Browsing by Author "Knebl, Robert"

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    Ein 1λ5, 3λ5, 5λ3-Triphosphabenzol-Derivat
    (1986) Fluck, Ekkehard; Becker, Gerd; Neumüller, Bernhard; Knebl, Robert; Heckmann, Gernot; Riffel, Heinz
    Die erste Ringverbindung mit (PC)3-Gerüst, die Titelverbindung 3, wurde wie unten skizziert hergestellt. Die 13C-NMR-Daten deuten auf einen hohen Ylid-Charakter der Gruppierung C4-P5-C6 hin.
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    A 1λ5,3λ5,5λ3-triphosphabenzene derivative
    (1986) Fluck, Ekkehard; Becker, Gerd; Neumüller, Bernhard; Knebl, Robert; Heckmann, Gernot; Riffel, Heinz
    The first ring compound containing the (P=C)3 skeleton, the title compound 3, was prepared as shown below. 13C-NMR data indicate a highly ylidic character of the C4-P5-C6 grouping.
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    3,3-dimetil-1-fosfabutin, (CH3)3C-C≡P : kolebatel'nyje spektry i poljarizujemost' svjazi C≡P
    (1986) Pazanovskij, I. I.; Pljamovatyj, A. Ch.; Sakirov, I. Ch.; Stepanova, Ju. S.; Becker, Gerd; Knebl, Robert; Weeber, Ute; Ismajeva, Eleonora A.; Sagidullin, R. R.; Pudovik, Arkadij N.
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    Alkylidynephosphines : syntheses and reactivity
    (1987) Becker, Gerd; Becker, Winfried; Knebl, Robert; Schmidt, Helmut; Hildenbrand, Ute; Westerhausen, Matthias
    In the past, different methods have been utilized for the preparation of alkylidynephosphines. Whereas, however, small amounts of thermally instable derivatives might be obtained from reactions in the gas phase, the synthesis of phosphines which are stable under an inert atmosphere, as for instance those with a tert-butyl or a 1-adamantyl substituent at the carbon atom of the PEC group, is best started with tris (trimethylsilyl) phosphine itself or with the more reactive lithium bis (trimethylsilyl) phosphide.2 tetrahydrofuran complex. Treatment of either compound with acyl halides results in the formation of acylbis (trimethylsilyl) phosphines which, at room temperature, rearrange to the corresponding trimethylsilyl [1-(trimethylsiloxy) alkylidene] isomers. As traces of hydrogen halide accelerate the conversion of tris (trimethylsilyl) phosphine to the triacyl derivatives, the use of the lithium phosphide is strongly recommended in all cases where impure acyl halides are used. In the presence of small amounts of solid sodium hydroxide suspended in an etherial solvent, the thus prepared trimethyl[1-(trimethylsiloxy)-alkylidene]phosphines eliminate hexamethyldisiloxane to yield the required alkylidyne compounds. Running the decomposition without a solvent at a higher temperature, Regitz and coworkers were able to improve this method further.
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    Ein Derivat des 1λ5, 3λ5, 5λ3-Triphosphabenzols
    (1987) Fluck, Ekkehard; Becker, Gerd; Neumüller, Bernhard; Knebl, Robert; Heckmann, Gernot; Riffel, Heinz
    The title compound was prepared by reacting 1,1,3,3-tetrakis(dimethylamino)-1λ5,3λ5-diphosphete with 2,2-dimethylpropylidynephosphane and characterized by NMR spectra and X-ray structure analysis.
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    Električeskije svoijstva adamantilfosfaetina AdC≡P
    (1986) Pacanovskij, Igor I.; Išmajeva, Eleonora A.; Stepanova, Ju. S.; Becker, Gerd; Becker, Winfried; Knebl, Robert; Pudovik, Arkadij N.
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    From 1,3-Diphosphacyclobutadiene to 1,3,5-triphosphabenzene
    (1987) Fluck, Ekkehard; Neumüller, Bernhard; Heckmann, Gernot; Braun, Roland; Becker, Gerd; Knebl, Robert; Riffel, Heinz
    Alkyl- and aryldiaminodifluorophosphoranes 1 can easily be obtained by fluorination of alkyl- and aryldiaminophosphanes with sulfur tetrafluoride, SF4 1. Peralkylated alkyldiaminodifluorophosphoranes react with one mole of n-butyllithium to form P-fluoro-ylides, a class of compounds which had not been described previously. Methylbis(dimethylamino)difluorophosphorane 2, e.g., reacts with butyllithium to give methylenebis(dimethylamino)fluorophosphorane 3, a colorless liquid, b.p. 42 °C (10 Torr)2: For P-chloro-ylides such as (t-C4H9)2PCI=CHSi(CH3)3, the chloro ligand is substituted by the alkyl group upon reaction with methyl-or n-butyllithium3,4; however, P-fluoro-ylides behave in a different way. If 2 is reacted with two moles of butyllithium, the main product is the crystalline, colorless 1,1,3,3-tetrakis(dimethylamino)-1δ 5, 3δ 5-diphosphete or 1,1,3,3-tetrakis(dimethylamino)-δ 5, 3δ 5-diphosphacyclobutadiene 4 (chemical shift σ(P) = 48.9 ppm)5.
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    Phosphane und Arsane mit Heteroatomen niederer Koordinationszahl
    (1985) Becker, Gerd; Becker, Winfried; Knebl, Robert; Schmidt, Helmut; Weeber, Ute; Westerhausen, Matthias
    In der anorganischen und elementorganischen Chemie steht gegenwärtig die Frage nach der Existenz, der Synthese und der Reaktivität von Verbindungen, die unter Beteiligung eines Hauptgruppenelementes aus der dritten oder einer höheren Periode eine homo- oder heteronukleare (np-mp)π-Bindung ausbilden und die entgegen der allgemeinen Erwartung bei Zimmertemperatur thermisch stabil sind, im Blickpunkt des Interesses.Während aber unsere Kenntnisse über entsprechende Systeme aus der dritten und vierten Hauptgruppe nur langsam zunehmen, war bei den Alkylidenphosphanen und teilweise auch -arsanen eine überaus rasche Entwicklung zu verzeichnen [2-4]. Nachdem jedoch diese beiden Substanzklassen in den letzten Jahren intensivst bearbeitet worden sind, werden jetzt auch die von verschiedenen Seiten Phosphaalkine genannten Alkylidinphosphane R-C≡P eingehender untersucht. Dabei kommt einer Klärung der Frage, ob sie aufgrund ihrer Reaktivität eher als Homologe der Nitrile anzusehen sind oder ob sie im Sinne der Schrägbeziehungen im Periodensystem Ähnlichkeiten mit Alkinen aufweisen, entscheidende Bedeutung zu.
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    Polarity and polarisability of 3,3-dimethyl-1-phosphabutyne
    (1987) Ismajeva, Eleonora A.; Pacanovskij, Igor I.; Stepanova, J. Z.; Becker, Gerd; Knebl, Robert; Weeber, Ute; Pudovik, Arkadij N.
    The progress attained in the field of onecoordinated phosphorus compounds was summerised recently in review (Usp. Chim., 1985, v. 54, p. 418). Formerly we have been analysed (Izv.Akad.Nauk USSR, Ser.chim., 1984, p. 415) the polarity of P°C triple bond in phosphaalkynes on the grounds of literary date on dipole moments defined by microwave spectroscopy. In this work the dipole moment of 3,3-dimethyl-1-phosphabutyne (I) was determined in cyclohexane solution:μ exp.=1,24±0,05D, α=1,250, γ=0,078, Po=31,876 cm3. Analysis of all known up to date experimental date on polarity of phosphaalkynes brings us to the conclusion about small polarity of P°C triple bond and slight sensitivity of this value (0,7±0,2D towards carbon atom) to vareing of substituent at Csp-atom. We can only note slight tendency of the increasing m(P≡C) in the phosphaalkynes RC=P (R=H, CH3, F, CH=CH2, CN, tBu) with the growth of -I - effect of substituent R.
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    Poljarnost' i poljarizujemost' 3,3-dimetil-1-fosfabutina
    (1986) Išmajeva, Eleonora A.;; Pacanovskij, Igor I.; Stepanova, Ju. S.; Becker, Gerd; Knebl, Robert; Weeber, Ute; Pudovik, Arkadij N.
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