Abtrennung und gas-chromatographische Bestimmung von Fluoridspuren

Zusammenfassung Spuren an Fluorid können aus wäßrigen Lösungen mit (C₂H₅)₃SiCl in m-Xylol oder mit (C₆H₅)₄SbOH in CH₂Cl₂ ausgeschüttelt werden. Von verschiedenen untersuchten Mitfällungsreaktionen erwies sich die Adsorption an Hydroxylapatit als am günstigsten.Durch Gas-Chromatographie mit Flammenionisationsdetektor können noch 0,05 g F^–/ml m-Xylol als (C₂H₅)₃SiF bestimmt werden. Wegen der normalerweise auftretenden schwankenden Blindwerte von etwa 0,5–1,5 g F^– lassen sich jedoch Mengen von weniger als ca. 3 g F^– in der Regel nicht mehr bestimmen.

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Separation and gas-chromatographic determination of traces of fluoride

Traces of fluoride can be separated from aqueous solution by extraction with (C₂H₅)₃SiCl in m-xylene or with (C₆H₆)₄SbOH in CH₂Cl₂. Furthermore, several coprecipitation reactions were tested; adsorption on hydroxyl apatite is most suitable.Determination of 0.05 g F^–/ml can be performed by gas chromatography of (C₂H₅)₃SiF in m-xylene using flame ionisation detectors; but variable blanks of 0.5–1.5 g F^– normally prevent the determination of less than ca. 3 g F^–.

     

Replacement of Trimethylamine in Trimethylamine‐trispentafluoroethyl‐borane. Structures of [(C2F5)3BNMe3], [NMe4][(C2F5)3BOH], and K[(C2F5)3BCH2(CO)C6H5]

Trimethylamine‐tris(pentafluoroethyl)borane [(C₂F₅)₃BNMe₃] ( 1 ) reacts at 190 °C with water under displacement of the trimethylamine ligand to yield the hydroxy‐tris(pentafluoroethyl)borate [(C₂F₅)₃BOH]^? ( 2 ). In tributylamine 1 reacts with alkynes HC≡CR to form novel ethynyl‐tris(pentafluoroethyl)borate anions [(C₂F₅)₃BC≡CR]^? – R = C₆H₅ ( 3 ), C₆H₄CH₃ ( 4 ), Si(CH(CH₃)₂)₃ ( 5 ) – in moderate yields. Compound 3 adds water across the triple bond to form the novel anion [(C₂F₅)₃BCH₂(CO)C₆H₅]^? ( 6 ). The structures of [(C₂F₅)₃BNMe₃], [NMe₄][(C₂F₅)₃BOH] and K[(C₂F₅)₃BCH₂(CO)C₆H₅] have been determined by x‐ray crystallography.     

Polymerization of propylene by zirconocenium catalysts with different counter-ions

Propylene was polymerized by binary zirconocenium catalysts derived from rac-ethylenebis(1-η⁵-indenyl)dimethylzirconium and cation forming agents (C₆H₅)₃C+(C₆F₅)₄B^? and (C₆F₅)₃B. Polymerizations were also performed with the ternary systems of Et[Ind]₂ZrCl₂, Et₃Al, and the cation forming agents. The catalyst systems, with the inert noncoordinating counter-ion, (C₆F₅)₄B^?, have much higher activity and stereoselectivity than the ones with the CH₃B^?(C₆F₅)₃ counter-ion. Much less active still are catalysts having BF₄^? or (C₆H₅)₄B^? counter-ions. Similar but smaller effects of counter-ion structure on ethylene polymerization were observed. © 1994 John Wiley & Sons, Inc.     

Optisch aktive übergangsmetall-komplexe XX. Optisch aktive cyclopentadienyl-perfluoropropyl-kobalt-komplexe mit zweizähnigen schiff-basen

In the reaction of C₅H₅ Co(C₃F₇)(CO)I with the Schiff base NN′, derived from S-(-)-?-phenylethylamine and pyridine carbaldehyde-2, the salt [C₅H₅Co(C₃F₇)NN′]⁺ I^? (Ia,b) is formed, which can be transformed to [C₅H₅ Co(C₃F₇)NN′]⁺ PF₆^? (IIa,b). The sodium salt Na⁺ [NN″]^? of the Schiff base, derived from S-(-)-α-phenylethylamine and pyrrol carbaldehyde-2, in the reaction with C₅H₅ C0(C₃F₇)(CO)I yields the neutral complex C₅H₅ Co(C₃F₇)NN″ (IIIa,b). The diastereoisomeric pairs IIa,b and IIIa,b are separated by fractional crystallisation and chromatography respectively into the optically pure components which differ in their ¹H NMR spectra. The IR, UV, CD, mass spectra and optical rotations of the new compounds IIa, IIb, IIIa and IIIb are compared.     

Optisch aktive übergangsmetall-komplexe : XVIII. Über die reaktion von C5H5Co(CO)(C3F7)j mit isonitrilen

In the reaction of C₅H₅Co(CO)(C₃F₇)I with isonitriles in the molár ratio $\text{1}\text{1}$ the brown complexes C₅H₅Co(CNR)(C₃F₇)I are formed. The fluorine atoms of the α-CF₂ groups are diastereotopic because of the asymmetric center at the Co atom. With (—)-α-phenylethylisonitrile a pair of diastereoisomers is obtained which could not be separated.C₅H₅Co(CO)(C₃F₇)I and C₅H₅Co(CNR)(C₃F₇)I react with excess isonitrile with the formation of benzene soluble, yellow salts [C₅H₅Co(CNR)₂(C₃F₇)]⁺I^?, which can be transformed into the corresponding PF^?₆ salts. The new compounds were characterised by C, H, N, Co analyses, molecular weight determinations, IR, ¹H NMR, ¹⁹F NMR, ¹³C NMR, ESCA and mass spectra.     

Über Pentafluorphenylthio-Metallkomplexe

The compounds M(CO)₅ · THF (M = Cr, Mo, W) react with sodium mercaptide, NaSR (R = C₆F₅, C₆H₅, C₂H₅), to give the mercapto-pentacarbonylmetallate anions [M(CO)₅ · · SR]^?. The preparation of some pentafluorophenylthio complexes, e. g. [(C₆H₅)₃P]₂MSC₆F₅(M = Cu, Ag, Au), [(C₆H₅)₃P]₂Hg(SC₆F₅)₂, is reported.     

Univalent Gallium Complexes of Simple and ansa‐Arene Ligands: Effects on the Polymerization of Isobutylene

Using [Ga(C₆H₅F)₂]⁺[Al(OR^F)₄]^?( 1 ) (R^F=C(CF₃)₃) as starting material, we isolated bis‐ and tris‐η⁶‐coordinated gallium(I) arene complex salts of p‐xylene (1,4‐Me₂C₆H₄), hexamethylbenzene (C₆Me₆), diphenylethane (PhC₂H₄Ph), and m‐terphenyl (1,3‐Ph₂C₆H₄): [Ga(1,4‐Me₂C₆H₄)_2.5]⁺ ( 2⁺ ), [Ga(C₆Me₆)₂]⁺ ( 3⁺ ), [Ga(PhC₂H₄Ph)]⁺ ( 4⁺ ) and [(C₆H₅F)Ga(μ‐1,3‐Ph₂C₆H₄)₂Ga(C₆H₅F)]²⁺ ( 5²⁺ ). 4⁺ is the first structurally characterized ansa‐like bent sandwich chelate of univalent gallium and 5²⁺ the first binuclear gallium(I) complex without a Ga?Ga bond. Beyond confirming the structural findings by multinuclear NMR spectroscopic investigations and density functional calculations (RI‐BP86/SV(P) level), [Ga(PhC₂H₄Ph)]⁺[Al(OR^F)₄]^?( 4 ) and [(C₆H₅F)Ga(μ‐1,3‐Ph₂C₆H₄)₂Ga(C₆H₅F)]²⁺{[Al(OR^F)₄] ^?}₂ ( 5 ), featuring ansa‐arene ligands, were tested as catalysts for the synthesis of highly reactive polyisobutylene (HR‐PIB). In comparison to the recently published 1 and the [Ga(1,3,5‐Me₃C₆H₃)₂]⁺[Al(OR^F)₄]^? salt ( 6 ) (1,3,5‐Me₃C₆H₃=mesitylene), 4 and 5 gave slightly reduced reactivities. This allowed for favorably increased polymerization temperatures of up to +15 °C, while yielding HR‐PIB with high contents of terminal olefinic double bonds (α‐contents=84–93 %), low molecular weights (M_n=1000–3000 g mol^?1) and good monomer conversions (up to 83 % in two hours). While the chelate complexes delivered more favorable results than 1 and 6 , the reaction kinetics resembled and thus concurred with the recently proposed coordinative polymerization mechanism.     

Interaction of pentafluoropyridine with 4-nitrophenol and pentafluorophenol in the presence of potassium fluoride and 18-crown-6-ether

The reactions of 4-nitro- and pentafluorophenols with C₅F₅N, 4-ArOC₅F₄N and 2,4-(ArO)₂C₅F₃N (Ar = 4-NO₂C₆H₄, C₆F₅) in the presence of KF and catalitic amounts of 18-crown-6- -ether at various temperatures have been investigated. The leaving ability of the C₆F₅O-group is shown to be higher than that of the 4-NO₂C₆H₄O-group in the reactions of 4-ArOC₅F₄N, 2,4-(ArO)₂C₅F₃N and 2,4,6-(ArO)₃C₅F₂N with F^?-anion, which is in agreement with the order of the basicity of anions (C₆F₅O^?<4-NO₂C₆H₄O^?). The reaction pathways of pentafluoropyridine with ArO^?-anions are discussed.     

Fine‐Tuning of Lewis Acidity: The Case of Borenium Hydride Complexes Derived from Bis(phosphinimino)amide Boron Precursors

Reactions of bis(phosphinimino)amines LH and L′H with Me₂S ? BH₂Cl afforded chloroborane complexes LBHCl ( 1 ) and L′BHCl ( 2 ), and the reaction of L′H with BH₃ ? Me₂S gave a dihydridoborane complex L′BH₂ ( 3 ) (LH=[{(2,4,6‐Me₃C₆H₂N)P(Ph₂)}₂N]H and L′H=[{(2,6‐iPr₂C₆H₃N)P(Ph₂)}₂N]H). Furthermore, abstraction of a hydride ion from L′BH₂ ( 3 ) and LBH₂ ( 4 ) mediated by Lewis acid B(C₆F₅)₃ or the weakly coordinating ion pair [Ph₃C][B(C₆F₅)₄] smoothly yielded a series of borenium hydride cations: [L′BH]⁺[HB(C₆F₅)₃]^? ( 5 ), [L′BH]⁺[B(C₆F₅)₄]^? ( 6 ), [LBH]⁺[HB(C₆F₅)₃]^? ( 7 ), and [LBH]⁺[B(C₆F₅)₄]^? ( 8 ). Synthesis of a chloroborenium species [LBCl]⁺[BCl₄]^? ( 9 ) without involvement of a weakly coordinating anion was also demonstrated from a reaction of LBH₂ ( 4 ) with three equivalents of BCl₃. It is clear from this study that the sterically bulky strong donor bis(phosphinimino)amide ligand plays a crucial role in facilitating the synthesis and stabilization of these three‐coordinated cationic species of boron. Therefore, the present synthetic approach is not dependent on the requirement of weakly coordinating anions; even simple BCl₄^? can act as a counteranion with borenium cations. The high Lewis acidity of the boron atom in complex 8 enables the formation of an adduct with 4‐dimethylaminopyridine (DMAP), [LBH ? (DMAP)]⁺[B(C₆F₅)₄]^? ( 10 ). The solid‐state structures of complexes 1 , 5 , and 9 were investigated by means of single‐crystal X‐ray structural analysis.     

Pentafluorphenyliod(III)-Verbindungen. 2. Fluor-Aryl Substitution an Iodtrifluorid: Synthese von Pentafluorphenylioddifluorid C6F5IF2 und Bis(pentafluorphenyl)iodonium Pentafluorphenylfluoroboraten [(C6F5)2I]+[(C6F5)nBF4−n]−

Pentafluorophenyliodine(III) Compounds. 2. Fluorine-Aryl Substitution Reactions on Iodinetrifluoride: Synthesis of Pentafluorophenyliodinedifluoride C₆F₅IF₂ and Bis(pentafluorophenyl)iodonium Pentafluorophenylfluoroborates[(C₆F₅)₂I]⁺[(C₆F₅)_nBF_4?n]^? Mono- and disubstitution can be achieved in the fluorine-aryl substitution reaction on the low-temperature phase IF₃ in CH₂Cl₂ at ?78°C depending on the aryl transfer reagent. With B(C₆F₅)₃ [(C₆F₅)₂I]⁺ [(C₆F₅)_nBF_4?n]^? (68% yield) and with Cd(C₆F₅)₂ C₆F₅IF₂ (97% yield) is obtained whereas with C₆F₅SiMe₃ no fluorine-aryl substitution takes place on IF₃ even under basic conditions (EtCN or F^? addition). At ?78°C in EtCN solution IF₃ does not disproportionate but attacks the solvent under formation of HF.     

Autoinduced Catalysis and Inverse Equilibrium Isotope Effect in the Frustrated Lewis Pair Catalyzed Hydrogenation of Imines

The frustrated Lewis pair (FLP)‐catalyzed hydrogenation and deuteration of N‐benzylidene‐tert‐butylamine ( 2 ) was kinetically investigated by using the three boranes B(C₆F₅)₃ ( 1 ), B(2,4,6‐F₃‐C₆H₂)₃ ( 4 ), and B(2,6‐F₂‐C₆H₃)₃ ( 5 ) and the free activation energies for the H₂ activation by FLP were determined. Reactions catalyzed by the weaker Lewis acids 4 and 5 displayed autoinductive catalysis arising from a higher free activation energy (2 kcal mol^?1) for the H₂ activation by the imine compared to the amine. Surprisingly, the imine reduction using D₂ proceeded with higher rates. This phenomenon is unprecedented for FLP and resulted from a primary inverse equilibrium isotope effect.     

Very-low-pressure pyrolysis of nitroso- and pentafluoronitrosobenzene C?NO bond dissociation energies

The high-pressure absolute rate constants for the decomposition of nitrosobenzene and pentafluoronitrosobenzene were determined using the very-low-pressure pyrolysis (VLPP) technique. Bond dissociation energies of DH⁰(C₆H₅? NO) = 51.5 ± 1 kcal/mole and DH⁰ (C₆F₅? NO) = 50.5 ± 1 kcal/mole could be deduced if the radical combination rate constant is set at log k_r(M^?1·sec^?1) = 10.0 ± 0.5 for both systems and the activation energy for combination is taken as 0 kcal/mole at 298°K. δH_f⁰(C₆H₅NO), δH_f⁰(C₆F₅NO), and δH_f⁰(C₆F₅) could be estimated from our kinetic data and group additivity. The values are 48.1 ± 1, –160 ± 2, and – 130.9 ± 2 kcal/mole, respectively. C–X bond dissociation energies of several perfluorinated phenyl compounds, DH⁰(C₆F₅–X), were obtained from the reported values of δH_f⁰(C₆F₅X) and our estimated δH_f⁰(C₆F₅) [X = H, CH₃, NO, Cl, F, CF₃, I, and OH].     

Isobutene polymerization initiated by [CP*TiMe2]+ in the presence of a series of novel,weakly coordinating counteranions

The highly electrophilic borane B(C₆F₅)₃ reacts with n‐octadecanol (n‐C₁₈H₃₇OH) and n‐octadecanethiol (n‐C₁₈H₃₇SH) to form the 1:1 adducts (n‐C₁₈H₃₇EH)B(C₆F₅)₃ (E = O or S). The latter are acidic and react with Cp*TiMe₃ in methylene chloride and toluene to give methane and the complexes [Cp*TiMe₂][(n‐C₁₈H₃₇E)B(C₆F₅)₃], which are very good initiators for the carbocationic polymerization of isobutene (IB) from ?40 to ?20 °C. High conversions to high molecular weight polyisobutene (PIB) in methylene chloride and moderate conversions to high molecular weight PIB in toluene are observed and are consistent with the anions [(n‐C₁₈H₃₇E)B(C₆F₅)₃]^? being very weakly coordinating. Although polymerization in methylene chloride is too rapid for the temperature to be controlled, polymerization in toluene is slower, and the temperatures can be controlled so that Arrhenius‐type plots of the logarithm of the number‐average molecular weight versus T^?1 = 1/T may be obtained. Activation energies for the degree of polymerization in these polymerization reactions and similar polymerizations carried out with n‐C₁₈H₃₇EH:borane ratios of 1:2 and with the activators [Ph₃C][B(C₆F₅)₄] and Al(C₆F₅)₃ range from ?11 to ?27 kJ mol^?1, values comparable to those for most conventional IB polymerization initiators. However, the values of the weight‐average and number‐average molecular weights are unusually high for the temperatures used, and this is consistent with current theories of the role of weakly coordinating anions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3302–3311, 2002     

Synthesis and application of molybdenum (III) complexes bearing weakly coordinating anions as catalysts of isobutylene polymerization

Acetonitrile ligated molybdenum (III) complexes of the structure [MoCl(NCCH₃)₅]²⁺ bearing different weakly coordinating anions [B(C₆F₅)₄]^? (WCA a), [B{C₆H₃(m‐CF₃)₂}₄]^? (WCA b) and [(C₆F₅)₃B‐C₃H₃N₂‐B(C₆F₅)₃]^? (WCA c) were applied as homogeneous catalysts of the polymerization of isobutylene. High monomer conversions were obtained in short reaction times (<30 min). The molecular weight of the resulting polyisobutylene is nearly independent of parameters such as temperature, solvent, monomer concentration, but is strongly influenced by the type of WCA and by chain transfer reactions which were observed in these systems. Highly reactive low molecular weight polyisobutylenes (M_n < 2000 g/mol) were obtained with a high content of exo double bond end groups as shown by ¹H NMR analysis. Furthermore, experiments were performed to reduce the isomerization of these exo end groups into other internal double bonds by varying the polymerization parameters. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3775–3786, 2010     

Photochemical and thermal reactions of η5-cyclopentadienyltetracarbonylvanadium and bis(pentafluorophenyl)acetylene

The photolysis of (η⁵-C₅H₅)V(CO)₄ in the presence of one or two equivalents of bis(pentafluorophenyl)acetylene yields (η⁵-C₅H₅)V(CO)₂(C₆F₅CCC₆F₅). One carbon monoxide ligand in this acetylene adduct can be photochemically displaced by triphenylphosphine to yield (η⁵-C₅H₅)V(CO)[P(C₆H₅)₃](C₆F₅CCC₆F₅). This complex is also obtained by the photolysis of (η⁵-C₅H₅)V(CO)₃P(C₆H₅)₃ in the presence of bis(pentafluorophenyl)acetylene. In vacuo, melt-phase thermolysis of (η⁵-C₅H₅)V(CO)₂(C₆F₅CCC₆F₅) and bis(pentafluorophenyl)acetylene produces (η⁵-C₅H₅)V(CO)(C₆F₅CCC₆F₅)₂. This diacetylenic complex as well as the perfluorinated organic compounds 2,3,5,6-tetrakis(pentafluorophenyl)-1,4-benzoquinone, 2,3,4,5-tetrakis(pentafluorophenyl)cyclopentadienone and 2,3,4,5,6,7-hexakis(pentafluorophenyl)cycloheptatrienone are also obtained from thermal reactions of (η⁵-C₅H₅)V(CO)₄ and bis(pentafluorophenyl)acetylene in solution. Photolysis of (η⁵-C₅H₅)V(CO)(C₆F₅CCC₆F₅)₂ in the presence of carbon monoxide produces (η⁵-C₅H₅)V(CO)₂(C₆F₅CCC₆F₅). The photochemical and thermal reactions of bis(pentafluorophenyl)acetylene and (η⁵-C₅H₅)V(CO)₄ are compared and contrasted with similar reactions of diphenylacetylene and (η⁵-C₅H₅)V(CO)₄.     

Influence of Cyclopentadienyl Ring‐Tilt on Electron‐Transfer Reactions: Redox‐Induced Reactivity of Strained [2] and [3]Ruthenocenophanes

In contrast to ruthenocene [Ru(η⁵‐C₅H₅)₂] and dimethylruthenocene [Ru(η⁵‐C₅H₄Me)₂] ( 7 ), chemical oxidation of highly strained, ring‐tilted [2]ruthenocenophane [Ru(η⁵‐C₅H₄)₂(CH₂)₂] ( 5 ) and slightly strained [3]ruthenocenophane [Ru(η⁵‐C₅H₄)₂(CH₂)₃] ( 6 ) with cationic oxidants containing the non‐coordinating [B(C₆F₅)₄]^? anion was found to afford stable and isolable metal?metal bonded dicationic dimer salts [Ru(η⁵‐C₅H₄)₂(CH₂)₂]₂[B(C₆F₅)₄]₂ ( 8 ) and [Ru(η⁵‐C₅H₄)₂(CH₂)₃]₂[B(C₆F₅)₄]₂ ( 17 ), respectively. Cyclic voltammetry and DFT studies indicated that the oxidation potential, propensity for dimerization, and strength of the resulting Ru?Ru bond is strongly dependent on the degree of tilt present in 5 and 6 and thereby degree of exposure of the Ru center. Cleavage of the Ru?Ru bond in 8 was achieved through reaction with the radical source [(CH₃)₂NC(S)S?SC(S)N(CH₃)₂] (thiram), affording unusual dimer [(CH₃)₂NCS₂Ru(η⁵‐C₅H₄)(η³‐C₅H₄)C₂H₄]₂[B(C₆F₅)₄]₂ ( 9 ) through a haptotropic η⁵–η³ ring‐slippage followed by an apparent [2+2] cyclodimerization of the cyclopentadienyl ligand. Analogs of possible intermediates in the reaction pathway [C₆H₅ERu(η⁵‐C₅H₄)₂C₂H₄][B(C₆F₅)₄] [E=S ( 15 ) or Se ( 16 )] were synthesized through reaction of 8 with C₆H₅E?EC₆H₅ (E=S or Se).     

A Silylene–Borane Lewis Pair as a Tool for Trapping a Water Molecule: Silanol Formation and Dehydrogenation

The Lewis acid B(C₆F₅)₃ and the cyclic silane (Ar^N₂Si)₃ ( 1 ) (Ar^N=o-(CH₃)₂NCH₂C₆H₄) are useful precursors to access the silylene(II)–borane adduct Ar^N₂Si-B(C₆F₅)₃ ( 2 ). Treatment of 2 with water led to coordination and gave the Lewis pair (Ar^N₂H₂O)Si-B(C₆F₅)₃ ( 3 ) that exhibits a hydrogen-bond-stabilized silanol unit. It can be converted into the siloxane [(HAr^N)₂SiOB(C₆F₅)₃]₂O ( 6 ) by dehydrogenation in the presence of a base. Heteronuclear NMR spectroscopic data to characterize the compounds were supported by quantum-chemical calculations.     

Bis(fluorbenzoyloxy)methylphosphanoxide

Bis(fluorbenzoyloxy)methyl phosphane oxides CH₃P(O)[OC(O)R]₂ [R = C₆H₄2F (1), C₆H₄3F (2), C₆H₄4F (3), C₆H₃2,6F₂ (4), C₆H2,3,5,6F₄ (5)] were prepared by treating silver salts of carboxylic acids AgOC(O)R with CH₃P(O)C?₂ (IR-, ¹H-, ¹⁹?F-and ³¹P{¹H}-NMR-data). The mixed anhydrides 1–5 show unusual thermal stability at room temperature. Stability against hydrolysis decreases with increasing number of fluorine-atoms. The reaction of R′P(O)C?₂ [R′ = CH₃, C₆H₅, (CH₃)₃C] with M^IOC(O)R_F [R_F = CF₃, C₂F₅, C₆F₅; M^I = Ag^I, Na^I T?^I] was investigated.     

Synthesen und Eigenschaften von Pentafluorethylkupfer(I)‐ und ‐(III)‐Verbindungen: Cu(C2F5) · D, [Cu(C2F5)2]– und (C2F5)2CuSC(S)N(C2H5)2

Syntheses and Properties of Pentafluoroethylcopper(I) and ‐copper(III) Compounds: CuC₂F₅ · D, [Cu(C₂F₅)₂]^–, and (C₂F₅)₂CuSC(S)N(C₂H₅)₂ The reactions of Cd(C₂F₅)₂ · D and Zn(C₂F₅)₂ · D (D = 2 CH₃CN, 2 DMF), respectively, with copper(I) halides in the presence of halides quantitatively yield the CuC₂F₅ compounds CuC₂F₅ · D and [Cu(C₂F₅)₂]^–. The CuC₂F₅ complexes are identified by NMR spectroscopy, while [Cu(C₂F₅)₂]^– is isolated as PNP salt (PNP = (C₆H₅)₃PNP(C₆H₅)₃⁺). Both compounds are excellent C₂F₅ group transfer reagents, even at low temperature. Oxidation of [Cu(C₂F₅)₂]^– with [(C₂H₅)₂NC(S)S]₂ yields the crystalline Cu(III) compound (C₂F₅)₂CuSC(S)N(C₂H₅)₂ (monoclinic, C2/c).     

Facile access to the pnictocenium ions [Cp*ECl]+ (E = P, As) and [(Cp*)2P]+: chloride ion affinity of Al(OR(F))3

The pnictocenium salts [Cp*PCl]⁺[μCl]^? ( 1 a ), [Cp*PCl]⁺[ClAl(OR^F)₃]^? ( 1 b ), [Cp*AsCl]⁺[ClAl(OR^F)₃]^? ( 2 ), and [(Cp*)₂P]⁺[μCl]^? ( 3 ), in which Cp*=Me₅C₅, μCl=(^FRO)₃Al? Cl? Al(OR^F)₃, and OR^F=OC(CF₃)₃, were prepared by halide abstraction from the respective halopnictines with the Lewis superacid PhF→Al(OR^F)₃. 1 The X‐ray crystal structures of 1 a , 2 , and 3 established that in the half as well as in the sandwich cations the Cp* rings are attached in an η²‐fashion. By using one or two equivalents of the Lewis acid, the two new weakly coordinating anions [μCl]^? and [ClAl(OR^F)₃]^? resulted. They also stabilize the highly reactive cations in PhF or 1,2‐F₂C₆H₄ solution at room temperature. The chloride ion affinities (CIAs) of a range of classical strong Lewis acids were also investigated. The calculations are based on a set of isodesmic BP86/SV(P) reactions and a non‐isodesmic reference reaction assessed at the G3MP2 level.