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  • 1
    Electronic Resource
    Electronic Resource
    Low-temperature redetermination of the structures of three gold compounds (1992)
    Springer
    Journal of chemical crystallography 22 (1992), S. 397-401 
    Details
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of KAuCl4 (1), previously reported in the non-centrosymmetric space groupPc, has been successfully redetermined inP21/c; the gold atoms occupy centers of symmetry. The scatter of chemically equivalent bond lengths is greatly reduced and the precision of bond lengths and angles correspondingly improved. The structure of Cl3PAuCl (2), determined in 1962, has been redetermined to obtain more precise values for molecular dimensions; new values are Au-P 2.198, Au-Cl 2.279(2)Å. Short Au⋯Au contacts (3.081 Å) connect the molecules in chains. The structure of Ph3PSAuCl (3), for which a very long Au-Cl bond (2.555 Å) had been reported, was redetermined and gave a normal Au-Cl bond length of 2.265(2) Å; the previous value was probably a typing error. All redeterminations were carried out at −95°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01195399
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  • 2
    Electronic Resource
    Electronic Resource
    Trinuclear Gold(I) Complexes with Various Coordination Modes of N,N-dimethyldithiocarbamate (2000)
    Springer
    Journal of cluster science 11 (2000), S. 153-167 
    Details
    ISSN: 1572-8862
    Keywords: gold ; dithiocarbamate ; tris(diphenylphosphino)methane ; gold–gold interactions
    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 compounds [Au3(S2CNMe2)3{μ 3-(PPh2)3CH]} (1) and [Au3(S2CNMe2)(μ-S2CNMe2){μ 3-(PPh2)3CH}]ClO4 (2) are obtained by reaction of [Au3Cl3{μ 3-(PPh2)3CH}] with three equivalents of sodium dimethyldithiocarbamate or two equivalents of the same reagent in the presence of excess NaClO4. Reaction of 2 with the group 11 metal complexes [AuCl(tht)], CuCl or [Au(C6F5)(tht)] takes place with displacement of [M(S2CNMe2)]n (M=Cu, Au) and formation of the new complexes [Au3X(μ-S2CNMe2){μ 3-(PPh2)3CH}]ClO4 (X=Cl (3), X=C6F5 (4)); further reaction of 3 with [Ag(OClO3)(tht)] (tht=tetrahydrothiophene) affords the dicationic species [Au3(μ-S2CNMe2){μ 3-(PPh2)3CH}(tht)](ClO4)2 (5). Treatment of [Au3Cl3{μ 3-(PPh2)3CH}] with one equivalent of NaS2CNMe2 allows the substitution of only one chlorine atom, giving rise to the complex [Au3Cl2(S2CNMe2){μ 3-(PPh2)3CH}] (6), in which the dithiocarbamate ligand acts as monodentate rather than bidentate bridging as observed in compounds 3–5. The crystal structures of complexes 1 and 2 have been established by X-ray diffraction studies and show close gold–gold contacts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009068916229
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  • 3
    Electronic Resource
    Electronic Resource
    MarkSim (2000)
    Springer
    Semigroup forum 92 (2000), S. 445-453 
    Details
    ISSN: 1432-2137
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 2 ) and evaluates the model parameters for that point. The application currently contains surfaces for Latin America and Africa, and other regions will later be added. Use of the software is demonstrated by generating daily weather data files for running one of the DSSAT crop models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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  • 4
    Electronic Resource
    Electronic Resource
    The use of geographical information systems in biodiversity exploration and conservation (1997)
    Springer
    Biodiversity and conservation 6 (1997), S. 947-958 
    Details
    ISSN: 1572-9710
    Keywords: geographic information systems ; species distribution ; climate mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We describe a method for applying geographical information systems (GIS) to exploring biodiversity in the wild relatives of crop species and illustrate its application to the wild common bean (Phaseolus vulgaris L.). We use the latitude, longitude and altitude of the location of origin of each accession in a germplasm collection of wild P. vulgaris, along with long-term monthly mean values of rainfall, temperature and diurnal temperature range for about 10000 stations throughout Latin America to produce maps indicating areas with ‘bean-favouring’ climates. In a test case, these identify a new suitable area in Colombia where wild P. vulgaris has been reported in the literature, and two more areas which are strong candidates on other grounds. Dividing the ‘bean-favouring’ climates into clusters identifies areas that have similar climates but are geographically remote, where we can expect to find wild beans with similar ecological adaptation. We discuss the implications of these results for conserving and improving the common bean, and the application of these methods to other species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018311513176
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and Structure of a p-Terphenoquinone and Paramagnetic Species Derived TherefromPart 12 of ‘Quinones’. Part 11: [1]. (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 1739-1751 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3,5,3″,5″-Tetra(tert-butyl)-p-terphenoquinone (12b) was synthesized and characterized by its spectroscopic and X-ray structural data. The ground state of 12b is singlet with a strong contribution of a biradical structure. Paramagnetic derivative of 12b, such as the semiquinone radical anion (12bτ) and its O-protonated form, the phenoxy radical (18), were studied by ESR and ENDOR spectroscopy.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760430
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  • 6
    Electronic Resource
    Electronic Resource
    Gold complexes with selenium ligands, I. Preparation and crystal structures of phenylselenolato-gold(I) complexes (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1975-1978 
    Details
    ISSN: 0009-2940
    Keywords: Gold complexes ; Selenium ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Triphenylphosphine)phenylselenolatogold(I), Ph3PAuSePh (1), and the corresponding dppm derivative, [(dppm)(AuSePh)2] (3), are prepared from Me3SiSePh and the appropriate (phosphine)chlorogold(I) complex. The reaction between Ph3PAuCl, Ph2Se2 and AgSbF6 leads to the salt [(Ph3PAu)2SePh]+SbF-6 (2), with a bridging PhSe ligand. X-ray structure analyses of 1 and 2 confirm the expected linear geometry at gold and reveal short Au-Au contacts; both compounds may thus be regarded as loose dimers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231008
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  • 7
    Electronic Resource
    Electronic Resource
    Cyclophanes, XXXV. DNMR, molecular mechanics, and crystal structures of 2,11-dithia[3.3]orthometacyclophane and 2,11-dithia[3.3]orthoparacyclophane (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2381-2386 
    Details
    ISSN: 0009-2940
    Keywords: Dithiacyclophanes ; DNMR ; Molecular mechanics ; Cyclophanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of 2,11-dithia[3,3]orthometacyclophane (5) and 2,11-dithia[3,3]orthoparacyclophane (6) by dithiol-dibromide coupling are described. Whereas the yield of 5 is not significantly affected by the substrate pairing, that of 6 is. Both compounds exhibit a temperature-dependent 1H-NMR spectrum. An energy barrier of 11.0 ± 0.2 kcal/mol (45.7 ± 0.8 kJ/mol) has been calculated for 5, but that of 6 was too low to be determined. Slightly contrasting results were obtained from two different molecular mechanics programs for the relative energies of the six limiting conformations of 5. Crystal structure determinations of 5 and 6 have been carried out, and the conformational behavior of 5 and 6 in solution and in the solid state is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231221
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  • 8
    Electronic Resource
    Electronic Resource
    Darstellung und Kristallstrukturen einiger mit N,N'-Dimethylharnstoff verbrückter Diphosphorverbindungen; NMR-Untersuchung einer λ4P+λ4P+-Diphosphorverbindung (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 35-43 
    Details
    ISSN: 0009-2940
    Keywords: Diphosphorus compounds, mixed valence λ4P+λ4P+, PP-bonded ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation and Single-Crystal X-ray Structure Investigations of some N,N′-Dimethylurea-Bridged Diphosphorus Compounds: NMR Studies of a λ4P+ λ4P+ -Diphosphorus CompoundThe synthesis of N,N′-dimethylurea-bridged diphosphorus compounds involving the structural elements λ3Pλ4P+ (3b, 3c, and 7) and λ4P+λ4P+ (4 and 8) is described. The salts 4 and 8 were obtained by methylation of the λ3Pλ4P+ compounds 3c and 7 with MeOSO2CF3. The λ3P atom in 3c and 7 coordinates to tungsten(0) with formation of the ionic pentacarbonyl derivatives 9 and 10. The NMR spectra of the diphosphonium salt 4 were completely analyzed using NOE and 2D shift correlation experiments (13C,1H and 31P,1H). The single crystal X-ray structure determinations of 3b and 9 are reported. 3b found to crystallize as a hemisolvate with dichloromethane. The RR/SS diastereomer is present in the crystal. The PP distance amounts to 219.1 pm. Both phosphorus atoms interact weakly with the chloride ion (293, 312 pm). 9 crystallizes as a hemisolvate with toluene, the RS/SR diastereomer being present. A PP distance of 224.7 pm and weak interactions between the phosphorus atoms and an oxygen atom of the anion (305, 308 pm) are found.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230108
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  • 9
    Electronic Resource
    Electronic Resource
    Neue planare π-Systeme, II1) Zur Darstellung und Struktur von Tetrakis(phenylethinyl)ethen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1471-1475 
    Details
    ISSN: 0009-2940
    Keywords: Polyacetylenes ; Cross conjugation ; Alkenes, tetraethynyl ; π-Systems, planar ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Planar π-Systems, II1). - On the Preparation and Structure of Tetrakis(phenylethynyl)etheneThe preparation of tetrakis(phenylethynyl)ethene (1 b) has been repeated. Among various routes to this highly unsaturated cross-conjugated π-system, the dimerization of bromide 2 via the carbene 3 is the most simple one. Full spectroscopic data for 1 b are reported for the first time, as is its X-ray structural analysis at - 95°C.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240623
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  • 10
    Electronic Resource
    Electronic Resource
    Neue Dienophile und Diene, III. Über die Addition von Cyanacetylen an [2.2]Paracyclophan (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2015-2022 
    Details
    ISSN: 0009-2940
    Keywords: Dienophiles, triple-bond ; Cyclobutadiene ; Cyclophanes ; Diels-Alder adducts ; Nenitzescu systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Dienophiles and Dienes, III.  -  On the Addition of Cyanoacetylene to [2.2]ParacyclophaneHeating a benzene solution of [2.2]paracyclophane (2) in the presence of excess cyanoacetylene (1b) at 160°C in a sealed ampoule provides the novel 2:1-addition product 10, as well as the previously obtained cycloadducts 7-9. It is suggested that these Nenitzescu hydrocarbon systems are formed via the cyclobutadiene intermediates 17 and 18. This hypothesis is supported by the isolation of the side-products 1,2,4-and 1,2,3-tricyanobenzene (11 and 12). When a mixture of 7 and 8 is pyrolyzed at 220°C the novel dihydronaphthalene 24 is formed; the mechanism of this isomerization is discussed. The structures of 10 and 24 were confirmed by X-ray structure determination.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231012
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