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  • 1
    Electronic Resource
    Electronic Resource
    Structural and Functional Investigations on Diiron Complexes: Catalase-Like Activity and Mechanistic Studies on the Formation of (μ-Peroxo)diiron(III) Adducts (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1537-1543 
    Details
    ISSN: 1434-1948
    Keywords: Iron(III) ; Peroxo Complexes ; Kinetics ; Hydrogen Peroxide ; Catalase ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new diiron complex [Fe2(tbpo){O2As(CH3)2}(CH3O)(CH3OH)](ClO4)3 · 5 CH3OH · 2 H2O (1) containing a (μ-alkoxo)(μ-dimethylarsinato)diiron(III) core was synthesized using the heptadentate ligand N,N,N′,N′-Tetrakis(2-benzimidazolylmethyl)-1,3-diamino-2-propanol (Htbpo). The complex was characterized structurally by X-ray crystallography. 1reproduces the coordination mode and the stoichiometry of the proposed purple acid phosphatase-arsenate inhibitor complex. More importantly, 1 is a good functional model for the activation of small molecules, since the solvent molecule in the coordination sphere of each iron ion can be substituted very easily by a small substrate molecule. This is confirmed by the comparatively high pH-dependent catalase-like activity of 1. In order to study the influence of the cacodylate bridge on the formation of the metastable adduct with hydrogen peroxide, the analogous hydroxo-bridged complex [Fe2(tbpo)(OH)(NO3)2](NO3)2 · CH3OH · 2 H2O (2) was employed. The reactions of 1and 2 with H2O2 were studied as a function of [H2O2], pH, temperature, and pressure, and the kinetic results including the activation parameters are reported. In the case of compound 2 the reaction proceeds in one step, and the observed first order rate constant, kobs, shows a linear dependence on the hydrogen peroxide concentration with a zero intercept. For complex 1 the kinetic traces could be fitted to two exponential functions. One of the observed pseudo-first-order rate constants, kobs1, exhibits a linear dependence on the hydrogen peroxide concentration with a zero intercept, whereas the other rate constant, kobs2, was independent of the hydrogen peroxide concentration. A mechanistic interpretation is presented.Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2005/1999/99068_s.pdf or from the author.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Stereoselective Radical Additions using chiral 1,3-dioxolanones derived from lactic and malic acid (1995)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 113-124 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hydrogen abstraction of radical intermediates yielded by radical addition to the methylene compound 6, shows excellent facial selectivity. Conformational analyses of the radical intermediates were carried out by quantum chemical calculations and explain these results. The chiral radicals 7 and 8, yielded from the chiral bromides 3 and 4, lead with ethyl acrylate to the adducts 28 and 29 with more 96% de. The adduct 28 was converted to the optically active γ-valerolactone 30. The structures of the bromides 3, 4 and 31 as well as the radical adducts 19a, 24 and 25 have been verified by X-ray diffraction analysis.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19953370126
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  • 3
    Electronic Resource
    Electronic Resource
    1,2,3-Triphosphetenes, First Examples of a New Class of Phosphorus HeterocyclesReactive E=C(p-p)π Systems, Part 41. Part 40: see ref. [1]. (1996)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 2 (1996), S. 208-213 
    Details
    ISSN: 0947-6539
    Keywords: heterocycles ; insertion reactions ; phosphaalkynes ; phosphorus ylides ; triphosphetenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hitherto unknown 1,2,3-triphosphetenes RC=P—PCF3—PCF3 (3a-d) are formed as main products in reactions of phosphaalkynes R—C≡P [R = iPr2N (1a), tBu (1b), Me2EtC (1c), 1-methylcyclohexyl (1d)] with the cyclotetraphosphane (PCF3)4 (2). According to NMR results the CF3 groups in 3a-d have a trans disposition; an X-ray diffraction study of 3a confirms this structure. The P—P bond lengths in 3a are equal [2.201 (2) and 2.204 (2) Å] and correspond to single bonds. A considerable shortening is observed for the sp2-C-N bond (1.336 Å) which, together with the elongation of the P=C bond (1.746 Å), indicates effective π donation of the lone pair on nitrogen. Surprisingly, 3a can be prepared in quantitative yields by reaction of the PP ylide Me3P=PCF3 (6) with 1 a (molar ratio: 2:1). In contrast, the corresponding reactions of 6 with the alkyl-substituted phosphaalkynes 1b-d lead to the novel phosphorus ylides Me3P=C(R)—P—PCF3—PCF3PCF3 [R = tBu (10a), Me2EtC (10b), 1-methylcyclohexyl (10c)] in good yields. In their molecular groundstate structures, determined by X-ray diffraction, the lone pair on the phosphano P atom prefers the syn position with respect to the ylidic P=C bond. An unusual lengthening of the sp2-C-C bond [1.553 (4) (10a), 1.543 (6) (10b), 1.551 (4) Å (10c)] to values typical for sp3-C/sp3-C distances is observed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19960020213
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  • 4
    Electronic Resource
    Electronic Resource
    New Strategies for the Generation of Large Heteropolymetalate Clusters: The β-B-SbW9 Fragment as a Multifunctional Unit (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1232-1237 
    Details
    ISSN: 0947-6539
    Keywords: antimony ; heteropolyanions ; polyoxometalates ; synthesis design ; tungsten ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proceeding from the α-B-SbW9O33 fragment 1, various novel large heteropolyanions ([Na2Sb8W36O132(H2O)4]22- (2), [Sb2W22O74(OH)2]12- (3) and [Sb2W20M2O70(H2O)6](14-2n)- (4); Mn+ = Fe3+, Co2+, Mn2+, Ni2+) have been obtained in crystalline form by systematic synthesis. Their unexpected structures have been studied by X-ray diffraction: 2, 3 and 4 contain β-SbW9 units connected to each other by Sb3+ ions, WO2/WO2OH groups, and WO2/Mn+ (H2O)3 groups, respectively. Structural details and especially the systematic synthesis strategy for the formation of these interesting polytungstates are discussed in order to explain the unusual behaviour of 1 in aqueous solution under different reaction conditions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030810
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  • 5
    Electronic Resource
    Electronic Resource
    Kristallstruktur des N-Nitrosodimethylamins (1975)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 1130-1137 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal Structure of N-NitrosodimethylamineThe crystal structure of the title compound has been determined from single crystal low temperature X-ray counter data collected at - 130°C. Bond lengths in the exactly planar molecule were found to be N — N 1.320(6), N — O 1.260 (6), C — N 1.461 (7) and 1.465 (7) Å. The bonding in the molecule is significantly closer to the polar structure compared to the free molecule in the gas phase, this being stabilised by intermolecular π interactions perpendicular to the planes of the molecules.
    Notes: Die Struktur des festen N-Nitrosodimethylamins bei - 130°C wurde durch Röntgenstruktur-analyse bestimmt. Das Molekül ist im Kristall exakt planar. Die Bindungslängen bei - 130°C sind: N — N 1.320(6), N — O 1.260(6), C — N 1.461(7) und 1.465(7) Å. Senkrecht zu den Molekülebenen verlaufende intermolekulare π-Wechselwirkungen stabilisieren einen höheren Anteil der polaren Struktur am Bindungszustand gegenüber dem freien Molekül der Gasphase.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19751080419
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  • 6
    Electronic Resource
    Electronic Resource
    Die Kristall-und Molekülstruktur von 4,4,6,6-Tetrafluor-1,3,5,2λ5,4λ5,6λ5-triazatriphosphorin-2,2-diamin (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 2622-2627 
    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 and Molecular Structure of 4,4,6,6-Tetrafluoro-1,3,5,2λ5,4λ5,6λ5-triazatriphosphorine-2,2-diamineThe crystal structure of the geminal isomer of N3P3F4(NH2)2 (3) was determined by X-ray analysis and was refined to R = 0.035. Crystals of the compound are orthorhombic, space group Pnma. The six-membered (P—N)3 ring is planar within the limits of error. In the (NH2)2 P—N—P(F2) segment the P—N bond lengths are 1.597 and 1.524Å with the shorter one on the side of the PF2 group. In the (F2)P—N—P(F2) segment the P—N bond length is 1.564 Å. The mean bond lengths in each P—N—P segment are nearly equal. The mean values for the P—F and P—Namine bond lengths were found to be 1.532 and 1.602 Å, respectively. The endocyclic angles are: N—P—N 110.4°, 120.5°; P—N—P 125.7°, 117.2°.
    Notes: Die Struktur des geminalen N3P3F4(NH2)2 (3) wurde aus Röntgenbeugungsdaten bestimmt und zu einem R-Wert von 3.5% verfeinert. Die Verbindung kristallisiert orthorhombisch in der Raumgruppe Pnma. Der (P—N)3-Ring ist innerhalb der Fehlergrenzen planar. Die P—N-Abstände betragen im (NH2)2 P—N—P(F2)-Segment 1.597 und 1.524 Å mit dem kürzeren Abstand auf der Seite der PF2-Gruppe. Im (F2)P—N—P(F2)-Segment ergibt sich die P—N-Bindungslänge zu 1.564 Å. Damit sind die Mittelwerte der Bindungslängen in jedem P—N—P-Segment nahezu gleich groß. Die Mittelwerte für die P—F- und die P—NAmin-Bindungslängen betragen 1.532 bzw. 1.602 Å. Die N—P—N-Winkel im Ring wurden zu 110.4° und 120.5°, die P—N—P-Winkel zu 125.7° und 117.2° beobachtet.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761090733
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  • 7
    Electronic Resource
    Electronic Resource
    Die Kristall- und Molekülstruktur von [Bis(trimethylsilyl)amino]-bis(trimethylsilylimino)phosphoran (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 3183-3189 
    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 and Molecular Structure of [Bis(trimethylsilyl)amino]-bis(trimethylsilylimino)phosphoraneThe crystal structure of the title compound 1 was determined from single crystal X-ray data (measured at +18 and -130°C) and was refined to R = 0.043 (-130°C). The compound crystallizes in the monoclinic space group C2/c. Comparison of bond lengths in 1 at the two temperatures demonstrates the necessity of a correction for shortening due to thermal motion for the SiR3-groups (R = methyl). The planar threefold nitrogen coordination of the phosphorus seems to favor the assumption of pπ-pπ-bonds. The P-Nimine and P-Namine bond lengths were found to be 1.515 and 1.638 Å, respectively; Nimine-Si 1.703, Namine-Si 1.787 Å, angle P = N-Si 146.8° (all values for -130°C).
    Notes: Die Struktur der Titelverbindung 1 wurde aus bei + 18 und - 130°C ermittelten Diffraktometer-Einkristalldaten bestimmt und zu einem R-Wert von 4.3% (-130°C) verfeinert. Die Verbindung kristallisiert monoklin in der Raumgruppe C2/c. Z = 4. Ein Vergleich der Bindungslängen in 1 bei den verschiedenen Temperaturen zeigt für die endständigen Trimethylsilylgruppen die Notwendigkeit einer Korrektur der durch thermische Schwingungen scheinbar verkürzten Abstände. Das zentrale Phosphoratom weist eine planare dreifache Koordination von Stickstoffatomen auf. Bindungslängen und die Symmetrie des Moleküls deuten auf die Existenz von pπ-pπ-Bindungen zwischen Phosphor und Stickstoff hin. Der P-NImin-Abstand beträgt 1.515, der P-NAmin-Abstand 1.638 Å. Die NImin-Si- und NAmin-Si-Bindungslängen wurden zu 1.703 bzw. 1.787 Å beobachtet. Der P = N-Si-Winkel beträgt 146.8° (alle Werte für -130°C).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100924
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  • 8
    Electronic Resource
    Electronic Resource
    Kristall- und Molekülstrukturen des S3N2+-Radikalkations in S3N2+SO3CF3- · 1/2 CH3CN und von S3N2(NSO2F) (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 226-232 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal and Molecular Structures of the S3N2+ Radical Cation in S3N2+SO3CF3- · 1/2 CH3CN and of S3N2(NSO2F)The molecular and crystal structures of S3N2+SO3CF3- · 1/2 CH3CN (1) and S3N2NSO2F (2) were determined from single crystal X-ray diffraction data. The S3N2+ radical cation in 1 is planar, two cations being connected through weak S—S bonding interactions to form dimers with a chair configuration. The S3N2 ring of 2, in which the NSO2F group is covalently bonded to one of the S atoms of the S — S group, is not planar; the S — S bond is weaker than in 1.
    Notes: Die Röntgenstrukturanalysen von S3N2+SO3CF3- - 1/2 CH3CN (1) und S3N2NSO2F (2) zeigen in 1 ein planares S3N2+-Radikalkation, wobei zwei Kationen über schwache S-S-Wechselwirkungen zu sesselförmigen Dimeren assoziiert sind. Der an einem S-Atom der S — S-Gruppe substituierte S3N2-Ring in 2 ist nicht planar; die S — S-Bindung ist schwächer als in 1.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19801130123
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  • 9
    Electronic Resource
    Electronic Resource
    Zur Existenz eines Silaolefins: Synthese und Kristallstrukturen von Wittig- und Diels-Alder-Produkten in Reaktionen lithiierter fluorsilylfunktioneller Diazasilacyclopentene mit Benzaldehyd und Methacrolein (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 282-289 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Existence of a Silaolefin: Synthesis and Crystal Structures of Wittig and Diels-Alder Products in Reactions of Lithiated (Fluorosilyl)diazasilacyclopentenes with Benzaldehyde and MethacroleinLithium salts of 1,2-diaza-3-sila-5-cyclopentenes react with fluorosilanes and aminofluorosilanes to give 4-(fluorosilyl)-substituted compounds 1 - 4. By reaction with tert-butyllithium 1 - 4 themselves form lithium salts 5 - 8, which react with fluorosilanes in a second substitution giving 9 and 10.5 and 7 undergo a Wittig-type reaction with benzaldehyde to form the benzylidene derivative 11. Spirocyclic Diels-Alder adducts (12, 13) are obtained from the reaction of 5 and 6 with 2-methyl-2-propenal. The propenylidene derivative 14 is formed as a by product. With excess 2-methyl-2-propenal, 12 reacts as a dienophile giving the oligocyclic Diels-Alder adducts 15 and 16. The crystal structures of 11 and 15 are reported.
    Notes: Lithiumsalze der 1,2-Diaza-3-sila-5-cyclopentene reagieren mit Fluorsilanen und Aminofluorsilanen zu den 4-(Fluorsilyl)-substituierten Verbindungen 1 - 4. In Reaktion mit tert-Butyllithium bilden 1 - 4 erneut Lithiumsalze (5 - 8), die mit Fluorsilanen unter Zweitsubstitution zu 9 und 10 reagieren. In Wittig-analoger Reaktion reagieren 5 und 7 mit Benzaldehyd zum Benzyliden-Derivat 11. Spirocyclische Diels-Alder-Addukte (12, 13) werden aus 5 und 6 mit 2-Methyl-2-propenal erhalten. Als Nebenprodukt entsteht das Propenyliden-Derivat 14. Mit überschüssigem Dien (2-Methyl-2-propenal) reagiert 12 als Dienophil zu den oligocyclischen Diels-Alder-Addukten 15 und 16. Kristallstrukturen von 11 und 15 werden mitgeteilt.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160132
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  • 10
    Electronic Resource
    Electronic Resource
    Umlagerung von azabicyclischen Hydroxylamin-Derivaten unter Sauerstoff-Insertion (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1107-1117 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Rearrangement with Oxygen-Insertion in Azabicyclic Hydroxylamine DerivativesN-Hydroxy-2-azabicyclo[2.2.1]hept-5-ene (1) is rearranged to the oxaazabicyclic compounds 3, 4, and 8 by the reaction with either tosyl or benzoyl chloride. The structure of 3 was proved by X-ray analysis. Experiments with [18O]tosyl chloride as well as products of the intermediate 12 with methanol are consistent with a heterolysis in the intermediate 11 formed by N-tosylation  -  in contrast to the homolytic1) Meisenheimer rearrangement.
    Notes: N-Hydroxy-2-azabicyclo[2.2.1]hept-5-en (1) wird bei der Umsetzung mit Tosyl- und Benzoylchlorid umgelagert zu den Oxaazabicyclen 3, 4 und 8. Die Struktur von 3 wurde durch Röntgenstrukturanalyse bewiesen. Versuche mit [18O]Tosylchlorid sowie die Abfangprodukte mit Methanol sprechen für eine ionische Spaltung in dem durch N-Tosylierung gebildeten Intermediären 11, im Gegensatz zum radikalischen Ablauf der sonst analogen Meisenheimer-Umlagerung.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160325
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