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  • 1
    Electronic Resource
    Electronic Resource
    Intermetallic s̰ and ∞ Communication in Heterodinuclear μ-Cyclooctatetraene ComplexesCooperative effects in ∞ ligand bridged dinuclear complexes, Part 21; Part 20: J. Heck, J. Körnich, J. Organomet. Chem. in press; Part 19: U. Hagenau, J. Heck, E. Hendrickx, A. Persoons, T. Schuld, H. Wong, Inorg. Chem. 1996, 35, 7863-7866. (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1151-1159 
    Details
    ISSN: 0947-6539
    Keywords: bridging ligands ; cyclooctatetraene ; EPR spectroscopy ; heterodinuclear complexes ; structure elucidation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of [(C5R5)Cr(∞6-Cot)] (R = H, Me; Cot = cyclooctatetraene) with [(CO)3Fe(∞-cis-cyclooctene)2] affords the heterodinuclear complexes [(C5R5)Cr{μ-∞5(Cr):∞3(Fe)-Cot}Fe(CO)3] (R = H: 1, R = Me: 2) in quite good yields. One of the CO ligands in 1 and 2 can be easily substituted by a phosphane ligand, PR3 (R = Me, Ph, OEt, F) to obtain [(C5R5)Cr{μ-∞5(Cr):∞3(Fe)-Cot}Fe-(CO)2PR3] (R = H, R = Me: 3a; R = H, R = Ph: 3b; R = Me, R = Me: 4a; R = Me, R = Ph: 4b; R = Me, R = OEt: 4c; R = Me, R = F: 4d). The X-ray structure determinations of 2, 3a, and 4c showed exclusively synfacial coordination of the two metal ligand moieties, despite the bulky C5Me5 (Cp*) ligand in 2 and 4c. However, the steric demand of Cp* gives rise to structural distortions in 2 and 4c, compared to the Cp-containing products 1 and 3a, and an elongation of the Cr-Fe distance from 293 pm to 303 and 304 pm, respectively. The heterodinuclear complexes were investigated by cyclic voltammetry and ESR spectroscopy in order to elucidate the role of the permethylation of the cyclopentadienyl ligand and the influence of phosphane ligands with different π-accepting abilities. The ESR spectroscopic results reveal surprisingly large 31P hyperfine coupling constants (hfcc). These can be explained by a superposition of two different electron spin transfer mechanisms, which include a s̰- and a π-bonding mode between the Cr and Fe centers.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030721
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  • 2
    Electronic Resource
    Electronic Resource
    Fructose-Derivate in ungewöhnlicher Konformation: Kristall- und Molekülstruktur der 1,4,5-Tri-O-acetyl-2,3-O-isopropyliden-β-D-fructopyranose (1976)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 3346-3357 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Derivatives of Fructose in Unusual Conformation:Crystal and Molecular Structure of 1,4,5-Tri-O-acetyl-2,3-O-isopropylidene-β-D-fructopyranoseThe title compound 2b crystallizes in two modifications, a tetragonal one (space group P42212) and a hitherto unknown lower melting trigonal one. The crystal structure of the trigonal modification (space group P32) was determined by X-ray analysis using direct methods and refining to a final R of 0.034 for all 1400 reflections. The pyranose ring of 2b in the crystal adopts a 3C6(D) chair conformation somewhat flattened at C-3 with axial orientation of the C-1 acetoxymethylene group and the C-4 acetyl group. 270 MHz 1H n. m. r. spectra of 2b in solution reveal rapid chair-chair interconversion between the extreme conformations 5C2(D) (≈ 3C6(D)) and 2C5(D), the former also dominating in the equilibrium to an extent of about 65%. In the free compound 2a an even larger amount of 5C2(D) conformation is observed, namely approx. 80% in pyridine at room temperature.
    Notes: Die Titel-Verbindung 2b kristallisiert in zwei Modifikationen, einer tetragonalen (Raumgruppe P42212) und einer bisher unbekannten trigonalen mit niedrigerem Schmelzpunkt. Von der trigonalen Modifikation (Raumgruppe P32) wurde eine Röntgenstrukturanalyse unter Verwendung der Direktmethode und Verfeinerung bis zum R-Faktor von 0.034 für alle 1400 Reflexe durchgeführt. Der Pyranose-Ring von 2b liegt im Kristall in einer an C-3 abgeflachten 3C6(D)-Sesselkonformation mit axialer Orientierung der C-l-Acetoxymethylengruppe und der Acetylgruppe an C-4 vor. 270-MHz-1H-NMR-Spektren von 2b in Lösung zeigen schnelle Sesselinversion zwischen den extremen Konformationen 5C2(D) (≈ 3C6(D)) und 2C5(D). wobei auch hier die 5C2(D)-Konformation mit einem Anteil von ca. 65% im Gleichgewicht überwiegt. Bei der freien Verbindung 2a wird sogar ein Anteil von annähernd 80% der 5C2(D)-Konformation in Pyridin bei Raumtemperatur beobachtet.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19761091010
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  • 3
    Electronic Resource
    Electronic Resource
    Anionenaktivierung, IV. Kristall- und Molekülstruktur des Adduktes von Malononitril mit 18-Krone-6 (1,4,7,10,13,16-Hexaoxacyclooctadecan) (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 2249-2253 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Anion Activation, IV. Crystal and Molecular Structure of the Malononitrile Adduct of 18-Crown-6 (1,4,7,10,13,16-Hexaoxacyclooctadecane)The structure of the adduct 2 malononitrile · 18-crown-6 has been determined from X-ray data and refined to R = 0.049. The complex crystallizes in the space group P21/c. The molecules of malononitrile are hydrogen bonded (C—H · · · ·O) to the crown ether forming a three-dimensional hole of about 100 pm diameter as observed in bicyclic amino polyethers. The complexed crown ether has approximately D3d symmetry like its KSCN complex.
    Notes: Die Struktur des Adduktes 2 Malononitril · 18-Krone-6 wurde röntgenographisch bestimmt und bis zu einem R-Faktor von 0.049 verfeinert. Die Verbindung kristallisiert in der Raumgruppe P21/c. Die Malononitrilmoleküle bilden über C—H · · · ·O-Wasserstoffbrücken mit dem Kronenether analog den bicyclischen Aminopolyethern einen dreidimensionalen Hohlraum von ca. 100 pm Durchmesser. Der Kronenether hat wie im KSCN-Komplex annähernd D3d-Symmetrie.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100623
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  • 4
    Electronic Resource
    Electronic Resource
    Magnesium-acetylacetonat, Mg3[MeC(O)CHC(O)Me]6, und Magnesium-(diethoxyphosphinyl)acetonat, Mg3[(EtO)2P(O)CHC(O)Me]6, dreikernige Chelatkomplexe (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 3529-3534 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Magnesium Acetylacetonate, Mg3[MeC(O)CHC(O)Me]6, and Magnesium (Diethoxyphosphinyl)acetonate, Mg3[(EtO)2P(O)CHC(O)Me]6- Trinuclear Chelate ComplexesThe title compounds 1 and 2 have been investigated by X-ray structure analysis and found to be trimeric. Each Mg atom is coordinated by six O atoms with a distorted octahedral array. The bridging of the central Mg atom with the terminal ones is achieved by common O atoms of the carbonyl groups. Whereas the preparation of magnesium (diethoxyphosphinyl)acetonate (2) has been reported previously, magnesium acetylacetonate (1) has been obtained for the first time by dehydration of Mg(acac)2(H2O)2.
    Notes: Röntgenuntersuchungen ergaben für die Titelverbindungen 1 und 2 trimere Strukturen. Jedes Mg-Atom ist von sechs O-Atomen verzerrt oktaedrisch koordiniert. Die Verbrückung des zentralen Mg-Atoms mit den endständigen erfolgt durch gemeinsame O-Atome der Car-bonyl-Gruppen. Magnesium-(diethoxyphosphinyl)acetonat (2) wurde nach Literaturangaben hergestellt, die Darstellung von Magnesium-acetylacetonat (1) erfolgte erstmals durch Entwässerung von Mg(acac)2(H2O)2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180909
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  • 5
    Electronic Resource
    Electronic Resource
    2,5-Dioxabicyclo[2.2.2]octan-Derivate: Konformation von Methyl-2,6-anhydro-α-D-hexopyranosiden (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 3919-3926 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,5-Dioxabicyclo[2.2.2]octane Derivatives: Conformation of Methyl 2,6-Anhydro-α-D-hexopyranosidesRing opening of methyl 2,6:3,4-dianhydro-α-D-altropyranoside (5) with KOH in water at 150°C yields almost exclusively the hitherto unknown methyl 2,6-anhydro-α-D-mannopyranoside (6). 1H NMR spectra of this compound and of all other α-anomers of this series suggest a conformation of the pyranose ring intermediate between the boat 2,5B(D) and the twist boat 5S1(D). This was verified by X-ray analysis of methyl 3,4-di-O-acetyl-2,6-anhydro-α-D-altropyranoside (2).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19801131225
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  • 6
    Electronic Resource
    Electronic Resource
    Über Metallalkyl- und -aryl-Verbindungen, XXVI1) Zur Existenz von Lithium-Magnesium-Methyl-Verbindungen. Die Kristallstruktur von Bis[(N,N,N′N′-tetramethylethylendiamin)lithium]-tetra-μ-methylmagnesat, ein Metallorganyl mit Lithium-Methyl-Magnesium-Brücken (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 209-213 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Alkyl and Aryl Compounds, XXVI1) On the Existence of Lithium Magnesium Methyl Compounds. The Crystal Structure of Bis[N, N, N′,N′-tetramethylethylenediamine)lithium] Tetra-μ-methylmagnesate, an Organometallic Compound with Lithium Methyl magnesium BridgesUsing the bidentate ligand N, N, N′, N′-tetramethylethylenediamine (tmeda), the solvate-free compounds [Li(tmeda)Me3Mg]2 (2) and [Li(tmeda)]2Me4Mg (1) are prepared. The crystal structure of 1 has been determined (monoclinic space group P21/c). In the center of the molecule the Mg atom is coordinated tetrahedraly by four methyl groups. These form bridges to both Li atoms which in turn are linked to the chelating tmeda ligands.
    Notes: Mit dem zweizähnigen Liganden N, N, N′,N′-Tetramethylethylendiamin (tmeda) werden solvatfreies [Li(tmeda)Me3Mg]2 (2) und [Li(tmeda)]2Me4Mg (1) dargestellt. Die Struktur von 1 wurde röntgenographisch bestimmt (monokline Raumgruppe P21/c). Im Zentrum des Moleküls ist das Mg-Atom tetraedrisch von vier Methylgruppen umgeben. Diese bilden paarweise Brücken zu den beiden Li-Atomen, welche ihrerseits an die tmeda-Chelat-Liganden gebunden sind.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811140121
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  • 7
    Electronic Resource
    Electronic Resource
    Kristall- und Molekülstruktur von Di-μ-iodo-tetrakis[tris(phenylethinyl)phosphin]dikupfer (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 3078-3083 
    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 Structure of Di-μ-iodo-tetrakis[tris(phenylethynyl)phosphine]dicopperThe preparation and the properties of the title compound are described. The X-ray analysis has shown that the triclinic unit cell of the complex contains two dimeric molecules {[(C6H5—C≡C)3P]2CuI}2. Therein both Cu1 atoms are coordinated approximately tetrahedraly and linked by two iodine bridges. The bond lengths and angles as well as the vC≡C and δ31P NMR values are compared with those of uncoordinated P(C≡C-C6H5)3, used firstly as ligand.
    Notes: Darstellung und Eigenschaften der Titelverbindung werden beschrieben. Die Röntgenstrukturanalyse ergab, daß die trikline Elementarzelle des Komplexes zwei dimere Moleküle {[(C6H5—C≡C)3P]2CuI}2 enthält. Darin sind die beiden Cu1-Atome annähernd tetraedrisch koordiniert und durch zwei Iodbrücken verknüpft. Die Bindungslängen und -winkel sowie die vC≡C— und δ31P-NMR-Werte werden mit denen des unkoordinierten P(C≡C—C6H5)3 verglichen, das erstmals als Ligand verwendet wurde.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100913
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  • 8
    Electronic Resource
    Electronic Resource
    Phosphorhaltige Kohlenhydrate, XVI. Ringerweiterung von Furanose-Ringen zu 1,2λ5-Oxaphosphorinanen (1977)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 3190-3200 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Phosphorus-containing Carbohydrates, XVI. Ring Expansion of Furanose Rings to 1,2λ5-OxaphosphorinanesThe Abramov reaction of 2,3:5,6-diO-isopropylidene-α-D-mannofuranose (1) with dimethyl phosphite yields the blocked 1,2λ5-oxaphosphorinane 2 by intramolecular transesterification. The X-ray analysis of the tosylate 3 gives evidence of two types of symmetry independent molecules, A and B, in the unit cell. These differ in the relative position of the tosyloxy group and the hetero six-membered ring. The latter adopts a nearly ideal boat conformation B1,4(D) in A, and is twisted towards a scew conformation 2S4(D) in B. The phosphoryl oxygen is found in axial, the phosphono-methyl group in equatorial position. 1H NMR spectra at 270 MHz allow a complete assignment of all couplings. The conformation in solution is consistent with a slightly distorted boat conformation.
    Notes: Die Abramov-Reaktion von 2,3:5,6-Di-O-isopropyliden-α-D-mannofuranose (1) mit Dimethylphosphit führt unter innerer Umesterung zum blockierten 1,2λ5-Oxaphosphorinan 2. Die Röntgenstrukturanalyse des Tosylats 3 ergibt zwei symmetrieunabhängige Moleküle A und B in der Elementarzelle. Die Tosyloxygruppe nimmt in beiden Molekülen unterschiedliche Stellungen zum Heterosechsring ein. Der Ring in A liegt in einer fast idealen Bootkonformation B1,4(D) vor, der Ring in B ist in Richtung auf eine Twistbootkonformation 2S4(D) verdreht. Der Phosphorylsauerstoff steht axial, die Phosphonomethylgruppe äquatorial. 1H-NMR-Spektren bei 270 MHz führen zur Aufklärung aller Kopplungsparameter. Die Konformation in Lösung entspricht einer leicht verdrillten Bootkonformation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19771100925
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  • 9
    Electronic Resource
    Electronic Resource
    Synthese, Strukturaufklärung und Konformationsuntersuchungen 1→4-verknüpfter Disaccharidglycoside vom 2,3-Anhydro-4-O-(hex-2-enopyranosyl)-α-D-allopyranosid-Typ (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1023-1034 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Structure Elucidation, and Conformational Studies of 1→4-Linked Disaccharide Glycosides of the 2,3-Anhydro-4-O-(hex-2-enopyranosyl)-α-D-allopyranoside TypeTriacetyl-D-glucal (1) or tetraacetyl-2-hydroxy-D-glucal (6) and 2,3-anhydro-α-D-allopyranosides 2 or 7, respectively, undergo smooth acid-catalyzed allylic rearrangement reactions to yield the crystalline α-linked disaccharide derivatives 4, 5, and 9 with hex-2-enopyranosyl structure in the non-reducing rings in good yields. By hydrogenation of 4 and 5, 8 is obtained, in which the α-linkage can be demonstrated. X-ray analysis confirms the interglycoside α-linkage in the considerably stretched disaccharide derivative 5. Both the saccharide ring adopt SO5 sofa conformations, in which only C-5 and C-5′ ae observed significantly below the plane of the remaining ring atoms. The NMR data of 5 and 9 suggest also SO5 sofa conformation in solution. On the contrary the β-isomer 10 adopts 5SO sofa conformation which is consistent with the allylic effect.
    Notes: Durch sauer katalysierte Addition der 2,3-Anhydro-α-D-allopyranoside 2 bzw. 7 an Triacetyl-D-glucal (1) bzw. Tetraacetyl-2-hydroxy-D-glucal (6) lassen sich unter Allylumlagerung die α1→4-verknüpften Disaccharide 4, 5 und 9 mit Hex-2-enopyranosyl-Struktur im nicht-reduzierenden Saccharidring milde und in guten Ausbeuten kristallin gewinnen. Durch Hydrierung von 4 und 5 wird 8 erhalten, bei dem die interglycosidische α-Verknüpfung nachgewiesen wird. Die Röntgenstrukturanalyse von 5 bestätigt die α-Verknüpfung in dem erheblich gestreckten Disaccharidderivat. Beide Saccharidringe weisen eine SO5-Sofakonformation auf, bei der nur die Atome C-5 und C-5′ wesentlich aus der Ebene der übrigen Ringatome nach unten herausstehen. Konformationsbetrachtungen legen auch in Lösung für 5 und 9 das Vorliegen einer SO5-Sofakonformation nahe. Das interglycosidische β-Isomere 10 weist dagegen eine 5SO-Sofakonformation auf, was auf den Allyleffekt zurückgeführt werden kann.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120324
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  • 10
    Electronic Resource
    Electronic Resource
    Solid-State Photocyclodimerization of 1-Thiocoumarin (= 2H-1-Benzothiopyran-2-one)Dedicated to Prof. Hans-Dieter Scharf, TU Aachen, on the occasion of his 65th birthday (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 1079-1082 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Irradiation (λ 〉 390 nm) of 2H-1-benzothiopyran-2-one (1) in the solid state affords selectively 6aα,6bα,12bα,12cα -tetrahydrocyclobuta[1,2-c:4,3-c′]bis[1]benzothiopyran -6,7-dione (2), the head-to-head (HH) cis-cisoid-cis-dimer, while irradiation of 1 in the solid state using shorter wavelengths (λ 〉 340 nm) affords a mixture of all four cis-fused tricyclic dimers 2-5. These results represent a novel wavelength effect in solid-state photochemistry.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780504
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