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  • 1
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition Reactions of Organometal Complexes, I. The Synthesis of Four-membered Metalla-Heterocycles by [2 + 2] Cycloaddition of (Isonitrile)-cobalt Complexes and Isocyanates or IsothiocyanatesThe reaction of C5H5(PMe3)CoCNR (R = Me, Ph) with isocyanates OCNR' (R' = Me, Ph) leads to the metalla-heterocycles in nearly quantitative yields. The analogous four-membered ring compounds (4-6) are obtained from C5H5(PMe3)CoCNR (R = Me, Ph, c-C6H11) and SCNMe. In the reactions of C5H5(PMe3)CoCNtBu with SCNMe and of C5H5(PMe3)CoCNMe with SCNtBu the complex (4) is also formed. The X-ray structure analyses of 4 and 5 show the presence of planar four-membered CoCNC rings together with a trigonal-planar coordination of the corresponding C, N and C ring atoms. The protonation and methylation reactions of the metalla-heterocycles 1-5 yield diaminocarbene complexes, in most cases by preserving the four-membered CoCNC-ring. The structure of these complexes is discussed on the basis of their IR and NMR data.
    Notes: Die Reaktion von C5H5(PMe3)CoCNR (R = Me, Ph) mit Isocyanaten OCNR' (R' = Me, Ph) führt nahezu quantitativ zu den Metalla-Heterocyclen (1-3). Die analogen Vierring-Verbindungen (4-6) sind ausgehend von C5H5(PMe3)CoCNR (R = Me, Ph, c-C6H11) und SCNMe zugänglich. Bei den Umsetzungen von C5H5(PMe3)CoCNtBu mit SCNMe und von C5H5(PMe3)CoCNMe mit SCNtBu bildet sich ebenfalls der Komplex (4). Die Röntgenstrukturanalysen von 4 und 5 beweisen das Vorliegen planarer CoCNC-Vierringe mit ebenfalls trigonal-planar koordinierten C-, N- und C-Atomen. Die Protonierungs- und Methylierungsreaktionen der Metalla-Heterocyclen 1-5 ergeben -- in den meisten Fällen unter Erhalt der CoCNC-Vierringstruktur - Diaminocarben-Komplexe. Ihre Struktur wird anhand der IR- und NMR-Daten diskutiert.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1465-1475 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azo Bridges from Azines, IV1). Intramolecular [2 + 2] Photocycloaddition of Parallel C=C and N=N BondsThe parallel C=C and N=N bonds in the rigid molecules 1 - 10 photocyclize nearly quantitatively, forming 1,2-diazetidines 11 - 20. Their structure is confirmed by spectroscopic methods and for 13 by X-ray analysis. Radiation induced denitrogenation, the normal reaction for similar compounds without neighbouring C=C bonds, is suppressed even with the sensitive derivatives of 2,3-diazabicyclo[2.2.1]heptene. Photocyclization of 6, carrying two neighbouring C=C bonds, includes only the norbornene bond.
    Notes: In den starren Molekülen 1 - 10 reagieren die benachbarten parallelen C=C- und N=N-Bindungen nahezu quantitativ unter Photocyclisierung zu den 1,2-Diazetidinen 11 - 20, deren Struktur spektroskopisch und für 13 durch Kristallstrukturanalyse bewiesen wird. Die in Abwesenheit der C=C-Bindung beobachtete Photo-Denitrogenierung unterbleibt selbst bei den empfindlichen Derivaten des 2,3-Diazabicyclo[2.2.1]heptens. Photocyclisierung von 6 mit zwei zur N=N-Bindung benachbarten C=C-Bindungen tritt nur mit der Norbornendoppelbindung ein.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 2291-2307 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Structurally Dynamical Organometal Complexes, II. Synthesis, Structure, and Dynamics of the Complexes C5H5M(2-R′C3H4)PR3 (M=Pd, Pt)The complexes C5H5M(2-R′C3H4)(M=Pd with R′=Me, t-Bu; M=Pt with R′=Me) react with an equimolar amount of PR3 (PR3=P(i-Pr)3, P(i-Bu)3, PPh2 (t-Bu), PCy3, PPhCy2) to form the compounds C5H5M(2-R′C3H4)PR3. The 1H and 13C NMR spectra indicate that in the complexes C5H5Pd(2-t-BuC3H4)PR3 and C5H5Pt(2-MeC3H4)PR3 within the temperature range of - 60 to +60°C the cyclopentadienyl ligand is monohapto-(σ-)and the allylic ligand trihapto-(π-)bonded. The complexes C5H5Pd(2-MeC3H4)PR3 exist in solution as a mixture of two isomers, (h5-C5H5)Pd(h1-allyl)PR3 (A) and (h1-C5H5)Pd(h3-allyl)PR3 (B). For complex 14 (PR3=PPhCy2) the thermodynamic and kinetic data of the intramolecular isomerisation process A ⇌ B have been determined. The X-ray structural analysis of 5 proves that the monohapto coordination of the C5H5 and the trihapto coordination of the 2-t-BuC3H4 ligand is retained in the crystal.
    Notes: Die Komplexe C5H5M(2-R′C3H4) (M=Pd mit R′=Me, t-Bu; M=Pt mit R′=Me) reagieren mit einer äquimolaren Menge PR3 (PR3=P(i-Pr)3, P(i-Bu)3, PPh2(t-Bu), PCy3, PPhCy2) zu den Verbindungen C5H5M(2-R′C3H4)PR3. Die 1H- und 13C-NMR-Spektren weisen daraufhin, daß in den Komplexen C(5H5Pd(2-t-BuC3H4)PR3 und C5H5Pt(2-MeC3H4)PR3 im Temperaturbereich von -60 bis +60°C der Cyclopentadienylligand monohapto- (σ-) und der Allylligand trihapto- (π-) gebunden ist. Die Komplexe C5H5Pd(2-MeC3H4)PR3 liegen in Lösung als Isomerengemisch von (h5-C5H5)Pd(h1-allyl)PR3 (A) und (h1-C5H5)Pd(h3-ally)PR3 (B) vor. Für 14 (PR3=PPhCy2) werden die thermodynamischen und kinetischen Daten der intramolekularen Isomerisierung A ⇌ B ermittelt. Die Röntgenstrukturanalyse zeigt, daß in 5 auch im Kristall der C5H5-monohapto- und der 2-t-BuC3H4-Ligand trihapto-koordiniert sind.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 423-432 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transanular Interactions of the Azo Chromophore in Isodrin-type Systems1)The unusual transanular photoreactivity of the azo-compound 5 is also reflected in its photoelectron spectrum. The investigation of compounds 5, 13 and 14 reveals an effective interaction in 5 (through-bond and through-space) with H ij = -0.62 eV between πNN and πCC. This experimental value fits in well with known parameters of analogous isodrin-type systems. The excited states are looked into by means of semiempirical calculations with model compounds 17 and 19. Both the n-π+* and (at shorter wavelength) the π-π+* transition are conducive to an intramolecular photocycloaddition. X-ray diffraction has been used to determine the πNN,πCC-transanular distance (2.91Å).
    Notes: Die ungewöhnliche transanulare Photoreaktivität der Azoverbindung 5 spiegelt sich auch im Photoelektronenspektrum wider. Die Untersuchung der Verbindungen 5, 13 und 14 läßt eine effektive Wechselwirkung (through-bond und through-space) von Hij = -0.62 eV zwischen πNN und πNN in 5 erkennen. Dieser experimentelle Wert steht in ausgezeichneter Übereinstimmung mit bekannten Parametern analoger isodrinartiger Systeme. An den Modellverbindungen 17 und 19 werden die angeregten Zustände mit Hilfe semiempirischer Rechnungen untersucht. Sowohl der n-;π+* - als auch der kurzwellige π-π+* Übergang sind einer intramolekularen Photocycloaddition förderlich. Durch Röntgenbeugung wird der πNN, πCC-Transanularabstand zu 2.91 Å ermittelt.
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  • 5
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Arene(phosphane)metal Complexes, V1). On the Addition of Carbanions to (Benzene)ruthenium(II) and -osmium(II) Complexes. The Crystal and Molecular Structure of (exo-6-n-C4H9-η5-C6H6)OsI(PMe3)2The complex [C6H6RuCl(PMe3)2]PF6 (1) reacts with methyllithium to give a mixture of products that contains (η5-C6H6CH3)RuCH3(PMe3)2 (2) as the main component. From 1 and LiC6H5/LiBr the bromide 3 is primarily formed but the final product is (η5-C6H6C6)H5RuC6H5(PMe3)2 (4). Reaction of [C6H6OsI(PMe3)2]PF6 (5) with organyllithium compounds LiR (R = CH3, C2H5, n-C3H7, n-C4H9, t-C4H9, C6H5) yields the complexes (η5-C6H6R)OsI(PMe3)2 (6 - 11). 31P NMR spectra of 6 - 11 indicate restricted rotation at low temperatures around the metal-ring axis. According to X-ray structure analysis of 9 (R = n-C4H9) the cyclohexadienyl ring possesses an envelope conformation. The n-butyl group occupies the exo-position at the sp3-C atom.
    Notes: Der Komplex [C6H6RuCl(PMe3)2]PF6 (1) reagiert mit Methyllithium zu einem Produktgemisch, welches (η5-C6H6CH3)RuCH3(PMe3)2 (2) als Hauptkomponente enthält. Aus 1 und LiC6H5/LiBr entsteht über 3 bei längeren Reaktionszeiten (η5-C6H6C6H5)RuC6H5(PMe3)2 (4). Die Umsetzung von [C6H6OsI(PMe3)2]PF6 (5) mit Organyllithium-Verbindungen LiR (R = CH3, C2H5, n-C3H7, n-C4H9, t-C4H9, C6H5 ergibt die Komplexe (η5-C6H6R)OsI(PMe3)2 (6 - 11), in denen nach den 31P-NMR-Spektren die Rotation um die Metall-Ring-Bindung bei tiefen Temperaturen stark eingeschränkt ist. Die Röntgenstrukturanalyse von 9 (R = n-C4H9) beweist die „Envelope“-Konformation des Cyclohexadienylrings. Die n-Butylgruppe befindet sich in der exo-Position am sp3-C-Atom.
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  • 6
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereoisomeric Flavor Compounds, XVI. - Structure and Properties of Optically Pure 2-Methyl-4-propyl-1,3-oxathiane 3-OxidesOxidation of cis-2-methyl-4-propyl-1,3-oxathiane (1) by NaIO4 yields diastereomeric sulfoxides (equatorial/axial relation 3:1), which were separated by liquid chromatography. From optically pure (2S,4R)-1 the sulfoxides 2 (75%) and 3 (25%) and from (2R,4S)-1 the sulfoxides 2′ (75%) and 3′ (25%) were generated. For 3 an X-ray structure analysis was performed.
    Notes: Durch Oxidation von cis-2-Methyl-4-propyl-1,3-oxathian (1) mit NaIO4 entstehen diastereomere Sulfoxide (äquatorial/axial-Verhältnis 3:1), die flüssigkeitschromatographisch rein erhalten werden. Aus optisch reinem (2S,4R)-1 werden die Sulfoxide 2 (75%) und 3 (25%), aus (2R,4S)-1 die Sulfoxide 2′ (75%) und 3′ (25%) erhalten. Für 3 wurde eine Röntgenstrukturanalyse durchgeführt.
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  • 7
    ISSN: 0170-2041
    Keywords: Aryl coupling, intramolecular ; Biaryls, ester-type bridged, preparation and stereostructure of ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A practicable two-step procedure for the preparation of a series of lactone-type bridged biaryls 7 as favorable substrates for subsequent atropisomer-selective ring-opening reactions is described. Due to the efficiency of the coupling step, which tolerates even a tert-butyl group next to the biaryl axis and avoids problems of regioselectivity, a variety of differently substituted representatives is prepared. These cover a broad range of steric hindrance and thus molecular distortion. The structures are investigated mainly by NMR spectroscopy and X-ray diffraction, showing the lactones 7 to be helically distorted, depending on the size of the residues R.
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  • 8
    ISSN: 0009-2940
    Keywords: Imido ligands ; Oxo ligands ; Pentamethylcyclopentadienyl ligand ; Molybdenum complexes ; Tungsten complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organometallic Imido Complexes - Highervalent Derivatives of the d-Metal Acids, 3[4b]. - Synthesis and Reactions of Pentamethylcyclopentadienyl Imido Complexes of Molybdenum and Tungsten and an Efficient Strategy for the Synthesis of the Organometallates NBu4[Cp*MO3] (M = Mo, W)A convenient and new entry into the chemistry of highvalent pentamethylcyclopentadienyl halfsandwich complexes of molybdenum and tungsten is described. The reaction of Mo-(NtBu)2Cl2 or W(NtBu)2Cl2(py)2 with Cp*Li (Cp* = η5-C5Me5) provides a high-yield route to new complexes Cp*Mo-(NtBu)2Cl (1a) and Cp*W(NtBu)2Cl (1b) which are converted into a variety of diimido, monoimido, and oxo derivatives. Treatment of 1a,b with MeLi yields the highly volatile methyl derivatives Cp*Mo(NtBu)2Me (2a) and Cp*W(NtBu)2Me (2b), while protolysis of 1a,b with an excess of HCl gas leads to selective cleavage of only one imido function with formation of Cp*Mo(NtBu)Cl3 (3a) and Cp*W(NtBu)Cl3 (3b). In contrast, protolysis of 1a,b with aqueous HCl provides a high-yield route to the well-known organometallic oxides [Cp*MoO2]-(μ-O) (4a) and [Cp*WO2](μ-O) (4b). These two key compounds are easily converted into the organomolybdate and organotungstate salts NBu4[Cp*MoO3] (5a) and NBu4[Cp*WO3] (5b) by cleavage of the M-O-M bridge with NBu4[OH]. The X-ray structure of 3a is reported.
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  • 9
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Main Group Element Transition Metal Multiple Bonds, IV. Catalytic Assistance by [Cp(CO)3Mo]2 in the Aggregation of Metallo-arsanes via Arsenic Metal Double Bond Complexes2)The metallo-arsanes Cp(CO)3M—AsMe2 (1a, b) (M = Mo, W) are converted to the double arsenido-bridged dinuclear complexes [(μ-AsMe2)Mo(CO)2Cp]2 (3a, b) in the presence of [Cp(CO)3Mo]2. Due to the unusual mild conditions of aggregation the intermediate formation of the double bonded species Cp(CO)2M=AsMe2 (2a, b) is postulated. The crystal structure of 3a is reported, which shows mutual trans arrangement of the cyclopentadienyl and CO ligands.
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  • 10
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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