysis. All four compounds have the same feature, that the tetraazabicyclononane unit assumes a cage-like structure with the aryltriazene moieties lying parallel to one another so that the aryl rings are held together by π – π stacking. Crystal data: 1a C17H18N10O4, triclinic, space group P − 1, a = 9.8899(10), b = 13.0845(13), c = 16.458(2) Å, α = 94.095(2)°, β = 107.004(2)°, γ = 111.027(2)°, V = 1863.5(3) Å3 and Z = 4; 1b, C19H18F6N8, orthorhombic, space group Pbca, a = 15.3210(8), b = 10.9512(6), c = 24.5698(13) Å, V = 4122.4(4) Å3 and Z = 8; 1c C19H18N10, monoclinic, space group P21/n a = 6.3742(6), b = 13.7343(13), c = 21.542(2)Å, β = 97.738(2)°, V = 1868.8(3) Å3, and Z = 4; 1d, C19H18N10, monoclinic, space group P21/c, a = 18.205(2), b = 17.398(2), c = 12.784(12) Å, β = 109.480(2)°, V = 3818.0(6) Å3, and Z = 8.
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    Characterization and structural analyses of trimethoxy and triethoxybenzo[b]thiophene (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 289-295 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; centrosymmetric ; methoxybenzo [b] thiophene ; estrogen receptor ; tubulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structures of two methoxybenzo [b] thiophenes have been determined by three-dimensional, single-crystal X-ray diffractometry. Both 3-(3′,4′,5′-trimethoxybenzoyl)-2-(4′-methoxyphenyl)-6-methoxybenzo[b]thiophene and 3-(3′,4′,5′-triethoxybenzoyl)-2-(4′-methoxyphenyl)-6-methoxybenzo[b]thiophene (hereafter referred to as I and II, respectively) crystallize in the triclinic centrosymmetric space group $$P \bar 1$$ (No. 2, C1) with two formula units per cell with a = 6.842(1) Å, b = 12.602(2) Å, c = 13.815(2) Å, α = 94.80(1)°, β = 98.27(2)°, and γ = 100.59(2)° and a = 10.600(1), b = 11.415(2), c = 12.137(2) Å, α = 94.57(1)°, β = 101.18(1)°, and γ = 110.45(1)°, respectively. The phase problems were solved by direct methods and the respective final full-matrix least-squares refinements converged to R = 0.039 and 0.068. The structures differ in the orientation of the trimethoxy and triethoxy groups of the benzoyl ligands. The molecules in the crystal lattice are held together by van der Waals forces. Selected bond distances, angles, and torsion angles are tabularized as well as reference to the synthesis of the title compounds and peripheral studies.
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    Synthesis and crystal structure of a polymeric erbium(III)–sodium(I) coordination complex of picolinic acid N-oxide (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 413-418 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; coordination polymer ; erbium(III)–sodium(I) carboxylate complex ; picolinic acid N-oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new Er(III)–Na(I) coordination polymer of stoichiometry [NaEr2L5(H2O)6(NO3)](NO3)·3.5H2O (HL = picolinic acid N-oxide) has been synthesized and characterized by single-crystal X-ray analysis. Crystals are triclinic, PĪ with a = 9.823(2), b = 12.453(2), c = 20.643(4) Å; α = 98.49(3), (β = 101.40(3), γ = 108.69(3)°; V = 2284(1) Å3; Z = 2. Of the two independent eight-coordinate erbium(III) ions in this complex, one is surrounded by four bidentate chelating L ligands, and the other by one bidentate chelating L ligand, four aqua ligands and two anti-carboxylate oxygen atoms from two neighboring [ErL4] units. The sodium(I) ion is in a distorted octahedral environment, being coordinated by a unidentate nitrate anion, three aqua ligands and two anti-carboxylate oxygen atoms from two adjacent [ErL4] units. The complex is built from zigzag chains of syn-anti carboxylate-bridged erbium(III) moieties directed in the a direction, which are cross-linked pairwise by aqua-bridgeddimericsodium(I) units. The resulting composite polymeric chains are further connected by hydrogen bonds to form a three-dimensional network.
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    Crystal structure and two-stage hydrolysis of dimethoxo (meso-tetra(4-methoxyphenylporphyrinato))tin(IV), Sn(tmpp)(OMe)2 (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 481-486 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; tin porphyrin ; two-stage hydrolysis ; methanolate ; trans equivalent axial ligand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In this work, we determine the crystal structure of dimethoxo(meso-tetra(4-methoxyphenylporphyrinato))tin(IV), Sn(tmpp)(OMe)2 (1). Experimental results indicate that the tin atom has an octahedral geometry. The geometry around the tin center has Sn(1)–O(5) = 2.020(6), Sn(1)–O(6) = 2.003(7) Å and an average Sn(1)–N = 2.10(1) Å. The two methoxo groups are unidentately coordinated to the tin(IV) atom. Two-stage hydrolysis of Sn(tmpp)(OMe)2 in CDCl3 was observed by 1H and 13C NMR spectroscopy. Compound (1) crystallizes in the space group P21/n with a = 14.7492(1), b = 19.2022(3), c = 16.0806(2) Å, β = 94.104(1)°, and Z = 4.
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    Synthesis and structural characterization of a novel polymeric gadolinium(III)–copper(II) complex of iminodiacetic acid (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 475-479 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; coordination polymer ; gadolinium(III)-copper(II) complex ; iminodiacetic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A novel polymeric Gd2Cu3 complex of iminodiacetic acid (H2L1=NH{CH2COOH}2), namely, Gd2Cu3(L1)6, 1, has been synthesized and structurally characterized. In the title complex, the Gd3+ ion is nine-coordinated by six O atoms from three bidentate chelating carboxylate groups and three O atoms from three anti-anti bridging carboxylic groups of six L1 ligands; the Cu2+ ion is six-coordinated by four O and two N atoms from two chelating L1 ligands. Each pair of Gd(III) atoms is bridged by three L1 ligands, each of which also chelates with one copper(II) ion, thus forming a Gd2Cu3 cluster unit. Such cluster units are cross-linked by flexible L1 ligands into a three-dimensional coordination framework. The title complex crystallizes in the trigonal space group P-3c1 (No. 165) with a = b = 13.433(4), c = 14.770(6) Å; V = 2308(1) Å3; Dcalca = 1.859 g cm−3; Z = 2.
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    Structure of a deaza dimer of 4-methyl-3H-1,2,4-triazole-3,5(4H)-dione (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 15-18 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; dimer ; triazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the monoclinic space group, P21/n; a = 9.0024(5), b = 5.8135(3), c = 15.2232(8) Å, β = 91.153(4)° Z = 4; and R = 0.050 based on 853 observed, unique reflections. The structure consists of two fused five-membered triazole rings, oriented relative to each other at 152°.
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    Crystal structures of two substituted biphenyl derivatives: 5,5′-di t-butyl-2-2′-biphenyldiol and 5,5′-dimethyl-2,2′-biphenyldiol (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 157-161 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; biphenyl ; mutual orientation ; strong H-bonds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 5,5′-Di t-butyl-2,2′-biphenyldiol (I), C20H26O2, crystallizes in the orthorhombic space group P212121 with a = 18.243(2), b = 9.947(2), c = 9.685(3) Å, and Z = 4; 5,5′-dimethyl-2,2′-biphenyldiol (II), C14H14O2, crystallizes in the monoclinic space group P21/c with a = 9.959(2), b = 7.932(3), c = 15.392(2) Å, β = 105.43(2)°, and Z = 4. The aromatic rings are tilted by 52.7(1) and 43.8(1)° to each other in compounds (I) and (II), respectively. Strong intra- and inter-molecular H-bonds connect the molecules in the crystals.
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    Synthesis, spectroscopic studies, and crystal structure of tris(tetra-n-butylammonium) hexakisisothiocyanatoindate(III) (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 317-321 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; indium complexes ; isothiocyanate complexes ; octahedral coordination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The reaction of a 1:10 molar ratio between indium chloride and tetra-n-butylammonium thiocyanate in ethanol affords the complex [(n-C4H9)4N]3[In(NCS)6] (1), the structure of which has been established by X-ray diffraction. This compound crystallizes in the cubic space group Pa3¯ with eight formula units in the unit cell. The formula unit consists of three separate cationic tetra-n-butylammonium groups and an independent hexakisisothiocyanatoindium anionic group. The six near linear thiocyanate ligands coordinate octahedrally through the nitrogen atom to the indium metal center. The coordination of the n-butyl groups to the ammonium-nitrogen atom is tetrahedral. The complex has also been characterized by IR, 1H and 13C NMR, physical properties, and X-ray powder analysis.
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    Crystal structures of a series of 3,8-di[-2-aryl-1-azenyl]-1,3,6,8-tetraazabicyclo[4.4.1]undecanes (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 145-156 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; bicycloundecane ; triazene ; bis-triazene ; nitro substituent ; carboalkoxy substituent ; π–π stacking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of a series of 3,8-di[-2-aryl-1-azenyl]-1,3,6,8-tetraazabicyclo[4.4.1]undecanes (1–5) have been determined by single crystal X-ray diffraction analysis. In all five compounds, the tetraazabicycloundecane portion of the molecule assumes a cage-like, folded structure with the aryltriazene moieties aligned approximately parallel; the structure is held in the folded configuration by either intramolecular or intermolecular π–π stacking forces. Crystal data: 1 C19H22N10O4, monoclinic space group P21/c, a = 10.1846(7), b = 9.9556(7), c = 20.819(2) Å, β = 98.725(1)°, V = 2086.5 (3) Å3, Z = 4; 2 C23H28N8O4, triclinic, space group Pī, a = 6.7064(7), b = 12.9662(14), c = 14.054(2) Å, α = 94.796(2), β = 91.621(2), γ = 104.836(2)°, V = 1175.7(2) Å3, Z = 2; 3 C19H22N10O4, monoclinic, space group P21/c, a = 14.237(2), b = 13.520(2), c = 11.5805(12) Å, β = 113.514(2)°, V = 2044.0(4) Å3, Z = 4; 4 C21H22N10, monoclinic, space group C2/c, a = 54.247(3), b = 11.5531(7), c = 12.9670(7) Å, β = 95.710(1)°, V = 8086.4(8) Å3, Z = 16; 5 C25H32N8 04, monoclinic, space group P21/c, a = 10.2908(7), b = 16.5687(12), c = 15.1662(10) Å, β = 94,188(1)°, V = 2579.0(3) Å3, Z = 4.
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    Synthesis and crystal structure of 4,5-dibromo[2.1.1]triblattene (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 351-354 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; dibromotriblattene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Reaction of 4-bromopentacyclo[7.3.0.02,7.03,11.06,10]dodec-11-ene (1) with Br2—CCl4 afforded 4,4,5-tribromopentacyclo[7.3.0.02,7.03,11.06,10]dodecane (2) in 89–94% yield. Subsequent treatment of 2 with KOt-Bu-t-BuOH resulted in competitive elimination of the elements of HBr and of Br2 with concomitant formation of 4,5-dibromopentacyclo[7.3.0.02,7.03,11.06,10]dodec-11-ene (3, 76%) and 1 (17%), respectively. The structure of 3 was established unequivocally via application of X-ray crystallographic methods. Crystal data for 3: monoclinic, C2/c, a = 9.895(1), b = 9.0963(7), c = 12.471(1) Å, β = 106.875(8)°, z = 4.
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  • 43
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    Synthesis, crystal structure, and molecular modeling (AM1) of Methyl 6-chloro-4-(2-chlorophenyl)-5-formyl-2-methyl-1, 4-dihydropyridine-3-carboxylate (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 237-243 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; AM1 ; x-ray diffraction ; dihydropiridines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis and structural characterization of Methyl 6-chloro-4-(2-chlorophenyl)-5-formyl-2-methyl-1,4-dihydropyridine-3-carboxylate is described. The structure was refined to R1 = 0.0470 for 2665 reflections (with I 〉 2σ(I)). Crystal data: C15H13C12NO3, monoclinic,space group P21/c, a = 11.163(9), b = 14.484(8), c = 9.422(7) Å, V = 1512.9(19) Å3, Z = 4. The results of crystallographic and molecular modeling (AM1) were compared. The Cl atom attached to the phenyl group has two possible orientations, having 75% (sp) and 25% (ap) occupancy, respectively. The molecules in the crystal are held together by means of intermolecular hydrogen bonds of the type N=H...O and by C=H...O interactions.
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    Synthesis and crystal structure of a tetranuclear manganese(IV) cluster [L4Mn4O6](ClO4)4·2H2O (L = 1,4,7-triazacyclononane) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 251-254 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; manganese(IV) cluster ; adamantane-shaped complex ; tetranuclear complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A tetranuclear manganese (IV) complex, [L4Mn4O6](ClO4)4·2H2O (1), with 1,4,7-triazacyclononane (L) as the capping ligands, has been synthesized and characterized by X-ray diffraction; monoclinic, space group P21/n with a = 21.335(6) Å, b = 11.387(3) Å, c = 21.788 (6) Å, β = 111.410 (6)°, V = 4928 (2) Å, Z = 4. Each manganese atom has a distorted octahedral environment comprised of three facially coordinated amine nitrogen atoms and three oxygen atoms, and the cation is an idealized tetrahedron. The Mn4O6 4+ cation corresponds to an adamantane skeleton.
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  • 45
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    Structure of a C2-symmetric bis(benzyloxy)trishomocubanone (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 747-750 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; trishomocubanone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of a bis(benzyloxy)trishomocubanone with molecular C2 symmetry reveals that substitution of benzyloxy groups has little effect on the trishomocubane cage.
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  • 46
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    Crystal structure of ethyl 4-methylthio-3-phenyl-2-thioxo-2,3-dihydro-1,3-oxazole-5-carboxylate (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 237-240 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; 1,3-oxazoline-2-thione ; resonance structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound C13H13NO3S2 crystallizes in the triclinic space group $$P\bar 1$$ (Z=2) with lattice constantsa=8.382(2),b=10.042(2),c=10.134(2) Å, α=119.35(1)°, β=101.40(1)° and γ=90.54(1)°. The interplanar angle between the least squares planes of the 1,3-oxazoline ring and the phenyl ring amounts to 90.2°, thus hindering conjugation between the benzene and heterocyclic system. The observed bond parameters of the five-membered heterocycle suggest a significant contribution from a zwitterionic dipolar limiting structure [38.7(5)%] to the description of this ring system. The particular contributions of the resonance structures were estimated by calculations using the HOSE model on the base of the observed bond lengths.
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  • 47
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    Synthesis and structure ofexo-11-cyano-endo-11-(trimethylsilyloxy)pentacyclo[5.4.0.02,6.03,10.05,9]undecan-8-one (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 267-271 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; pentacycloundecan-8-one ; pentacycloundecane-8,11-dione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of an asymmetric pentacyclo[5.4.0.02,6.03,10.05,9]undecan-8,11-dione derivative is reported, in which Me3SiCN has been added across one of the keto groups. The cage structure demonstrates the expected effects of this addition.
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  • 48
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    Structure of the product formed via Cu(I)-promoted oxidative dimerization ofexo-8-ethynylpentacyclo[5.4.0.02,6.03,10.05.9]undecan-endo-8-ol (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 543-547 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; diyne ; oxidative dimerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure consists of two acetyl-substituted PCU cages linked by a diyne fragment. The conformation about the linker is midway between staggered and eclipsed, and the acetyl groups are somewhat distorted due to the proximity to the bulky cage units.
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  • 49
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    Crystal structure oftrans-tetrachlorobis[2-(2-1H-imidazolyl)-1H-imidazolium]cadmium(II), [Cd(H3biim)2Cl4] (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 695-699 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; 2,2'-bi-1H-imidazole ; cadmium chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The reaction between cadmium(II) chloride and 2,2'-bi-1H-imidazole (H2biim) in an acidic solution affords [Cd(H3biim)2Cl4] (H3biim=2-(2-1H-imidazolyl)-1H-imidazolium) in 63% yield. The compound crystallizes in the triclinic space groupP1, wherea=8.072(2),b=8.100(2),c=8.593(2) Å, α=75.89(2), β=62.94(2), γ=63.29(1)°,V=446.4(2) Å3, andZ=1. The central Cd atom exhibits an octahedral geometry composed of a Cl4N2 core. The Cd-N bond distance is 2.392(2) Å. Cd−Cl distances are 2.5919(9) and 2.671(1) Å.
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  • 50
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    X-ray structures of two methoxybenzo[b]thiophenes (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 801-806 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; centrosymmetric ; methoxybenzo[b]thiophene ; estrogen receptor ; tubulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structures of two methoxybenzo[b]thiophenes have been determined by three-dimensional, single-crystal X-ray diffractometry. Both 3-(4′-hydroxy-3′, 5′-dimethoxybenzoyl)-2-(4′-methoxyphenyl)-6-methoxybenzo[b]thiophene and 3-(2′,6′-dimethoxybenzoyl)-2-(4′-methoxyphenyl)-6-methoxybenzo[b]thiophene (hereafter referred to asI andII, respectively) crystallize in the monoclinic centrosymmetric space groupP21/n (No. 14, C 2h 5 ) with four formula units-per cell witha=6.866(1),b=28.638(2),c=11.830(2) Å, and β=105.52(1)° anda=9.328(1),b=7.977(1),c=29.650(4) Å, and β=97.87(1)°, respectively. The phase problems were solved by direct methods and the respective final full-matrix least-squares refinements converged toR=0.046 and 0.031. The structures differ in the positioning of the dimethoxy groups of the benzoyl ligands and the addition of a hydroxyl group inI. The molecules in the crystal lattice are held together by van der Waals forces plus the addition of hydrogen bonding in compoundI. Selected bond distances and angles and torsion angles are tabularized.
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    Reaction of vinylmagnesium bromide with hexacyclo[10.2.1.02,11.04,9.04,14.09,13]pentadeca-5,7-diene-3,10-dione: Transannular hemiketal formation (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 429-433 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; hexacyclopentadeca-5,7-diene-3,10-dione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Reaction between vinylmagnesium bromide and the cage dione leads to attack of only one equivalent of Grignard and intramolecular nucleophilic attack on the second ketone. The product compound crystallizes in the monoclinic space group, P21/a, witha=9.509(1),b=11.071(2),c=12.492(4) Å, β=104.32(2)°, andZ=4.
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  • 52
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    The crystal and molecular structure of 6,8,15,16b,16c,17-hexahydro-16b,16c-diphenyl-7H,16H-6a,7a,15a,16a-tetraazanaphtho[5,6]azulano[2,1,8-ij]naptho[f]azulene-7,16-dione (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 365-368 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; receptor ; clip shaped molecule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of a clip containing molecule is described. The structure was solved by vector search methods and refined by least squares methods toR l=0.0768 [I〉2σ(I)]. Crystal data: C40H30N4O2·HCCl3, triclinic, space group $$P\bar 1$$ ,a=9.302(2),b=12.981(2),c=15.765(2)Å, α=65.91(2)°, β=76.40(2)°, γ=80.15(1)°,V=1682.9(4)Å3, Z=2.
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    Synthesis and X-ray analysis of 1-((1S)-phenylethyl)-azetidine-(2R)-piperidinamide (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 639-642 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; chiral auxiliaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of a new azetidine-2-carboxylic amide derivative is described. The structure was solved by direct methods and refined by least squares methods toR1=0.0393 for 4264 reflections (withI〉2σ(I)) The structure consists of two independent molecules which are chemically the same with slight differences in geometry. Crystal data: C17H24N2O, monoclinic, space groupP21,a=8.3782(4),b=20.0342(13),c=9.7769(8) Å, β=109.687(6)°,V=1545.1(2)Å3,Z=4.
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    Crystal structures of two 1,2-bis-(1-aryl-3-methyltriazene-3-yl-)ethanes with aryl substituents of opposite polarity (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 5-10 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; triazene ; bis-triazene ; nitrile substituent ; methoxy substituent ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of 1,2-bis-{1-(2-cyanophenyl)-3-methyltriazen-3-yl-}ethane (1) and 1,2-bis-{1-(2-methoxyphenyl)-3-methyltriazen-3-yl-}ethane (2) have been determined by single crystal X-ray diffraction analysis. Bis-triazene (1) exists as the “staggered” conformation in the solid state, with an anti-anti configuration around the N2–N3 bond of the triazene units, whereas 2 assumes a “gauche” conformation with the syn-syn configuration in the triazene units. Crystal data: 1 C18H18N8, triclinic, space group P −1, a = 6.108(2), b = 8.118(3), c = 9.600(4)Å, α = 101.37(7)°, β = 96.47(7)°, γ = 102.71(5)°, V = 449.1(3)Å3, Z = 2; 2 C18H24N6O2, monoclinic, space group P 21/n, a = 13.119(5), b = 7.745(2), c = 19.201(2)Å, β = 96.47(7)°, V = 1910.3(9)Å3, Z = 4.
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    Crystal structures of the hydrated disodium and paraquat salts of 1,8-disulfonato-3,4,5,6-acridinetetracarboxylic acid (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 39-46 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; 1,8-disulfonato-3,4,5,6-acridinetetracarboxylic acid ; 3,4,5,6-tetracarboxyacridine-1,8-disulfonate ; paraquat ; hydrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Two hydrated salts of 1,8-disulfonato-3,4,5,6-acridinetetracarboxylic acid, H2L, have been characterized by single-crystal X-ray analysis. Compound 1, Na2L·9 $$ - \frac{1}{2}$$ H2O, crystallizes in the monoclinic space group C2/c with a = 42.005(1), b = 6.838(1), c = 23.807 (1) Å, β = 122.71 (1)°, and Z = 8. Compound 2, (paraquat)L·2H2O, belongs to the triclinic space group $${P\bar 1}$$ with a = 9.940(1), b = 11.543(1), c = 14.033(1) Å, α = 105.45(1), β = 95.82(1), γ = 100.14(1)° and and Z = 2. All four carboxyl groups in the 3,4,5,6-tetracarboxyacridine-1,8-disulfonate dianion L2− are un-ionized. In 1 the distorted octahedrally coordinated sodium cations, the anions, and the lattice water molecules are joined together by hydrogen bonds to generate a three-dimensional network. In the crystal structure of 2, a host framework composed of L2− ions and water molecules accommodate the paraquat dications within two channel systems running parallel to the a and b axes.
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    Crystal structures of four dibromomethylene-functionalized cage compounds (1998)
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    Journal of chemical crystallography 28 (1998), S. 259-266 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; heptacyclotetradecane ; hexacyclotetradecane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystal structures of four dibromomethylene-functionalized hexa- and heptacyclotetradecane cages are reported. 7-(Dibromomethylene)heptacyclo[6.6.0.02,6.03,13.04,11.05,9.010,14]tetradecane (3): orthorhombic, Pnma, a = 14.744(1), b = 11.237(1), c = 7.4625(7) Å Z = 4; R = 0.0531 for 504 observed reflections. 7,12-Bis(dibromomethylene)heptacyclo[6.6.0.02,6.03,13-04,11 .05,9.010,14]tetradecane (4): monoclinic, I2/a, a = 11.257(1), b = 9.5844(8), c = 13.884(2) Å, β = 92.254(8)° Z = 4; R = 0.0413 for 663 observed reflections. 10,14-bis(dibromomethylene)hexacyclo[6.6.0.02,6.03,13.04,11.05,9]tetradecane (6): monoclinic, P21/n, a = 8.118(1), b = 15.273(4), c = 12.826(3) Å, β = 104.20(1)° Z = 4; R = 0.0384 for 1392 observed reflections. 14-(dibromomethylene)hexacyclo[6.6.0.02,6.03,13.04,11.05,9]tetradecan-10-one (7): monoclinic, P21/n, a = 8.2879(7), b = 15.273(1), c = 10.0565(9) Å, β = 92.271(8)° Z = 4; R = 0.0320 for 1402 observed reflections. The functional groups lead to slight shortening of bond lengths.
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    A dinuclear cyano-bridged complex based on hexacyanoferrate(III) and samarium(III) nitrate: synthesis and crystal structure (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 303-307 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; samarium(III) complexes ; iron(III) complexes ; cyanide-bridges ; dinuclear complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new complex, [Sm(DMF)4(H2O)4Fe(CN)6]·H2O (DMF = N, N-dimethylformamide), has been synthesized and characterized by X-ray single crystal structure and thermogravimetric analyses. The complex crystallizes in the P21/n space group, with lattice parameters a = 17.583(4) Å, b = 8.870(2) Å, c = 19.845(6) Å, β = 95.98(3)°, V = 3078(1) Å3, D x = 1.679 Mg m−3, D m = 1.65(1) Mg m−3, Z = 4. The molecular structure shows that a cyano-bridged bimetallic structure is obtained. The Sm atom is coordinated by eight oxygen atoms of four water molecules and four DMF molecules and one nitrogen atom of the bridging cyanide ligand. The iron atom assumes approximately an octahedral environment surrounded by six CN ligands. The hydrate water molecule is hydrogen-bonded to one of the O atoms bound to Sm. Each terminal CN ligand of the Fe(CN) 6 3− entity is hydrogen-bonded to some O atoms of water molecules. An infrared spectrum is also reported.
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    Gold(III)-pteridine compounds: synthesis, spectral, and X-ray diffraction studies on new adducts between sodium tetrabromoaurate(III) and lumazine derivatives (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 565-570 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; complexes ; pteridine ; lumazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In aqueous hydrobromic medium, Na[AuCl4] reacts with 1,3-dimethyllumazine (1,3-dimethyl-pteridine-2,4(1H,3H)-dione, DLM) or 1,3,6,7-tetramethyllumazine (DLMD) to give three adducts with simplified formulas Na[AuBr4](DLMD), Na[AuBr4](DLM), and Na[AuBr4](DLM)2. These compounds have been characterized by means of analytical techniques, and IR and NMR spectroscopies. Single-crystal x-ray diffraction studies have been made on the Na[AuBr4](DLM)2 compound. The crystals belong to the orthorhombic Pbca space group, with a = 15.249(1), b = 15.238(2), c = 21.563(2) Å, Z = 8, and R = 0.053. The structure consists of planar [AuBr4]− anions and Na+ cations weakly linked to two crystallographically independent DLM molecules. The Na+ cation interacts weakly with four oxygen and one nitrogen atoms from four different pteridine molecules, its environment may be described as a very distorted square pyramid.
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    Molecular structure of AlH3[N(CH2CH2)3CH]2 (1998)
    Springer
    Journal of chemical crystallography 28 (1998), S. 649-651 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; aluminum ; hydride ; complex ; quinuclidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Reaction of AlH3[N(CH2CH2)3CH] with hexamethyltrisiloxane, (OSiMe2)3, gives rise to the bis-quinuclidine complex AlH3[N(CH2CH2)3CH]2, which has been characterized by 1H and 13C NMR spectroscopy and X-ray crystallography. The molecular structure of AlH3[N(CH2CH2)3CH]2 consists of a trigonal bipyramidal aluminum with axial coordination of the quinuclidine ligands. Crystal data: orthorhombic, space group Pbcn, a = 10.6895(9), b = 12.266(1), c = 12.3794(9) Å, V = 1623.2(2) Å3, and Z = 4.
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    Synthesis and crystal structure of a new lithium cyclohexaphosphate hydrate: Li6P6O18·10H2O (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 323-327 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; cyclohexaphosphate ; hydrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis and crystal structure of a novel hydrate of lithium cyclohexaphosphate are reported. Li6P6O18·10H2O crystallizes in the space group C2/c with a = 15.113(5), b = 12.006(2), c = 15.892(2) Å, β = 122.85(2)°, and Z = 4. The structure consists of P6O18 ring layers stacked along the c direction in between which are located the lithiumions and water molecules. Two LiO4 tetrahedra share common edges with LiO5 pseudosquare pyramids to form two independant Li3O9 units. About 50% of the water molecules have fractional occupancy rates and form fragments of molecules. A linear relationship is established between the relative cell volume V/Z and the hydration degree, n, for all the known hydrates: Li6P6O18·nH2O.
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    Synthesis and structure of a bis(ethynyl)-substituted oxahexacyclic cage ether (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 347-349 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; pentacycloundecane ; triple bonds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Intramolecular dehydration of a cage-diol results in the title compound. This crystallizes in the monoclinic space group P21/c; a = 8.6403(8), b = 9.5698(7), c = 14.062(1) Å β = 107.47(7)° and Z = 4.
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    A cobalt(II) complex with the N,N,O-tridentate ligand 6-amino-5-formyl-1,3-dimethyluracilato-benzoyl-hydrazone (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 283-286 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; complexes ; cobalt ; benzoylhydrazone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of bis-(6-amino-5-formyl-1,3-dimethyluracilato benzoylhydrazone)cobalt(II) dimethylformamide solvate is described. This compound crystallizes in the triclinic system, space group P1¯, Z = 2 with a = 9.7368(8), b = 12.346(1), c = 17.184(1) Å, α = 78.372(6), β = 74.585(6), γ = 71.113(5)°, and V = 1869.0(3) Å3. The coordination polyhedron around the metal ion displays a slightly flattened M(NNO)2 octahedral shape. Both ligands bind in a trident fashion through the benzoylic oxygen atom, the hydrazone nitrogen atom closer to the uracil ring, and the deprotonated nitrogen atom of the amino group. The two ligands exhibit quite different conformations: one of them is almost planar, whereas the other is severely twisted.
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    Synthesis and crystal structure of 4,4′-bis(4-pyridylethyl)biphenyl, noncovalently hydrogen bonded two-dimensional networks (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 641-646 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; hydrogen bonds ; 1H and 13C NMR ; FTIR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new pyridine containing compound, 4,4′-bis(4-pyridylethyl)biphenyl 1, was synthesized and its structure was determined by X-ray crystallography. Two kinds of two-dimensional networks linked by hydrogen bonds were obtained with different crystal solvents: 1·2H2O, monoclinic, space group P21/n with a = 8.3280(10), b = 5.5990(10), c = 24.054(4) Å, β = 98.79(2)°, V = 1108.4(3) Å3, Z = 2, Dc = 1.200 g cm−3, R1 = 0.0558; 1·CH3OH·2H2O, triclinic, space group P-1 with a = 8.3310(10), b = 12.861(2), c = 13.111(2) Å, α = 64.110(10), β = 75.000(10), γ = 83.750(10)°, V = 1220.7(3) Å3, Z = 2, Dc = 1.177 g cm−3, R1 = 0.0529. It is interesting that in the hydrate the host molecule of 1 contains an essentially flat biphenyl section, while in the methanol complex the host molecule of 1 contains a substantial twist in the center of the biphenyl section. The compounds were also characterized by NMR and FTIR spectroscopies. The 1H and 13C NMR assignments for 1 were carried out by 2D NMR spectral measurements in acetonitrile-d 3.
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    X-ray crystal structures of [HB(3,4,5-Me3pz)3[2Zn, [H2B(3,4,5-Me3pz)2]Zn(μ-3,4,5-Me3pz)2Zn[H2B(3,4,5-Me3pz)2], and [H2B(pz)2]2Zn (pz = pyrazolyl ring) (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 665-670 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; poly(pyrazolyl)borate ligands ; zinc(II)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [HB(3,4,5-Me3pz)3]2Zn (1) and [H2B(3,4,5-Me3pz)2]Zn(μ-3,4,5-Me3pz)2Zn[H2B(3,4,5-Me3pz)2] (2) are present in equal amounts in a crystal in the triclinic space group, P-1 with a = 11.5924(11) Å, b = 12.7799(12) Å, c = 15.7317(14) Å α = 107.905(2)° β = 96.796(2)°, γ = 105.786(2)°, and Z = 1. The structure of 1 is a trigonally distorted octahedron and is very similar to the structure of [HB(3,5-Me2pz)3]2Zn showing that the introduction of the third methyl group on the pyrazolyl ring does not impact on structure. [H2B(pz)2]2Zn (3) is orthorhombic, Pca2(1) with a = 10.1473(3) Å, b = 11.1117(2) Å, c = 14.1831(5) Å, α = β = γ = 90° and Z = 4. The zinc(II) centers in both 2 and 3 are similar and have pseudotetrahedral structures.
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    Structure and properties of cobalt(II) complex with a tetraaza macrocycle containing 2-pyridylmethyl pendant arms (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 335-338 
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    ISSN: 1572-8854
    Keywords: Crystal structure ; cobalt(II) complex ; tetraaza macrocycle ; 2-pyridylmethyl pendant arms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex [Co(L)]Cl2·10H2O (1) (L = 2,13,-bis(2-pyridylmethyl)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07.12]docosane) has been synthesized and structurally characterized. Compound 1 crystallizes in the triclinic system, space group P-1 with a = 9.731(2) Å, b = 9.789(2) Å, c = 11.998(1) Å, α = 66.66(1)°, β = 76.95(1)°, γ = 87.99(2)°, V = 1020.4(3) Å3, and Z = 1. The crystal structure of 1 shows that the complex is centrosymmetric and the cobalt(II) ion has a slightly distorted octahedral geometry with four nitrogen atoms of the macrocycle and two nitrogen atoms of the pendent arms at the axial positions. Cyclic voltammetry for 1 undergoes reversible one-electron oxidation to the Co(III) and irreversible one-electron reduction to the Co(I).
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    Crystal structure of 2,3-dihydronaphto[2,3-b) [1,5] dioxepin (2000)
    Springer
    Journal of chemical crystallography 30 (2000), S. 459-462 
    Details
    ISSN: 1572-8854
    Keywords: Crystal structure ; chemical synthesis ; 2,3-dihydronaphto[2,3-b] [1,5) dioxepin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The X-ray single crystal structure of C13H12O2 compound was determined. It crystallizes in the orthorombic space group P212121 with a = 7.8847(7), b = 9.639(1), c = 13.432(2) Å, Z = 4 and V = 1020.8(3) Å3. The final R converged to 0.037 for 1763 independent reflexions. The title compound forms layers parallel to (1 0 0) planes and the three dimensional cohesion of the crystal is assumed by Van der Waals interactions. The molecule consists of two six-membered rings (A and B) and a seven-membered ring (C). A and B rings are planar, whereas the C ring has a chair conformation
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    Surf-riding and oscillations of a ship in quartering waves (1995)
    Springer
    Journal of marine science and technology 1 (1995), S. 24-36 
    Details
    ISSN: 1437-8213
    Keywords: surf-riding ; nonlinear ; wave ; ship motion ; stability ; chaos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract The behavior of a ship encountering large regular waves from astern at low frequency is the object of investigation, with a parallel study of surf-riding and periodic motion paterns. First, the theoretical analysis of surf-riding is extended from purely following to quartering seas. Steady-state continuation is used to identify all possible surf-riding states for one wavelength. Examination of stability indicates the existence of stable and unstable states and predicts a new type of oscillatory surf-riding. Global analysis is also applied to determine the areas of state space which lead to surf-riding for a given ship and wave conditions. In the case of overtaking waves, the large rudder-yaw-surge oscillations of the vessel are examined, showing the mechanism and conditions responsible for loss of controllability at certain vessel headings.
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    A note on multiple flow equilibria (1989)
    Springer
    Pure and applied geophysics 130 (1989), S. 743-749 
    Details
    ISSN: 1420-9136
    Keywords: Dynamic systems ; multiple equilibrium ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A set of ordinary differential equations describing a mechanical system subject to forcing and dissipation is considered. A topological argument is employed to show that if all time-dependent solutions of the governing equations are bounded, the equations admitN steady solutions, whereN is a positive odd integer and where at least (N−1)/2 of the steady solutions are unstable. The results are discussed in the context of atmospheric flows, and it is shown that truncated forms of the quasigeostrophic equations of dynamic meteorology and of Budyko-Sellers climate models satisfy the hypotheses of the theorem.
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    An infrared spectroscopic and single-crystal X-ray study of malayaite, CaSnSiO5 (1999)
    Springer
    Physics and chemistry of minerals 26 (1999), S. 546-553 
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    ISSN: 1432-2021
    Keywords: Key words Malayaite ; Infrared spectroscopy ; Crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Powder infrared spectroscopy and X-ray diffraction techniques on single crystals were used to study the thermal behaviour of malayaite, CaSnSiO5. Infrared spectra show a discontinuity in the temperature evolution of phonon frequencies and absorbance near 500 K. However, crystal structure data collected at 300, 450, 550, 670, and 750 K show no evidence of a symmetry-breaking phase transition and no split positions. The most obvious change with heating is a tumbling motion of the SnO6 octahedra and an increase of the anisotropic displacement factors of Ca. The thermal evolution of the mean-square vibrational amplitude of the Ca atom shows a pronounced change in slope near 500 K. The evidence suggests that the 500 K anomaly in malayaite is more similar in character to the 825 K (β-γ) transition as opposed to the 496 K (α-β) transition in synthetic titanite.
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    Compression of witherite to 8 GPa and the crystal structure of BaCO3II (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 467-473 
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    ISSN: 1432-2021
    Keywords: Key words Witherite ; High pressure ; Aragonite ; Crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Natural witherite (Ba0.99Sr0.01CO3) has been studied by single-crystal X-ray diffraction in the diamond anvil cell at eight pressures up to 8 GPa. At ambient pressure, cell dimensions are a = 5.3164(12) Å, b = 8.8921(19) Å, c = 6.4279(16) Å, and the structure was refined in space group Pmcn to R(F) = 0.020 from 2972 intensity data. The unit cell and atom position parameters for the orthorhombic cell were refined at pressures of 1.2, 2.0, 2.9, 3.9, 4.6, 5.5, 6.2, and 7.0 GPa. The volume-pressure data are used to calculate equation of state parameters K T0 = 50.4(12) GPa and K′ = 1.9(4). At approximately 7.2 GPa, a first-order transformation to space group P3¯1c was observed. Cell dimensions of the high-pressure phase at 7.2 GPa are a = 5.258(6) Å, c = 5.64(1) Å. The high pressure structure was determined and refined to R(F) = 0.06 using 83 intensity data, of which 15 were unique. This high-pressure phase appears to be more compressible than the orthorhombic phase with an estimated initial bulk modulus (K 7.2GPa) of 10 GPa.
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    Structure of Cu-bearing orthopyroxene, Mg(Cu.56,Mg.44)Si2O6, and behavior of Cu2+ in the orthopyroxene structure (1997)
    Springer
    Physics and chemistry of minerals 24 (1997), S. 463-476 
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    ISSN: 1432-2021
    Keywords: Key words Cu2+-beearing orthopyroxene ; Orthopyroxene ; Crystal structure ; Jahn-Teller effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  Cu-bearing pyroxene, Mg(Cu.56,Mg.44)Si2O6, has been synthesized by a flux method and crystal structure refinement has been performed by single crystal X-ray diffraction. It is found that the crystal structure is orthorhombic (space group Pbca) with unit cell dimensions of a=18.221(4), b=8.890(1), c=5.2260(7)Å and the cell volume of 846.5( )3Å3. In the M2-site one of the M-O bonds(M-O3B) is extremely expanded from 2.444(2) in enstatite to 2.732(2), thus the coordination polyhedron around M2-site is regarded as square pyramidal rather than square planar or octahedral. It is also found that the M1-site in the pyroxene structure is occupied almost exclusively by Mg, while the M2-site is almost evenly occupied by Mg and Cu. The observed extreme site preference shown by Cu2+ is unusual among the divalent cations with similar ionic sizes.
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    Displacive phase transitions in C-centred clinopyroxenes: spodumene, LiScSi2O6 and ZnSiO3 (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 719-731 
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    ISSN: 1432-2021
    Keywords: Key words Clinopyroxene ; Spodumene ; ZnSiO3 ; LiScSi2O6 ; Phase transition ; High-pressure ; Crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The clinopyroxenes spodumene (LiAlSi2O6), LiScSi2O6 and ZnSiO3, all with space group C2/c at ambient conditions, were studied under high pressures by single-crystal X-ray diffraction in a diamond-anvil cell. Changes in the evolution of the unit-cell parameters, optical properties and the appearance of h + k odd reflections characteristic of a primitive lattice, indicate that all three pyroxenes undergo phase transitions. The transitions are mostly displacive in character, and are non-quenchable. Transition pressures are 3.19 GPa in spodumene, ∼0.6 GPa in LiScSi2O6 and 1.92 GPa in ZnSiO3. The space group of all three high-pressure phases was determined to be P21/c by structure refinement to single-crystal X-ray intensity data collected in the DAC. In the ZnSiO3 clinopyroxene the intermediate P21/c phase further transforms to a second C2/c phase (HP-C2/c) at 4.9 GPa (confirmed by structure refinement). The volume change at this transition is about 2.6%, three times larger than in the first phase transition, and typical of the P21/c→ HP-C2/c phase transitions found previously in MgSiO3, FeSiO3, etc. These results therefore provide the first direct evidence that the HP-C2/c and the HT-C2/c structures of pyroxenes are distinct polymorphs with the same space group. The phase transition from C2/c to P21/c symmetry in spodumene and LiScSi2O6 therefore occurs because the polymorphs stable at ambient conditions are isotypic to the high-temperature C2/c phases of clinopyroxenes such as pigeonite and clinoenstatite.
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    Synthetic MgGa2O4-Mg2GeO4 spinel solid solution and β-Mg3Ga2GeO8: chemistry, crystal structures, cation ordering, and comparison to Mg2GeO4 olivine (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 179-193 
    Details
    ISSN: 1432-2021
    Keywords: Key words Spinel ; Wadsleyite ; Spinelloid ; Olivine ; Crystal structure ; Cation ordering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  Structural parameters and cation ordering are determined for four compositions in the synthetic MgGa2O4-Mg2GeO4 spinel solid solution (0, 8, 15 and 23 mol% Mg2GeO4; 1400 °C, 1 bar) and for spinelloid β-Mg3Ga2GeO8 (1350 °C, 1 bar), by Rietveld refinement of room-temperature neutron diffraction data. Sample chemistry is determined by XRF and EPMA. Addition of Mg2GeO4 causes the cation distribution of the MgGa2O4 component to change from a disordered inverse distribution in end member MgGa2O4, [4]Ga = x = 0.88(3), through the random distribution, toward a normal cation distribution, x = 0.37(3), at 23 mol% Mg2GeO4. An increase in ao with increasing Mg2GeO4 component is correlated with an increase in the amount of Mg on the tetrahedral site, through substitution of 2 Ga3+⇄ Mg2++Ge4+. The spinel exhibits high configurational entropy, reaching 20.2 J mol−1 (four oxygen basis) near the compositional upper limit of the solid solution. This stabilizes the spinel in spite of positive enthalpy of disordering over the solid solution, where ΔH D  = αx + βx 2, α = 22(3), β = −21(3) kJ mol−1. This model for the cation distribution across the join suggests that the empirically determined limit of the spinel solid solution is correlated with the limit of tetrahedral ordering of Mg, after which local charge-balanced substitution is no longer maintained. Spinelloid β-Mg3Ga2GeO8 has cation distribution M1[Mg0.50(2)Ga0.50(2)] M2[Mg0.96(2)Ga0.04(2)] M3[Mg0.77(2) Ga0.23(2)]2 (Ge0.5Ga0.5)2O8 (tetrahedral site occupancies are assumed). Octahedral site size is correlated to Mg distribution, where site volume, site distortion, and Mg content follow the relation M1〈M3〈M2. The disordered cation distribution provides local electrical neutrality in the structure, and stabilization through increased configurational entropy (27.6 J mol−1; eight oxygen basis). Comparison of the crystal structures of Mg1+ N Ga2−2 N Ge N O4 spinel, β-Mg3Ga2GeO8, and Mg2GeO4 olivine reveals β-Mg3Ga2GeO8 to be a true structural intermediate. Phase transitions across the pseudobinary are necessary to accommodate an increasing divergence of cation size and valence, with addition of Mg2GeO4 component. Octahedral volume increases while tetrahedral volume decreases from spinel to β-Mg3Ga2GeO8 to olivine, with addition of Mg and Ge, respectively. Furthermore, M-M distances increase regularly across the join, suggesting that changes in topology reduce cation-cation repulsion.
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    Hydrogen bonding interactions in phase A [Mg7Si2O8(OH)6] at ambient and high pressure (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 225-233 
    Details
    ISSN: 1432-2021
    Keywords: Key words Hydrogen bonding ; Neutron diffraction ; Dense hydrous magnesium silicate (DHMS) ; Crystal structure ; High pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  Neutron powder diffraction data of phase A (Mg7Si2O8(OH)6) were collected at ambient pressure and 3.2 GPa (calculated from the compressibility of phase A) from the deuterated compound, and the structure was refined using the Rietveld method. The derived crystal structure implies that hydrogen atoms occupy two distinct sites in phase A, both forming hydrogen bonds of different lengths with the same oxygen atom. This picture is supported by IR spectra, which exhibit two absorption bands at 3400 and 3513 cm−1 corresponding to OH stretching vibrations, and proton NMR spectra, which display two peaks with equal intensities and isotropic chemical shifts of 3.7 and 5 ppm. The D-D distance [D(1)-D(2) distance] at ambient pressure was found to be 2.09 ± 0.02 Å from the neutron diffraction data and 2.09 ± 0.05 Å from the NMR spectra. At 3.2 GPa, there is no statistically significant increase in the O-D interatomic distance while the hydrogen bonding interaction D···O appears to increase for one of the hydrogen sites, D(1), which has the stronger hydrogen bonding interaction compared with the other hydrogen, D(2), at ambient pressure. The O-D bond valences, determined indirectly from the D···O distances were 0.86 and 0.91 at ambient pressure, and 0.83 and 0.90 at 3.2 GPa, for D(1) and D(2), respectively.
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    Bifurcations in Spherical MHD Models (1998)
    Springer
    Studia geophysica et geodaetica 42 (1998), S. 320-327 
    Details
    ISSN: 1573-1626
    Keywords: MHD ; stability ; bifurcations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract A series of numerical studies on the behaviour of magnetic fields and motions in a spherical body of an electrically conducting incompressible fluid have been carried out. The magnetic field was assumed to be maintained by a given electromotive force inside the body and to continue as a potential field in outer space. In view of the motion an external forcing was taken into account, and boundary conditions were considered which correspond to a stress-free surface. The stability of several steady states has been studied as well as the evolutions starting from unstable states. In this paper a configuration with a poloidal magnetic field and a differential rotation, both symmetric about the same axis, is considered. This configuration is stable only for sufficiently small Hartmann numbers but evolves, if disturbed, in the case of larger Hartmann numbers toward a non-axisymmetric state. In this case the well-known symmetrization effect of differential rotation in magnetic fields is destroyed.
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    The Equation of State of Lakes (2000)
    Springer
    Aquatic geochemistry 6 (2000), S. 1-17 
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    ISSN: 1573-1421
    Keywords: lakes ; density ; compressibility ; expansibility ; conductivity ; stability ; pvt properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract In recent years, a number of workers have studied the stability of deep lakes such as Lake Tanganyika, Lake Baikal and Lake Malawi. In this paper, the methods that can be used to determine the effect that the components of lakes have on the equation of state are examined. The PVT properties of Lakes have been determined by using apparent molal volume data for the major ionic components of the lake. The estimated PVT properties (densities, expansibility and compressibilities) of the lakes are found to be in good agreement with the PVT properties (P) of seawater diluted to the same salinity. This is similar to earlier work that showed that the PVT properties of rivers and estuarine waters could also be estimated from the properties of seawater. The measured densities of Lake Tanganyika were found to be in good agreement (± 2 × 10-6 g cm-3) with the values estimated from partial molal properties and the values of seawater at the same total salinity (ST = 0.568‰). The increase in the densities of Lake Tanganyika waters increased due to changes in the composition of the waters. The measured increase in the measured density (45 × 10-6 g cm-3) is in good agreement (46 × 10-6 g cm-3) with the values calculated for the increase in Na+, HCO3 -, Mg2+, Ca2+ and Si(OH)4. Methods are described that can be used to determine the conductivity salinity of lakes using the equations developed for seawater. By combining these relationships with apparent molal volume data, one can relate the PVT properties of the lake to those of seawater.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009626325650
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    Effect of rock discontinuities on certain rock strength and fracture energy parameters under uniaxial compression (1993)
    Springer
    Geotechnical and geological engineering 11 (1993), S. 81-105 
    Details
    ISSN: 1573-1529
    Keywords: Rock discontinuities ; uniaxial compression ; fracture mechanics ; stability ; scale effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary Five series of test blocks of Pendeli marble with artificially created discontinuities of different crack densities (simulating three mutually orthogonal joint sets) were tested in uniaxial compression in order to study the effect of discontinuities on: (a) the compressive strength and the modulus of elasticity, and (b) certain fracture energy parameters expressed by the ratio W A/W V, where W A is the surface energy and W V the volume elastic strain energy. Mathematical relationships are derived similar to those suggested by other authors relating strength parameters to crack densities. Such relationships clearly show a reduction in strength with increased crack density. The experimental results obtained permit the extension of Persson's relation (which refers to ideal intact rock) to the more realistic case of discontinuous rock mass by introducing the appropriate term that takes into consideration the effect of rock mass discontinuities on the energy ratio W A/W V. A comparison between laboratory results and field observations was subsequently carried out assuming the rock mass to behave as a linearly elastic material, obeying the Hoek and Brown failure criterion. This comparison showed that laboratory results can be extended to larger scale. Furthermore, in order to predict the in situ strength and stability of a rock mass in uniaxial compression (which is of major importance in underground excavations) certain concepts are proposed based on laboratory tests, in situ investigations and first principles of linear elastic fracture mechanics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423337
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    The effect of normal stress-friction angle relationship on the stability analysis of a rockfill dam (1994)
    Springer
    Geotechnical and geological engineering 12 (1994), S. 113-121 
    Details
    ISSN: 1573-1529
    Keywords: Greywacke ; normal stress ; rockfill ; shear strength ; stability ; triaxial testing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary Accurate stability analysis must consider the variation of the angle of friction of rockfill with the confining pressure. In reality, with increasing depth of a rockfill dam, the apparent friction angle decreases, whereas near the surface it tends to be higher. Conventional methods which employ a constant friction angle throughout the depth of a rockfill shell often yield a lower factor of safety (conservative) for shallow slip planes. On the contrary, they produce a higher factor of safety for deepseated slips subjected to increased normal (confining) stresses. This paper compares the constant friction angle approach with the variable friction angle method based on the stability analysis of a large rockfill dam, and the associated practical implications are discussed. In the latter analysis, the effect of normal stress on the friction angle of rockfill is incorporated through experimental observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429769
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    Improvements in resource recovery at Stauffer's Big Island Mine (1988)
    Springer
    Geotechnical and geological engineering 6 (1988), S. 195-214 
    Details
    ISSN: 1573-1529
    Keywords: Room and pillar mining ; yield pillars ; rock mechanics ; stability ; evaporites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Summary Significant increases in extraction ratio on the order of 6 to 8%, equivalent to as much as 142 t/m of panel advance, have occurred at the Big Island Mine during the last five years with the help of a practical rock mechanics program. This increase in resource recovery has also contributed to improvements in productivity. Both conventional and continuous machine mining have been used to mine two flat-laying trona beds at depths of 250 and 260 m in the Green River Formation in southwestern Wyoming. Conventional room and pillar mining originally was conducted in panels with extraction ratios of 58 to 60%. The use of yield pillars has allowed the panel extraction to increase to 66%. Continuous machine mining was introduced recently, with a 64% extraction ratio using long, narrow pillars and wide rooms. Further improvements in resource recovery seem feasible in the light of present mining experience. The rock mechanics program consisted of field instrumentation to determine the pillar and roof response to mining, and computer modelling to evaluate and help determine the stability of various layouts, which were then adopted for mining.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00880974
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  • 80
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    Onset of viscous fingering for miscible liquid-liquid displacements in porous media (1993)
    Springer
    Transport in porous media 10 (1993), S. 285-291 
    Details
    ISSN: 1573-1634
    Keywords: Miscible displacement ; stability ; length effect ; critical velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract The displacement of one fluid by another miscible fluid in porous media is an important phenomenon that occurs in petroleum engineering, in groundwater movement, and in the chemical industry. This paper presents a recently developed stability criterion which applies to the most general miscible displacement. Under special conditions, different expressions for the onset of fingering given in the literature can be obtained from the universally applicable criterion. In particular, it is shown that the commonly used equation to predict the stable velocity ignores the effects of dispersion on viscous fingering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616814
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  • 81
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    Heat and mass transfer in unsaturated porous media at a hot boundary: I. One-dimensional analytical model (1991)
    Springer
    Transport in porous media 6 (1991), S. 281-298 
    Details
    ISSN: 1573-1634
    Keywords: Seasonal heat storage ; heat transport ; unsaturated soils ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract We present a model of heat and mass transfer in an unsaturated zone of sand and silty clay soils, taking into account the effects of temperature gradients on the advective flux, and of the enhancement of thermal conduction by the process of latent heat transfer through vapor flow. The motivation for this study is to supply information for the planned storage of thermal energy in unsaturated soils and for hot waste storage. Information is required on the possibility of significant drying at a hot boundary, as this would reduce the thermal conductivity of a layer adjacent to the boundary and, thus, prevent effective heat transfer to the soil. This study indicates the possibility that the considered system may be unstable, with respect to the drying conditions, with the occurrence of drying depending on the initial and the boundary conditions. An analysis performed for certain boundary conditions of heat transfer and for given soil properties, disregarding the advective flux of energy, indicated that there are initial conditions of water content for which heating will not cause significant drying. Under these conditions, fine soils may be better suited for heat transfer at the hot boundary, due to their higher field capacity, although their heat conduction coefficients at saturation are lower than those of sandy soils. At present, these conclusions are limited to the range of 50–80°C. Potential effects of solute concentration at the hot boundary are indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00208954
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    Orbital Migration Of Giant Planets: Using Numerical Integration To Investigate Consequences For Other Bodies (1999)
    Springer
    Earth, moon and planets 87 (1999), S. 103-115 
    Details
    ISSN: 1573-0794
    Keywords: Accretion ; exoplanetary system ; extrasolar planets ; numerical integration ; orbital migration ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A number of extrasolar planets have been detected in close orbits around nearby stars. It is probable that these planets did not form in these orbits but migrated from their formation locations beyond the ice line. Orbital migration mechanisms involving angular momentum transfer through tidal interactions between the planets and circumstellar gas-dust disks or by gravitational interaction with a residual planetesimal disk together with several means of halting inward migration have been identified. These offer plausible schemes to explain the orbits of observed extrasolar giant planets and giant planets within the Solar System. Recent advances in numerical integration methods and in the power of computer workstations have allowed these techniques to be applied to modelling directly the mechanisms and consequences of orbital migration in the Solar System. There is now potential for these techniques also to be applied to modelling the consequences of the orbital migration of planets in the observed exoplanetary systems. In particular the detailed investigation of the stability of terrestrial planets in the habitable zone of these systems and the formation of terrestrial planets after the dissipation of the gas disk is now possible. The stability of terrestrial planets in the habitable zone of selected exoplanetary systems has been established and the possibility of the accretion of terrestrial planets in these systems is being investigated by the author in collaboration with Barrie W. Jones (Open University), and with John Chambers (NASA-Ames) and Mark Bailey of Armagh Observatory, using numerical integration. The direct simulation of orbital migration by planetesimal scattering must probably await faster hardware and/or more efficient algorithms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017996927696
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