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  • Articles  (220)
  • crystal structure  (220)
  • Springer  (220)
  • 1995-1999  (220)
  • 1960-1964
  • 1945-1949
  • 1
    ISSN: 1349-9432
    Keywords: organic crystal ; racemic form ; second-harmonic generation ; refractive index ; nonlinear optical coefficient ; crystal structure ; oriented-gas model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Linear and nonlinear optical properties of racemic (±)2-(α-methylbenzylamino)-5-nitropyridine ((±)MBANP) single crystals have been comprehensively investigated and compared with those of the enantiomorph (–)2-(α-methylbenzylamino)-5-nitropyridine ((–)MBANP) crystals. (±)MBANP crystal exhibits very high chemical and physical stability, but relatively small nonlinear optical coefficients (d31 = 6.8 pm/V, d32 = 4.7 pm/V, d33 = 0.84 pm/V). A comparison between the nonlinear optical coefficients of (±)MBANP and (–)MBANP demonstrates the validity of the oriented-gas model in molecular crystals that neglects all the contributions from intermolecular interaction.
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  • 2
    ISSN: 1572-8854
    Keywords: Amines ; crystal structure ; pentacycloundecane-8,11-dione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures of three compounds formedvia nucleophilic attack of a heterocyclic secondary amine on PCU-8,11-dione, with the concomitant intramolecular attack of one keto oxygen on the carbon of the other ketone, are presented. In all three compounds, the bridging oxygen contains substantial p-character, and the bonds to the “attacking” nitrogen are significantly shorter than would be expected.
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  • 3
    Electronic Resource
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    Springer
    Journal of chemical crystallography 25 (1995), S. 57-62 
    ISSN: 1572-8854
    Keywords: phase diagram ; buffered chloroaluminate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The phase diagram of the buffered neutral aluminum chloride + 1-ethyl-3-methyl-1H-imidazolium chloride + sodium chloride (AlCl3-EMIC-NaCl) ternary melt system can be represented by a binary phase diagram composed of (EMI)AlCl4 and NaAlCl4. In the binary phase diagram, the salts are liquid at, or near, room temperature for a wide range of compositions. At the 1∶1 composition, the congruently melting compound (EMI)(Na)(AlCl4)2 with m.p.=36.7°C is formed. Crystals of this mixed organic-inorganic salt were grown for single crystal x-ray diffraction analysis. The compound crystalizes in the space group $$P\bar 1$$ with lattice parametersa=10.321(1) Å,b=10.895(3) Å,c=9.284(4) Å, α=98.31(2)°, β=100.83(4)°, γ=101.95(3)°. Data collected at −120°C gave final residuals ofR=0.037 andR w=0.045 using 2713 observed reflections. The packing diagram reveals Na+ ion zig-zag chains running along thea-axis with each Na+ surrounded by four AlCl 4 − units, reminiscent of NaAlCl4. The AlCl 4 − ions form a distorted square planar coordination sphere around Na+ at an average Na−Al distance of 3.76(4) Å. Using a sodium ionic radius of 1.16 Å, a new AlCl 4 − ionic radius of 2.60 Å is calculated. This radius is 0.21 Å shorter than the reported thermodynamic radius.
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  • 4
    ISSN: 1572-8854
    Keywords: Calixarene ; complex ; crystal structure ; chirality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound was obtained by treatment ofp-tert-butylcalix[4]arene with (+) camphorsulfonyl chloride in triethylamine and toluene. A (1∶2) complex with toluene has been found. Its structure has been determined by X-ray crystallography. Crystals are triclinic with space group P1,a=16.426(3),b=18.553(3),c=13.661(2) Å, α=94.78(2), β=110.76(2), γ=72.83(2)°,V=3720(2) Å3,d c =1.127 g/cm3 Z=2. Refinement based on 10495 observed reflections led to a finalR value of 0.100. The two independent molecules of calixarene in the asymmetric unit are in the cone conformation and the calixarene cavities are empty. The guest molecule occupies the interhost space. The norborane skelton of (+) camphorsulfonyl group is the same as ones found in literature. Only van der Waals interactions exist between the host and the guest molecules.
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  • 5
    ISSN: 1572-8854
    Keywords: Mercury(II) terpyridine complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [Hg(terpy)2](CF3SO3)2·0.5(CH3)2CO crystallizes in the triclinic $$P\bar 1$$ space group witha=14.631(6),b=15.258(4),c=18.785(7) Å, α=69.66(2), β=70.72(1), γ=88.55(1)°. The crystal structure consists of two independent [Hg(terpy)2]2+ cations, four trifluoromethanesulfonate anions and an acetone molecule in the asymmetric unit. Each mercury atom is coordinated by two tridentate terpyridine ligands forming an irregular six-coordination polyhedron. The Hg−N bond lengths range from 2.27(2) to 2.53(2) Å.
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  • 6
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    Journal of chemical crystallography 26 (1996), S. 677-681 
    ISSN: 1572-8854
    Keywords: Anthraquinone ; crystal structure ; intramolecular hindrance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the monoclinic space group, P21/c;a=12.938(1),b=11.041(1),c=19.285(2) Å, β=104.314(8)°,Z=4. Refinement based on 1660 unique observed reflections converged toR=0.054. The anthraquinone moiety is distorted due to intramolecular steric hindrance from the tosylate groups.
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  • 7
    ISSN: 1572-8854
    Keywords: Ruthenium(II) complex ; terpyridine ; triphenylphosphine ; ruthenium-nitro complex ; crystal structure ; pseudo-lattice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complexmer,trans-[Ru(NO2)(trpy)(PPh3) 2 + ][PF 6 − ] crystallizes in the centrosymmetric monoclinic space groupP21/n withZ=4; the ruthenium atom lies close toy=1/4 and all data withh+l=2n+1 are systematically weak. The trpy ligand is not strictly planar, but has a “dish-like” geometry. The nitro ligand is rotated from the plane of the Ru(trpy) moiety, the N3Ru/NO2 interplanar angle being 32.5o. Ruthenium-ligand distances are: Ru−PPh3=2.418(4) Å and 2.429(4) Å, Ru−NO2=2.063(12) Å, Ru−N(trpy, outer)=2.100(12) Å and 2.116(12) Å and Ru−N(trpy, central)=2.004(11) Å.
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  • 8
    ISSN: 1572-8854
    Keywords: Betaine ; 4-dimethylaminopyridinioacetate ; hydrogen bonding ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystalline dihydrate and hydrochloride trihydrate of a new betaine, namely, L·2H2O (1) and [L2H]Cl·3H2O(2) (L=p-Me2NC5H4N+CH2CO2), have been synthesized and characterized by X-ray crystallography. Molecule L in compound1 [space groupPbcn, witha=15.732(3),b=7.894(2),c=18.304(4) Å, andZ=8] possesses approximateC s symmetry. The formation of hydrogen bonds by water molecules bridging neighboring carboxy oxygen atoms leads to an infinite two-dimensional network composed of a packing of two different kinds of 12-membered rings. In compound2 [space group PT witha=7.341(2),b=9.543(2),c=17.010(4) Å, α=82.43(2)°, δ=80.34(2)°, λ=74.05(2)°, andZ=2], the carboxylate groups of a pair of betaine molecules are bridged by a proton to form a dimeric cation L2H+ with a very strong asymmetric hydrogen bond of length 2.464(7) Å. The crystal structure features a hydrogen-bonded corrugated ribbon comprising an alternate arrangement of edge-sharing centrosymmetric (H2O)4(Cl−)2 and (H2O)4 rings running parallel to thea axis.
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  • 9
    ISSN: 1572-8854
    Keywords: Bidentate ligand ; crystal structure ; pyrazolyl group ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound lies on a site of C2 symmetry, with the two planar pyrazolyl moieties oriented at 86.1° to one another. The hydrogen atoms were located and refined.
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  • 10
    ISSN: 1572-8854
    Keywords: Ruthenium(II) ; bipyridyl ; phenyldi(o-tolyl)phosphine ; solvate ; hydrogen bonding ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complexcis-[Ru(bpy)2{PPh(o-tolyl)2}Cl+][ClO4 −] crystallized from a solution in dichloromethane as the dichloromethane-water solvate. The structure was refined toR=4.5% for those 2433 reflections with |F o|〉6σ(|F o|). The octahedral Ru(II) cation is associated with metal-ligand distances as follows: Ru−Cl=2.434(3)Å, Ru-PPh(o-tol)2=2.382(2)Å, and Ru−N=2.037(7)–2.088(7)Å. The structure is stabilized by a hydrogen-bonded CH2Cl2...ClO4 −...H2O channel which incorporates adventitious water of crystallization.
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  • 11
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    Journal of chemical crystallography 26 (1996), S. 661-665 
    ISSN: 1572-8854
    Keywords: N,N′-bis(2-hydroxyphenyl)butanediamide ; crystal structure ; hydrolysis product
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of N,N′-bis(2-hydroxyphenyl)butanediamide has been determined. The molecule consists of two 2-hydroxyphenyl moieties which are attached (at the 2 position) to the two nitrogens of the butanediamide. The compound C16H16N2O4 crystallizes in the monoclinic space group P21/c witha=5.576(1),b=4.8853(6),c=25.397(6) Å and β=90.58(1)°.
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  • 12
    ISSN: 1572-8854
    Keywords: Ruthenium(II) complex ; organoruthenium compound ; bis(1,2-diphenylphosphino)ethane ligand ; ruthenium-nitro complex ; crystal structure ; cyclopentadienyl derivative ; methanol solvate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title complex crystallizes in the centrosymmetric monoclinic space group C2/c (No. 15) withZ=8. The structure was refined toR=4.49% for those 2745 independent reflections with 2θ=5–50o and |F σ|〉6σ(F). Ruthenium-ligand distances are as follows: Ru-P=2.284(2) and 2.286(2) Å, Ru-NO2=2.049(6) Å and Ru-C(Cp)=2.210(10)-2.246(9) Å. Bond lengths within the nitro ligand are N(1)-O(1)=1.226(10) Å and N(1)-O(2)=1.244(10) Å. The methanol of solvation is ordered but is subject to large thermal vibrational motions.
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  • 13
    ISSN: 1572-8854
    Keywords: Ruthenium(II) complex ; tri-n-propylphosphine ; terpyridine ; ruthenium-nitro complex ; crystal structure ; disordered ligands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complexmer,trans-[Ru(NO2)(trpy)(PPr3) 2 + ][ClO 4 − ]crystallizes in the centrosymmetric orthorhombic space group Pnma withZ=4. Both the ruthenium(II) cation and the perchlorate ligand lie about crystallographic mirror planes. The nitro ligand is not coplanar with the Ru(trpy) moiety and suffers from two fold disorder about its Ru−N bond such that the two sets of oxygen atoms have symmetry-related sites above or below the crystallographic mirror plane. The n-propyl groups within the PPr3 ligands suffer from disorder of their C(α) and C(β) atoms but share common C(γ) sites. Ruthenium-ligand distances are: Ru−PPr3=2.398(2)Å, Ru−NO2=2.053(7) Å, Ru−N(trpy, outer)=2.078(6) and 2.092(6) Å and Ru−N(trpy, central) =1.965(6) Å.
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  • 14
    ISSN: 1572-8854
    Keywords: 2-Methylnaphthalene ; hexachlorocyclopentadiene ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 2-Methylnaphthalene undergoes Diels-Alder addition and substitution with hexachlorocyclopentadiene to give two products, 1,2,3,4,5,6,7,8,13,13,14,14-dodecachloro-1,4,4a,4b,5,8,8a,12b-octahydro-10-methyl-1,4;5,8-dimethanotriphenylene 1 and 1,2,3,4,5,6,7,8,13,13,14,14-dodecachloro-1,4,4a,4b,5,8,8a,12b-octahydro-10-(1′,2′,3′,4′,5′-pentachlorocyclopentadienyl)methyl-1,4;5,8-dimethanotriphenylene 2. The molecular structure of 2 has been characterized by X-ray crystallography: C26H9Cl17, monoclinic, space group P21/c, with a = 15.316(3), b = 13.698(3), c = 16.116(3) Å, β = 96.113(3)°, and Z = 4.
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  • 15
    ISSN: 1572-8854
    Keywords: Copper(II) complex ; crystal structure ; coordination polymer ; betaine ; dicarboxylate ligand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three polymeric copper(II) complexes of a flexible double betaine, namely, [{Cu(L)Cl2(H2O)} n ]·2 n H2O (1), [{Cu(L)Br2(H2O)} n ]·2nH2O (2), and [{Cu(L)(H2O)4} n ](ClO4)2n ·2nH2O (3) [L=−O2CCH(Me3N+)CH2CH2CH(Me3N+CO2], have been prepared and characterized by singlecrystal X-ray analysis. Isomorphous complexes (1) and (2) crystallize in space groupC2/c (No. 15) witha=17.725(3),b=5.958(2),c=19.077(3) Å, β=110.70(1)o,V=1881.4(4) Å3, Z=4 anda=18.268(4),b=5.948(3),c=19.166(5) Å, β=109.08(2)o,V=1964.7(9) Å3, Z=4, respectively. Complex (3) belongs to space groupPĪ (No. 2) witha=6.203(1),b=9.293(2),c=12.035(2) Å, α=86.56(2), β=87.33(3), γ=71.23(2)o,V=655.4(2) Å3 and Z=1. The crystal structure of (1) and (2) features an infinite zigzag chain composed of an alternate arrangement of metal atoms and double betaines ligands, with each Cu(II) atom in a distorted CuX2O3 [X-Cl, Br] square-pyramidal geometry, and hydrogen bonding between adjacent chains leads to a layer structure concentrated the (200) family of planes. Complex (3) exhibits a layer structure corresponding to the (001) family of planes, in which neighboring chains constructed from the metal atoms and the double betaine ligands are cross-linked by hydrogen bonding between the aqua ligands. The Cu(II) atom is coordinated in a CuO6 octahedral geometry with Jahn-Teller distortion.
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  • 16
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    Journal of chemical crystallography 26 (1996), S. 503-508 
    ISSN: 1572-8854
    Keywords: Tin(IV) sodium(I) complex ; ethylenediaminetetraacetic acid ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract NaSn(OH)(edta)(H2O) is monoclinic, space groupP21/c, witha=9.747(3)Å,b=9.121(3)Å,c=16.430(6)Å, β=98.69(4)°, Å3, andZ=4. The coordination environment of Sn(IV) is a capped octahedron. Sn−O distances range from 1.990(6)Å to 2.351(7)Å. Na(I) is five coordinated to three different edta molecules. Na−O distances range from 2.283(9)Å to 2.414(7)Å. The edta ligand presents the E, G/R conformation. The crystal structure is composed of sheets parallel to (001): inside a sheet Sn(OH)(edta) molecules are connected to each other by the Na(I) interactions.
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  • 17
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    Journal of chemical crystallography 26 (1996), S. 515-518 
    ISSN: 1572-8854
    Keywords: Antiarrhythmic agent ; crystal structure ; absolute configuration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the orthorhombic space groupP212121, withZ=4,a=4.770(1)Å,b=6.620(1)Å,c=37.550(7)Å,R=0.04. The most important factors affecting conformation of the molecules are: the protonation state of the N(9) atom andortho-substitution of the benzene ring in the acetanilide system. Protonation promotes an extended form of the molecule and 2,6-substitution forces a twist of at least 60° between the benzene ring and amide group planes. The resulting separation of lipophilic (xylidine) and amine groups, being two important pharmacophores, equals about 5Å in tocainide and all other structures comprising the amino-2,6-dimethylacetanilide system.
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  • 18
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    Journal of chemical crystallography 26 (1996), S. 553-557 
    ISSN: 1572-8854
    Keywords: Silver(I) complex ; synthesis ; crystal structure ; spectroscopic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The reaction of [Ph3PAgI]4 with sodium phenylacetate in MeOH and CH2Cl2 at room temperature gave rise to a binuclear silver complex with triphenylphosphine and phenylacetate mixed ligands, [Ph3PAg(O2CCH2Ph)]2. The crystal and molecular structure of the complex has been determined by single crystal X-ray diffraction analysis. The space group is $$P\bar 1$$ witha=9.198(2),b=9.516(2),c=13.842(3) Å, α=102.00(3), β=108.34(3), γ=93.58(3)°,Z=1, andDc=1.506 g cm−3. The silver atoms are each coordinated by one phosphorus atom from triphenylphosphine and two oxygen atoms from the carboxylate groups in a T-shape. The complex is further characterized by its IR,1H, and31P NMR spectra.
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  • 19
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    Journal of chemical crystallography 28 (1998), S. 69-72 
    ISSN: 1572-8854
    Keywords: Co(III) complex ; crystal structure ; kinetics ; steric effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the orthorhombic space group Pnma, with a = 7.9209(5), b = 9.818(1), c = 16.867(2) Å, and Z = 4. The structure was solved employing 1864 independent x-ray reflections with I〉2σ(I) by Patterson and difference Fourier techniques and refined by full-matrix least-squares to R = 0.036. The trans-[CO(NH3)4(NH2CH3)Cl](ClO4)2 molecule is on a crystallographic mirror plane. The cobalt ion is in an elongated octahedral coordination with four equatorial ammonia ligands [average Co–N distance equal to 1.966(2) Å], an axial methylamine [Co–N=1.965(3)Å], and an axial chlorine ion [Co–Cl=2.2771(9)Å]. Kinetic steric effects of the complex are interpreted in terms of structural results.
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  • 20
    ISSN: 1572-8854
    Keywords: Cerium(IV) ; β-diketonate ; volatility ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The cerium(IV) β-diketonate compounds [Ce(β-diket)4] [where β-diket = tmhd (2,2,6,6-tetramethylheptane-3,5-dionate) 1, pmhd (1-phenyl-5-methylhexane-1,3-dionate) 2] were prepared by reacting cerium(IV) ammonium nitrate [CAN; Ce(NH4)2(NO3)6] with the respective Na(β-diket) compound in ethanol, and structurally characterized by single crystal X-ray diffraction. Compound 1 crystallizes in the triclinic space group $$P \bar 1$$ with a = 12.472(4), b = 19.972(5), c = 21.436(3) Å, α = 97.05(7), β = 90.16(2), γ = 106.55(3)°, V = 5076(2) Å3, Z = 4, T = 150(2) K. Compound 2 crystallizes in the monoclinic space group P21/n. with a = 14.817(6), b = 17.123(6), c = 19.146(3) Å, β = 105.46(4)°, V = 4682(3) Å3, Z = 4, T = 150(2) K. Crystals of 1 contain two independent [Ce(tmhd)4] molecules, with four chelating tmhd ligands bonded to each metal in a distorted dodecahedral arrangement; the cerium atom in 2 is also bonded to four chelating pmhd ligands but in this case the coordination geometry is closer to square antiprism. Both complexes are air and moisture stable. Sublimation studies reveal that 1 sublimes almost quantitatively, while 2 is comparatively involatile.
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  • 21
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    Journal of chemical crystallography 28 (1998), S. 577-579 
    ISSN: 1572-8854
    Keywords: (−)—Crinine ; Pancratium ; alkaloid ; Amaryllidaceae ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract (−)—Crinine, C16H17NO3, is an alkaloid extracted from the bulbs of Pancratium maritimum L. (Amaryllidaceae). The compound crystallizes in the space group P212121 with cell dimensions a = 6.040(1), b = 12.382(1), c = 17.861(2) Å, with Z = 4. The molecule has five rings and an OH group. The N-containing, five-membered ring and the D ring have envelope conformations. The A and B rings have distorted chair and half-chair conformations, respectively.
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  • 22
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    Journal of chemical crystallography 28 (1998), S. 639-643 
    ISSN: 1572-8854
    Keywords: Tungsten(II) ; diiodo ; carbonyl ; trimethylphosphite ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [WI2(CO)3{P(OMe)3}2]crystallizes in the orthorhombic space group Pca21, with a = 26.924(5), b = 10.726(2), c = 14.136(3) Å, and Z = 8. There are two molecules in the asymmetric unit, the metal atoms in each case being seven-coordinate with a capped fac-(CO)3 octahedral geometry. The molecular dimensions in the two molecules are nearly identical. The W–P distance to the capping atom 2.397 Å (average) is significantly shorter than the other W–P distance, 2.525 Å (average).
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  • 23
    ISSN: 1572-8854
    Keywords: Pyrimidine ; carboxamide ; sulfonyl ; chiral ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three novel dihydropyrimidine compounds N8,6-di(4-nitrophenyl)-(3R)-ethyl-(7R)-methyl-5-oxo-2,3,6,7-tetrahydrooxazolo[3,2,c] pyrimidine-8-carboxamide (2), N8,6-di((4-methylphenyl)-sulfonyl)-(3R)-ethyl-5-oxo-(7R)-phenyl-2,3,6,7-tetrahydrooxazolo [3,2,c]pyrimidine-8-carboxamide (3) and N8,6-di ((4-methylphenyl)sulfonyl)-(3R)-ethyl-(7R)-methyl-5-oxo-2,3,6,7-tetrahydrooxazolo[3,2,c] pyrimidine-8-carboxamide (4) have been prepared (from 2-amino-1-butanol of 64.4% e.e.) and structurally characterized by X-ray crystallography. All three compounds contain stereogenic centers, but the crystal of (2) chosen was found to be racemic whilst those of (3) and (4) were found to be homochiral. Compound (2) crystallizes in the monoclinic space group P21/c, with a = 17.958(4), b = 12.431(2), c = 9.653(2) Å, β = 96.20(3)°, U = 2142.3(7) Å3, Z = 4, and D c = 1.449 g cm−3. Compounds (3) and (4) both crystallize in the monoclinic space group P21, with a = 9.349(2), b = 5.824(5), c = 26.513(8) Å, β = 99.43(2)°, U = 1424.1(13) Å3, Z = 2 and D c = 1.389 g cm−3 for (3), and a = 5.9526(9), b = 16.3521(10), c = 13.2263(11) Å, β = 92.81(12)°, U = 1285.9(2) Å3, Z = 2 and D c = 1.378 g cm−3 for (4).
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  • 24
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    Journal of chemical crystallography 29 (1999), S. 1127-1132 
    ISSN: 1572-8854
    Keywords: crystal structure ; phenyl-substituted cyclopentenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures of two stereoisomers of tetraphenyl- and pentaphenyl-substituted cyclopentenes 1 and 2 have been determined by X-ray analysis. An envelope conformation 1E has been ascertained for the cis isomer 1a, whereas the cis, cis isomer 2a, which crystallizes in two different space groups, P1¯ and P21/n, displays a twisted 2T1 conformation. The phenyl substituents are all tilted with respect to the cyclopentene ring in both structures. Compound 1a crystallizes in the space group P21/a with a = 18.553(3), b = 6.006(2), c = 19.355(5), β = 102.67(4)°, and V = 2104.2(g) Å3 for Z = 4; compound 2a I crystallizes in P21/n with a = 10.064(2), b = 20.756(5), c = 12.245(3) Å, β = 95.21(2)°, and V = 2547(1) Å3 for Z = 4; compound 2aII crystallizes in P1¯ with a = 10.117(3), b = 11.750(2), c = 12.359(2) Å, α = 111.25(2), β = 94.84(2), γ = 108.78(2)°, and V = 1262.3(6) Å3 for Z = 2.
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  • 25
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    Journal of chemical crystallography 28 (1998), S. 447-452 
    ISSN: 1572-8854
    Keywords: Bimetallic EDTA complex ; crystal structure ; antimony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis and crystal structure of a new EDTA complex, [CaSb2(EDTA)2(H2O)8]n, are reported. This compound crystallizes in the monoclinic space group P21/n, with a = 7.132(1) Å, b = 21.893(3) Å, c = 10.891(2) Å, β = 91.15(2)°. Sb(EDTA) entities are connected through carboxylate bridges to the calcium atoms resulting in layers parallel to the (101) plane. These layers are linked through a weak Sb···O bond (3.171 Å). Pyrolysis of this complex under sulfur vapor, between 400 and 800°C, leads to a mixture of the monometallic sulfides. Pyrolysis in air above 700°C allows the easy preparation of the mixed oxide CaSb2O6.
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  • 26
    ISSN: 1572-8854
    Keywords: Steroid ; pregnadiene ; x-ray diffraction ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound is C29H34O4, tetragonal, P43, a = b = 10.310(1), c = 23.871(2)Å. The A, B, C, and D rings adopt envelope, half-chair, chair, and distorted chair conformations, respectively. The phenyl ring is planar. The methyl substituents at the A/B, C/D, and at C(17) are axial; and the –OCOCH3 group at C(17) and phenyl ring at C(16) are equatorial. The molecules in the crystal are held together by van der Waals forces and several C–H···O hydrogen bond interactions.
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  • 27
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    Journal of chemical crystallography 28 (1998), S. 539-543 
    ISSN: 1572-8854
    Keywords: Antimalarial ; crystal structure ; peroxy bridge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of the antimalarial compound Artemisinin (formerly known as Qinghaosu), C15H22O5 has been determined by direct methods. Crystals are orthorhombic colorless needles, space group P212121, Z = 4. D c = 1.299 g cm −3, with unit cell parameters a = 6.3543(9), b = 9.439(3), c= 24.066(4) Å. The molecule incorporates a fused ring system containing a six-membered ring C which includes an oxygen bridge and a peroxy-bridge. The ring C has a distorted boat conformation and the C - O - O - C torsion angle is 47.8(2)°. Rings A and D have symmetrical chair and distorted chair conformations, repectively. Ring junctions A/B, A/D, and C/D are cis, junction B/D is trans. All inter-molecular contacts are van der Waals. The absolute configuration of Artemisinin was determined from the refined value of the Flack x parameter. [The atomic coordinates given in a previous structure analysis, “Crystal Structure and Absolute Configuration of Qinghaosu,” Qinghaosu Research Group, Institute of Biophysics, Academica Sinica, Scientia Sinica, Vol. XXIII No. 3, 380 (1980), do not display the molecule in its absolute configuration.]
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  • 28
    ISSN: 1572-8854
    Keywords: 1-1′-Diphosphaferrocene conformation ; P···P secondary bonding ; bis-[W(CO)5](l,l′-diphosphaferrocene system) ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structures of (3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocen-2-yl)carboxylic acid (1) and its bis-[W(CO)5] pentane solvate complex (2) have been determined by X-ray analysis. The compound 1 crystallizes in the monoclinic P21 /n space group with Z = 4; a = 7.8404(9), b = 14.9441(16), c = 11.7730(14) Å, β = 92.773(10)°, V = 1377.8(3) Å3, and Dcalc = 1.553 g cm−3. The compound 2 crystallizes in the triclinic $$P\bar 1$$ space group with two complex molecules and one pentane molecule in the unit cell. Cell parameters: a = 10.7070(2), b = 12.577(2), c = 13.239(3) Å, α = 84.00(2), β = 77.58(1), γ = 66.06(1)°, V = 1591.0(5) Å3, and Dcalc = 2.100 g cm−3 .The fully eclipsed conformation of the phospholyl rings with P···P secondary bonding of 3.353(1) Å is observed in 1 and a partially eclipsed conformation is found in 2. The 10 possible conformations of 1,1′-diphosphaferrocenes were described as the function of conformational parameter θ and observed geometry of the phospholyl rings.7 We suppose that the earlier conclusions concerning the destabilizing nature of 1,1′-diphosphaferrocene conformations with θ 〈 100° cannot be considered as general. The mode of W – P coordination, the structural changes of 1 by W(CO)5 coordination, the structural effect of phospholyl rings substitution by the –COOH group, and hydrogen bonds are analyzed.
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  • 29
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    Journal of chemical crystallography 28 (1998), S. 635-638 
    ISSN: 1572-8854
    Keywords: Cobalt(II) ; 2-aminobenzenethiol ; trimethylphosphite ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A cobalt-thiolato-phosphite complex [Co(o-SC6H4NH2){P(OMe)3}3]PF6 has been prepared and characterized by X-ray crystallography. The complex crystallizes in the triclinic space group $$P\bar 1$$ with a = 10.590(4), b = 11.122(3), c = 13.577(5) Å, α = 101.85(1), β = 108.50(1), γ = 101.75(1)°, V = 1420.6(8) Å3, and Z = 2. The structure comprises discrete [Co(o-SC6H4NH2){P(OMe)3}3]+ cations and PF 6 − anions where the metal atom is coordinated in a highly distorted square-pyramidal environment by one chelate o-SC6H4NH 2 − (abt) and two P(OMe)3 ligands in the basal positions, and a third P(OMe)3 in the axial site with Co–N,, 1.847(5), Co–S, 2.166(2), Co–P, 2.157(2), 2.147(2), and 2.125(2) Å.
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  • 30
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    Journal of chemical crystallography 29 (1999), S. 1265-1269 
    ISSN: 1572-8854
    Keywords: crystal structure ; corticosteroid ; de-oxy corticosterone-21-hemisuccinate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Synthetic glucocorticoid de-oxy corticosterone-21-hemisuccinate crystallizes in the monoclinic space group C2, with a = 21.896(2), b = 7.596(3) and c = 14.291(3) Å, Z = 4. Ring A is a distorted half chair, ring B and C are in the chair configuration and ring D is in the 14α-half chair configuration. The ring junctions B/C and C/D are both trans. The molecule as a whole is slightly convex towards the β-side, with an angle of 18.4(2)° between the C(10)--C(19) and C(13)--C(18) vectors. In addition to packing and stacking interaction, intermolecular hydrogen bonding plays an important role in structural association. The X-ray structure determination of the title compound was undertaken to study its high binding affinity to serum protein like globulin.
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  • 31
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    Journal of chemical crystallography 29 (1999), S. 1291-1293 
    ISSN: 1572-8854
    Keywords: crystal structure ; pyrazolo[3,4-d]pyrimidine ; fungicidal activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound 1-phenyl-3-methylthio-4-imino-5-allyl-pyrazolo[3,4-d]pyrimidine, C15H15N5S, has been synthesized and characterized by x-ray diffraction: orthorhombic, space group Pbca, with a = 17.3480(9), b = 8.5022(5), c = 19.8132(11) Å. Z = 8, V = 2922.4(3) Å3. The compound shows a fully delocalized pyrazolo[3,4-d]pyrimidine system with a sp2 hybridization of the N(4) atom.
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  • 32
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    Journal of chemical crystallography 29 (1999), S. 243-246 
    ISSN: 1572-8854
    Keywords: Thorium ; dimethoxyethane ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The molecular structure of ThBr4(DME)2 (DME = 1,2-dimethoxyethane), the first structurally characterized thorium complex containing a simple bidentate ether ligand, is described. The eight-coordinate complex presents a distorted dodecahedral geometry, with Th—Br and Th—O bond lengths in the ranges 2.8516(13)–2.8712(13) Å and 2.564(8)–2.620(8) Å, respectively. ThBr4(DME)2 is monoclinic, space group P21/n, a = 7.672(1), b = 14.581(1), c = 15.847(2) Å, β = 102.24(1)°, V = 1732.4(3) Å3, and Z = 4.
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  • 33
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    Journal of chemical crystallography 29 (1999), S. 295-298 
    ISSN: 1572-8854
    Keywords: Copper ; crystal structure ; synthesis ; Schiff base ligand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title complex Cu(C8H7O2N)2(OH2) crystallized in the orthorhombic space group, Pbca with unit cell parameters: a = 15.242(2), b = 11.782(4), c = 17.946(4) Å, and Z = 8. Two nitrogen atoms, two phenolic oxygen atoms of the ligand, and one water molecule are coordinated with copper to form a distorted tetragonal pyramidal polyhedron.
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  • 34
    ISSN: 1572-8854
    Keywords: Europium ; terbium ; betaine ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three dimeric lanthanide(III) complexes, [Eu2(bet)8(H2O)4](CIO4)6 (1), [Tb2(bet)8(H2O)4](ClO4)6 (2), and [Eu2(bet)4(H2O)8] Cl6·6H2O (3) (bet = Me3N+CH2COO−, trimethyl-aminoacetate), have been prepared and structurally characterized by X-ray crystallography. Complex 1 crystallizes in the monoclinic space group P21/c, with a = 11.7807(8), b = 27.757(5), c = 11.7980(8) Å, β = 99.500(4)°, V = 3805.1(8) Å3, and Z = 2. Complex 2 is isomorphous to complex 1, crystallizing in the monoclinic space group P21/c, with a = 11.7769(14), b = 27.725(3), c = 11.795(5) Å, β = 99.668(14)°, V = 3797(2) Å3, and Z = 2. Complex 3 crystallizes in the orthorhombic space group Pbca, with a = 12.5664(8), b = 17.8645(9), c = 22.2573(8) Å, V = 4996.6(4) Å3 and Z = 4. Both complexes 1 and 2 comprise quadruply carboxylate-O,O′-bridged [M2(bet)4]6+ dimeric cores (M = Eu, Tb), and each metal ion is further coordinated by two terminal aqua ligands and two monodentate bet carboxylates to form a distorted square-antiprismatic coordination geometry. Complex 3 also has a [Eu2(bet)4]6+ core, in which two bet ligands act in the η1:η1:μ2 bridging fashion, and the other two bet ligands in the less common η2:η1:μ2 bridging fashion, namely bridging-chelate mode. Each europium(III) ion in complex 3 is further coordinated by four water molecules to complete a monocapped square antiprism.
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  • 35
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    Journal of chemical crystallography 29 (1999), S. 199-201 
    ISSN: 1572-8854
    Keywords: Manganese (II) ; phenanthroline ; polymeric complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new polymeric manganese(II) complex, [Mn(II)(phen)(ClCH2COO)2]n, was obtained from the reaction of Mn(ClCH2COO)2 with phen and its structure was determined by x-ray crystallography. The complex crystallizes in the monoclinic system, space group C2/c with a = 19.706(4), b = 11.381(3), c = 7.482(3) Å, β = 94.01(3)°, V = 1674.0(8) Å3, and Z = 4. The structure consists of an infinite chain. The manganese atom is located on a twofold axis and presents a distorted octahedral coordination sphere, which consists of the two N atoms of a phen ligand (Mn—N = 2.304(2) Å) and four carboxylato ligands. The Mn···Mn distance within the chain is 4.53 Å, and the carboxylato bridges present a syn-anti conformation.
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  • 36
    ISSN: 1572-8854
    Keywords: copper(II) ; Schiff base ; polymidazole ; crystal structure ; properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The square-planar complex [Cu(MIMH)(CH3CO2)](ClO4) (1) (MIMH = [(4-methylimidazol-5-yl)methylene]histamine) was prepared and structurally characterized. Complex 1 crystallizes in the monoclinic space group P21/n with a = 10.5331(10), b = 12.6177(10), c = 12.9773(10) Å, β = 107.710(10)°, V = 1643.0(2) Å3, and Z = 4. Single-crystal X-ray analysis reveals that the copper(II) atom in 1 has a distorted square-planar environment defined by three nitrogen atoms from the Schiff base ligand and one oxygen atom from the acetate group. The Cu—N bond lengths range from 1.950(3) to 2.015(3) Å and the Cu—O(1) bond length is 1.952(2) Å. The electronic spectra of 1 in aqueous solutions indicates that 1 forms adducts of square-pyramidal geometry with H2O. Cyclic voltammetry of 1 in DMF solution shows that there is some degradation of 1 upon reduction.
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  • 37
    ISSN: 1572-8854
    Keywords: pyrazolyl derivative ; substituted pentane ; crystal structure ; bidentate ligand
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    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the centrosymmetric space group C2/c with a = 14.4005(23), b = 7.0494(12), c = 11.2462(20) Å, β = 101.572(13)° and Z = 4; the molecule lies on a crystallographic C 2 axis. Hydrogen atoms were both located and refined.
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  • 38
    ISSN: 1572-8854
    Keywords: crystal structure ; Frentizole ; immunomodulator ; structure-function relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystals of Frentizole (from ethanol/water) are monoclinic, space group P21/c, with a = 11.187(4), b = 7.392(2), c = 32.727(6) Å, β = 92.77(2)°, Z = 8, D o = 1.47 g/cm3, and D c = 1.472 g/cm3. There are two independent molecules in the crystallographic asymmetric unit with very different conformations. In molecule A the urea group is in the plane of the benzothiazole ring (0.9°) whereas in molecule B the dihedral angle between them is 4.4°. The dihedral angle between the planes of the phenyl group and the benzothiazole ring are ±157° and ±12°, respectively, in the two molecules. The molecules are linked by a pair of N–H···N hydrogen bonds involving the urea nitrogen and two other N–H···N bonds involving the urea nitrogen and the nitrogen of the benzothiazole group.
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  • 39
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    Journal of chemical crystallography 29 (1999), S. 1255-1259 
    ISSN: 1572-8854
    Keywords: crown ether ; crystal structure ; lariat ; sodium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A dibenzo-14-crown-4 ether with a novel monooxyacetone sidearm is prepared and its structure with sodium perrhenate is determined. The structure crystallizes in P21/c with cell dimensions: a = 8.107(2) Å, b = 28.138(3) Å, c = 10.293(2) Å, and β = 104.173(9)°; giving a volume of 2276.6(7) Å3. This structure is compared to other sodium complexes of dibenzo-14-crown-4 lariat ethers and is found to be the only one with intramolecular bonding between the sidearm and the cation. Possible reasons for this observation are discussed.
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  • 40
    ISSN: 1572-8854
    Keywords: dodecanuclear heterobimetallic ; molybdenum-copper cluster ; cage ; μ6-S ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex (Ph4P)2[Mo2S2O2(S2)(S4)] reacts with CuBr to give the dodecanuclear heterobimetallic Mo—Cu—S cage cluster: (Ph4P)2[{Mo2Cu2O2S2(S2)2}3(μ6-S)] (1), which crystallizes in the triclinic space group P1¯, a = 14.445(5), b = 15.396(5), c = 18.858(5) Å, α = 103.12(3), β = 101.93(2), γ = 113.92(3)°, and V = 3517(2) Å3 for Z = 2. The anion 1 can be described as a cage with S2− at the center binding to six Cu atoms; the cage has two big windows each composed of a puckered Cu3S6 9-membered ring.
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  • 41
    ISSN: 1572-8862
    Keywords: Cluster core M6E8 ; structural characteristics ; crystal structure ; hexacobalt cluster complex ; phosphine ; sulfide bridging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Two new members of the hexanuclear series [Co6S8(PR3)6] n+, complexes [Co6S8(PMe2Ph)6](ClO4) (1) and [Co6S8P(OMe)3 6] (2), have been synthesizes and characterized by X-ray diffraction analyses. Their formation process was postulated to go through trinuclear μ3--S bridged moieties. The structural characteristics of the M6E8P6 skeleton of a whole series of [M6E8(PR3)6] n+ (M=Co, Cr, Fe, Mo; E=S, Se, Te) complexes are presented in terms of atomic distances and core volumes.
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  • 42
    ISSN: 1572-8862
    Keywords: Palladium ; gold ; cluster ; phosphine ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract [Au2Pd14(μ3-CO)7(μ2-CO)2(PMe3)11](PF6)2 has been synthesized from [Pd8(CO)8(PMe3)7] and AuCl(PCy3) in the presence of TIPF6. It has been characterised on the basis of mass spectrometry, infrared and NMR spectroscopy, and a single crystal X-ray diffraction study. The structure is based on a palladium-centered Au2Pd11 icosahedron which shares an edge with a Pd5 trigonal bipyramid.
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  • 43
    ISSN: 1572-8862
    Keywords: Niobium(III) ; edge-sharing bioctahedra ; di-p-tolylformamidinato ; thiomethoxide ; double-bond ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of NaEt3BH with Nb2(μ-SMe2)3Cl6 results in the transfer of a hydride ion to dimethylthioether with concomitant production of methane. Further reaction with potassium di-p-tolylformamidinate, KDTolF, yields Nb2(μ-SMe)2(μ-DTolF)2η2-DTolF:)2.2 toluene, 1. In the latter, two thiomethoxide ions and two DTolF groups bridge the trivalent niobium atoms. Each of the other two DTolF groups chelate a metal atom to give the molecule an edge-sharing bioctahedral structure, The niobium-niobium distance of 2.655(2) A is consistent with the presence of a double bond between the metal atoms.
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  • 44
    ISSN: 1572-8862
    Keywords: Rhenium ; dirhenium complexes ; rhenium–rhenium multiple bonds ; isocyanide ligands ; carbonyl ligand ; structural isomers ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of the unsymmetrical, coordinatively unsaturated dirhenium(II) complex [(XylNC)(OC)CIRe(μ-dppm)2ReCl2]O3SCF3 (dppm = Ph2PCH2PPh2) with one equivalent of XylNC in CH2Cl2 affords a fifth structural isomer of the [Re2Cl3(μ-dppm)2(CO)(CNXyl)2] + cation; this is believed to have a CO-bridged structure of the type [(XylNC)ClRe(μ-Cl)(μ-CO)(μ-dppm)2ReCl(CNXyl)]+. The latter complex reacts with a further equivalent of XylNC in the presence of Tl+ to form the [Re2Cl2(μ-dppm)2(CO)(CNXyl)3]2+ cation, which has been shown by IR spectroscopy, and by the X-ray crystallographic characterization of its neutral congener Re2Cl2(μ-dppm)2(CO)(CNXyl)3, to contain a very weak and unsymmetrical CO bridge.
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  • 45
    ISSN: 1572-8862
    Keywords: Silver ; iron ; carbonyl ; cluster ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The oxidation of the [Fe(CO)4]2− dianion with Ag+ salts occurs through a particularinner-sphere mechanism, which involves an intermediate cascade of silver clusters stabilized by Fe(CO)4 ligands. The last detectable Ag-Fe cluster of the sequence is the [Ag13{μ-Fe(CO)4}8]3− trianion, which has been selectively obtained by using ca. 1.7 equivalents of Ag+ per mole of [Fe(CO)4]2−. The [Ag13{μ-Fe(CO)4}8]3−- trianion has been isolated in a crystalline state with several quaternary cations, and has been characterized by X-ray diffraction studies of its bis(triphenylphosphine)iminium salt. [N(PPh3)2]3 [Ag13{μ 3-Fe(CO)4}8]·2(CH3)2CO, monoclinic, space group P21 (No.4),a = 16.284(2) Å,b =18.767(5) Å,c = 25.905(4) Å,β = 90.46(1)°,V = 7916(3) Å3,Z = 2,R = 0.0324. The molecular structure of the anion consists of a centered cuboctahedron of silver atoms with the triangular faces capped by Fe(CO)4 units. Chemical reduction of ( Ag13{μ 3-Fe(CO)4}8]3− affords the corresponding [Ag13{μ 3-Fe(CO)4)8]4−, which in turn gives [Ag13{μ 3-Fe(CO)4)8]5− and [Ag6{μ 3-Fe(CO)4}4]– upon further reduction. Electrochemical investigations confirm the reversibility of the [Ag13{μ 3-Fe(CO)4}8]3−/4− redox change. Furthermore, in spite of some electrode poisoning effects, evidence of the existence of the [Ag13{μ 3-Fe(CO)4}8]5− pentaanion was obtained. The yet structurally uncharacterized [Ag6{μ 3-Fe(CO)4)4]2− dianion is quantitatively obtained by reaction of [Fe(CO)4]2− with ca. 1.5 equivalents of Ag+ or by addition of one equivalent of Ag+ to solutions of the [Ag5{Fe(CO)4}4]3− trianion. All attempts to isolate its quaternary salts as crystalline materials failed owing to formation of amorphous insoluble precipitates. The above series ofμ 3-Fe(CO)4 octa-capped cuboctahedral Ag13 clusters can be envisioned as the Ag+ . Ag and Ag− cryptates of the [Ag12{μ}3-Fe(CO)4}8]4− cryptand. respectively.
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  • 46
    ISSN: 1572-8862
    Keywords: Osmium ; unsaturated cluster ; ortho-metallation ; siloxyl ligand ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of Os3(CO)10(NCMe)[Si(OMe)3](μ-H),1, with PMe2Ph yielded the new complex Os3(CO)10(PMe2Ph)[Si(OMe)3](μ-H),2 by substitution of the MeCn ligand with the phosphine ligand. When heated to 125°C compound2 was decarbonylated and transformed into the new unsaturated cluster complex Os3(CO)8[μ-PMe2(C6H4)][Si(OMe)3](μ-H)2,3 in 54% yield. Compound3 was characterized by a single crystal X-ray diffraction analysis, osmium bonds. The phenyl ring of the phosphine ligand has undergoneortho-metallation by a neighboring metal atom. A terminally coordinated Si(OMe)3 ligand is coordinated to the third osmium atom. The cluster is unsaturated by the amount of 2 electrons, and there is an open coordination site on the siloxyl substituted osmium atom that is partially filled by a weak interaction with one of the π-bonds of theortho-metalled phenyl ring. Complex3 reacts with CO at 1 atm to reform compound2 in 85% yield in 5 h at 40°C. Crystal Data: for3: space group = P21/n,a = 9.911(2) Å,b = 18.451(6) Å,c = 14.872(2) Å,β = 95.64(2)°,Z = 4, 1994 reflections,R = 0.028.
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  • 47
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    Journal of cluster science 6 (1995), S. 549-566 
    ISSN: 1572-8862
    Keywords: Molybdenum ; tungsten ; di-μ-oxo bridge ; sexadentate ligands ; asymmetric distortion ; stereoselectivity ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Binuclear oxomolybdenum(V) and oxotungsten(V) complexes of the type, [M 2(O)2(μ-X)(μ-X 1)]”, where M=Mo, W;X.X 1=O, S; L=edta, pdta (n=2-), tpen, tppn (n=2+) (edta4– =ethylenediaminetetraacetate(4–), pdta=R- orR,S-propylenediaminetetraacetate(4–), tpen=N,N,N 1,N1-tetrakis(2-pyridyhnethyl)-ethylenediamine, and tppn=R- orR,S-N,N,N 1,N1-tetrakis(2-pyridylmethyl)-propylenediami ne) are reviewed with respect to their preparation, structure, spectroscopic properties, reactivities, and in particular asymmetric distortion around the bicyclo [4.1.1 ] type core and stereoselectivity related to this distortion,
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  • 48
    ISSN: 1572-8862
    Keywords: Dynamic disorder ; crystal structure ; ruthenium cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The disorder in the X-ray crystal structures of Ru3(CO)11(L), L=CN t Bu 1 and PMe3 3 has been re-examined. Crystallographic data for 1 at 100 K: C16H9NO11Ru3, space group P21/n, a=11.796(5), b=11.748(2), c=16.040(7) Å, β=109.81(3)°, Z=4, 6077 reflections, R=0.028. For 3 at 223 K: C14H9O11PRu3, space group P21/n, a=8.5971(15), b=12.391(7), c=40.345(8) Å, β=94.43(2)°, Z=8, 7966 reflections, R=0.031. The disorder present in 1 and 3 at room temperature disappears reversibly on cooling, showing that it is dynamic in origin. The ligator atoms of the isonitrile and phosphine ligands move by a maximum of ∼0.8 Å, indicating that the whole cluster does not rotate intact within the crystal lattice, but rather that the Ru3 triangle effectively oscillates within a relatively rigid ligand polyhedron. The crystal structure of Ru3(CO)9{P(OMe)3 3} 7, which crystallizes in triclinic (7-t) and monoclinic (7-m) modifications is also reported. Both modifications have two independent molecules in the asymmetric unit, and both modifications display dynamic disorder in the metal framework. Crystalllographic data for 7-t at 173 K: C18H27O18P3Ru3, space group P-1, a=11.8085(18), b=15.915(2), c=17.350(3) Å, α=99.929(14), β=101.811(14), γ=90.630(12)°, Z=4, 11242 reflections, R=0.048. For 7-m at 120 K: C18H27O18P3Ru3, space group P21/c, a=11.708(8), b=15.922(5), c=33.950(10) Å, β=99.29(4), Z=8, 10191 reflections, R=0.027.
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  • 49
    ISSN: 1572-8854
    Keywords: Molecular mechanics ; molecular dynamics ; MNDO ; CMPO ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of N,N-diisobutyl-2-(octylphenylphosphinyl)acetamide, or CMPO was recently determined. The compound crystallizes in the space group P21/c witha=13.446(6),b=22.280(7),c=17.217(7) Å, β=92.07(4)°, andD calc=1.05 g/cm3 forZ=8 @20°C). Molecular mechanics, molecular dynamics, and MNDO calculations were also performed on CMPO utilizing the SYBYL1 suite of programs. The results from these calculations are compared to the crystal structure and to similar calculations performed on CMPO using ALCHEMY2,3. In general, the results from the calculations agree fairly well with the parameters from the crystal structure.
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  • 50
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    Journal of chemical crystallography 25 (1995), S. 223-226 
    ISSN: 1572-8854
    Keywords: Antifungal alkaloids ; 3-methylsampangine ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 3-Methylsampangine, C16H10N2O, crystallizes in the monoclinic space group P21/c witha=7.260(3),b=10.697(5),c=15.342(6) Å, and β=102.69(4). All nonhydrogen atoms of this potent antifungal agent are planar to within 0.082 Å. The title compound exhibits potentin vitro antifungal activity againstC. neoformans, C. albicans andA. fumigatus.
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  • 51
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    Journal of chemical crystallography 25 (1995), S. 295-298 
    ISSN: 1572-8854
    Keywords: Cage-diol ; crystal structure ; photooxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An unusual photooxidation was noted upon photolytic cage closure of a substituted tricyclo[6.2.1.02.7]undecane-exo, exo-diol. The resultant compound, which may be regarded as a mono-reduced pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione, was characterizedvia X-ray crystallography. This species could be reduced to the tricyclo[6.2.1.02,7]undecane-endo, exo-diol under conditions previously shown to be inert for the parent dione.
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  • 52
    ISSN: 1572-8854
    Keywords: Benzonaphthodioxosuberane ; crystal structure ; radermachol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of the title compound (2) C21H16O4 has been determined by an X-ray analysis, by direct methods from diffractometer data and refined by full-matrix least squares. The compound (2) crystallizes in the space group P21/a, with cell parameters:a=36.432(5),b=5.512(3),c=8.269(5) Å, β=108.0(3)°,z=4,D c =1.397 g/cm−3,R=7.8 for 1136 observed reflections. The conformation of the tetracyclic ring system shows a folding of two planar parts of the carbon skeleton about an axis passing thorough C8 and C16 of the seven membered ring C.
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  • 53
    ISSN: 1572-8854
    Keywords: Ruthenium(II) complex ; tri-n-propylphosphine ; bipyridyl ; crystal structure ; disorder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complexcis-[Ru(bpy)2(PPr3)Cl+][ClO 4 − ] · 0.5 (toluene) crystallizes as a racemate in the monoclinic space group P21/n. Both the PPr3 ligand and the toluene of crystallization are subject to disorder. Ruthenium—ligand distances are: Ru−PPr3=2.348(2) Å, Ru−Cl=2.426(2) Å and Ru−N(bpy)=2.035(6)–2.112(5) Å.
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  • 54
    ISSN: 1572-8854
    Keywords: Organoiron complex ; dinuclear complex ; crystal structure ; phosphonium ylid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the centrosymmetric monoclinic space group P21/n withZ=4. The cation consists of two (η5-C5h5)Fe(CO) units which are linked via a metal-metal bond (Fe(1)−Fe(2)=2.530(1) Å), a bridging carbonyl ligand (Fe(1)−C(4)=1.912(8) Å. Fe(2)−C(4)=1.940(9) Å) and a bridging phosphonium ylid ligand (Fe(1)−C(1)=1.991(6) Å, Fe(2)−C(1)=1.985(6) Å and C(1)−P(1)=1.781(6) Å).
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  • 55
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    Journal of chemical crystallography 26 (1996), S. 747-752 
    ISSN: 1572-8854
    Keywords: Phosphine oxide ; quaternary ammonium ; water-soluble phosphine ; crystal structure ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the centrosymmetric triclinic space group $$P\bar 1$$ withZ=4. The crystallographic asymmetric unit contains two independent cations; interatomic distances within these include P=O=1.47(1) and 1.47(1) Å, P−C6H5=1.78(2)–1.81(1)Å and P−CH2CH2NMe3 +=1.80(1) and 1.81(1) Å. The phosphine oxide moiety is involved in intermolecular hydrogen bonding ()...H−C, with O...H≥2.42Å) and the iodide is involved in I...H−C contacts with I...H≥3.10Å.
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  • 56
    ISSN: 1572-8854
    Keywords: Organotin ; crystal structure ; flavone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The 1∶1 adduct of chlorotriphenyltin with 2′,6′-dimethoxyflavone, (C35H29O4ClSn)Mr=667.78, crystallizes in the triclinic space groupP1 with the following data:a-9.094(2),b=12.369(3),c=14.674(3) Å, α=74.78(2), β=77.00(2), γ=73.06(3)°,V=1503.8(4) Å3,Z=2, Mo-Kα, μ=9, 8 cm−1,Dc=1.475 g cm−3, F(000)=676,T=293K. The structure was solved by direct-methods and has been refined to a finalR value (l〉3σ(I)) of 0.0301. The flavone coordinates to the tin atom through the carbonyl oxygen atom. The metal center exhibits a trigonal bipyramidal configuration with the three phenyl groups in equatorial positions.
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  • 57
    ISSN: 1572-8854
    Keywords: Pyrazolyl group ; crystal structure ; bidentate ligand ; hydrogen bonding
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    Topics: Geosciences , Physics
    Notes: Abstract The title compound consists of two planar pyrazolyl fragments oriented at 73.0° to each other and linked to a common carbon atom. All hydrogen atoms were located unambiguously and their positions were refined.
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  • 58
    ISSN: 1572-8854
    Keywords: Ruthenium(II) complex ; bipyridyl ; diphenyl(o-tolyl)phosphine ; dichloromethane solvate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complexcis-[Ru(bpy)2 {PPh2(o-tol)}Cl][ClO4] crystallizes from dichloromethane as the sesqui-dichloromethane solvate. The complex crystallizes in the monoclinic space group P21/n with Z=4. The structure was refined toR=5.50% for those 2552 independent reflections with |F 0|〉6σ(|F 0|) The octahedral Ru(II) cation is associated with the following bond lengths: Ru-PPh2(o-tol)=2.360(3)Å. Ru−Cl=2.433(2)Å and Ru−N(bpy)=2.041(8)–2.095(8)Å. Both the perchlorate anion and the dichloromethane molecules of solvation exhibit large amplitudes of vibration. One dichloromethane molecule lies in a general position, the other lies about an inversion center and suffers from disorder.
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  • 59
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    Journal of chemical crystallography 26 (1996), S. 615-619 
    ISSN: 1572-8854
    Keywords: Disordered trifluoromethyl group ; quinoline ; crystal structure ; AM1 calculation ; mefloquine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallized in space groupPna21 with lattice constantsa=13.406(1),b=18.799 (4), andc=4.785(1). The molecule is essentially flat with only fluorine atoms, methylene hydrogen atoms, and the hydroxyl hydrogen atom out of the plane of the quinoline ring. Only one of the trifluoromethyl groups of the title compound is disordered following a pattern observed in other crystal structures. Quantum chemical calculations at the AM1 level are consistent with this phenomenon. Although the carbon atom of the fixed trifluoromethyl group is further from the quinoline nitrogen atom than the carbon atom of the disordered trifluoromethyl group, the fluorine atoms of the fixed trifluoromethyl group more closely approach the quinoline nitrogen atom by 0.3 Å if the C(8)−C(10) bond in the crystal structure is freely rotated.
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  • 60
    ISSN: 1572-8854
    Keywords: Halobismuthate(III) ; phenanthroline ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The reaction between bismuthate oxide and phen (1,10-phenanthroline) in acid medium led to the isolation of the unusual [(PhenH)(PhenH2)][BiCl6]·2H2O derivative, which has been characterized by X-ray analysis and IR spectroscopy. The compound crystallizes in the triclinic space group $$[\text[P\bar 1]]$$ with a = 8.313(2), b = 9.349(2), c = 9.807(3) Å, α = 86.39(3), β = 110.27(3) and γ = 106.48(3)°. The crystal structure is made of [BiCl6]3− anions and [(PhenH)(PhenH2)]3+ cations. A network of hydrogen bond interactions involving the two clathrated water molecules, the phenanthroline moiety and the chlorines characterizes the entire structure.
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  • 61
    ISSN: 1572-8854
    Keywords: Strontium ; triphenylsiloxy ; crystal structure ; ammonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title complex [Sr2(OSiPh3)4(NH3)5]·0.5C7H8 was prepared by the reaction of strontium metal granules with triphenylsilanol in an ammoniacal-toluene solution at −40°C. It crystallizes in monoclinic space group P21/n with a = 14.465(3), b = 20.715 (6), c = 25.199(6) Å, β = 95.98(2)°, and Z = 4. The complex has a dimeric structure with one terminal and three bridging triphenylsiloxy ligands, the remaining coordination sites being occupied by five ammonia molecules. The central Sr2O4N5 moiety adopts a distorted M2X9 face-sharing bioctahedral arrangement.
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  • 62
    ISSN: 1572-8854
    Keywords: Copper ; 1,10-phenanthroline ; trifluoroacetate ; crystal structure ; magnetic exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound [Cu(phen)(O2CCF3)2]n (phen = 1,10-phenanthroline) has been synthesized and its crystal structure determined. It crystallizes in monoclinic space group C2/c, with a = 19.229(7), b = 11.281(5), c = 7.621(2) Å, β = 104.305(12)°, and Z = 4. The crystal structure is polymeric, being built from infinite zigzag chains of trifluoroacetate bridged copper(II), with the phenanthroline ligands being stacked between the chains. The variable-temperature (13–300 K) magnetic susceptibility and ESR data are reported and a weak ferromagnetic exchange interaction is observed with the exchange parameter estimated as J = 2.9 cm−1.
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  • 63
    ISSN: 1572-8854
    Keywords: 2-[1,5-Dimethyl-4-hexenyl]-6-hydroxy-5-methyl-1,4-benzoquinone ; 2-[1,5-dimethyl-4-hexenyl]-6-amino-3-hydroxy-5-methyl-1,4-benzoquinone ; 2-[1,5-dimethyl-4-hexenyl]-3-amino-6-hydroxy-5-methyl-1,4-benzoquinone ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures of isoperezone (1), aminoperezone (2), and isoaminoperezone (3) have been determined by single-crystal X-ray diffraction. Compound (1) yields orange crystals, orthorhombic space group P212121 with unit cell dimensions a = 6.271(6), b = 30.373(7), c = 7.257(1) Å, and Z = 4; compound (2) yields purple crystals, orthorhombic space group P212121 with unit cell dimensions a = 6.498(3), b = 7.500(1) c = 29.200(6) Å, and Z = 4; compound (3) yields purple crystals, monoclinic space group P21 with unit cell dimensions a = 7.354(1), b = 7.511(1), c = 13.283(1) Å, β = 102,07(1)°, and Z = 2. The side chains in (1)–(3) are oriented out of the plane of the quinone ring at an angle of 124, 144, and 97°, respectively. The molecules in the crystal are held together by hydrogen-bonding networks and van der Waals interactions.
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  • 64
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    Journal of chemical crystallography 28 (1998), S. 217-220 
    ISSN: 1572-8854
    Keywords: Metal carbonyl complexes ; chelate complexes ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The x-ray crystal structure of the complex η2-PDOW(CO)4 (five-membered ring, PDO = 2, 2, 4, 7, 7-pentamethyl-3,6-dithiaoctane) is reported. The complex crystallizes in the monoclinic crystal system, space group P21/c, [#14] with unit cell parameters a = 14.002(14) Å, b = 9.340(10) Å, c = 15.094(12) Å, β = 92.67(4)°, V = 1972(3) Å3; Z = 4. The arrangement of the ligands around the metal atom is distorted from octahedral geometry. Large C–O bond distances and short W–C bond distances of the carbonyl groups located at a trans position with respect to PDO is indicative of a trans influence. The W–S(1) and W–S(2) bond distances of 2.545(3) and 2.545(2) Å, respectively, are shorter than observed for closely related complexes.
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  • 65
    ISSN: 1572-8854
    Keywords: Triphenylsiloxy ; silanol ; borane ; crystal structure ; adduct
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    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the triclinic space group $$P \bar 1$$ , with a = 14.458(6), b = 14.630(5), c = 14.721(8) Å, α = 79.75(2), β = 80.11(3), γ = 80.50(3)°, and Z = 2. The crystal structure consists of molecules of (Ph3SiO)3B and Ph3SiOH linked by an weak B···(silanol) acceptor-donor bond, additionally stabilized by OH(silanol)···O(siloxy) hydrogen bonds. The average B–O, Si–O distances and B–O–Si angle are 1.369, 1.649 Å and 137.2°, respectively.
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  • 66
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    Journal of chemical crystallography 29 (1999), S. 1081-1084 
    ISSN: 1572-8854
    Keywords: cobalt(II) ; bipyridine ; maleato ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Preparation of the mononuclear cobalt(II) complex, [Co(bipy)(maleato) (H2O)3]·H2O (1) where bipy = 2,2′-bipyridine, were accomplished by reaction of an aqueous solution containing sodium maleate and an ethanolic solution of Co(NO3)2·6H2O and bipy. The crystal structure of complex (1) was determined by X-ray crystallography. The complex crystallizes in the monoclinic space group P21/n with a = 9.477(3), b = 7.660(2), c =23.526 (3) Å, β = 97.64(2)°, V = 1692.6(6) Å3, and Z = 4. The structure consists of discrete mononuclear cobalt molecules. The cobalt atom is six-coordinate and presents a slightly distorted octahedral geometry, which consists of the two imine N atoms of bipy, a terminal carboxylate O atom from maleato ligand, and a water O atom in the basal plane with Co—N bond distances of 2.116(2) and 2.124(3) Å and Co—O distances of 2.075(2) and 2.088(2) Å, respectively. The relatively shorter Co—O distances are due to the trans effect of the bipy ligand. The octahedral coordination is completed the other two water molecules. The coordinate and the lattice water molecules were identified by TG study.
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  • 67
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    Journal of chemical crystallography 29 (1999), S. 1107-1110 
    ISSN: 1572-8854
    Keywords: crystal structure ; ytterbium ; lanthanide ; coordination complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The preparation and structural characterization of [YbI2(DME)2] are reported. The complex crystallizes in the triclinic space group P 1¯: a = 13.0094 (10), b=14.504(3), c = 14.668 (3) Å, α = 115.281(10) β = 106.74(2), γ = 105.97(2)°. The metal center of the complex exhibits a distorted pentagonal bipyramidal coordination geometry which involves a rare example of a monodentate DME ligand.
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  • 68
    ISSN: 1572-8854
    Keywords: copper (II) ; histamine ; self-assembly ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract A new monomeric copper (II) complex with histamine (him), [Cu(II)(him)2(No3)2], has been prepared by the reaction of Cu(NO3)2 with histaminium dichloride and its structure was determined by x-ray crystallography. The complex crystallizes in the triclinic system, space group $$P\bar 1$$ with a = 5.7238(4), b = 8.7094(7), c = 9.2481(11) Å, α = 69.693(8), β = 73.242(7), γ = 71.050(7)°, V = 400.84(6) Å3, and Z = 1. The structure consists of discrete [Cu(II)(him)2(NO3)2] molecules in which the metal atom is centrosymmetrically coordinated by two histamine ligands forming an equatorial plane with Cu–N(imidazole ring) being 2.032(2) and Cu–N(NH2 group) being 2.023(2) Å. Two O atoms from nitrate anions coordinate on the elongated axial positions with Cu–O being 2.549(2) Å. In the crystal structure, the molecules are organized by hydrogen bonds forming a two-dimensional network.
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  • 69
    ISSN: 1572-8854
    Keywords: xanthenol ; complex ; crystal structure ; H-bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound 14-hydroxy-14-phenyldibenzo[a,j]xanthene 1 formed a (1:1) complex with diethyl ether. 1,4-Dioxane was also enclathrated, but with a variable stoichiometric ratio. Single crystal X-ray crystallography was used to elucidate the crystal structure of the 1·diethyl ether complex. Crystals are orthorhombic with space group P212121, a = 8.532(3), b = 15.040(4), c = 18.491(5) Å, V = 2373(1) Å3, d c = 1.256 g/cm3, and Z = 4. Host and guest molecules were found to associate via hydrogen bonds, with the guest molecules residing in undulating channels lined by host molecules.
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  • 70
    ISSN: 1572-8854
    Keywords: crystal structure ; methyl propiolate ; sulfenic acid ; vinyl sulfoxide ; leinamycin
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    Notes: Abstract Evidence for the formation of unstable sulfenic acids (RSOH) as reaction intermediates is commonly provided by trapping these compounds with methyl propiolate. The crystal structure of a vinyl sulfoxide derived from the trapping of a sulfenic acid with methyl propiolate is reported here. The title compound C12H12O5S crystallized in the triclinic space group,P1¯ with unit cell parameters: a = 6.1600(4), b = 9.7286(7), c = 11.3698(8) Å, α = 112.024(1), β = 94.662(1), γ = 95.429(1)°, and Z = 2.
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  • 71
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    Journal of chemical crystallography 29 (1999), S. 1137-1139 
    ISSN: 1572-8854
    Keywords: acyclic nucleoside analog ; acyclovir ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound 9[1-(2-hydroxy ethoxy)-3-hydroxy propyl] guanine crystalizes in the tetragonal system, space group P41212 with a = 11.106 (1), c = 20.558 (2) Å, and Z = 8. The acyclic chain C1′¯O1′¯C4′¯C5′¯O5′ is in the extended configuration and the glycosidic torsion angle (C4¯N9¯C1′¯O1′) is 125.1 (8)°. The molecules are held together by Van der Waal's forces.
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  • 72
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    Journal of chemical crystallography 29 (1999), S. 1205-1210 
    ISSN: 1572-8854
    Keywords: organic sulfate ; crystal structure ; DTA/TG/DSC ; vibrational spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [1-(2-ammoniumethyl) piperazinium] sulfate denoted PIPS has a monoclinic unit cell. The parameters are: a = 6.6521(3), b = 7.8756(5), c = 19.197(1) Å, β = 94.43(1)° and the space group is P21/n. The preparation, thermal analysis, and IR spectrometric investigation are described. The PIPS structure exhibits a complex three-dimensional network of H-bonds connecting all its components.
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  • 73
    ISSN: 1572-8854
    Keywords: crystal structure ; copper(II) complexes ; dinuclear complexes
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    Notes: Abstract A chemical Janus, binuclear copper(II) complexes, {[Cu(TPA)Cl][Cu(BPA)Cl]}(ClO4)2 (TPA = Tris(2-pyridylmethyl) amine, BPA = bis-(2-pyridylmethyl)amine) containing two different ligands has been synthesized and characterized by X-ray single crystal analysis. Crystal data: triclinic, space group P1$sm, a = 12.529(3), b = 12.655(3), c = 13.458(3) Å, α = 70.48(3), β = 67.40(3), γ = 75.81(3)°, D x = 1.648 mg m−3, and Z = 2. The molecular structure shows that the binuclear copper complex consists of two positive cation and two perchlorate anions. The positive cations moieties have different ligands. Cu(1) is coordinated by four nitrogen atoms from TPA and one chloride atom, forming a square-pyramidal geometry, whereas the coordinate number of Cu(2) is four, three of which are from BPA, one from chloride. There are two weak bonds between the Cl(2a) ion and the Cu(2) ion (2.844 Å) and the distance of Cu(2)=O(13) is 2.750(9) Å.
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  • 74
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    Journal of chemical crystallography 29 (1999), S. 513-521 
    ISSN: 1572-8854
    Keywords: nanotechnology ; molecular devices ; triptycene ; crown ether ; crystal structure ; thallium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The incorporation of 9,10-triptycene unit in a crown ether is examined from a structural perspective. Insertion of a triptycene group into 18-crown-6 stretches the crown into an ellipse, as seen in structures presented here of 9,10-triptyceno-22-crown-6 and its thallium complex. Symmetric addition of two triptycene groups into 18-crown-6 results in the sterically congested bis(9,10-triptyceno)-26-crown-6, whose crown cavity is filled with the π-clouds of two arene groups. The larger bis(9,10-triptyceno)-32-crown-8 is more sterically relaxed. The structures of these bis(triptyceno)crown ether molecules are the first with two triptycene groups simultaneously linked through their 9 and 10 positions, thereby forming a simple molecular gearing mechanism. The compound 9,10-triptyceno-22-crown-6 (1) crystallizes in the orthorhombic space group Pbca with a = 10.7962(7), b = 15.826(3), c = 31.147(5) Å, V = 5321.8(12) Å3, and Z = 8; its complex with TlNO3 (Tl-1) crystallizes in the monoclinic space group P21/c with a = 8.1884(14), b = 19.552(2), c = 20.575(4) Å, β = 97.062(8)°, V = 3269.2(9) Å3, and Z = 4; bis(9,10-triptyceno)-26-crown-6 (2) crystallizes in the triclinic space group P $$\bar 1$$ with a = 8.6488(11), b = 10.7718(12), c = 12.3324(12) Å, α = 111.58(1), β = 100.55(1), γ = 106.43(1)°, V = 970.3(5) Å3, and Z = 1; and bis(9,10-triptyceno)-32-crown-8 (3) crystallizes in the orthorhombic space group Pna21 with a = 20.186(3), b = 8.558(2), c = 25.623(2) Å, V = 4426.2(14) Å3, and Z = 4.
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  • 75
    ISSN: 1572-8854
    Keywords: crystal structure ; complexes ; pteridine ; lumazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Single-crystal X-ray diffraction studies have been performed on the complex cis-diaqua-bis(1,3-dimethylpteridine-2,4(1H,3H)-dione-O4,N5) copper(II) perchlorate monohydrate, [Cu(DLM)2(H2O)2](ClO4)2 · H2O. This compound crystallizes in the orthorhombic system, P212121 space group, Z = 4 with a = 8.749(1) Å, b = 14.213(1) Å, c = 21.200(2) Å, and V = 2636.2(4) Å3. The metal ion is surrounded in octahedral geometry by two mutually quasi-perpendicular N5,O4-coordinated lumazine chelators with the O4 atoms trans and the N5 atoms cis. The polyhedron is completed by two cis-coordinated water molecules. The absolute configuration of the complex can be described, following Bailar's nomenclature, as the enantiomer Λ of the stereoisomer 4M. A three-dimensional hydrogen-bond network is defined by water molecules, perchlorate anions, and the O2 of the pteridine A.
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  • 76
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    Journal of chemical crystallography 29 (1999), S. 1271-1275 
    ISSN: 1572-8854
    Keywords: crystal structure ; pregnen ; progestin ; 4-pregnen-21-ol-3,20-dione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Synthetic steroid de-oxy corticosterone (4-pregnen-21-ol-3,20-dione) crystallizes in the monoclinic space group P21, with a = 11.706(2); b = 11.171(3), c = 13.966(3) Å, and β = 100.94(2)°, Z = 4. Ring A tends to acquire the conformation of a half-boat, rings B and C are in the chair configuration, and ring D is a 13β, 14α-half-chair. The ring junctions B/C and C/D are both trans, whereas the ring junction A/B is quasi-trans. The molecule as a whole is slightly convex toward the β-side, with an angle of 16.01(0.36)° between the C10--C19 and C13--C18 vectors. Molecular packing and stacking interactions play the major role in structural association. Cohesion of the crystal is due to van der Waals interactions.
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  • 77
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    Journal of chemical crystallography 29 (1999), S. 629-633 
    ISSN: 1572-8854
    Keywords: heterometallic polymeric cluster ; polythiometalate ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex (NH4)2 WS4 reacts with AgNO3 and La(NO3)3 · 6H2O in a mixture of DEF/DMF (DEF—N,N′-diethylformamide), to give a new heterometallic square-chain polythiometalate {[W4Ag5S16]2 · [La(DEF)2(DMF)6] · [La(DEF)4(DMF)4]}n (1). 1 crystallizes in the monoclinic space group P2/c, a = 19.5534(8), b = 16.9552(6), c = 22.3479(9) Å, β = 106.053(1)°, V = 7120.1(5) Å3, and Z = 2. The anion polymeric chain of 1 can be regarded as an octanuclear cyclic cluster of [W4Ag4S16]4− fragments linked through Ag+ ions. The polymeric chain is extended through the parallel edges of the square unit. The mean W—Ag distance is 2.963(16) Å. The La3+ cations are coordinated by different solvent molecules, the average La—O bond of these large trivalent cations is 2.47(1) Å.
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  • 78
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    Journal of chemical crystallography 29 (1999), S. 565-569 
    ISSN: 1572-8854
    Keywords: orotic acid complex ; crystal structure ; copper(II) complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound [(C5H2N2O4)Cu(H2O)2]n has been synthesized and its structure determined at room temperature. The primary coordination sphere at the Cu ion is square planar with the orotate dianion coordinating at the metal through heterocyclic nitrogen atom and adjacent oxygen of the carboxylate group, the remaining coordination sites are occupied by two water molecules. The orotate dianion is tricoordinated to one copper via N1 and one oxygen of the carboxylato group and to another copper atom via the other oxygen of the carboxylato group. The coordination at copper is extended to five by the other oxygen of the carboxylate group of another orotate molecule. Thus, the molecules are associated to form chains, the carboxylato group acting as a bridge between the metal ions, the orotato-group being tridentate. The title compound crystallizes in the monoclinic space group. P21/n1 with a = 9.515(5), b = 6.925(2), c = 11.861(6) Å, β = 95.285(9)°, D calc = 2.17 g cm−3, and z = 4.
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  • 79
    ISSN: 1572-8854
    Keywords: crystal structure ; manganese complex ; disubsituted oxamide ; addition compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of the addition compound, Mn(phen)3(PMoxdH2)(ClO4)2 was established by X-ray crystallography, where PMoxdH2 is N,N′-bi(2-pyridylmethyl)-oxamide. Six nitrogen atoms of the three 1,10-phenanthroline bind to the manganese ion and the oxygen atom of PMoxdH2 is uncoordinated. The addition compound crystallizes in the monoclinic space group C2/c, with lattice parameters a = 23.780(6), b = 11.948(5), c = 18.466(6) Å, β = 117.38(3)°, V = 4659(3) Å3, and Z = 4.
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  • 80
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    Journal of chemical crystallography 29 (1999), S. 329-333 
    ISSN: 1572-8854
    Keywords: Carbene ; crystal structure
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    Topics: Geosciences , Physics
    Notes: Abstract Base-promoted reaction of 11-methylenepentacyclo[5.4.0.02,6.03,10.05, 9]undecan-8-one (5) with diethyl diazomethylphosphonate when performed in the presence of excess cyclohexene, resulted in the formation of the corresponding cycloalkylidenecarbene, 6, which subsequently was trapped in situ to afford 8-methylene-11-(7′-bicyclo[4.1.0]heptylidene)pentacyclo-[5.4.0.02, 6.03, 10.05, 9]undecane (7, obtained in 44% yield as a mixture of exo, endo isomers). Subsequent reaction of 7 with dichlorocarbene (generated under phase transfer catalytic conditions) produced the corresponding mono- and di-:CCl2 adducts [i.e., 8 (64% yield) and 9 (5% yield), respectively]. The structure of 9 was established unequivocally via application of single crystal X-ray analysis: Triclinic, P1¯, a = 6.276(2), b = 8.700(2), c = 18.550(3) Å, α = 76.52(3), β = 87.59(3), γ = 70.88(4)° Z = 2; D calc 1.486 g cm−3.
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  • 81
    ISSN: 1572-8854
    Keywords: pseudo-square pyramidal Cu(II) complex ; trans-4-styrylpyridine ; crystal structure ; IR, electronic, and EPR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Single crystals of the title Cu(II) complex, [Cu(stpy)4(ONO2)(ONO2)′] [stpy = trans-4-styryl-pyridine] have been prepared and characterized by elemental and thermal analyses, IR, electronic and EPR spectral measurements, and X-ray crystal structure determination. The complex crystallizes in the monoclinic space group P21/c with unit-cell parameters, a = 12.985(2), b = 22.865(8), c = 17.024(10) Å, β = 112.29(3)°, and Z = 4. The structure consists of discrete monomeric units of [Cu(stpy)4(ONO2)(ONO2)′]. The equatorial positions of the Cu(II) polyhedron are occupied by nitrogen atoms of the four stpy ligands and the axial positions by the oxygens of two unidentate nitrate anions. One of these oxygens is at rather longer distance [2.609(3) Å] and may be considered to be semicoordinated. If this semibond is ignored, the coordination geometry lies closer to an idealized square pyramid than to the trigonal bipyramid geometry. IR spectra reveal nitrogen coordination from stpy and asymmetry in the monodentate oxygen binding of the two nitrate ligands. The optical reflectance band at 600 nm suggests pseudo-square-based pyramidal geometry around Cu(II). Well-resolved Cu(II) hyperfine features in the EPR spectra reveal the absence of exchange interactions between adjacent copper centers. Optical and EPR spectra of a methanolic solution of the complex indicate solvent interactions. Thermogravimetric analysis shows the complex to be stable up to 175°C.
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  • 82
    ISSN: 1572-8854
    Keywords: contrast agents ; crystal structure ; ortho ester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 1-(4-Bromobenzyl)-4-methyl-2,6,7-trioxabicyclo[2.2.2]octane, C13H15BrO3, has been synthesized from 4-bromophenylacetic acid chloride via the oxetan ester (3-methyl-3-oxetanyl)methyl-2-(4-bromophenyl)acetate. The crystal structure of the title compound has been determined at low temperature (120 K), by X-ray diffraction methods. This compound crystallizes in the monoclinic space group P21/n (No. 14), Z = 4, with lattice parametersa = 6.019(5), b = 20.990(5), c = 9.915(2) Å, and β = 101.29(1)°.
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  • 83
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    Journal of chemical crystallography 29 (1999), S. 561-564 
    ISSN: 1572-8854
    Keywords: crystal structure ; Raman spectrum ; silver azide ; azide
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    Topics: Geosciences , Physics
    Notes: Abstract Silver nitrate reacts with sodium azide to give white powdery silver azide, which can be crystallized in aqueous ammonia. The compound belongs to orthorhombic space group Ibam with a = 5.600(1), b = 5.980(6), c = 5.998(1) Å, and Z = 4. The layer-type structure is constructed from edge-sharing regular rectangles, each composed of silver atoms at its vertices with an enclosed azide anion in a tilted orientation. The linear and asymmetrical structure of the azide anion in crystalline silver azide has been confirmed by its Raman spectrum.
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  • 84
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    Journal of chemical crystallography 29 (1999), S. 729-733 
    ISSN: 1572-8854
    Keywords: crystal structure ; yttrium complexes ; isothiocyanate complexes ; octahedral coordination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structural analysis of [(n-C4H9)4N]3[Y(NCS)6] (I) using single-crystal diffraction data and full-matrix least squares refinement has been carried out. The hexaisothiocyanate complex crystallizes in the centrosymmetric triclinic space group P $${\bar 1}$$ (No. 2) with unit cell constants of a = 12.431(1), b = 12.866(1), c = 22.750(2) Å, α = 90.78(1), β = 92.05(1), γ = 96.67(1)°, and Z = 2. The molecular unit consists of three separate cationic tetra-n-butylammonium groups and an independent hexakisisothiocyanatoyttrate anionic group in which the six thiocyanate ligands are octahedrally coordinated through the N atom to the Y central ion. Selected bond distances and angles are presented as well as the synthesis and peripheral studies of (I).
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  • 85
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    Journal of chemical crystallography 29 (1999), S. 793-796 
    ISSN: 1572-8854
    Keywords: copper complex ; crystal structure ; dibenzoylmethane complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Bis(dibenzoylmethane)copper Cu(dbm)2 has been synthesized and its structure determined by x-ray diffraction. It crystallizes in the monoclinic system, space group C2/c, with a = 25.936(3), b = 5.9806(8), c = 16.4908(16) Å, β = 114.998(8)°, Z = 4, and V = 2318.3(4) Å3. The Cu atom is located at a symmetry center and surrounded by four O atoms from two dbm molecules to form a plane square coordination environment. On the a–c plane the molecules are orderly arranged to result in a layered structure, and parallel to crystallographic b-axis they form a molecular column due to the effect of aromatic stacking.
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  • 86
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    Journal of chemical crystallography 29 (1999), S. 809-812 
    ISSN: 1572-8854
    Keywords: tungsten(II) ; dibromo ; carbonyl ; diphenylcyclohexylphosphine ; but-2-yne ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [WBr2(Co)(PPh2Cy)2(η2-MeC2Me)]·CH2Cl2 (Cy = cyclohexyl) crystallizes in the monoclinic space group, P21/n, with a = 10.606(12), b = 23.11(3), c = 18.19(2) Å, β = 106.070(10) Dcalc = 1.610g cm−3 for Z = 4. The tungsten coordination geometry can best be considered as a distorted octahedron, with the but-2-yne ligand occupying one coordination site, which has a trans-Br(2) group. The equatorial plane is made up of trans-PPh2Cy groups, with the bromo and carbonyl ligands occupying the other two sites.
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  • 87
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    Journal of chemical crystallography 29 (1999), S. 837-839 
    ISSN: 1572-8854
    Keywords: acyclonucleoside analog ; 6-(phenyl selenyl) uracil derivative ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound, 1-(ethoxymethyl)-6-(phenylselenyl)-5-ethyl uracil, crystallizes in the monoclinic space group P21/n with unit cell parameters a = 5.304(1), b = 21.261(4), c = 13.996(4) Å, β = 94.30(2)°, and Z = 4. The acyclic chain C1′, O4′, C4′, C5′ is in fully extended form and nearly perpendicular to the uracil base. The molecules are held together by van der Waal's forces.
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  • 88
    ISSN: 1572-8854
    Keywords: mercury halides ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis, characterization and single crystal X-ray structure of three compounds of general formula HgI2R (R = phen[1], dmph [2] and bpy[3]) are presented. The crystal data for the three compounds are: [1], triclinic, space group P $$\bar 1$$ (#2) a = 7.902(2), b = 9.479(2), c = 10.002(2) Å, α = 91.45(2), β = 111.34(2), γ = 100.82(2)° [2]: monoclinic, space group C2/c (#15) a = 15.670(3), b = 11.640(2), c = 9.730(2) Å, β = 114.57(3)° [3]: triclinic, space group P1¯ (#2) a = 9.472(1), b = 9.507(1), c = 9.023(1) Å, α = 98.46(1), β = 102.89(1), γ = 119.62(1)°. Compounds [1] and [2] are monomers, with highly distorted tetrahedral environments around Hg. In [3], instead, there is a significant intermolecular I···Hg interaction leading to the formation of softly bound dimers linking two pentacoordinated cations. The structure is compared with related ones in the literature.
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  • 89
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    Journal of chemical crystallography 29 (1999), S. 907-911 
    ISSN: 1572-8854
    Keywords: tungsten(II) ; Iodo ; carbonyl ; cis-bis(diphenylphosphino)ethene ; but-2-yne ; cationic ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex [WI(CO)(cis-dppen)(η2-MeC2Me)2]I·CH2Cl2(1) is prepared as a by-product from the reaction of equimolar quantities of [WI2(CO)(NCMe)(η2-MeC2Me)2] and cisdppen {dppen = bis(diphenylphosphino)ethene}. Complex 1, [WI(CO)(cis-dppen)(η2-MeC2Me)2]I·CH2Cl2 crystallizes in the triclinic space group $${\text{P}}\bar 1$$ with a = 11.189(13), b = 12.331(14), c = 15.395(17) Å, α = 83.61(1), β = 86.06(1), γ = 64.48(1)°, U = 1904 Å3, and Z = 2. The metal environment in the cation can best be considered as a distorted octahedron with the two but-2-yne groups taking up individual sites trans to phosphorus atoms of the dppen ligand. The coordination sphere is completed by mutually trans-carbonyl and iodide groups.
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  • 90
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    Journal of chemical crystallography 29 (1999), S. 955-959 
    ISSN: 1572-8854
    Keywords: crystal structure ; intramolecular hydrogen bond ; 4-(1,4-dimethoxy-2-naphthyl)-4-hydroxycyclohexanone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Intramolecular hydrogen bonding in the solid state is reported for the title compound and its ethylene ketal. The title compound crystallizes in the triclinic space group, $$P\bar 1$$ with a = 9.590(3), b = 9.620(3), c = 9.844(2) Å, α = 97.67(2), β = 105.25(2), γ = 115.47(2), and Z = 2. The ethylene ketal crystallizes in the monoclinic space group, P21/c, with a = 7.230(2), b = 22.639(3), c = 10.839(2) Å, β = 101.47(2), and Z = 4. The intramolecular hydrogen bond length of 1.79 Å is the same for the ketone and ketal, but the O—H---O valence angle is 144° for the ketone and 165° for the ketal.
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  • 91
    ISSN: 1572-8854
    Keywords: neotame ; crystal structure ; methanol solvate ; thermal analysis ; powder X-ray diffractometry ; 13C solid-state nuclear magnetic resonance spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of the methanol solvate (empirical formula: 2C20H30N2O5·3CH3OH) of a new dipeptide sweetener, neotame (N-(3,3-dimethylbutyl)-L-α-aspartyl-L-phenylalanine 1-methyl ester), has been determined. Crystal data: a = 9.8989(1), b = 18.1331(1), c = 27.5725(1) Å, orthorhombic, space group P212121, with Z = 4. Each unit cell includes 8 neotame and 12 methanol molecules. Disorder exists in one neotame molecule and one methanol molecule. The crystals were characterized by the following techniques: hot-stage microscopy (HSM), Karl-Fischer titrimetry (KFT), powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC), thermogravimetry (TGA), 13C solid-state nuclear magnetic resonance (SSNMR) spectroscopy. Under HSM at a heating rate of 10°C/min in silicone oil, the sample melts at 64–84°C and liberates bubbles at 71–86°C. DSC in open pans shows two overlapping endotherms at 56 and 71°C, probably due to melting and desolvation, respectively. TGA in open pans shows 5.9% weight loss due to desolvation below 70°C. Under house vacuum (23 mm Hg) over phosphorus pentoxide at 23°C, the methanol solvate produces pure amorphous anhydrate, which converts to crystalline neotame monohydrate in the presence of moisture.
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  • 92
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    Journal of chemical crystallography 29 (1999), S. 977-982 
    ISSN: 1572-8854
    Keywords: cyano allyl radical ; thermal arrangement ; crystal structure ; isomer ; NMR, MM2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The preparation, separation, crystal structure and 1H NMR spectra are reported for the two geometrical isomers of 1,1′-bi-3-cyanocyclohex-2-enylidene. The E-isomer crystallized as thin plates in the monoclinic space group P21/n with a = 5.3980(5), b = 7.0757(7), c = 15.300(2) Å, β = 94.571(2)°, and Z = 2. The structure has symmetry C2h. The Z-isomer crystallized as needles in the triclinic space group P1¯ with a = 7.0790(6), b = 11.3155(9),c = 15.386(1) Å, α = 104.943° β = 90.164(2)°, γ = 99.494(2)°, and Z = 4. The compound crystallized with two molecules per asymmetric unit. In C6D6, 1H NMR signals of the 2-vinyl protons appear almost identical. However, in a mixture of C6D6 and pyridine-d 5, the 2-vinyl protons can be distinguished. The structures compare favorably with MM2 calculations.
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  • 93
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    Journal of chemical crystallography 29 (1999), S. 1009-1013 
    ISSN: 1572-8854
    Keywords: crystal structure ; nickel complex ; xanthosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex [Ni(XsH−1)2(H2O)4]·6H2O (XsH−1: xanthosinate) was isolated from the reaction of nickel carbonate with xanthosine in aqueous solution. The octahedral coordination is supported by the reflectance measurements. Single-crystal X-ray diffraction studies show that the crystals belong to the triclinic P1 space group, with a = 7.152(1), b = 8.830(1),c = 13.783(1) Å, α = 82.024(1)°, β = 86.155(1)°, γ = 70.900(1)°, and D = 1.643 mg/m3, forZ = 1. Nickel is six coordinate with four water molecules, and two N7 atoms from xanthosinato ligands. A complicated hydrogen-bonding network is present, all possible donors taking part in it.
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  • 94
    ISSN: 1572-8854
    Keywords: manganese ; pyridine-2-thiolate ; bis(diphenylphosphino)methane ; carbonyl ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The dimeric complex [Mn2(μ-pyS)2(CO)6] (1) reacted with 2 M equivalents of both PPh3 and PHPh2 to give the respective monomeric phosphine complexes [Mn(pyS)(L)(CO)3][L = PPh3 (2) and PHPh2 (3)]; with 4 M equivalents of dppm, it yielded the complex [Mn(pyS)(η1-dppm)2(CO)2](4). An X-ray structure determination of 4 shows that it crystallizes in the monoclinic space group P21/n with a = 11.027(3), b = 24.984(7), c = 18.379(5) Å, β = 99.870(8)°, V = 4988(2) Å3, and Z = 4. The complex has an octahedral geometry with the chelating pyS ligand and two CO groups occupying the equatorial sites and the two monodentate dppm ligands lying in the trans positions.
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  • 95
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    Journal of chemical crystallography 29 (1999), S. 1037-1041 
    ISSN: 1572-8854
    Keywords: crystal structure ; imidazolidine ; triazene ; bis-triazene ; methoxy substituent ; π-π stacking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of 1,3-di-2-[(4-methoxyphenyl)-1-diazenyl]imidazolidine (1) has been determined by single crystal X-ray diffraction analysis. This novel bis-triazene assumes a close-to planar structure with the aryltriazene moieties aligned in diametrically opposed directions, unlike many other previously reported bis-triazenes, which assume a folded structure. The structure of 1 is compared with the closely related, non-cyclic bis-triazene analogue (2), and also compared with the structure of the simple mono-triazene (3). Crystal data: 1 C17H20N6O2, monoclinic, space group C2/c, a = 34.948(3), b = 5.925(5), c = 8.1225(6) Å, β = 100.8420(10)°, and V = 1652.0(2) Å3, for Z = 4.
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  • 96
    ISSN: 1572-8854
    Keywords: crystal structure ; tritylaziridine ; acrylate ; spectroscopic features
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of 2-{(R)-1-Hydroxy-1-[(2S)-1-tritylaziridin-2-y1] methy1}acrylate is described. Crystal data: C26H25NO3, orthorhombic, space group P212121, a = 9.6954(5), b = 13.1458(5), c = 16.7885(7) Å, V = 2139.8(2) Å3, Z = 4. The (R,S) diastereomer shows an intramolecular hydrogen bonding N···H—O under formation of a five-membered ring with N···O distance of 2.664 Å. IR, 1H NMR and 13C NMR data are discussed. The 1H NMR of the (R,S) diastereomer shows a singlet- whereas the (S,S) diastereomer exhibits a doublet-pattern for the hydroxyl proton.
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  • 97
    ISSN: 1572-8854
    Keywords: absolute configuration ; asymmetric synthesis ; azabicyclo[3.2.1]octadiene ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallized in space group P21 with a = 12.647(8), b = 14.542(4), c = 17.077(16) Å, β = 97.51(6)°, and D calc = 1.143 mg/m3 for Z = 4. There are two chemically-equivalent C27H41NO8Si molecules in the crystallographic asymmetric unit. Each contains three chiral centers, one of known absolute configuration based upon the (R)-pantolactone,—CH*—CMe2—CH2—O—CO—, moiety. The structural study was greatly complicated by disorder of an —OSiMe2(t-Bu) group in one molecule.
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  • 98
    ISSN: 1572-8862
    Keywords: Rhenium ; dirhenium complexes ; rhenium-rhenium multiple bonds ; isocyanide ligands ; carbonyl ligand ; structural isomers ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The monocarbonyl complex Re2Cl4(µ-dppm)2(CO) reacts with xylyl isocyanide in acetonitrile to afford the bioctahedral complex (CO)Cl2Re(µ-dppm)2 ReCl2(CNxyl), 2b. This is a different structural isomer from the edge-sharing bioctahedral complex Cl2Re(µ-Cl)(µ-dppm)2ReCl(CNxyl) or this same stoichiometry which A formed when acetone is be reaction solvent. The complex2b reacts with a further equivalent of xylNC in the presence of TlO3SCF3 in dichloromethane to form a red complex of composition [Re2Cl3(µ-dppm)2 (CO)(CNxyl)2]O3SCF3. 3, which has the open bioctahedral structure [(xylNC)2ClRe(µ-dppm)2ReCl2(CO)]O3SCF3. This is a third isomeric form of this dirhenium cation: the previously isolated green and yellow forms have edge-sharing bioctahedral structures. Crystal data for3 at 295 K: orthorhombic space group Pbca (No. 61) witha=22.654(5) Å,b=22.717(4) Å,c=27.324(4) A,V= 14061(7) Å3, andZ = 8. The structure was refined to R = 0.059 (R, = 0.134 ) for 14164 data. The Re-Re distance is 2.3833(8) Å.
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  • 99
    ISSN: 1572-8862
    Keywords: Ruthenium ; thioether macrocycle ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of a mixture of cis-3,7,11-trimethyl-1,5,9-trithiacyclododecane, cis-Me312S3, 1 and trans-3,7,11-trimethyl-l,5,9-trithiacyclododecane, trans-Me312S3, 2, with Ru6(CO)17(μ 6-C), 3, yielded three new cluster compounds Ru6(CO)13(μ-η3-cis-SCH2CHMe(CH2SCH2CHMe)2CH2)(μ 6-C) 4, and two isomers of Ru6(CO)13(μ-η3-cis-SCH2CHMe(CH2SCH2CHMe)2CH2)(μ 6-C) 5a and 5b. The molecular structures of 4 and 5b were established by single crystal X-ray diffraction analyses. In both complexes, the macrocycles have adopted tridentate coordination with one of the sulfur atoms in a bridging position. Two carbonyl ligands occupy bridging positions in each compound. Crystal Data for 4·Me2CO: space group=P21/n, a=11.295(1) Å, b=17.547(3) Å, c=20.318(3) Å, β=93.71(1)°, Z=4, 2900 reflections, R=0.025. Crystal Data for 5b·1.5 C6H6: space group=Pbca, a=31.8900(8) Å, b=23.4330(6) Å, c=21.6240(4) Å, Z=16, 12163 reflections, R=0.040.
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  • 100
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    Journal of thermal analysis and calorimetry 50 (1997), S. 569-586 
    ISSN: 1572-8943
    Keywords: crystal structure ; metal(II) picolinate and quinaldinate ; thermal degradation of imidazole and pyrazole complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Complexes of the type M(Pa)2(HAz)2 and M(QA)2(HAz)2 (M=cobalt(II) and nickel(II); HPa=picolinic acid, HQa=quinaldic acid; HAz=azoles like imidazole (Him), pyrazole (HPz), benzimidazole (HBzIm) etc.) show a similar thermal behaviour. In the first step of decomposition the corresponding azolinium picolinates or quinaldinates (H2AzPa, H2AzQa) are split off with formation of polymeric mixed ligand complexes M(Pa)(Az) or M(Qa)(Az). X-ray analysis of Co(Qa)2(HBzIm)2 XIIIa illustrates a proton transfer and a subsequent thermal removal of benzimidazolinium quinaldinate (H2BzImQa): Hydrogen bridges from pyrrole nitrogen of the benzimidazole to the non-coordinated oxygen of the quinaldinate predetermine the thermal initiated proton transfer. The high volatility of the heterocyclic acids and the nitrogen coordination are responsible for the formation of the mixed ligand complex Co(Qa)(BzIm) XIVa. Exceptions are the complexes M(Pa)2(HPz)2 XIa-b and M(Qa)2(HIm)2 XVIIa-b. Pyrazole is eliminated from the complexes XIa-b with formation of the solvent-free inner complex M(Pa)2 XIIa-b. From compounds XVIIIa-b quinaldic acid or their decomposition products are split off and a high temperature modification of M(Im)2 XVIIIa-b is formed at elevated temperature. XVIIIa-b are decomposed to the cyanides M(CN)2 similarly to the thermal behaviour of Cu(Im). In the first step the thermal degradation of imidazole and pyrazole adducts of copper(II) picolinates and quinaldinates is characterized by the elimination of azoles. The reason for this thermal behaviour is the weaker coordination of the azole heterocycles in copper chelate compounds.
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