Untersuchungen zur Lewis-Acidität fluorierter Sulfonium-Ionen

On the Lewis Acidity of Fluorinated Sulfonium Ions NMR investigations show, that sulfonium salts [(CF₃)_nSF_3?n]⁺ AsF₆^? ( 1–3 , n = 0–2) add CH₃CN under formation of ψ-pentacoordinated sulfuranonium ions [(CF₃)_nSF_3?n · NCCH₃]⁺ ( 1a – 3a ,) with the donor in an axial position. In solution NSF₃ ( 4 ,) forms similar salts [(CF₃)_nSF_3?n · NSF₃]⁺ AsF₆^? ( 1b-3b ,) with weaker donor-acceptor interactions. With NSF₂NMe₂ ( 5 ,) the step of the primary addition products is passed very quickly, by fluoride-migration from 1 , and 2 , persulfuranonium ions [(CH₃)₂NSF₃NSF₂]⁺ ( 6 ,) and [(CH₃)₂NSF₃NSFCF₃]⁺ ( 7 ,), respectively, are formed, while from 3 , only decomposition products (Me₂NSF₂⁺, CF₃SSCF₃, CF₄) were obtained.     

Selektive Cyclotetramerisierung von Propargylalkohol: katalytische Reaktionen hoher Selektivität und Geschwindigkeit an Nickelkomplexen

Selective Cyclotetramerization of Propargylic Alcohol: Catalytic Reactions with High Selectivity and Reaction Rate by Nickel Complexes It is shown propargylic alcohol reacts with different nickel catalysts to form cyclotetrameres in a selective reaction. Main product of the reaction is 1,3,5,7-tetrakis(hydroxymethyl)-cycloocta(1,3,5,7)-tetraene. The reaction is extremely fast; when it is carried out without solvents at 114°C turnover numbers of 10⁶ catalytic cycles/mol Ni × h can be observed. The influence of phosphines is different: In solvents aromatic compounds, and cyclotetrameres are formed, when solvents are not used, phosphines have no controlling effect. The reaction can also be catalyzed by iron complexes to form cyclotetrameres, cobalt complexes yield a mixture of cyclotrimeres and cyclotetrameres. Supported Nickel or Raney-Nickel can also catalyze the cyclotetramerization. The investigations show that the 1-azadiene ligands in bis(cinnemaldehydeanil)-nickel(0) are substituted by propargylic alcohol in a fast reaction. After the substitution the catalytic reaction takes place at “ligand free nickel”.     

Stabile Bis(η-alkin)MCl2-komplexe; Darstellung und reaktivität

The synthesis and reactivity of {(η⁵-C₅H₄SiMe₃)₂Ti(CCSiMe₃)₂} MCl₂ (M = Fe: 3a; M = Co: 3b; M = Ni: 3c) is described. The complexes 3 are accessible by the reaction of (η⁵-C₅H₄SiMe₃) ₂Ti(CSiMe₃)₂ (1) with equimolar amounts of MCl₂ (2) (M = Fe, Co, Ni). 3a reacts with the organic chelat ligands 2,2′-dipyridyl (dipy) (4a) or 1,10-phenanthroline (phen) (4b) in THF at 25°C to afford in quantitative yields (η⁵-C₅H₄SiMe₃)₂Ti(CSiMe₃)₂ (1) and [Fe(dipy)₂]Cl₂ (5a) or [Fe(phen)₂]Cl₂ (5b). 1/n[Cu^IHal]_n (6) or 1/n[Ag^IHal]_n (7) (Hal = Cl, Br) react with {(η⁵ -C₅H₄SiMe₃)₂Ti(CCSiMe₃)₂}FeCl₂ (3a), by replacement of the FeCl₂ building block in 3a, to yield the compounds {(η⁵-C₅H₄SiMe₃)₂Ti(C CSiMe₃)₂}Cu^IHal (8) or {(η⁵-C₅H₄SiMe₃)₂Ti(CSiMe₃)₂}Ag^IHal (9) (Hal = Cl, Br), respectively. In 8 and 9 each of the two Me₃SiCC-units is η²-coordinated to monomeric Cu^I Hal or Ag^IHal moieties. Compounds 8 and 9 can also be synthesized by the reaction of (η⁵-C₅H₄SiMe₃)₂ Ti(CSiMe₃)₂ (1) with 1/n[Cu^IHal]_n (6) or 1/n [Ag^IHal]_n (7) in excellent yields. All new compounds have been characterized by analytical and spectroscopic data (IR, ¹H-NMR, MS). The magnetic moments of compounds 3 were measured.