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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 79 (1967), S. 99-100 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: 1,2-Diphospha-3,4-diboretanes ; 1,3-diphospha-2,4,5-triborolane derivative ; preparation ; molecular structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,2-Diphospha-3,4-diboretanes and 1,3-Diphospha-2,4,5-triborolane: Synthesis and Structure as well as Calculations on the Molecular Structure On the Effect of Substituents on the Structure of 1,2-Diphospha-3,4-diboretane[2 + 2]-Cyclocondensation reactions led to the synthesis of the 1,2-diphospha-3,4-diboretanes [(t-BuP)2B2(NMe2)2], 1 a, and [(t-BuP)2B(NMe2)B(NiPr2)], 1 b. Their molecular structures have been determined by X-ray methods, and these are compared with the structure of [(t-Bu)P—BN(iPr2)]2, 2 a. Compounds 1 show a folded B2P2 four membered ring having tert.-butyl groups in anti-positions. Ab initio calculations on 1,2-diphospha-3,4-diboretanes demonstrate that two conformers with anti-orientation of the substituents at the phosphorus atoms can be expected. These differ by the relative orientation of the almost planar P2BR groups to the BP2 plane. The influence of substituents (H and NH2 at the B atoms, and H and Me at the P atoms) on the ring conformation has been studied. Finally, the first derivative of a 1,3-diphospha-2,4,5-triborolane, 3 a, is reported.
    Notes: Durch [2 + 2]-Cyclokondensationen wurden die 1,2-Diphospha-3,4-diboretane [(t-BuP)2B2(NMe2)2], 1 a, und [(t-BuP)2B(NMe2)B(NiPr2)], 1 b, dargestellt, ihre Molekülstrukturen mit Röntgenbeugungsmethoden bestimmt und mit der Struktur von [(t-Bu)P—B(NiPr2)]2, 2 a, verglichen. In den Verbindungen 1 liegen gefaltete B2P2-Vierringe vor mit anti-ständigen tert.-Butylgruppen, während das Ringsystem in 2 a planar gebaut ist, die tert.-Butylgruppen aber ebenfalls anti-Stellung einnehmen. Ab initio-Rechnungen an 1,2-Diphospha-3,4-diboretanen belegen, daß zwei unterschiedliche Konformere mit anti-Orientierung der Substituenten an den P-Atomen stabil sind, die sich durch die relative Orientierung der annähernd trigonal-planaren P2BR-Baugruppen zur BP2-Ebene voneinander unterscheiden. Der Einfluß von Substituenten (H und NH2 am B-Atom, H und CH3 am P-Atom) wird ermittelt. Beschrieben wird ferner das erste Derivat eines 1,3-Diphospha-2,4,5-triborolans, 3 a.
    Additional Material: 8 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 1945-1953 
    ISSN: 0044-2313
    Keywords: Bismutoxideiodides ; totale pressure measurements ; mass spectrometry ; thermodynamic data ; melting diagram ; barogram ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the System Bi2O3/BiI3The temperature functions of decomposition pressures of the ternary compounds on the quasibinary line Bi2O3/BiI3 were determined by total pressure measurements and mass spectrometry. The barogram of the system was constructed and the melting diagram precised. The enthalpies of formation and the standard entropies of the solid phases were derived from the decomposition functions: (Values see Inhaltsübersicht).
    Notes: Die Temperaturabhängigkeit der Zersetzungsdrücke der auf dem quasibinären Schnitt Bi2O3/BiI3 existierenden ternären Verbindungen wurde durch Gesamtdruckmessungen mit dem Membrannullmanometer und dem Massenspektrometer ermittelt. Das Zustandsbarogramm für das System wurde aufgestellt und das Zustandsdiagramm präzisiert. Unter Zugrundelegung der Zersetzungsgleichungen wurden die Standardbildungsenthalpien und Standardentropien der festen ternären Phasen hergeleitet: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} \Delta {\rm H}_{\rm B}^{\rm o} \,({\rm BiOI, f, 298) = - 268,1} \pm {\rm 6,3}\,{\rm kJ}\,{\rm mol}^{{\rm - 1}} \\ {\rm S}^ \circ \,({\rm BiOI, f, 298) = 116,9} \pm {\rm 7,1}\,{\rm J}\,{\rm mol}^{{\rm - 1}} \,{\rm K}^{{\rm - 1}} \\ \Delta {\rm H}_{\rm B}^{\rm o} \,({\rm Bi}_{\rm 4} {\rm O}_{\rm 5} {\rm I}_{\rm 2} {\rm, f, 298) = - 1148,8} \pm 20{\rm,9}\,{\rm kJ}\,{\rm mol}^{{\rm - 1}} \\ {\rm S}^ \circ \,({\rm Bi}_{\rm 4} {\rm O}_{\rm 5} {\rm I}_{\rm 2} {\rm, f, 298) = 367,1} \pm 25{\rm,1}\,{\rm J}\,{\rm mol}^{{\rm - 1}} \,{\rm K}^{{\rm - 1}} \\ \Delta {\rm H}_{\rm B}^{\rm o} \,({\rm Bi}_{\rm 7} {\rm O}_{\rm 9} {\rm I}_{\rm 3} {\rm, f, 298) = - 2022,5} \pm 34{\rm,3}\,{\rm kJ}\,{\rm mol}^{{\rm - 1}} \\ {\rm S}^ \circ \,({\rm Bi}_{\rm 7} {\rm O}_{\rm 9} {\rm I}_{\rm 3} {\rm, f, 298) = 619,8} \pm 41{\rm,0}\,\,{\rm J}\,{\rm mol}^{{\rm - 1}} \,{\rm K}^{{\rm - 1}} \\ \Delta {\rm H}_{\rm B}^{\rm o} \,({\rm Bi}_{\rm 5} {\rm O}_{\rm 7} {\rm I, f, 298) = - 1471,2} \pm 20{\rm,1}\,{\rm kJ}\,{\rm mol}^{{\rm - 1}} \\ {\rm S}^ \circ \,({\rm Bi}_{\rm 5} {\rm O}_{\rm 7} {\rm I, f, 298) = 385,3} \pm 24{\rm,3}\,{\rm J}\,{\rm mol}^{{\rm - 1}} \,{\rm K}^{{\rm - 1}} \\ \end{array} $$\end{document}.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 6 (1967), S. 955-956 
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 6 (1967), S. 93-93 
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2018-09-21
    Description: Phosphorothioate nucleotides have emerged as powerful pharmacological substitutes of their native phosphodiester analogs with important translational applications in antisense oligonucleotide (ASO) therapeutics and cyclic dinucleotide (CDN) synthesis. Stereocontrolled installation of this chiral motif has long been hampered by the systemic use of phosphorus(III) [P(III)]–based reagent systems as the sole practical means of oligonucleotide assembly. A fundamentally different approach is described herein: the invention of a P(V)-based reagent platform for programmable, traceless, diastereoselective phosphorus-sulfur incorporation. The power of this reagent system is demonstrated through the robust and stereocontrolled synthesis of various nucleotidic architectures, including ASOs and CDNs, via an efficient, inexpensive, and operationally simple protocol.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2014-11-22
    Description: The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MER) Spirit and Opportunity. The fraction of sand 〈150 micron in size contains approx. 55% crystalline material consistent with a basaltic heritage, and approx. 45% X-ray amorphous material. The amorphous component of Rocknest is Fe-rich and Si-poor, and is the host of the volatiles (H2O, O2, SO2, CO2, and Cl) detected by the Surface Analysis at Mars (SAM) instrument and of the fine-grained nanophase oxide (npOx) component first described from basaltic soils analyzed by MER. The similarity between soils and aeolian materials analyzed at Gusev crater, Meridiani Planum and Gale crater implies locally sourced, globally similar basaltic materials, or globally and regionally sourced basaltic components deposited locally at all three locations.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN11260
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  • 8
    Publication Date: 2019-07-13
    Description: The Mars rover Curiosity has encountered silica-enriched bedrock (as strata and as veins and associated halos of alteration) in the largely basaltic Murray Fm. of Mt. Sharp in Gale Crater. Alpha Particle X-ray Spectrometer (APXS) investigations of the Murray Fm. revealed decreasing Mg, Ca, Mn, Fe, and Al, and higher S, as silica increased (Fig. 1). A positive correlation between SiO2 and TiO2 (up to 74.4 and 1.7 wt %, respectively) suggests that these two insoluble elements were retained while acidic fluids leached more soluble elements. Other evidence also supports a silica-retaining, acidic alteration model for the Murray Fm., including low trace element abundances consistent with leaching, and the presence of opaline silica and jarosite determined by CheMin. Phosphate stability is a key component of this model because PO4 3- is typically soluble in acidic water and is likely a mobile ion in diagenetic fluids (pH less than 5). However, the Murray rocks are not leached of P; they have variable P2O5 (Fig. 1) ranging from average Mars (0.9 wt%) up to the highest values in Gale Crater (2.5 wt%). Here we evaluate APXS measurements of Murray Fm. bedrock and veins with respect to phosphate stability in acidic fluids as a test of the acidic alteration model for the Lower Mt. Sharp rocks.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-35224 , Lunar and Planetary Science Conference; Mar 21, 2016 - Mar 25, 2016; The Woodlands, TX; United States
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  • 9
    Publication Date: 2019-07-13
    Description: The Alpha Particle X-ray spectrometer (APXS) on the Curiosity rover in Gale Crater [1] is the 4th such instrument to have landed on Mars [2]. Along the rover's traverse down-section toward Glenelg (through sol 102), the APXS has examined four rocks and one soil [3]. Gale rocks are geochemically diverse and expand the range of Martian rock compositions to include high volatile and alkali contents (up to 3.0 wt% K2O) with high Fe and Mn (up to 29.2% FeO*).
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-27938 , Lunar and Planetary Science Conference; Mar 18, 2013 - Mar 22, 2013; TheWoodlands, TX; United States
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  • 10
    Publication Date: 2019-07-30
    Description: Characterizing the history of aqueous activity at the martian surface has been an objective of the Mars Exploration Rovers (MER) and the Mars Science Laboratory (MSL). Although the geologic context of the three landing sites are different, comparisons across the datasets can provide greater insight than using data from one mission alone. The Alpha Particle X-ray Spectrometer (APXS) is common to all three rovers (Spirit at Gusev crater, Opportunity at Meridiani Planum, and Curiosity at Gale crater) and provides a consistent basis for these comparisons. Soil and Dust: Fine grained basaltic soils and dust are remarkably uniform in chemical composition across multiple landing sites. These similarities in the concentrations of major, minor, and a few trace elements (Fig. 1) are indicative of planet-wide consistency in the composition of source materials for the soils. S and Cl vary by a factor of two in the soil and dust, but there is no clear association with any bulk cation (e.g., no correlation between S and total Ca, Mg, or Fe in soils). These volatile elements, however, are clearly associated with the nanophase-ferric iron component in the soil established by Mssbauer spectroscopy [1,2]. S and Cl likely originated as acidic species from volcanic out-gassing and subsequently coalesced on dust and sand grain surfaces, possibly with an affinity towards Fe3+ sites. Importantly, given the mobility of S and Cl in aqueous exposures, soil samples maintaining the typical molar S/Cl ratio of ~3.7:1 indicate minimal interactions with liquid water after the addition of S and Cl. In contrast to this well-established baseline, soil samples have been discovered at all three landing sites with atypical S/Cl ratios (e.g., subsurface soils), indicative of a more complex aqueous history.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN70395 , International Conference on Mars; Jul 22, 2019 - Jul 25, 2019; Pasadena, CA; United States
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