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  • 1
    Online Resource
    Online Resource
    Powder Diffraction : Theory and Practice (2008)
    Cambridge : Royal Society of Chemistry
    Details Availability
    Description / Table of Contents: A long awaited overview of powder diffraction in modern research include essential theory and introductory material, Powder diffraction is a widely used scientific technique in the characterization of materials with broad application in materials science, chemistry, physics, geology, pharmacology and archaeology. Powder Diffraction: Theory and Practice provides an advanced introductory text about modern methods and applications of powder diffraction in research and industry. The authors begin with a brief overview of the basic theory of diffraction from crystals and powders. Data collection strategies are described including x-ray, neutron and electron diffraction setups using modern day apparatus including synchrotron sources. Data corrections, essential for quantitative analysis are covered before the authors conclude with a discussion of the analysis methods themselves. The information is presented in a way that facilitates understanding the information content of the data, as well as best practices for collecting and analyzing data for quantitative analysis. This long awaited book condenses the knowledge of renowned experts in the field into a single, authoritative, overview of the application of powder diffraction in modern materials research. The book contains essential theory and introductory material for students and researchers wishing to learn how to apply the frontier methods of powder diffraction
    Type of Medium: Online Resource
    Pages: 604 p , Online-Ressource , 218 b&w, ill
    Edition: RSC eBook Collection 1968-2009
    URL: https://doi.org/10.1039/9781847558237
    Language: English
    Note: Ebook , Chapter 1: Principles of Powder Diffraction-- Chapter 2: Experimental Setups-- Chapter 3: The Intensity of a Bragg Reflection-- Chapter 4: General Data Reduction-- Chapter 5: The Profile of a Bragg Reflection for Extracting Intensities-- Chapter 6: Instrumental Contributions to the Line Profile in X-ray Powder Diffraction. Example of the Diffractometer with Bragg-Brentano Geometry-- Chapter 7: Indexing and Space Group Determination-- Chapter 8: Crystal Structure Determination-- Chapter 9: Rietveld Refinement-- Chapter 10: The Derivative Difference Minimization Method-- Chapter 11: Quantitative Phase Analysis-- Chapter 12: Microstructural Properties: Texture and Macrostress Effects-- Chapter 13: Microstructural Properties: Lattice Defects and Domain Size Effects-- Chapter 14: Two-dimensional Powder Diffraction using Area Detectors: The Experimental Setup-- Chapter 15: Powder Diffraction at Non-ambient Conditions-- Chapter 16: Local Structure from Total Scattering and Atomic Pair Distribution Function (PDF) Analysis-- Chapter 17: Computer Software for Powder Diffraction.
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  • 2
    Electronic Resource
    Electronic Resource
    Fluxionality in hexacoordinated copper(II) complexes with 2,2':6',2''-terpyridine (terpy) and related ligands: structural and spectroscopic investigations (1990)
    s.l. : American Chemical Society
    Inorganic chemistry 29 (1990), S. 2035-2042 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00336a002
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  • 3
    Electronic Resource
    Electronic Resource
    Trijodid-Ionen in einer Jodadditionsverbindung des p-Jod-N,N-dimethylanilins (1959)
    Springer
    Naturwissenschaften 46 (1959), S. 557-558 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00631288
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  • 4
    Electronic Resource
    Electronic Resource
    Beziehungen zwischen Bindungslängen und Bindungsstärken in Oxidstrukturen (1975)
    Springer
    Monatshefte für Chemie 106 (1975), S. 779-793 
    Details
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The vond valencev, which is a measure for bond strengths, was estimated byPauling, 19291, as the ratio of charge to coordination number of the cation. For non-regular coordination polyhedra, the bond valence depends strongly on the bond lengthL. Good results are obtained for the following relations ofv vs.L: $$\upsilon = \left( {\frac{{L(1)}}{L}} \right)^N $$ with exponentsN between 4.0 and 6.0 or $$L(\upsilon ) = L(1) - 2k log \upsilon $$ with most 2k-values between 0.75 and 1.1 Å. The bond valence sums are not very sensitive to the values ofN or 2k, resp., but very much to theL (1)-values (length for unit bond valence). Therefore theL (1)-values should be adapted to each structure. Some values ofL (1),N, 2k andL max are listed. The increase of mean bond lengths with increasing distortion of a coordination polyhedron can be estimated by $$\bar L = L(\bar \upsilon ) + 2k \log \upsilon /{}^n\sqrt {\upsilon _1 \cdot \upsilon _2 \cdots \upsilon _n \cdot } $$
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00902183
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  • 5
    Electronic Resource
    Electronic Resource
    Die Kristallstruktur von 1-Benzyl-1,4,4-trimethyl-1,2,6;-thia(VI)-diazin-3,5(4H)-dion (1973)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 106 (1973), S. 2807-2814 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Structure of 1-Benzyl-1,4,4-trimethyl-1,2,6-thia(VI)diazine-3,5(4H)-dioneThe structure of thc title compound was elucidated by X-ray diffraction: space group P211/c, a = 8.947, b = 21.055, c - 7.688 Å, β = 113.61°, Z = 4, Dm = 1.31 g·cm-3, Dx = 1.323 g·cm-3, R = 2.7%. The thiadiazine ring deviates slightly from planarity. C-4 is 0.17 Å out of plane. So one of the methyl groups at C-4 gets van der Waals contact with the benzyl group at S, which explains the shift of the n.m.r. signal of that methyl group to higher field (τ = 9.6). The molecule obeys nearly mirror symmetry. Weak C—H…O hydrogen bonds exist between adjacent molecules, which are possible because of the limiting polar formula:
    Notes: Die Struktur dcr Titelverbindung wurde mittels Röntgenbeugung aufgeklärt: Raumgruppe P21/c, a = 8.947, b = 21.055, c = 7.688 Å, β = 113.61°, Z = 4 Moleküle/Zelle, Dm = 1.31 g·cm 3, Dx = 1.323 g·cm-3, R = 2.7%. Der Thiadiazinring ist nicht ganz eben, sondern C-4 knickt um 0.17 Å so aus der Ringebene heraus, daß sich die eine der daran gebundenen Methylgruppen der an S gebundenen Benzylgruppe bis zum van der Waals'schen Kontakt nähert. Dadurch kann das zu hohem Feld verschobene NMR-Signal (τ = 9.6) dieser Methylgruppe erklärt werden. Insgesamt ist das Molekül fast spiegelsymmetrisch. Zwischen benachbarten Molekülen bestehen schwache C—H…O-Wasserstoffbrücken, die durch die polare Grenzformel erklärt werden können.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19731060908
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  • 6
    Electronic Resource
    Electronic Resource
    Polycarbonylverbindungen, XVI. Darstellung und Struktur des Schwefelanalogons des Quadratsäure-Dianions K2[C4S4]·H2O (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 2208-2215 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polycarbonyls, XVI. Synthesis and Structure of the Sulfur Analogue of Squaric Acid Dianion K2[C4S4·H2O]Sulfhydrolysis of 1,2- or 1,3-dithiosquaric acid diamides yields the sulfur analogue 4 of squaric acid dianion, the first member of the „thioxocarbons“. Spectroscopic data and intramolecular distances determined by X-ray diffraction indicate a symmetrical, delocalised electron system with C—C- and C—S-bond orders of n - 1.25 and 1.5, resp.
    Notes: Durch Sulfhydrolyse von 1,2- bzw. 1,3-Dithioquadratsäure-bisamiden entsteht das Schwefelanalogon 4 des Quadratsäure-Dianions, der erste Vertreter der „Thioxokohlenstoffe“. Spektroskopische Daten und die aus einer röntgenographischen Strukturbestimmung erhaltenen innermolekularen Bindungslängen weisen auf ein symmetrisches, delokalisiertes Elektronensystem mit C — C- bzw. C — S-Bindungsordnungen von n = 1.25 bzw. 1.5 him.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090627
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  • 7
    Electronic Resource
    Electronic Resource
    Struktur eines Tricarbonyl-1-isopropoxycarbonyl-1,2-diazepin-eisen-Komplexes (1970)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 82 (1970), S. 982-983 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19700822404
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  • 8
    Electronic Resource
    Electronic Resource
    Synthese, IR- und EPR-Spektren sowie die Kristallstruktur von HPPh3[WOCl4(OPPh3)] (1988)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 563 (1988), S. 70-78 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, I.R. and E.P.R. Spectra, and Crystal Structure of HPPh3[WOCl4(OPPh3)]Partial hydrolysis of the alkyne complex [WCl4(PhC≡CPh)]2 in the presence of triphenylphosphine and dichloromethane as oxidizing agent and solvent yields dark green crystals of the complex HPPh3[WOCl4(OPPh3)]. Attempts to prepare the compound directly by the reaction of WOCl3 with PPh3, OPPh3 and HCl in dichloromethane were unsuccessful.HPPh3[WOCl4(OPPh3)] was characterized by its i.r. and e.p.r. spectrum. As shown by a crystals structure determination (1835 independent, observed reflections, R = 0.056) the complex crystallizes monoclinically in the space group P21/n with four formula units per unit cell. The complex consists of HPPh3+ and [WOCl4(OPPh3)]- ions, in which the tungsten atom is in a distorted octahedral environment, surrounded by four equatorial chlorine atoms, by one axial oxygen atom (bond length WO = 172 pm), and by the oxygen atom of the OPPh3 molecule (WO = 206 pm).
    Notes: HPPh3[WOCl4(OPPh3)] entsteht in Form dunkelgrüner Kristalle bei der partiellen Hydrolyse des Diphenylacetylenkomplexes [WCl4(PhC≡CPh)]2 bei Anwesenheit von Triphenylphosphan und Dichlormethan als Oxidations- und Lösungsmittel. Versuche, die Verbindung aus WOCl3, PPh3, OPPh3 und HCl in Dichlormethan direkt herzustellen, mißlangen.HPPh3[WOCl4(OPPh3)] haben wir durch das IR- und das EPR-Spektrum charakterisiert. Nach der röntgenographischen Strukturanalyse (1835 unabhängige, beobachtete, beobachtete Reflexe, R = 5,6%) kristallisiert die Verbindung monoklin in der Raumgruppe P21/n mit vier Formeleinheiten pro Elementarzelle. Sie ist aus HPPh3+-Ionen und Anionen [WOCl4(OPPh3)]- aufgebaut, in denen das Wolframatom verzerrt oktaedrisch von vier äquatorial angeordneten Chloratomen und axial von einem terminalen O-Atom (Bindungsabstand WO = 172 pm) und von dem O-Atom des OPPh3-Moleküls (WO = 206 pm) umgeben ist.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19885630111
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  • 9
    Electronic Resource
    Electronic Resource
    Synthese und Struktur von N-Acylimidsäureestern (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3089-3104 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of Alkyl N-AcylimidatesAlkyl N-acylimidates 1 are prepared more easily and in higher yields than before by reaction of alkyl imidate hydrochlorides 5 with acyl halides 7 in the presence of 2.2 mol of base (14 examples). The X-ray analysis of a crystalline derivative (1dbd) shows, that the C = N- and the C = O parts are twisted significantly (torsional angle 77.6°). The stereochemical, dynamic, and electronic properties of the compounds 1 are interpreted by means of ab initio 3-21G calculations on conformers of the parent system HO-CH=N-CH=O (8). Low rotational (ca. 6 kcal/mol) and inversional (max. 8 kcal/mol) barriers indicate the many favourable electronic interactions between the C = N- and the C = O groups in such N-functionalised imine derivatives. The compounds 1 are significantly higher in energy than bisacylamines and are therefore suggested to be superior, more reactive synthetic C-N-C building blocks. The spectroscopic properties (IR, 13C- and 1H NMR, MS) are given and discussed.
    Notes: N-Acylimidsäureester 1 können durch Umsetzung von Imidsäureester-hydrochloriden 5 mit Acylhalogeniden 7 in Gegenwart von 2.2 mol Base wesentlich einfacher und in höherer Ausbeute dargestellt werden als bisher (14 Beispiele). Die röntgenographisch ermittelte Festkörper-Konformation eines Derivates (1dbd) zeigt, daß C = N- und C=O-Molekülteil stark gegeneinander verdrillt sind (Torsionswinkel 77.6°p). Die stereochemischen, dynamischen und elektronischen Eigenschaften der Verbindungen 1 werden mit Hilfe von ab initio-3-21 G-Berechnungen an den Konformeren des Grundsystems HO - CH=N-CH=O (8) gedeutet und verallgemeinert. Niedrige Rotationsbarrieren (ca. 6 kcal/mol) und niedrige Inversionsschwellen (max. 8 kcal/mol) verdeutlichen die zahlreichen günstigen Wechselwirkungsmöglichkeiten zwischen der C = N- und der C = O-Gruppe in solchen funktionalisierten Iminderivaten. Die Verbindungen 1 sind energiereicher als die isomeren Bisacylamine und sollten sich daher als reaktive C-N-C-Bausteine synthetisch eignen. Die spektroskopischen Eigenschaften (IR, 13C- und 1H-NMR, MS) werden mitgeteilt und diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180808
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesen, Struktur und Eigenschaften von 1,1-Dialkoxy-2-azapropenylium-Salzen (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1271-1279 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses, Structures, and Properties of 1,1-Dialkoxy-2-azapropenylium Salts1,1-Dialkoxy-2-azapropenylium salts 1 were synthesized by alkylation at the oxygen atom of N-methylenecarbamates 4 with trialkyloxonium salts 5, in cases, where steric hindrance makes N-alkylation difficult (4a); otherwise the iminium salts 6 are formed preferentially. A more general synthetic route to the salts 1 is based on the reaction of N-(alkoxymethyl)imidocarbonates 8 with acylium ions (acyl cleavage reaction). The salts are thermally not very stable; phenyl ester derivatives are easily converted into 4H-1,3-benzoxazine derivatives 11. - An X-ray analysis of 1aa shows an allenic structure with orthogonal π systems; for steric reasons the C-N-C bond angle is reduced to ca. 150°. - Quantum mechanical ab initio calculations predict high steric flexibility for the salts 1; in the parent compound (16a) an allenic structure is slightly (2-3 kcal/mol) favored over allylic forms (16d). Thermodynamically more stable are the isomeric iminium salts 6 and 17, respectively. - Depending on the substitution pattern in solution (IR, dynamic NMR spectroscopy) allenic (1a) or allylic (1b) structures are observed.
    Notes: 1,1-Dialkoxy-2-azapropenylium Salze 1 können durch O-Alkylierung am Carbonylkohlenstoff von N-Methylencarbamidsäureestern 4 mit Trialkyloxonium-Salzen 5 erhalten werden, falls eine N-Alkylierung sterisch erschwert ist (4a); andernfalls werden die Iminium-Salze 6 gebildet. Eine allgemeinere Darstellungsmethode für die Salze 1 beruht auf der Umsetzung von N-(Alkoxymethyl)-imidokohlensäureestern 8 mit Acylium-Ionen (Acylspaltung). Die Salze 1 sind thermische nicht sehr beständig Phenylester-Derivate gehen leicht in 4H-1,3-Benzoxazin-Derivate 11 über. - Die Kristallstrukturanalyse von 1aa ergibt eine allenische Struktur mit orthogonalen π-Systemen, wobei der C-N-C-Bindungswinkel auf ca. 150° reduziert ist (sterische Effekte). - Quantenmechanische Ab-initio-Berechnungen sagen hohe sterische Flexibilität der Salze 1 voraus, wobei beim Grundkörper allenische Strukturen (16a) geringfügig (ca. 2-3 kcal/mol) gegenüber allylischen Formen (16d) bevorzugt sind. Thermodynamisch günstiger als die Salze 1 (bzw. 16) sind die isomeren Iminium-Salze 6 bzw. 17. - Je nach Substitutionsmuster beobachtet man in Lösung (IR-, dynamische NMR-Spektroskopie) allenische (1a) oder allylische Strukturen (1b).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200802
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