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  • 1
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Diazadienes (DAD) (RN=CR′CR′=NR with R′=H or Me and R=n-,i- ort-alkyl, aryl oro,o′-substituted aryl) easily form the thermally inert title compounds [(DAD)-Ru(CO)2I2] (2). Their stereochemistry is unambiguously derived from1H-n.m.r. and i.r. data. One of the complexes (2h) cocrystallizes with the free diazadiene (1h) in a 1∶1 molar ratio. An x-ray diffraction study, which allows a comparison of the free and bound diazadiene. was performed with the monoclinic crystal and gave the following cell parameters: space group C 2/c, a=2237.0(5), b=1017.4(3) and c=1824.9(4) pm, β=105.13(2)°, Z=4. From 2781 observed reflections 293 parameters were refined, leading to a final R-value of 0.0346 (Rw=0.0340). The tilting of thep-tolyl group is a consequence of an intra-ligand repulsion R/R′, the R-conformation being almost equal in the (E,E,E)-shaped molecule (1h) (68°) and the (E,Z,E)-chelate in (2h) (72°). Complexes (2) are photolabile (with loss of CO), and on reduction they lose iodide, thus offering selective ways for the exchange of π-acceptor or σ-donor ligands for precatalyst formation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diazadienes as Controlling Ligands in Homogeneous Catalysis, VII1). Catalytic Synthesis and Structure of a Cyclooctatetraene with Twofold Vicinal Substitution - 1,4,5,8-Tetrakis[(p-tolyloxy)methyl]-1,3,5,7-cyclooctatetraeneThe catalytic reaction of 2-propynyl p-tolyl ether (propargyl p-tolyl either) with the diazadiene nickel complex 4 gives a highly symmetrical cycloocatetraene derivative 2. 1H NMR and 13C NMR spectra do not allow to distinguish between three possible substitution patterns (1,3,5,7; 1,4,5,8; 1,2,5,6). Double bond and substituent positions were determined by an X-ray structural analysis. The encountered pattern with a twofold vicinal substitution (1,4,5,8) was hitherto unknown for catalytically prepared cycloocatatetraenes. At the same time, 2 is the first cyclotetramer of a propargylic ether.
    Notes: Die katalytische Umsetzung von 2-Propinyl-p-tolylether (Propargyl-p-tolylether) mit dem Diazadien-nickelkomplex 4 führt zu einem hochsymmetrischen Cyclooctatetraenderivat 2. 1H-NMR- und 13C-NMR-Spektren erlauben aus Symmetriegründen keine Unterscheidung zwischen drei möglichen Substitutionsmusten (1,3,5,7; 1,4,5,8; 1,2,5,6). Durch eine Röntgenstrukturanalyse wurden die Substituentenstellung und die Lage der Doppelbindungen bestimmt. Das gefundene, doppelt vicinale 1,4,5,8-Substitutionsmuster war für katalytisch dargestellte Cyclooctatertraene bis jetzt unbekannt; zugleich ist 2 das erste Cyclotetramere eines Propargylethers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1943-1950 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Bis(diazadine)iron(0) ComplexesReduction of iron(II) compounds with alkali metal or via an alkylation with Grignard reagents in the presence of 1,4-diaza-1,3-dienes (DAD) yields the brown, paramagnetic, tetracoordinate iron(O) complexes Fe(DAD)2 2. Depending on the bulkiness of the DAD substituents, carbon monoxide does not add or adds more or less readily and reversibly to give deep green diamagnetic (DAD)2Fe(CO) 6, or in an irreversible manner to give red (DAD)-Fe(CO)3 8. A corresponding colour change occurs during the addition reactions of 2 are observed with dicyanogen, nitrosyl chloride, or a diazoalkane. Two molecules of a dialkyl acetylenedicarboxylate are added to sterically not too demanding complexes 2 and with concomitant C—C bond formation an airstable, deeply blue coloured ferracyclopentadiene 9 is formed. A single crystal X-ray investigation of monoclinic 9b was performed. The molecules of symmetry C2 contain two DAD-chelates and a tetrakis(alkoxycarbonyl)-1,3-butadiene-1,4-diyl chelate at the octahedral iron(II) center.
    Notes: Bei der Reduktion von Eisen(II)-Verbindungen mit Alkalimetallen oder über eine Alkylierung mit Grignard-Reagenzien in Gegenwart von 1,4-Diaza-1,3-dienen (DAD) entstehen die paramagnetischen, braunen, vierfach koordinierten Eisen(O)-Komplexe Fe(DAD)2 2. Je nach Größe der DAD-Substituenten addieren sie nicht, langsam oder rasch reversibel Kohlenoxide zu den diamagnetischen, labilen, tiefgrünen (DAD)2Fe(CO) 6 bzw. irreversible zu den stabilen, roten (DAD)Fe(CO)3 8. Auch Isocyanide zeigen unter Addition zu analogen 7 und 10 entsprechende Farbreaktionen. Ebenso wird mit Dicyan, Nitrosylchlorid oder Diazoalkan Addition beobachtet. An sterisch nicht zu anspruchsvolle 2 werden zwei Moleküle Acetylendicarbonester unter C—C-Verknüpfung zu einem tiefblauen, luftstabilen Ferracyclopentadien 9 addiert. Eine Einkristall-Röntgenstrukturanalyse an monoklinem 9b wurde durchgeführt. Das C2-symmetrische Komplexmolekül enthält zwei DAD-Chelatliganden und einen chelatgebundenen Tetrakis(alkoxycarbonyl)-1,3-butadien-1,4-diyl-Liganden am oktaedrisch koordinierten Eisen(II)-Zentrum.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 1868-1875 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 2-Functionalized N,N′-Dialkylimidazolium Salts from Glyoxal and AlkylaminesDiazadienes R—N=CH—CH=N—R (1: R = tert-butyl, 2: R = isopropyl), which are easily prepared from aqueous glyoxal and primary alkylamines, react with dry hydrogen chloride in non-aqueous solvents to form N,N′-dialkyl-substituted azomethine derivatives of 2-formylimidazolium chlorides, concomitant with the formation of alkylammonium chlorides. The tert-butylimine compound 3, the structure of which was established by singlecrystal X-ray diffraction, is hydrolyzed to give the aldehyde 4. The intermediate isopropylimine 5, an analogue to 3, is converted directly under transamination into the 2-aminomethyl derivative of the imidazolium system, and is isolated as its hydrochloride 6. With 6 as an example, an improved routine APT method in 13C NMR spectroscopy is presented, which makes assignments more reliable in cases where unusual 1JCH couplings might occur.
    Notes: Die aus Glyoxalhydrat und primären Alkylaminen leicht zugänglichen Diazadiene R—N=CH—CH=N—R (1: R = tert-Butyl, 2: R = Isopropyl) reagieren mit trockenem Chlorwasserstoff in wasserfreien Lösungsmitteln unter Eliminierung von Alkylammoniumchlorid zu N,N′-dialkylierten Azomethinderivaten der 2-Formylimidazoliumchloride. Die tert-Butylimin-Verbindung 3, deren Struktur durch eine Einkristallröntgenanalyse belegt ist, läßt sich im Sauren zum Aldehyd 4 hydrolysieren. Das 3-analoge Isopropylimin 5 reagiert unter Transaminierung gleich weiter zum 2-Aminomethylderivat des Imidazoliumsystems und wird als Hydrochlorid 6 erhalten. Am Beispiel von 6 wird ein verbessertes Routine-APT-Verfahren für die 13C-NMR-Spektroskopie vorgestellt, welches bei konstantem Zeitaufwand die Sicherheit der Zuordnung erhöht, insbesondere falls ungewöhnliche 1JCH-Kopplungskonstanten auftreten könnten.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    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
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  • 6
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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