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1998 (1)
1Author    Marcus Sigl, Annette Schier, Hubert SchmidbaurRequires cookie*
 Title    Lewis Acid Catalyzed Z to E Isomerization of 1,2-Bis(diphenyl- phosphino)ethene  
 Abstract    Z-l,2-Bis(diphenylphosphino)ethene, cis-Ph2PCH=CHPPh2, forms 1:2 adducts with GaBn and GaL, the former of which has been identified in an X-ray diffraction study as the complex of the isomerized ligand, E-Ph2PCH=CHPPh2. The GaL complex is believed to be analogous on the basis of analytical and spectroscopic data. InBr3 affords a 1 :1 complex with an ionic structure [(Ph2PCH=CHPPh2)2lnBr2]+ [InBr4]_ in which the cation contains the original cis-ligand. With Inl^ also a 1:1 adduct is obtained, where the metal triiodide unit is attached to only one phosphorus atom of the non-isomerized (cis) ligand in the solid state. There is rapid site exchange of the Inl3 unit in chloroform solution as followed by NMR spectroscopy. -The metal halide induced Z/E isomerization of Ph2PCH=CHPPh2 has been studied in various solvents and at variable temperature with stoichiometric and catalytic amounts of AIX3 and GaX3 Lewis-acids. InX3 compounds proved ineffective (X = Cl, Br, I). Anhydrous AlBr3 was found to be most efficient, giving a 90% Z/E conversion in 10 min at 100°C in toluene. A mechanism is proposed which is compatible with the experimental data. 
  Reference    Z. Naturforsch. 53b, 1301—1306 (1998); received August 13 1998 
  Published    1998 
  Keywords    Z/E Isomerization, Phosphino-Ethenes, Lewis Acid Catalysis, Gallium Halides, Aluminium Halides, Indium Halides 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-1301.pdf 
 Identifier    ZNB-1998-53b-1301 
 Volume    53