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1Author    Norbert Kuhn, Joanna Fahl, Riad Fawzi, Cäcilia Maichle-Mößmer, Manfred SteimannRequires cookie*
 Title    Stable Carbene Adducts of Chlorine [1]  
 Abstract    The carbene adducts 3a-c (R 1 = Me, Et, iso-Pr; R2 = Me) are formed from the 2,3-dihydro-imidazol-2-ylidenes la-c and 1,2-dichloroethane as air-sensitive solids in good yields. The compounds exhibit a reactive Cl-Cl bond. Benzene is chlorinated by 3a,b to give chlorobenzene and the imidazolium salts 10a,b under mild conditions. 3c acts as a chloride donor to give with AICI3 and S 0 2 the 2-chloroimidazolium salts 12c andl3c (X = A1C14, S 0 2C1). On hydrolysis, the less reactive hydrate salt 14c is formed from 3c. The X-ray structures of 10a and 14c are reported. 
  Reference    Z. Naturforsch. 53b, 720—726 (1998); eingegangen am 23. Februar 1998 
  Published    1998 
  Keywords    Carbene, Chlorine, X-Ray Data 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0720.pdf 
 Identifier    ZNB-1998-53b-0720 
 Volume    53 
2Author    Vincenzo Calò, Angelo NacciRequires cookie*
 Title    Influence of Ionic Liquids on Pd-Catalyzed Carbon-Carbon Bond Formation  
 Abstract    Rates of Heck-type reactions, catalysed by a Pd-catalyst with benzothiazole carbene as ligands, are strongly influenced by tetrabutylammonium bromide utilized as solvent. 
  Reference    Z. Naturforsch. 56a, 702—706 (2001) 
  Published    2001 
  Keywords    Ionic Liquids, Heck Reaction, Palladium, Carbenes, Aryl Acrylates 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0702.pdf 
 Identifier    ZNA-2001-56a-0702 
 Volume    56 
3Author    Kuhn3, Thomas Kratz3, G. Erald, H. EnkelbRequires cookie*
 Title    N orbert  
 Abstract    The carbene adduct 5 is formed from the 2-tel-luroimidazoline 4 and iodine. The X-ray structure analysis reveals a dimeric structure in the solid state. 
  Reference    Z. Naturforsch. 51b, 295 (1996); eingegangen am 21. Juli 1995 
  Published    1996 
  Keywords    Tellurium, Carbene, Iodine Reaction, X-Ray 
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 TEI-XML for    default:Reihe_B/51/ZNB-1996-51b-0295_n.pdf 
 Identifier    ZNB-1996-51b-0295_n 
 Volume    51 
4Author    Norbert Kuhn3, Joanna Fahl3, Roland Boeseb, Gerald HenkelcRequires cookie*
 Title    Zur Reaktion von 2,3-Dihydroimidazol-2-ylidenen mit Pentafluorpyridin: Carbene als Reaktionspartner in der nucleophilen aromatischen Substitution [1] On the Reaction of 2,3-Dihydroimidazol-2-ylidenes with Pentafluoropyridine: Carbenes as Reactants in Nucleophilic Aromatic Substitution [1]  
 Abstract    The 2,3-dihydro-l,3,4,5-tetraalkylimidazol-2-ylidenes 3 (R = Me, i'so-Pr) react immediately with pentafluoropyridine to form the 2-tetrafluoropyridylimidazolium salts 4 in good yields. In contrast with the tetramethyl derivative 4a, alkyl fluoride is eliminated from the isopropyl salt 4b to give 1 -isopropyl-4,5-dimethyl-2-tetrafluoropyridylimidazole, which dimerises via hydrogen bridges in the solid state (7). The X-ray structures of l,3-diisopropyl-4,5-dimethyl-2-tetrafluoropyridylimidazolium chloride (5) and 7 are reported. 
  Reference    Z. Naturforsch. 53b, 881—886 (1998); eingegangen am 9. April 1998 
  Published    1998 
  Keywords    Carbenes, Imidazoles, Pyridines, Nucleophilic Aromatic Substitution, Hydrogen Bonds 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0881.pdf 
 Identifier    ZNB-1998-53b-0881 
 Volume    53 
5Author    N. Orbert, K. Uhn, M. Anfred, Steim Ann, Gerd Weyers, HerrnRequires cookie*
 Title    Synthese und Eigenschaften von l,3-Diisopropyl-4,5-dimethylimidazolium- 2-car boxy lat. Ein stabiles Carben-Addukt des Kohlendioxids [1]  
 Abstract    The reaction of 2,3-dihydro-l,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (5) with C 0 2 gives the imidazolium-2-carboxylate 6 . The compound can be transformed into the salts of its corresponding Broenstedt acid 8 . The cationic acid chloride 10a is obtained from 6 and thionyl chloride. Chemical properties and spectroscopic data indicate 6 to be less basic than its anionic counterparts, e. g. PhC02 . The X-ray structure of 
  Reference    Z. Naturforsch. 54b, 427—433 (1999); eingegangen am 27. November 1998 
  Published    1999 
  Keywords    Carbenes, Imidazoles, Carboxylic Acids, X-Ray Data 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-0427.pdf 
 Identifier    ZNB-1999-54b-0427 
 Volume    54 
6Author    Norbert Kuhn, Manfred Steimann3, Gerd Weyers3, Gerald Henkelh, HerrnRequires cookie*
 Title    l,3-DHSopropyl-4,5-dimethylimidazolium-2-N,N'-diisopropylamidinat, ein neuartiges Retain [1] 1,3-Diisopropyl-4,5-dimethylimidazolium-2-N,N'-diisopropylamidinate, a Novel Betaine [1]  
 Abstract    The imidazolium-2-amidinate 6 is obtained from the reaction of 2,3-dihydro-1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (4) with diisopropylcarbodiimide (5) as stable solid. Overcrow­ ding causes a lowered symmetry of the amidinate fragment indicated both by structural and NMR data. The strongly basic properties of 6 allow facile protonation with HC1 to the cationic amidine derivatives 7 and 8 . The ketoamidine 10 is formed by a ring opening reaction of 6 with water. I he X-ray structures of 6 and 10 are reported 
  Reference    Z. Naturforsch. 54b, 434—440 (1999); eingegangen am 21. Dezember 1998 
  Published    1999 
  Keywords    Amidines, Carbenes, Carbon Diimides, Imidazoles, X-Ray Data 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-0434.pdf 
 Identifier    ZNB-1999-54b-0434 
 Volume    54 
7Author    Norbert Kuhn, Elke Niquet, Manfred Steimann, Isabel WalkerRequires cookie*
 Title    Methoxyalky 1-funktionalisierte 2,3-Dihy droimidazol-2-ylidene [ 1 ] Methoxyalkyl Functionalized 2,3-Dihydroimidazol-2-ylidenes [1]  
 Abstract    The 2,3-dihydro-l,3-di(methoxyalkyl)imidazol-2-ylidenes are obtained from the correspon­ ding cyclic thioureas and potassium. With CS2, the imidazolium dithiocarboxylates are formed. The results of X-ray structure determinations of two of these products are reported. 
  Reference    Z. Naturforsch. 54b, 1181—1187 (1999); eingegangen am 8. Juni 1999 
  Published    1999 
  Keywords    Carbenes, Imidazoles, Dithiocarboxylates, X-Ray Data 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-1181.pdf 
 Identifier    ZNB-1999-54b-1181 
 Volume    54 
8Author    AnthonyJ. Arduengo, JensR. Iiia, Fredric Goerlicha, WilliamJ. Davidsonb, Marshall5Requires cookie*
 Title    Carbene Adducts of Dimethylcadmium  
 Abstract    The first examples of carbene-cadmium complexes are reported from the reactions of a variety of imidazol-2-ylidenes or imidazolin-2-ylidenes with dimethylcadmium. Four new carbene complexes are characterized by NMR spectroscopy ('H , i?C and 1 n Cd). The cadmium centers are strongly shifted downfield (100 -1 5 0 ppm) by interaction with the carbenes. X-ray structures are reported for three carbene-cadmium 1:1 adducts. The cadmium centers exhibit distorted trigonal-planar geometries in which the carbene ligands have an average 18.2 pm longer bond distance to cadmium compared to the methyl groups. The planes of cadmium coordination are twisted with respect to the plane of the imidazole ring. The more basic imidazolin-2-ylidene is shown to displace imidazol-2-ylidenes from the cadmium center. 
  Reference    Z. Naturforsch. 54b, 1350—1356 (1999); received June 16 1999 
  Published    1999 
  Keywords    Carbene, Cadmium, Ylide, Carbene Complex, Imidazol-2-ylidene 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-1350.pdf 
 Identifier    ZNB-1999-54b-1350 
 Volume    54