Wieland Tyrra

A new synthesis of trifluoromethanethiolates—characterization and properties of tetramethylammonium, cesium and di(benzo-15-crown-5)cesium trifluoromethanethiolates

Abstract [NMe4]SCF3, CsSCF3 and [(B-15-C-5)2Cs]SCF3 (B-15-C-5: benzo-15-crown-5) are formed from reactions of the corresponding fluorides, trimethyl(trifluoromethyl)silane, Me3SiCF3, and elemental sulfur in glyme or THF. All compounds are colorless to pale ochre solids decomposing significantly above ambient temperature. Excellent agreement between experimental and theoretical vibrational frequencies, calculated at the B3PW91 level of theory, impressively confirms the salt-like nature of [NMe4]SCF3. The properties of the title compounds as nucleophilic SCF3 transfer reagents were checked with a variety of organic, organometallic and inorganic compounds.

Oxidative perfluoroorganylation methods in group 12–16 chemistry: The reactions of haloperfluoroorganics and In and InBr, a convenient new route to AgRf (Rf = CF3, C6F5) and reactions of AgRf with group 12–16 elements

Abstract Perfluoroiodo organics RfI (Rf=n-CnF2n+1 (n=1, 2, 3, 4, 6), i-C3F7, C6F5) and C6F5Br react with elemental indium in polyethers or THF to give spectroscopic evidence for compounds of the general composition InIIRfX (X=I, Br). All isolation attempts led to decomposition into InIII(Rf)2I and InII. In contrast, the reaction of In, 0.5Br2 and C6F5Br in THF selectively and quantitatively yielded In(C6F5)Br2·2THF which was structurally characterized. The reaction of In(C6F5)Br2·2THF and acetylacetone (Hacac) quantitatively gave the distorted octahedral molecule In(acac)Br2·2THF. Perfluoroorganosilver(I) compounds Ag(Rf) (Rf=CF3, C6F5) are conveniently and selectively prepared from AgF and Me3SiRf in several nitrile solvents. [PNP][AgI(CF3)2] ([PNP]=bis(triphenylphosphoranyliden)ammonium) is isolated from the reaction mixture after addition of one equivalent of [PNP]Cl. Using excess of [PNP]Cl, [PNP][AgI(CF3)Cl] is formed which is characterized by single crystal structure analysis. Besides its properties as a nucleophilic perfluoroorganylating reagent, AgRf exhibits to be an excellent oxidative perfluoroorganylation reagent in reactions with various elements of groups 12–16 to give the corresponding perfluoroorgano element compounds in moderate to excellent yields leaving elemental silver.

Darstellung, NMR-spektroskopische Charakterisierung und reaktionen von perfluoralkylsilber(I)-verbindungen☆

Abstract Perfluoroalkylsilver(I) compounds are obtained via ligand exchange reactions of AgNO 3 and Cd(R f ) 2 compounds in aprotic polar solvents. Equilibria between the neutral species AgR f · D and the ionic species [Ag(R f ) 2 ] − involve silver(1) ions and exhibit strange solvent-dependency. The 19 F- and 109 Ag-NMR data as well as the T t -values have been measured. Reactions with e.g. C 6 H 5 HgCl proceed at −30°C within a few minutes to give the corresponding phenyl(perfluoroalkyl)mercury derivatives. However, the versatility of AgR f reagents as perfluoroalkyl-group transfer reagents in DMF and N(C 2 H 5 ) 3 remains limited.

Syntheses and Properties of Tetrakis(pentafluorophenyl)tellurium, Te(C6F5)4, and Related Compounds — Single Crystal Structures of Tris(pentafluorophenyl)tellurium Bromide, Te(C6F5)3Br, Tris(pentafluorophenyl)tellurium Trifluoromethanesulfonate, [Te(C6F5)3][OSO2CF3], and Bis(pentafluorophenyl)tellurium Oxide, Te(C6F5)2O

Te(C6F5)4 was prepared from the reactions of TeCl4 or Te(C6F5)2Cl2 with Grignard reagents or AgC6F5 in moderate to good yields. Substitution reactions with Me3SiX (X = Cl, Br, OSO2CF3), with equimolar amounts of Br2, with AgNO3 and with H[BF4] or BF3·OEt2 yielded the Te(C6F5)3X derivatives (X = Cl, Br, OSO2CF3, NO3, BF4). Oxidation reactions of Cd, Hg, and Pd0 complexes led to Te(C6F5)2 and the corresponding bis(pentafluorophenyl) derivatives M(C6F5)2 (M = Cd, Hg, Pd) and with InBr to In(C6F5)2Br. From very slow hydrolysis of Te(C6F5)4 the oxide Te(C6F5)2O was prepared. The thermal decomposition, the NMR and mass spectra of the partially new compounds are discussed. The crystal structures of Te(C6F5)3Br (monoclinic, P21/a, Z = 4), [Te(C6F5)3][OSO2CF3] (monoclinic, P21/n, Z = 16) and [Te(C6F5)2O]2 (triclinic, P1¯, Z = 2) were determined. Die Synthesen und Eigenschaften von Tetrakis(pentafluorphenyl)tellur, Te(C6F5)4, und verwandten Verbindungen — Rontgenstrukturanalysen von Tris(pentafluorphenyl)-tellurbromid, Te(C6F5)3Br, Tris(pentafluorphenyl)tellurtrifluormethansulfonat, [Te(C6F5)3][OSO2CF3] und Bis(pentafluorphenyl)telluroxid, Te(C6F5)2O Te(C6F5)4 wurde durch die Umsetzungen von TeCl4 bzw. Te(C6F5)2Cl2 mit Grignardreagenzien oder AgC6F5 in masigen bis guten Ausbeuten dargestellt. Durch Substitutionsreaktionen mit Me3SiX (X = Cl, Br, OSO2CF3), mit aquimolaren Mengen Br2, mit AgNO3 sowie mit H[BF4] bzw. BF3·OEt2 entstanden die Te(C6F5)3X-Verbindungen (X = Cl, Br, OSO2CF3, NO3, BF4). Oxidationsreaktionen von Cd-, Hg- und Pd0-Komplexen ergaben Te(C6F5)2 und die entsprechenden Derivate M(C6F5)2 (M = Cd, Hg, Pd); InBr wurde zu In(C6F5)2Br oxidiert. Durch sehr langsame Hydrolyse von Te(C6F5)4 wurde Te(C6F5)2O dargestellt. Die thermischen Zersetzungen sowie die NMR- und Massenspektren der teilweise neuen Verbindungen werden diskutiert. Die Kristallstrukturen von Te(C6F5)3Br (monoklin, P21/a, Z = 4), [Te(C6F5)3][OSO2CF3] (monoklin, P21/n, Z = 16) und [Te(C6F5)2O]2 (triklin, P1¯, Z = 2) wurden bestimmt.

Preparation and properties of ZnBr(CF3)·2L — a convenient route for the preparation of CF3I

Abstract ZnBr(CF 3 )·2L (L=DMF, CH 3 CN) can easily be prepared by the reactions of CBrF 3 with elemental zinc in better than 60% yield. The reaction of ZnBr(CF 3 )·2DMF with iodine monochloride in DMF solution yields pure CF 3 I in better than 70% yield via an ecologically less damaging reaction pathway than the decarboxylation route using silver or mercury trifluoroacetates.

One-dimensional CuO–SnO2 p–n heterojunctions for enhanced detection of H2S

Highly crystalline SnO2 nanowires were synthesized and functionalized with copper particles in a CVD using Sn(OBut)4 and [CuII((C5H4N)(CHCOCF3))2]2 (1) as precursors respectively. Controlled oxidation of Cu to CuO led to the formation of CuO@SnO2 p–n heterojunctions, which were found to be highly sensitive and selective towards the detection of H2S gas. The change in the conductance upon exposure to H2S gas was attributed to the formation of CuS resulting in the shrinkage of the space charge region along the SnO2 nanowire and a concomitant increase of the conductivity channel in an individual nanowire.

Die Reaktionen von Bis(perfluoralkyl)cadmium-Komplexen mit Arylcarbonsäurechloriden: Synthese von Aryl-(perfluoralkyl)ketonen, (Perfluoralkyl-dihydropyridin)-arylcarbonsäureamiden, α,α-Bis(trifluormethyl)benzyl-alkoholen und Benzoesäure-α,α-bis(trifluormethyl)-benzylestern

Abstract Perfluoroalkylcadmium complexes react with aroyl halides in the presence of strong bases such as pyridine to give the corresponding ketones ArCOR f (which can be isolated in 5–51% yield) and (perfluoroalkyldihydropyridine)aroylamides. The pure substances are obtained by chromatography. Aroyl fluorides and α,α-bis(trifluoromethyl)benzyl alcohols and benzoic acid-α,α-bis(trifluoromethyl)benzyl esters can be isolated as by-products. The dependency of the products formed on the kind of bases used as well as the reaction mechanisms are described. All products were identified by their 19 F, 1 H, 13 C NMR, mass and IR spectra, and by elemental analysis.

Polar trifluoromethylation reations: syntheses of trifluoromethyl gallium, indium, and thallium compounds. The mechanism of polar trifluoromethyl group transfer

Abstract The reactions of Cd(CF 3 ) 2 complexes with GaCl 3 , InCl 3 , and TlX 3 (X: Cl, OCOCH 3 , OCOCF 3 ) in aprotic basic solvents have given the compounds Ga(CF 3 ) 3 ·dmf, Ga(CF 3 ) 2 Cl·dmf, [Cd(CH 3 CN) 2 ]-[Ga(CF 3 ) 4 ] 2 , In(CF 3 ) 3 ·2CH 3 CN, In(CF 3 ) 2 Cl·dmf, and Tl(CF 3 ) 3 ·2dmf, which have been characterized by NMR spectroscopy, mass spectrometry, vibrational spectroscopy, and elemental analysis. All trifluoromethylmetal halides formed as intermediates were detedted by 19 F NMR spectroscopy. The dependence of the chemical shifts and the coupling constants 2 J ) 203/205 Tl 19 F) on the number of CF 3 -groups bound to the central atom provides unambiguous evidence for the formular of trifluoromethyl gallates and thallates and the existence of the [Ga(CF 3 ) 4 − -anion has been confirmed by 71 Ga NMR spectroscopy. A mechanism for successful polar trifluoromethyl group transfer is discussed on the basis of Pearsons HSAB concept and the results of conductivity measurements.

Novel Air-Stable and Volatile Bis(pyridylalkenolato)palladium(II) and -platinum(II) Derivatives

Six novel homoleptic palladium(II) and platinum(II) complexes of donor-substituted alkenol ligands [PyCHC(R)OH; Py = pyridine, R = CH(3), CF(3), C(2)F(5), C(3)F(7)] of the general formula M[PyCHC(R)O](2) (M = Pd, Pt) were synthesized by reacting the deprotonated ligands with PdCl(2) and K(2)PtCl(4), respectively. Molecular structures, revealed by single-crystal X-ray diffraction analyses, showed a square-planar arrangement of ligands around palladium and platinum centers, with the pyridine-ring nitrogen atoms situated in a mutually trans position. The monomeric nature of the compounds in the solution state was confirmed by multinuclear ((1)H, (13)C, and (19)F) NMR spectroscopy. Thermal decomposition profiles recorded under a nitrogen atmosphere suggested their potential as volatile precursors to palladium and platinum materials. The volatility was increased upon elongation of the perfluoroalkyl chain, which suppressed the intermolecular interactions, as is evident in crystal packings. The volatility of these compounds was attributed to bidentate chelation of the alkenol units and cooperativity among the electron-back-donating nitrogen atom and interplay of electron-withdrawing C(x)F(y) groups, resulting in an effective steric shielding of the metal atoms.

The preparation of bis(pentafluorophenyl)iodine(III) sulphonates from the reactions of iodine(III) compounds with pentafluorobenzene in strong acids

Abstract Bis(pentafluorophenyl)iodine trifluoromethanesulphonate and bis(pentafluorophenyl)iodine 2,4,6-trinitrobenzenesulphonate can be prepared in approximately 80% yield from the reactions of iodine tris(trifluoroacetate), pentafluorobenzene and the corresponding sulphonic acid in trifluoroacetic acid. The 19F NMR data and vibrational spectra have been compared with those of related compounds.