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  • Articles  (660)
  • Triticum aestivum  (229)
  • crystal structure  (220)
  • fish  (211)
  • Springer  (660)
  • 1995-1999  (660)
  • 1
    ISSN: 1432-2145
    Keywords: Key words Male sterility ; Starch ; Triticum aestivum ; Water stress ; Anther ; Pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Water deficit during meiosis in microspore mother cells of wheat (Triticum aestivum L.) induces male sterility, which reduces grain yield. In plants stressed during meiosis and then re-watered, division of microspore mother cells seems to proceed normally, but subsequent pollen development is arrested. Stress-affected anthers generally lack starch. We employed light microscopy in conjunction with histochemistry to compare the developmental anatomy of water-stress-affected and normal anthers. The earliest effects of stress, detectable between meiosis and young microspore stages, were the degeneration of meiocytes, loss of orientation of the reproductive cells, and abnormal vacuolization of tapetal cells. Other effects observed during subsequent developmental stages were deposition of starch in the connective tissue where it is normally not present, hypertrophy of the middle layer or endothecial cells, and deposition of sporopollenin-like substances in the anther loculus. The resulting pollen grains lacked both starch and intine. These results suggest that abnormal degeneration of the tapetum in water-stressed anthers coupled with a loss of orientation of the reproductive cells could be part of early events leading to abortion of microspores.
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  • 2
    ISSN: 1432-1890
    Keywords: Key words Arbuscular mycorrhiza ; Hordeum vulgare ; Triticum aestivum ; Glomus intraradices ; Mycorrhiza-helper bacteria ; Secondary compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Colonization of Hordeum vulgare L. cv. Salome (barley)and Triticum aestivum L. cv. Caprimus (wheat) roots by the arbuscular mycorrhizal fungus Glomus intraradices Schenck & Smith leads to de novo synthesis of isoprenoid cyclohexenone derivatives with blumenin [9-O-(2′-O-β-glucuronosyl)-β-glucopyranoside of 6-(3-hydroxybutyl)-1,1,5-trimethyl-4-cyclohexen-3-one] as the major constituent and to transient accumulation of hydroxycinnamate amides (4-coumaroylagmatine and -putrescine). Accumulation of these compounds in mycorrhizal wheat roots started 2 weeks after sowing together with the onset of arbuscule formation and proceeded with mycorrhizal progression. Highest levels were reached in 3- to 4-week-old secondary roots (root branches of first and higher order) characterized by the formation of vesicles. In the final developmental stages, the fungus produced massive amounts of spores, enclosing the stele of older root parts (older than 5 weeks) characterized by cortical death. In these root parts, the secondary compounds were detected in trace amounts only, indicating that they were located in the cortical tissues. Some rhizosphere bacteria tested, i.e. Agrobacterium rhizogenes, Pseudomonas fluorescens, and Rhizobium leguminosarum, markedly stimulated both fungal root colonization and blumenin accumulation, thus, acting as mycorrhiza-helper bacteria (MHB). Application of blumenin itself strongly inhibited fungal colonization and arbuscule formation at early stages of mycorrhiza development. This was associated with a markedly reduced accumulation of the hydroxycinnamate amides 4-coumaroylputrescine and -agmatine. The results suggest that both the isoprenoid and the phenylpropanoid metabolism are closely linked to the developmental stage and the extent of fungal colonization. Their possible involvement in the regulation of mycorrhiza development is discussed.
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  • 3
    ISSN: 1432-1890
    Keywords: Key words Glomus mosseae ; Hydroponics ; Nitrate uptake ; Root respiration ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Oxygen and CO2 fluxes were measured in hydroponically grown mycorrhizal and non-mycorrhizal Triticum aestivum L. cv. Hano roots. The NO3 – uptake of the plants was used to estimate the amount of root respiration attributable to ion uptake. Plants were grown at 4 mM N and 10 μM P, where a total and viable mycorrhizal root colonisation of 48% and 18%, respectively, by Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe (BEG 107) was observed. The O2 consumption and NO3 – uptake rates were similar and the CO2 release was higher in mycorrhizal than in non-mycorrhizal wheat. This resulted in a significantly higher respiratory quotient (RQ, mol CO2 mol–1 O2) in mycorrhizal (1.27±0.13) than in non-mycorrhizal (0.79±0.05) wheat. As the biomass and N and P concentrations in mycorrhizal and non-mycorrhizal wheat were the same, the higher RQ resulted from the mycorrhizal colonisation and not differences in nutrition per se.
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  • 4
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    Plant cell reports 16 (1997), S. 663-667 
    ISSN: 1432-203X
    Keywords: Key words Embryogenesis ; Ovule culture ; Triticum aestivum ; Zygote
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ovules of the wheat breeding line Veery #5 were excised and transferred to culture within 24 h after pollination. When ovules were cultured on Phytagel-solidified medium, and the pericarp removed exclusively at the micropylar tip and the abaxial side, zygotes from up to 79.2% of the ovules underwent embryogenesis with the same developmental pattern as found in planta. Embryos from more than 50% of the cultured ovules germinated when transferred to regeneration medium. More than 100 plantlets were randomly chosen for transfer to soil, all of which developed to phenotypically normal and fertile plants. With this system, the entire process of zygotic embryogenesis can be studied using living material. Furthermore, the method could be used as an embryo rescue technique for plant breeding purposes.
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  • 5
    ISSN: 1432-203X
    Keywords: Key words Abscisic acid ; Anther culture ; Light ; Metallothionein ; Pollen embryogenesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cloned cDNA to the wheat (Triticum aestivum) early cysteine-labeled metallothionein has many characteristics of a molecular marker for pollen embryogenesis in this plant. This transcript was not detected in uninucleate microspores at the time of culture or in pollen at any stage during normal ontogeny; its mRNA did begin to increase in embryogenic microspores within 6 h of culture, peaked at around 24 h, declined, then leveled off through the 21-day-old embryoid stage. Additionally, the accumulation of the embryoid-abundant EcMt gene transcript showed a direct and positive correlation with an increase of ABA in embryogenic microspores and developing pollen embryoids. Irradiating cultures with high intensity white light or with far-red, or blue light, suppressed EcMt transcript accumulation and the ability of microspores to form embryoids; however, light did not affect ABA concentrations during the early stages of culture. These results suggest that although a promoter of pollen embryogenesis in bread wheat, ABA alone cannot maintain the sporophytic differentiation of microspores subjected to inhibitory regimes of light in vitro. Whether or not light acts directly or indirectly in suppressing EcMt gene expression and pollen embryogenesis remains unknown.
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  • 6
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    Theoretical and applied genetics 91 (1995), S. 618-626 
    ISSN: 1432-2242
    Keywords: Comparative maps ; Deletion lines ; Molecular-tagged chromosome regions (MTCRs) ; Triticum aestivum ; Hordeum vulgare
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Comparative genetic maps among the Triticeae or Gramineae provide the possibility for combining the genetics, mapping information and molecular-marker resources between different species. Dense genetic linkage maps of wheat and barley, which have a common array of molecular markers, along with deletion-based chromosome maps of Triticum aestivum L. will facilitate the construction of an integrated molecular marker-based map for the Triticeae. A set of 21 cDNA and genomic DNA clones, which had previously been used to map barley chromosome 1 (7H), were used to physically map wheat chromosomes 7A, 7B and 7D. A comparative map was constructed to estimate the degree of linkage conservation and synteny of chromosome segments between the group 7 chromosomes of the two species. The results reveal extensive homoeologies between these chromosomes, and the first evidence for an interstitial inversion on the short arm of a barley chromosome compared to the wheat homoeologue has been obtained. In a cytogenetically-based physical map of group 7 chromosomes that contain restriction-fragment-length polymorphic DNA (RFLP) and random amplified polymorphic DNA (RAPD) markers, the marker density in the most distal third of the chromosome arms was two-times higher than in the proximal region. The recombination rate in the distal third of each arm appears to be 8–15 times greater than in the proximal third of each arm where recombination of wheat chromosomes is suppressed.
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  • 7
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    Theoretical and applied genetics 92 (1996), S. 163-169 
    ISSN: 1432-2242
    Keywords: Bread wheat ; Triticum aestivum ; Culture medium ; Embryogenic callus ; Plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forty-eight bread wheat (Triticum aestivum L.) released cultivars and elite advanced lines were evaluated for their ability to produce embryogenic callus using three different media. Basal N6 medium supplemented with dicamba (E1), MS medium containing 2,4-D (E3) or MS medium containing 2,4-D plus different amino acids (E5) were used for callus initiation and maintenance. Plant regeneration was achieved on basal MS medium with indole-3-acetic acid (IAA) and 6-benzylamino purine (BAP) and rooting on MS with 1-naphthaleneacetic acid (NAA). Percentage regeneration varied widely with both genotype and initiation medium, with values ranging from 2% to 94%. The number of plantlets produced per embryo ranged from 6 to 42. Thirteen genotypes showed at least 50% regeneration after culture on E5 medium; 3 genotypes after culture on E3 initiation medium and 1 after initiation on E1. After four subcultures, over a 16-week period, 41 genotypes (85%) lost their ability to regenerate plants while the remaining 7 lines (15%) retained plant regeneration potential but at reduced levels. E3 medium was found to be the best for maintaining regeneration potential after four subcultures.
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  • 8
    ISSN: 1432-2242
    Keywords: Key words  Wheat ; Triticum aestivum ; Triticum peregrinum ; Chromosome addition lines ; RFLPs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   Analyses of RFLPs, isozymes, morphological markers and chromosome pairing were used to isolate 12 Triticum aestivum cv Chinese Spring (genomes A, B, and D)-T. peregrinum (genomes Sv and Uv) disomic chromosome addition lines. The evidence obtained indicates that each of the 12 lines contains an intact pair of T. peregrinum chromosomes. One monosomic addition line, believed to contain an intact 6Sv chromosome, was also isolated. A CS-7Uv chromosome addition line was not obtained. Syntenic relationships in common with the standard Triticeae arrangement were found for five of the seven Sv genome chromosomes. The exceptions were 4Sv and 7Sv. A reciprocal translocation exists between 4Sl and 7Sl in T. longissimum and evidence was obtained that the same translocation exists in T. peregrinum. In contrast, evidence for syntenic relationships in common with the standard Triticeae arrangements were found for only one Uv chromosome of T. peregrinum; namely, chromosome 2Uv. All other Uv genome chromosomes are involved in at least one translocation, and the same translocations were found in the U genome of T. umbellulatum. Evidence was also obtained indicating that the centromeric regions of 4U and 4Uv are homoeologous to the centromeric regions of Triticeae homoeologous group-6 chromosomes, that the centromeric regions of 6U and 6Uv are homoeologous to the centromeric regions of group-4 chromosomes, and that 4U and 4Uv are more closely related overall to Triticeae homoeologous group-6 chromosomes than they are to group-4 chromosomes.
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  • 9
    ISSN: 1432-2242
    Keywords: Key words Triticum spelta ; Triticum aestivum ; SDS-PAGE ; Acid-PAGE ; Seed storage proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Seed storage proteins of a few selected spelt forms and crosses have already been electrophoretically analysed by SDS-PAGE and acid-PAGE and compared with a few winter wheat cultivars. In the analyses presented here further important Central European spelt varieties were included, as well as modern winter wheat cultivars which were chosen as standards. In this study gliadin and glutenin band patterns of modern Central European winter wheat cultivars were analysed, in particular for a comparison with spelt varieties. An improved differentiation within and between the two species was obtained.
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  • 10
    ISSN: 1432-2242
    Keywords: Key words Fluorescence in situ hybridization ; Translocation ; WSMV resistance ; Thinopyrum intermedium ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   Thinopyrum intermedium is a promising source of resistance to wheat streak mosaic virus (WSMV), a devastating disease of wheat. Three wheat germplasm lines possessing resistance to WSMV, derived from Triticum aestivum×Th. intermedium crosses, are analyzed by C-banding and genomic in situ hybridization (GISH) to determine the amount and location of alien chromatin in the transfer lines. Line CI15092 was confirmed as a disomic substitution line in which wheat chromosome 4A was replaced by Th. intermedium chromosome 4Ai?2. The other two lines, CI17766 and A29-13-3, carry an identical Robertsonian translocation chromosome in which the complete short arm of chromosome 4Ai?2 was transferred to the long arm of wheat chromosome 4A. Fluorescence in situ hybridization (FISH) using ABD genomic DNA from wheat as a probe and S genomic DNA from Pseudoroegneria stipifolia as the blocker, and vice versa, revealed that the entire short arm of the translocation was derived from the short arm of chromosome 4Ai?2 and the breakpoint was located at the centromere. Chromosomal arm ratios (L/S) of 2.12 in CI17766 and 2.15 in A29-13-3 showed that the translocated chromosome is submetacentric. This translocated chromosome is designated as T4AL ⋅ 4Ai?2S as suggested by Friebe et al. (1991).
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  • 11
    ISSN: 1432-2242
    Keywords: Key words Aegilops markgrafii ; Triticum aestivum ; Addition lines ; Chromosome markers ; Homoeology ; Wheat ; Wheat microsatellites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We describe the use of wheat microsatellites for the discrimination of Aegilops markgrafii chromosomes. Twenty out of eighty eight wheat microsatellites (WMS) tested were able to distinguish Triticum aestivum-Ae. markgrafii addition lines. Six, three, three, one and six of 18 WMS can be used as markers for single Ae. markgrafii chromosomes B, C, D, F and G, respectively. Addition line A is not available but additional bands, appearing only in Ae. markgrafii and the T. aestivum-Ae. markgrafii amphiploid and not in any of the available addition lines, indicate that three WMS detect markers for Ae. markgrafii chromosomes A. Addition line E could not be detected by any of the WMS markers applied, although the 20 WMS represented all the homologous groups of wheat. All three WMS located on the short arm of group-2 chromosomes were located on Ae. markgrafii chromosome B; three of four WMS, located on the long arm of wheat group-2 chromosomes, were specific to Ae. markgrafii chromosome G and three of four WMS, specific to group-5 chromosomes, were markers for Ae. markgrafii chromosome C, indicating the homoeology of these wheat chromosome arms with the respective Ae. markgrafii chromosomes.
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  • 12
    ISSN: 1432-2242
    Keywords: Key words Aegilops tauschii ; Triticum aestivum ; Genetic mapping ; Molecular markers ; Agronomically important genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Aegilops tauschii is the diploid D-genome progenitor of bread wheat (Triticum aestivum L. em Thell, 2n=6x=42, AABBDD). A genetic linkage map of the Ae. tauschii genome was constructed, composed of 546 loci. One hundred and thirty two loci (24%) gave distorted segregation ratios. Sixty nine probes (13%) detected multiple copies in the genome. One hundred and twenty three of the 157 markers shared between the Ae. tauschii genetic and T. aestivum physical maps were colinear. The discrepancy in the order of five markers on the Ae. tauschii 3DS genetic map versus the T. aestivum 3D physical map indicated a possible inversion. Further work is needed to verify the discrepancies in the order of markers on the 4D, 5D and 7D Ae. tauschii genetic maps versus the physical and genetic maps of T. aestivum. Using common markers, 164 agronomically important genes were assigned to specific regions on Ae. tauschii linkage, and T. aestivum physical, maps. This information may be useful for map-based cloning and marker-assisted plant breeding.
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  • 13
    ISSN: 1432-2242
    Keywords: Key words Aegilops ventricosa ; Triticum aestivum ; Mayetiola destructor ; Hessian fly ; Resistance gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A new Hessian fly (Mayetiola destructor) resistance gene from Aegilops ventricosa and its transfer to hexaploid wheat is described. The 4D(4Mv) substitution line H-93-33 derived from the cross [(Triticum turgidum H-1-1×Aegilops ventricosa no. 11)×Triticum aestivum H-10-15] was highly resistant to the Spanish population tested. Resistance seemed to be inherited as a single dominant factor in the F2 generation resulting from a cross of H-93-33 with its susceptible parent (H-10-15). Resistance in Ae. venticosa no. 10 was located on chromosome 4Mv using Mv wheat/Ae. ventricosa addition lines. The resistance gene transferred from Ae. ventricosa no. 11 to H-93-33 (H27) is allelic with respect to that of Ae. ventricosa no. 10 and is non-allelic with respect to the genes H3 and H6 from Monon and Caldwell respectively. The assignment of H27 gene to chromosome 4Mv is further supported by its linkage to a gene encoding isozyme Acph-Mv1, previously located on chromosome 4Mv in the line H-93-33. A new marker from homoeologous chromosome group 4 (Amp-Mv2) present in H-93-33 and the 4Mv addition line is described.
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  • 14
    ISSN: 1432-2242
    Keywords: Key words Aegilops markgrafii ; Triticum aestivum ; RAPD ; Addition lines ; Leaf rust ; Powdery mildew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Aegilops markgrafii contains resistance genes to powdery mildew, leaf rust and stripe rust, and also has high crude protein and lysine contents, which can be useful for wheat improvement. These important traits are localized on different chromosomes. Disomic Triticum aestivum-Ae. markgrafii addition lines and euploid introgression lines showing leaf-rust and powdery mildew resistance were screened with RAPDs to detect chromosome-specific markers which can accelerate the breeding process. RAPD markers for all six available disomic addition lines were obtained. The additional chromosomes B, C, D, E, F and G were identified by three, three, three, two, one and seven primers, respectively. All three chromosome-B-specific RAPD markers demonstrated the presence of alien chromatin in the leaf-rust-resistant 42-chromosome introgression lines as well as in the segregating progeny. The three chromosome-C-identifying primers also demonstrated the presence of that chromosome in powdery mildew-resistant euploid introgression lines. The substitution lines (5A)5C and (5D)5C with different genetic backgrounds for both parents, in comparison to the lines mentioned above, showed the chromosome C-specific band with only two of the three primers. The chromosome F-specific primer and a primer evident on all the Ae. markgrafii chromosomes analysed did not generate the expected fragments on the chromosome Fdel addition line, indicating that the markers are located on the deleted part of chromosome F.
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  • 15
    ISSN: 1432-2242
    Keywords: Key words Wheat ; Triticum aestivum ; Transformation ; Nuclear male sterility ; DNA-integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Nuclear male sterility within Triticum aestivum is considered as the ideal basis for the development of a hybridization system for wheat. We engineered nuclear male sterility in wheat by introducing the barnase gene under the control of tapetum-specific promoters derived from corn and rice. A biolistic-mediated transformation method, based on the use of the poly(ADP-ribose)polymerase inhibitor niacinamide, was set up which enriched for low-copy integrations (1–3 copies). Most of these copies were not linked and segregated in the next generation.
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  • 16
    ISSN: 1432-2242
    Keywords: Key words Aegilops triuncialis ; Triticum aestivum ; Heterodera avenae ; Cereal cyst nematode ; Resistance gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The cereal cyst nematode (Heterodera avenae) is an important root parasite of common wheat. A high level of resistance was transferred to wheat from Aegilops triuncialis (TR lines) using the cross [(T. turgidum×Ae. triuncialis)×T. aestivum]. Low fertility (3–5 viable kernels per plant) was observed during the process but the surviving hybrid plants were highly vigorous. To obtain stable resistant lines further crosses to T. aestivum were performed. The resistance in TR lines seems to be transferred from the C genome of Ae. triuncialis (genomes CCUU). Ae. triuncialis was highly resistant to the two Spanish populations of H. avenae tested, as well as to four French races and two Swedish populations. The histological analysis showed a hypersensitive reaction in the roots of a resistant TR line inoculated with the Ha71 pathotype of H. avenae, whereas well-formed syncytia were observed in the roots of the susceptible control. Resistance to the H. avenae Ha71 pathotype seemed to be inherited as determined by a single dominant factor in the crosses between resistant TR lines and susceptible cultivars.
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  • 17
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    Cellular and molecular life sciences 51 (1995), S. 768-774 
    ISSN: 1420-9071
    Keywords: Cortisol ; stress ; heat ; Antarctic ; fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Radioimmunoassay was used to determine levels of the stress-inducible glucocorticoid, cortisol, circulating in the plasma of the extremely stenothermal Antarctic fishPagothenia borchgrevinki at rest and after heat stress. Fish sampled immediately after capture (−1.9°C) had low cortisol levels (10.4±1.4 ng ml−1, mean±SEM) as did fish which were laboratory rested for 3 days. Sudden exposure to 5°C (48h) resulted in a peak cortisol value after 3 h (69.9±6.8 ng ml−1) whereas exposure to 8°C (6h) resulted in a peak value after 1 h (73.5±8.0 ng ml−1). At both temperatures levels remained significantly elevated (p〈0.05) for the entire period of exposure. Increased temperature also resulted in a significant change in haemoglobin, haematocrit and mean cell haemoglobin concentration (MCHC) (p〈0.05). Plasma lactate was significantly elevated only after exposure to 8°C (p〈0.05). Plasma cortisol levels fromP. borchgrevinki are reported here for the first time and show this cryopelagic Antarctic species to have an unusual hormonal stress profile.
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  • 18
    ISSN: 1432-0975
    Keywords: Key words Dispersal ; coral reefs ; fish ; swimming ; Larvae ; Juveniles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  Characteristics of the pelagic stages of reef fishes have generally been investigated at the family level, which may mask important differences among species. Here the variation in sustained swimming ability of the late pelagic stages is examined among species, within two families (Pomacentridae and Chaetodontidae). The pomacentrids displayed a 7.5-fold difference in sustained swimming ability across 24 species, while the chaetodontids displayed a 2-fold difference across 10 species. The variation within the Pomacentridae was not related to pelagic larval duration, post-settlement habitat or taxonomy. There was, however, a significant correlation between sustained swimming ability and total length (TL) of individuals (r=0.435, P〈0.0001). Differences in the mean distance swum by pomacentrid species, however, was most strongly related to differences in mean wet weight (r=0.814, P〈0.0001). When the mean distance swum by species was scaled with respect to mean TL there was still a strong correlation with mean wet weight (r=0.644, P〈0.005). Among chaetodontid individuals TL and sustained swimming ability were not correlated (r=−0.004, P=0.978). Furthermore, sustained swimming ability was not significantly related to the trans-oceanic distribution of species in either family. The variation in sustained swimming ability, however, may contribute to explanations of the observed levels of gene flow within populations.
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  • 19
    ISSN: 1432-0789
    Keywords: 15N-labelled fertilizer ; Added N interaction Fertilizer N uptake ; Soil N uptake ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of 15N-labelled ammonium nitrate, urea and ammonium sulphate on yield and uptake of labelled and unlabelled N by wheat (Triticum aestivum L. cv. Mexi-Pak-65) were studied in a field experiment. The dry matter and N yields were significantly increased with fertilizer N application compared to those from unfertilized soil. The wheat crop used 64.0–74.8%, 61.5–64.7% and 61.7–63.4% of the N from ammonium nitrate, urea and ammonium sulphate, respectively. The fertilizer N uptake showed that ammonium nitrate was a more available source of N for wheat than urea and ammonium sulphate. The effective use of fertilizer N (ratio of fertilizer N in grain to fertilizer N in whole plant) was statistically similar for the three N fertilizers. The application of fertilizer N increased the uptake of unlabelled soil N by wheat, a result attributed to a positive added N interaction, which varied with the method of application of fertilizer N. Ammonium nitrate, urea and ammonium sulphate gave 59.3%, 42.8% and 26.3% more added N interaction, respectively, when applied by the broadcast/worked-in method than with band placement. A highly significant correlation between soil N and grain yield, dry matter and added N interaction showed that soil N was more important than fertilizer N in wheat production. A values were not significantly correlated with added N interaction (r=0.719). The observed added N interaction may have been the result of pool substitution, whereby added labelled fertilizer N stood proxy for unlabelled soil N.
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  • 20
    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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  • 21
    ISSN: 1420-9055
    Keywords: Phoxinus phoxinus ; fish ; Diplostomum phoxini ; Macrolecithus papilliger ; parasitism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of parasites on the breeding biology of the European minnow (Phoxinus phoxinus) was studied by examining 268 adult and 59 young-of-the-year minnows from an artificial Swiss Alpine lake for parasites during the breeding seasons in 1990 and 1991. Two trematode parasites;Diplostomum phoxini, in their brains, andMacrolecithus papilliger, in their guts, were found. The prevalence ofD. phoxini was 100% in both years. The mean abundance was 231 in 1990 and 448 in 1991; the difference was significant. Prevalence (and abundance) ofM. papilliger was 37.5% (1.04±0.39) in 1990 and 59.5% (2.68±0.55) in 1991; also significantly higher in 1991 than in 1990. No differences in prevalence or abundance between males and females were found. Numbers of both parasites were significantly correlated with fish length. There was seasonal variation in the abundance ofD. phoxini metacercariae, with a peak in June/July in both years. The prevalence ofM. papiller decreased after July in both years. Distribution of the two trematodes was overdispersed as indicated by the variance to mean (abundance) ratio. The observed seasonal variation inD. phoxini abundance also suggests that sublethal parasites could influence the population dynamics of their hosts.
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  • 22
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    Aquatic sciences 57 (1995), S. 106-118 
    ISSN: 1420-9055
    Keywords: Benthos ; fish ; vertical distribution ; predation risk ; selective fishing ; Lake Constance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To compare the vertical distributions of benthos and fish species of Upper Lake Constance (Bodensee), 552 benthos samples were taken with an Auerbach grab at four transects (10–250 m). An additional 54 samples (1–10 m) were collected elsewhere. Complementary data was taken from the literature. In winter, most fish feed on benthos, mainly chironomids, but in summer less than 5% do so. Formerly the bottom gill-netting aimed mainly at catchingCoregonus pidschian, but it now aims atPerca fluviatilis. Contrary to expectation, in winter the greatest abundance ofP. fluviatilis is much deeper (55 m) than that of its preferred food, i.e. chironomids (〈20 m). Comparably,C. pidschian also stayed deeper than its main food source (chironomids and mollusks).Lota lota, Salvelinus profundus andS. alpinus — unlike the unwanted cyprinids — also stay or stayed deeper than the attractive chironomids. It is argued that the fish reduce their “predation risk”, i.e. the risk of being gillnetted in the upper 50 m, by “selecting” the deeper less dangerous, but also less food-abundant habitat. Balancing predation risk against food abundance may have led to “survival of the deepest”.
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  • 23
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    Theoretical and applied genetics 90 (1995), S. 952-956 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Thinopyrum bessarabicum ; Protein/isozyme markers ; In situ hybridization ; Alien disomic additions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thinopyrum bessarabicum (2n=2x=14, JJ) is a self-fertile salt-tolerant grass species, and its hybridization with Triticum aestivum to achieve the transfer of this attributes has been promoted. For the detection of alien introgression, development of diagnostic markers of Th. bessarabicum chromosomes in the wheat background has emerged as an important aspect in our intergeneric hybridization program. Six proteins/isozymes-high-molecular-weight glutenins, superoxide dismutase, grain esterase, β-amylase, glutamate oxaloacetate transaminase and α-amylase —were identified as positive markers for detecting the presence of Th. bessarabicum chromosomes in the advanced backcross derivatives of T. aestivum/Th. bessarabicum//n* T. aestivum. Fluorescent in situ hybridization further enabled the detection of complete and translocated arms of Th. bessarabicum chromosomes in the T. aestivum background. These diagnostic markers served for tentatively characterizing a distinct set of Th. bessarabicum disomic additions to wheat (2n=44) and have facilitated establishing the homoeology of these added chromosomes.
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  • 24
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    Theoretical and applied genetics 91 (1995), S. 780-782 
    ISSN: 1432-2242
    Keywords: Physical mapping ; RFLP ; Cereals ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytologically based physical maps for the group 3 chromosomes of wheat were constructed by mapping 25 Triticum aestivum deletion lines with 29 T. tauschii and T. aestivum RFLP probes. The deletion lines divide chromosomes 3A, 3B, and 3D into 31 discrete intervals, of which 18 were tagged by marker loci. The comparison of the consensus physical map with a consensus RFLP linkage map of the group 3 chromosomes of wheat revealed a fairly even distribution of marker loci on the long arm, and higher recombination in the distal region.
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  • 25
    ISSN: 1432-2242
    Keywords: Key wordsSuppressor gene ; Powdery mildew resistance ; Gene location ; Triticum aestivum ; Secale cereale ; Monosomic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The chromosomal location of a suppressor for the powdery mildew resistance genes Pm8 and Pm17 was determined by a monosomic set of the wheat cultivar Caribo. This cultivar carries a suppressor gene inhibiting the expression of Pm8 in cv Disponent and of Pm17 in line Helami-105. In disease resistance assessments, monosomic F1 hybrids (2n=41) of Caribo × Disponent and Caribo × Helami-105 lacking chromosome 7D were resistant, whereas monosomic F1 hybrids involving the other 20 chromosomes, as well as disomic F1 hybrids (2n=42) of all cross combinations, were susceptible revealing that the suppressor gene for Pm8 and Pm17 is localized on chromosome 7D. It is suggested that genotypes without the suppressor gene be used for the exploitation of genes Pm8 and Pm17 in enhancing powdery mildew resistance in common wheat.
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  • 26
    ISSN: 1432-2242
    Keywords: Triticum timopheevii ; Triticum aestivum ; Chromosome substitution ; C-banding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Whether the two tetraploid wheat species, the well known Triticum turgidum L. (macaroni wheat, AABB genomes) and the obscure T. timopheevii Zhuk. (AtAtGG), have monophyletic or diphyletic origin from the same or different diploid species presents an interesting evolutionary problem. Moreover, T. timopheevii and its wild form T. araraticum are an important genetic resource for macaroni and bread-wheat improvement. To study these objectives, the substitution and genetic compensation abilities of individual T. timopheevii chromosomes for missing chromosomes of T. aestivum ‘Chinese Spring’ (AABBDD) were analyzed. ‘Chinese Spring’ aneuploids (nullisomic-tetrasomics) were crossed with a T. timopheevii x Aegilops tauschii amphiploid to isolate T. timopheevii chromosomes in a monosomic condition. The F1 hybrids were backcrossed one to four times to Chinese Spring aneuploids without selection for the T. timopheevii chromosome of interest. While spontaneous substitutions involving all At- and G-genome chromosomes were identified, the targeted T. timopheevii chromosome was not always recovered. Lines with spontaneous substitutions from T. timopheevii were chosen for further backcrossing. Six T. timopheevii chromosome substitutions were isolated: 6At (6A), 2G (2B), 3G (3B), 4G (4B), 5G (5B) and 6G (6B). The substitution lines had normal morphology and fertility. The 6At of T. timopheevii was involved in a translocation with chromosome 1G, resulting in the transfer of the group-1 gliadin locus to 6At. Chromosome 2G substituted for 2B at a frequency higher than expected and may carry putative homoeoalleles of gametocidal genes present on group-2 chromosomes of several alien species. Our data indicate a common origin for tetraploid wheat species, but from separate hybridization events because of the presence of a different spectrum of intergenomic translocations.
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  • 27
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    Theoretical and applied genetics 95 (1997), S. 1300-1304 
    ISSN: 1432-2242
    Keywords: Key words Flow cytometry ; Triticum aestivum ; DNA analysis ; Monosomics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Two complete, independently maintained sets of 21 monosomic wheat lines derived from cv. ‘Chinese Spring’ were analyzed for their DNA content at the G1 stage with flow cytometry. The DNA content of individual chromosomes was estimated by subtracting the value of a monosomic line from that of euploid wheat. Our data show that the estimated 2C DNA of individual wheat chromosomes in 21 monosomics at the G1 stage ranges from about 0.58 pg in chromosome 1D to approximately 1.12 pg in chromosome 3A. The A genome (2C=6.15 pg) seems to contain more DNA than the B (2C=6.09 pg) and D (2C=5.05 pg) genomes. Analysis of variance showed significant differences (α=0.01) in DNA content both among homoeologous groups and among genomes. Our estimates of interphase DNA content of wheat chromosomes from monosomic lines were poorly correlated to the chromosome sizes at metaphase (r=0.622, P≤0.01). This poor correlation might be due to differential coiling among chromosomes during cell division, possible bias of fluorochrome binding to heterochromatin, or heterogeneity among monosomic lines. Finally, flow cytometry may aid but cannot replace cytological checks in aneuploid maintenance.
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  • 28
    ISSN: 1432-2242
    Keywords: Key words Transgenic wheat ; Triticum aestivum ; Tritordeum ; Transgene inheritance ; Marker gene stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The stability and heritability of three marker genes was investigated in a population of twelve independent transgenic cereal lines (six wheat and six tritordeum). Integration patterns, inheritance of structural transgenes and inheritance of expression were analysed in the T0 and T1 generations for all 12 lines. Transmission and expression were analysed in the T2 generation for 9 lines and in the T3 generation for the six wheat lines. Inheritance of integration patterns was highly stable, and transmission of the transgenes and inheritance of their expression followed Mendelian ratios in the majority of lines. A gradual reduction in uidA expression was observed over three generations, which was not accompanied by a similar reduction in bar expression. Some unexpected phenomena associated with transgene inheritance were also observed and are discussed.
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  • 29
    ISSN: 1432-2242
    Keywords: C-banding ; Genomic in situ hybridization ; Triticum aestivum ; T. umbellulatum ; Chromosome addition and translocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A standard karyotype and a generalized idiogram of Triticum umbellulatum (syn. Aegilops umbellulata, 2n = 2x = 14) was established based on C-banding analysis of ten accessions of different geographic origin and individual T. umbellulatum chromosomes in T. aestivum — T. umbellulatum chromosome addition lines. Monosomic (MA) and disomic (DA) T. aestivum — T. umbellulatum chromosome addition lines (DA1U = B, DA2U = D, MA4U = F, DA5U = C, DA6U = A, DA7U = E = G) and telosomic addition lines (DA1US, DA1UL, DA2US, DA2UL, DA4UL, MA5US, (+ iso 5US), DA5UL, DA7US, DA7UL) were analyzed. Line H was established as a disomic addition line for the translocated wheat — T. umbellulatum chromosome T2DS·4US. Radiation-induced wheat — T. umbellulatum translocation lines resistant to leaf rust (Lr9) were identified as T40 = T6BL·6BS-6UL, T41 = T4BL·4BS-6UL, T44 = T2DS·2DL-6UL, T47 = ‘Transfer’ = T6BS·6BL-6UL and T52 = T7BL·7BS-6UL. Breakpoints and sizes of the transferred T. umbellulatum segments in these translocations were determined by in situ hybridization analysis using total genomic T. umbellulatum DNA as a probe
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  • 30
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    Theoretical and applied genetics 90 (1995), S. 1164-1168 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Puccinia graminis ; Allelism ; Inheritance ; Segregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Triticum aestivum L. cultivar ‘Waldron’ has long lasting resistance to most North American stem rust (Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. and E. Henn.) isolates. The objective of this research was to develop wheat lines monogenic for resistance to stem rust from ‘Waldron’ using allelism tests and tests for reaction to a series of ten stem rust cultures having a range of virulences. Twelve lines homozygous for single resistance genes were selected as parents of a diallel cross to test for allelism among genes for resistance. We identified 6 lines or groups of lines (WDR-A1, the WDR-B1 and WDR-B2 group, the WDR-C1 and WDR-C2 group, WDR-D1, the WDR-E1, WDR-E2, WDR-E3, and WDR-E4 group, and WDR-F1) that carried different single genes for resistance from ‘Waldron’. A seventh line (WDR-G1) probably has two genes for resistance, one in common with WDR-C1 and WDR-C2. The gene in the WDR-E group is probably the same as SrWld1, and the one in WDR-F1 the same as Sri11. ‘Waldron’ probably has two or more genes for resistance to stem rust that previous genetic studies did not detect.
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  • 31
    ISSN: 1432-2242
    Keywords: Wheat ; Triticum aestivum ; Triticum peregrinum ; Chromosome addition lines ; RFLPs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analyses of RFLPs, isozymes, morphological markers and chromosome pairing were used to isolate 12 Triticum aestivum cv Chinese Spring (genomes A, B, and D)-T. peregrinum (genomes Sv and Uv) disomic chromosome addition lines. The evidence obtained indicates that each of the 12 lines contains an intact pair of T. peregrinum chromosomes. One monosomic addition line, believed to contain an intact 6Sv chromosome, was also isolated. A CS-7Uv chromosome addition line was not obtained. Syntenic relationships in common with the standard Triticeae arrangement were found for five of the seven Sv genome chromosomes. The exceptions were 4Sv and 7Sv. A reciprocal translocation exists between 4S1 and 7S1 in T. longissimum and evidence was obtained that the same translocation exists in T. peregrinum. In contrast, evidence for syntenic relationships in common with the standard Triticeae arrangements were found for only one Uv chromosome of T. peregrinum.; namely, chromosome 2Uv. All other Uv genome chromosomes are involved in at least one translocation, and the same translocations were found in the U genome of T. umbellulatum. Evidence was also obtained indicating that the centromeric regions of 4U and 4Uv are homoeologous to the centromeric regions of Triticeae homoeologous group-6 chromosomes, that the centromeric regions of 6U and 6Uv are homoeologous to the centromeric regions of group-4 chromosomes, and that 4U and 4Uv are more closely related overall to Triticeae homoeologous group-6 chromosomes than they are to group-4 chromosomes.
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  • 32
    ISSN: 1432-2242
    Keywords: Key words Lodging ; Morphological traits ; QTL ; Triticum aestivum ; Triticum spelta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Lodging can strongly affect both the grain yield and the quality of wheat. Lodging represents a quantitative trait and is difficult to assess on a phenotypic basis. Marker-assisted selection (MAS) could therefore become an important tool in breeding for lodging resistance. In this study, we mapped and characterised quantitative trait loci (QTLs) for lodging resistance, as well as morphological traits correlated with lodging, in a segregating population of 226 recombinant inbred lines derived from the cross of the lodging-resistant wheat variety Forno with the susceptible spelt variety Oberkulmer. Lodging, plant height, leaf width, leaf-growth habit, culm stiffness, culm swinging, culm thickness, days to ear emergence and days to flowering were assessed in field trials at two locations in 1996 and at one location in 1997. Additionally, at one location weight and length parameters were also assessed. Plant height and culm stiffness explained 77% of the phenotypic variance of lodging in a multiple regression model over all three environments. QTL analysis of lodging and morphological parameters was based on a genetic map containing 230 loci with 23 linkage groups (2469 cM). With the method of composite interval mapping nine QTLs for lodging resistance were detected, explaining 63% of the phenotypic variance in a simultaneous fit. Seven of these QTLs coincided with QTLs for morphological traits, reflecting the correlations between these traits and lodging. In our population the most efficient way to improve lodging resistance would be by a combination of indirect selection on plant height and culm stiffness together with MAS on the two QTLs for lodging resistance which did not coincide with QTLs for morphological traits.
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  • 33
    ISSN: 1432-2242
    Keywords: Key words Erysiphe graminis ; Powdery mildew resistance ; QTL ; Triticum aestivum ; Triticum spelta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Powdery mildew is one of the major diseases of wheat in regions with a maritime or semi-continental climate and can strongly affect grain yield. The attempt to control powdery mildew with major resistance genes (Pm genes) has not provided a durable resistance. Breeding for quantitative resistance to powdery mildew is more promising, but is difficult to select on a phenotypic basis. In this study, we mapped and characterised quantitative trait loci (QTLs) for adult-plant powdery mildew resistance in a segregating population of 226 recombinant inbred lines derived from the cross of the Swiss wheat variety Forno with the Swiss spelt variety Oberkulmer. Forno possibly contains the Pm5 gene and showed good adult-plant resistance in the field. Oberkulmer does not have any known Pm gene and showed a moderate susceptible reaction. Powdery mildew resistance was assessed in field trials at two locations in 1995 and at three locations in 1996. The high heritability (h2=0.97) for powdery mildew resistance suggests that the environmental influence did not affect the resistance phenotype to a great extent. QTL analysis was based on a genetic map containing 182 loci with 23 linkage groups (2469 cM). With the method of composite interval mapping 18 QTLs for powdery mildew resistance were detected, explaining 77% of the phenotypic variance in a simultaneous fit. Two QTLs with major effects were consistent over all five environments. One of them corresponds to the Pm5 locus derived from Forno on chromosome 7B. The other QTL on 5A, was derived from the spelt variety Oberkulmer and did not correspond to any known Pm gene. In addition, five QTLs were consistent over three environments, and six QTLs over two environments. The QTL at the Pm5 locus showed a large effect, although virulent races for Pm5 were present in the mixture of isolates. Molecular markers linked with QTLs for adult-plant resistance offer the possibility of simultaneous marker-assisted selection for major and minor genes.
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  • 34
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    Theoretical and applied genetics 94 (1997), S. 472-479 
    ISSN: 1432-2242
    Keywords: Key words Genetic diversity ; RFLP ; Coefficient of parentage ; Triticum aestivum ; Gene pool
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Genetic diversity in a set of 11 red and 11 white wheat lines from the Eastern U.S. soft wheat germplasm pool was measured using restriction fragment length polymorphism (RFLP) assay and coefficients of parentage (COP) analysis. On average, 78% of all bands revealed by three enzymes with 48 RFLP clones were monomorphic. Average pairwise genetic similarity (GS) was 0.97 when data from all enzymes were pooled. Probe Polymorphic Information Content (PIC) indexes ranged from 0 to 0.73 with a mean of 0.2. Fewer than 55% of the probes revealed any polymorphism. The frequency of polymorphism in the Eastern U.S. soft white winter (SWW) wheat gene pool was much lower than that observed in the Eastern U.S. soft red winter (SRW) wheat gene pool. SWW lines formed a single group on a dendrogram based on cluster analysis of RFLP-derived GS estimates, while SRW lines did not form a single group. COP values for all pairs of the Eastern U.S. soft wheat lines ranged from 0.02 to 0.9 with a mean of 0.21. SWW wheat lines traced to 53 ancestral lines and had an average COP of 0.51. The SRW wheat gene pool had more complex parentages (mean COP=0.15 and a total of 65 ancestral lines). COPs were correlated with RFLP-based GS for all line pairs (r=0.73, P〈0.01). However, correlations between the two similarity measures were substantially lower when the SRW and SWW wheat gene pools were considered individually (r values of 0.23 and 0.28, respectively). The actual GS among unrelated lines in the U.S. Eastern soft wheat gene pool appears to be higher than that observed for unrelated landraces from Southwest Asia (0.96 vs. 0.905), suggesting that the ancestral landrace parents of this gene pool were themselves drawn from a base population where inbreeding, i.e., F, was greater than zero.
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  • 35
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    Theoretical and applied genetics 96 (1998), S. 69-75 
    ISSN: 1432-2242
    Keywords: Key words Aegilops umbellulata ; Co-linearity ; Comparative mapping ; Translocations ; Triticum aestivum ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A comparative genetic map of Aegilops umbellulata with wheat was constructed using RFLP probes that detect homoeoloci previously mapped in hexaploid bread wheat. All seven Ae. umbellulata chromosomes display one or more rearrangements relative to wheat. These structural changes are consistent with the sub-terminal morphology of chromosomes 2 U, 3 U, 6 U and 7 U. Comparison of the chromosomal locations assigned by mapping and those obtained by hybridization to wheat/Ae. umbellulata single chromosome addition lines verified the composition of the added Ae. umbellulata chromosomes and indicated that no further cytological rearrangements had taken place during the production of the alien-wheat aneuploid lines. Relationships between Ae. umbellulata and wheat chromosomes were confirmed, based on homoeology of the centromeric regions, for 1 U, 2 U, 3 U, 5 U and 7 U. However, homoeology of the centromeric regions of 4 U with wheat group-6 chromosomes and of 6 U with wheat group-4 chromosomes was also confirmed, suggesting that a re-naming of these chromosomes may be pertinent. The consequences of the rearrangements of the Ae. umbellulata genome relative to wheat for gene introgression are discussed.
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  • 36
    ISSN: 1432-2242
    Keywords: Key words RFLP analysis ; Triticum aestivum ; Genetic diversity ; Genetic similarity estimates ; Cluster analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Restriction fragment length polymorphisms (RFLPs) have been used to characterise the genetic diversity of wheat (Triticum aestivum) germplasm. One hundred and twenty-four accessions comprising all major Australian wheat varieties and lines important for breeding purposes were assayed for RFLPs with clones of known genetic location and selected to give uniform genome coverage. The objectives of this study were to determine RFLP-based genetic similarity between accessions and to derive associations between agronomically significant traits and RFLP phenotypes. Ninety-eight probes screened against genomic DNA digested with five restriction endonucleases detected a total of 1968 polymorphic fragments. Genetic similarity (GS) calculated from the RFLP data ranged from 0.004 to 0.409 between accessions, with a mean of 0.18. Cluster analysis based on GS estimates produced four groupings that were generally consistent with available pedigree information. Comparisons of the RFLP phenotypes of accessions containing disease resistance genes present on introgressed alien segments enabled the identification of specific alleles characteristic of these regions. Associations were derived for a range of stem-rust, leaf-rust and yellow-rust resistance genes. These results suggest that RFLP analysis can be used for the characterisation and grouping of elite breeding material of wheat and RFLP profiling can identify chromosome segments associated with agronomic traits.
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  • 37
    ISSN: 1432-203X
    Keywords: Abscisic acid ; Anther culture ; Light ; Metallothionein ; Pollen embryogenesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cloned cDNA to the wheat (Triticum aestivum) early cysteine-labeled metallothionein has many characteristics of a molecular marker for pollen embryogenesis in this plant. This transcript was not detected in uninucleate microspores at the time of culture or in pollen at any stage during normal ontogeny; its mRNA did begin to increase in embryogenic microspores within 6 h of culture, peaked at around 24 h, declined, then leveled off through the 21-day-old embryoid stage. Additionally, the accumulation of the embryoid-abundant EcMt gene transcript showed a direct and positive correlation with an increase of ABA in embryogenic microspores and developing pollen embryoids. Irradiating cultures with high intensity white light or with far-red, or blue light, suppressed EcMt transcript accumulation and the ability of microspores to form embryoids; however, light did not affect ABA concentrations during the early stages of culture. These results suggest that although a promoter of pollen embryogenesis in bread wheat, ABA alone cannot maintain the sporophytic differentiation of microspores subjected to inhibitory regimes of light in vitro. Whether or not light acts directly or indirectly in suppressing EcMt gene expression and pollen embryogenesis remains unknown.
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  • 38
    ISSN: 1432-203X
    Keywords: Key words Bread wheat ; Triticum aestivum ; Tritordeum ; Tissue electroporation ; Transient gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat scutella and tritordeum inflorescences were transformed by tissue electroporation with plasmid DNA containing a β-glucuronidase (GUS) gene (gus A) under the control of the rice actin1 promoter. Factors affecting electroporation efficiency were analysed. Important factors were electroporation voltage and pulse length, the volume of electroporation buffer, the osmoticum of electroporation buffer and medium, the osmoticum of pre-electroporation culture medium, and pre-electroporation incubation time and temperature. Maximum transient gene expression was obtained with a single pulse of 550 V/cm from a 960-μF capacitor, using 200 μl of electroporation buffer, after 2–3 h culture on media with 357 mOsm for wheat scutella or 1 day on media with 222 mOsm for tritordeum inflorescences, and 0.5–1 h pre-electroporation incubation with DNA at 24 °C. Under these conditions, up to 90% of the explants showed GUS expression, and up to 149 expression signals were recorded per replicate. Electroporated explants showed high rates of survival and retained the ability to regenerate plants via somatic embryogenesis.
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  • 39
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    Sexual plant reproduction 8 (1995), S. 266-272 
    ISSN: 1432-2145
    Keywords: Triticum aestivum ; Alloplasmic lines ; Apomixis ; Parthenogenesis ; Protein patterns ; 2-D gel electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An in vivo model system to study the initiation of embryo development is presented. From the so-called Salmon system of wheat (alloplasmic lines with a 1BL-1RS chromosome translocation), three completely isogenic and homozygous lines were produced by selection for uniformity in about 20 selfing/backcross generations as well as between sublines of doubled haploids. The line (aestivum)-Salmon is male fertile and sexual. The lines (caudata)-Salmon and (kotschyi)-Salmon are male sterile and have a parthenogenetic capacity of about 90%. The expression of nuclear-cytoplasmic male sterility is different for the two parthenogenetic lines. The initiation of autonomous embryo development at defined developmental stages of the ovaries and the maximum degree of parthenogenesis are identical in both parthenogenetic lines as proved by the auxin test and progeny analyses. The protein patterns from ovary extracts of the three isogenic lines were identical for more than 200 spots of 2-D polyacrylamide gels, confirming their homogeneity. However, one protein (P 115.1) was found 3 days before and during anthesis only in ovaries of the parthenogenetic lines. It seems to be involved in the initiation of parthenogenesis.
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  • 40
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    Entomologia experimentalis et applicata 91 (1999), S. 403-412 
    ISSN: 1570-7458
    Keywords: aphid ; Diuraphis noxia ; Triticum aestivum ; endosymbiont ; insect-plant interactions ; phloem ; amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The feeding behavior of Diuraphis noxia Mordvilko (Homoptera: Aphididae) on susceptible hosts causes both ultrastructural and tissue level damage which may affect phloem composition. Genetic evidence suggests that endosymbiotic bacteria in most aphids overproduce limiting amino acids to benefit hosts but that D. noxia depends less on endosymbionts for these nutrients, possibly due to an enriched diet. To determine whether D. noxia feeding damage results in higher concentrations of essential amino acids, stylet exudates were analyzed from wheat (Triticum aestivum) damaged to different degrees. Comparison of samples from undamaged and damaged susceptible wheat revealed changes in amino acid composition and an increase in levels of essential amino acids, indicating a nutritionally enhanced ingesta. The changes in stylet exudates paralleled changes in leaf exudates, indicating that the effects are systemic. Feeding damage is not observed on a resistant wheat host, var. Halt, and leaf exudates from infested Halt did not show changes in amino acid composition. Mean relative growth of nymphs was significantly lower on Halt than on susceptible Arapahoe, indicating that Halt is a less suitable host. Both varieties show similar amino acid levels in non-infested samples, suggesting that D. noxia infestation does not enhance the phloem environment in Halt. This study provides evidence that aphid feeding can generate a nutritionally enhanced phloem diet.
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  • 41
    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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  • 42
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    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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  • 43
    ISSN: 1572-8854
    Keywords: Calixarene ; complex ; crystal structure ; chirality
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    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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  • 44
    ISSN: 1572-8854
    Keywords: Mercury(II) terpyridine complex ; crystal structure
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    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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  • 45
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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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  • 46
    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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  • 47
    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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  • 48
    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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  • 49
    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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  • 50
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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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  • 51
    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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  • 52
    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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  • 53
    ISSN: 1572-8854
    Keywords: 2-Methylnaphthalene ; hexachlorocyclopentadiene ; crystal structure
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    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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  • 54
    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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  • 55
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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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  • 56
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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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  • 57
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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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  • 58
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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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  • 59
    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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  • 60
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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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  • 61
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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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  • 62
    ISSN: 1572-8854
    Keywords: Pyrimidine ; carboxamide ; sulfonyl ; chiral ; crystal structure
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    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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  • 63
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    Journal of chemical crystallography 29 (1999), S. 1127-1132 
    ISSN: 1572-8854
    Keywords: crystal structure ; phenyl-substituted cyclopentenes
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    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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  • 64
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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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  • 65
    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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  • 66
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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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  • 67
    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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  • 68
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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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  • 69
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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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  • 70
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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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  • 71
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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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  • 72
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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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  • 73
    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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  • 74
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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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  • 75
    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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  • 76
    ISSN: 1572-8854
    Keywords: pyrazolyl derivative ; substituted pentane ; crystal structure ; bidentate ligand
    Source: Springer Online Journal Archives 1860-2000
    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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  • 77
    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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  • 78
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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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  • 79
    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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  • 80
    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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  • 81
    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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  • 82
    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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  • 83
    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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  • 84
    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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  • 85
    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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  • 86
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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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  • 87
    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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  • 88
    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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  • 89
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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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  • 90
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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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  • 91
    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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  • 92
    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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  • 93
    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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  • 94
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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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  • 95
    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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  • 96
    ISSN: 1572-8854
    Keywords: Pyrazolyl group ; crystal structure ; bidentate ligand ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    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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  • 97
    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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  • 98
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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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  • 99
    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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  • 100
    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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