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21.
Zusammenfassung Die Elektronenstrukturen von Bis-durochinon-nickel(0) und der Komplexe vom Typ Olefin-Ni(0)-Chinon werden im Rahmen der LCAO-MO-Näherung diskutiert und zur Deutung der Absorptionsspektren herangezogen. Den im freien Durochmon auftretenden Übergängen lassen sich in den Komplexspektren jeweils nur wenig verschobene Banden zuordnen. Darüber hinaus wird eine intensive Charge-Transfer-Bande beobachtet, die einem Übergang vom höchsten besetzten Nickelzustand zum tiefsten unbesetzten Chinon-Orbital entspricht. Aus der Intensität der Bande, die im freien Chinon dem b
3g
2b
2
g-Übergang zugeordnet wird, ergibt sich für das gelöste Bis-durochinon-nickel(0)-Molekül die Symmetrie D
2h
. Während die Komplexe mit Durochinon in Übereinstimmung mit der Theorie diamagnetisch sind, weisen die analogen Verbindungen der Dimethylchinone magnetische Momente von 1,52 bzw. 2,75 B. M. auf, woraus auf eine Mitbeteiligung polarer Strukturen am Grundzustand dieser Komplexe geschlossen wird.
6. Mitteilung über Komplexe vom Typ des Bis-durochinon-nickel(0). 5. Mitt. vgl. [11]. 相似文献
The electronic structures of bis-duroquinone-nickel(0) and complexes of the type olefine-Ni(0)-quinone are discussed in the MO-LCAO approximation and used for an interpretation of the absorption spectra. The transitions of the free duroquinone can be correlated with transitions of the complexes at nearly the same wavelengths. In addition, an intense charge transfer band is observed which corresponds to a transition from the highest occupied nickel orbital to the lowest unoccupied quinone orbital. From the intensity of the band which corresponds to b 3g 2b2g in the free quinone, the symmetry D 2h for the dissolved bis-duroquinone-nickel(0) molecule is deduced. Whereas the duroquinone complexes are diamagnetic in agreement with theory, analogous compounds of the diméthylquinones exhibit magnetic momenta of 1.52 and 2.75 B. M. suggesting the participation of polar structures in the ground state of these complexes.
Résumé Les structures électroniques du bis-duroquinone-nickel(0) et des complexes du type oléfine-Ni(0)-quinone sont discutées dans le cadre del'approximationMO-LCAO et utilisées pour l'interprétation des spectres d'absorption. Aux transitions de la duroquinone libre peuvent être attribuées des bandes peu déplacées dans les spectres des complexes. En outre on observe une bande intense correspondant à une transition de la plus haute orbitale occupée du nickel à la plus basse orbitale libre de la quinone. L'intensité de la bande nommée b 3g 2b 2g dans la quinone libre indique la symétrie D 2h pour la molécule dissoute du bis-duroquinone-nickel(0). Tandis que les complexes de la duroquinone sont diamagnétiques en accord avec la théorie, des composés analogues des diméthylquinones présentent des moments magnétiques de 1,52 et de 2,75 B. M. d'où l'on infère la participation de structures polaires à l'état fondamental de ces complexes.
6. Mitteilung über Komplexe vom Typ des Bis-durochinon-nickel(0). 5. Mitt. vgl. [11]. 相似文献
22.
Josef Edinger Heinz Falk Norbert Müller 《Monatshefte für Chemie / Chemical Monthly》1984,115(6-7):837-852
The diastereomeric 2,3-Dihydrobilatrienes-abc derivatives (4Z, 9Z, 15Z)-7 and (4Z, 9Z, 15E)-7 bearing a cholesterylacetate moiety in position 3 of the chromophore are prepared. The reaction sequence contains an isomerisation step providing quantitative enantioselective formation of the chiral center in position 3. Configurations and conformations of the diastereomers are elucidated using1H- and13C-NMR spectra, NOE-difference spectra, 2D-NMR experiments (NOESY) and arguments from UV-VIS and CD data. It is concluded that the hydrophobic interactions between chromophore and cholesteryl-fragment yield a compact conformation where the two substructures are in close contact with each other. On the other hand these interactions seem to be too weak to induce significant changes in the chemistry, absorption spectra and conformational characterics of the bile pigment chromophore. Therefore hydrophobic interactions between chromophor and apolar amino acid residues of the protein in phytochrome should be of minor relevance for determining spectroscopic shifts. 相似文献
23.
A number of novel N-protected β-amino nitriles were prepared as substrates for two nitrile-converting microorganisms, Rhodococcus sp. R312 and Rhodococcus erythropolis NCIMB 11540. The respective biotransformation products, β-amino acids, are known to be pharmacological very potent compounds. 相似文献
24.
S. Jakobs Ulrike Schulz Angela Duparré Norbert Kaiser 《Analytical and bioanalytical chemistry》1997,358(1-2):242-244
SiO2 protective coatings have been deposited on polycarbonate substrates by plasma ion assisted deposition. The influence of ion energy on the water permeability and the surface topography of the coatings was studied by infrared spectroscopy and atomic force microscopy. Coatings deposited at sufficiently high ion energies show a barrier effect against moisture uptake and considerably reduced film roughness. Both effects are attributed to an increase of the packing densities of the coatings. 相似文献
25.
Sidika Polat Cakir 《Tetrahedron letters》2006,47(14):2451-2454
Suzuki coupling reactions between 2,4,6-trialkoxyphenylboronic acids and enol triflates have been found to occur in excellent yield, while the use of an enol tosylate failed to give any of the desired product. This coupling reaction has led to the synthesis of a lactone which could serve as a precursor to several calyxin analogues. 相似文献
26.
Norbert de Kimpe Bart de Corte Roland Verhe Laurent de Buyck Niceas Schamp 《Tetrahedron letters》1984,25(10):1095-1098
The reaction of organometallic reagents, e.g. alkyllithiums, cuprates and alkylcoppers, with α-haloimines gave selectively a variety of synthetically useful reactions, including coupling to 1,4-diimines, homologation, and production of heterocycles. 相似文献
27.
Josef Edinger Heinz Falk Walter Jungwirth Norbert Müller Ulrich Zrunek 《Monatshefte für Chemie / Chemical Monthly》1984,115(8-9):1081-1099
From an investigation of the ICD of bilatrienes-abc and 2,3-dihydrobilatrienes-abc induced by mixtures of CCl4 with (+)-cis-Pinane, (–)-lactic and (+)-tartaric acid esters it is concluded that specific interactions between chromophore and the chiral reagents afford a partial resolution of the labile racemate of helices. Attaching chiral residues covalently to the chromophore induces very low resolution of the same kind in case of apolar ligands like a cholesteryl-residue. However, with polar ligands as in the case ofBoc-lysyl derivatives enantiomeric excesses up to 90% are achieved depending on the solvent used.
Herrn Prof. Dr.Karl Schlögl zu seinem 60. Geburtstag gewidmet. 相似文献
28.
29.
Helmut Marko Norbert Müller Heinz Falk 《Monatshefte für Chemie / Chemical Monthly》1989,120(2):163-168
Summary The intermolecular complex formation of bilirubin and biliverdin with two proteins (basic pancreatic trypsin inhibitor and lysozyme) were studied by optical and chiroptical methods. Evidence for specific intermolecular interactions of biliverdin with both proteins was found. Bilirubin forms a soluble complex only with lysozyme.
UV-VIS und CD-spektroskopische Untersuchungen intermolekularer Wechselwirkungen von Gallenpigmenten mit kleinen Proteinen
Zusammenfassung Die intermolekulare Komplexbildung von Bilirubin und Biliverdin mit zwei Proteinen (basischer pankreatischer Trypsininhibitor und Lysozym) wurden mittels optischer und chiroptischer Spektroskopie untersucht. Für Biliverdin konnten intermolekulare Wechselwirkungen mit beiden Proteinen nachgewiesen werden. Bilirubin bildet nur mit Lysozym einen löslichen Komplex.相似文献
30.
Rhodococcus equi A4, Rhodococcus erythropolis NCIMB 11540 and Rhodococcus sp. R312 were investigated towards their ability to produce β-amino amides and acids from β-amino nitriles. The microorganisms show comparable trends: five-membered alicyclic 2-amino nitriles were transformed significantly faster than the six-membered compounds and the products of trans-2-amino nitriles (amides and acids) were formed considerably faster than the cis-counterparts (amides). The trans-five membered nitriles gave the amides (1b, 5b) in excellent enantiomeric excess (94-99%), the biotransformation of trans-six membered substrates resulted in the formation of the acid (3c, 7c) in excellent ee (87-99%). The ee's of the cis-compounds were throughout lower. Fifteen new substances were synthesized and characterized in the course of this work. 相似文献