Synthesis, NMR spectroscopic characterisation and reactions of 2,6-difluorophenylxenon fluoride, 2,6-F2C6H3XeF

[2,6-F₂C₆H₃Xe][BF₄] is quantitatively transferred into 2,6-F₂C₆H₃XeF in reactions with [NMe₄]F. The latter has been isolated as a colourless solid which is stable in dichloromethane solution at room temperature for approximately 1 h. 2,6-F₂C₆H₃XeF readily reacts with Me₃SiX (X = Cl, Br, CN, NCO, OCOCF₃, OSO₂CF₃, C₆F₅, 2,6-F₂C₆H₃) to give compounds of general compositions 2,6-F₂C₆H₃XeX which were identified by multinuclear NMR experiments. Evidence was found for C₆H₅Xe(2,6-F₂C₆H₃) as a product of the reaction with C₆H₅SiF₃.     

Bis(pentafluorophenylxenonium) tetrafluoroterephthalate, p-C6F5XeO(O)CC6F4C(O)OXeC6F5, a hypervalent compound with two xenon-carbon bonds

Bis(pentafluorophenylxenonium) tetrafluoroterephthalate (1) was obtained by metathesis reactions of pentafluorophenylxenonium and tetrafluoroterephthalate salts. The availability of suitable solvents for the metatheses hampered the optimization of the reaction. The new xenon-carbon compound with two polar Xe-O bonds was characterized by NMR spectroscopy in solution and by Raman spectroscopy in the solid state. From (CF₃)₂CHOH/MeCN solutions single crystals were obtained with four alcohol molecules attached to 1 by hydrogen bridges. The thermal properties of the intrinsically unstable title compound are reported.     

A widely varying range of products in reactions of C6F5BrF2, C6F5IF2, and C6F5IF4 with Lewis acids of different strength

The relative fluoride donor ability: C₆F₅BrF₂ > C₆F₅IF₂ > C₆F₅IF₄ was outlined from reactions with Lewis acids of graduated strength in different solvents. Fluoride abstraction from C₆F₅HalF₂ with BF₃·NCCH₃ in acetonitrile (donor solvent) led to [C₆F₅HalF·(NCCH₃)_n][BF₄]. The attempted generation of [C₆F₅BrF]⁺ from C₆F₅BrF₂ and anhydrous HF or BF₃ in weakly coordinating SO₂ClF gave C₆F₅Br besides bromoperfluorocycloalkenes C₆BrF₇ and 1-BrC₆F₉. In reactions of C₆F₅IF₂ with SbF₅ in SO₂ClF the primary observed intermediate (¹⁹F NMR, below 0 °C) was the 4-iodo-1,1,2,3,5,6-hexafluorobenzenium cation, which converted into C₆F₅I and 1-IC₆F₉ at 20 °C. The reaction of C₆F₅IF₄ with SbF₅ in SO₂ClF below −20 °C gave the cation [C₆F₅IF₃]⁺ which decomposed at 20 °C to C₆F₅I, 1-iodoperfluorocyclohexene, and iodoperfluorocyclohexane. Principally, the related perfluoroalkyl compound C₆F₁₃IF₄ showed a different type of products in the fast reaction with AsF₅ in CCl₃F (−60 °C) which resulted in C₆F₁₄. Intermediate and final products of C₆F₅HalF_n−1 (n = 3, 5) with Lewis acids were characterized by NMR in solution. Stable solid products were isolated and analytically characterized.     

The unusual reactivity of C3F7OCFCF2 with PBu3 and the complex hydrides M[EH4] (M: Li, Na; E: B, Al); preparation of potassium perfluoro-2-propoxyeth-1-enyltrifluoroborate K[C3F7OCFCFBF3]

The nucleophilic hydrodefluorination of C₃F₇OCFCF₂ with the complex hydrides Li[AlH₄], Li[BH₄] or Na[BH₄] proceeded non-stereoselectively and was accompanied by the formation of either cis- and trans-C₃F₇OCHCFH and/or C₃F₇OCHFCF₂H. The reaction of C₃F₇OCFCF₂ with PBu₃ followed by treatment with BF₃·OMe₂ or BF₃·OEt₂ yielded [C₃F₇OCFCFPBu₃] [BF₄] (cis and trans) and, probably, [trans-Bu₃PCFCFPBu₃] [BF₄]₂. The hydrolysis of the latter with pure water proceeded quickly while the former isomeric mixture formed the isomeric olefins C₃F₇OCFCFH slowly. The usage of aqueous NaOH instead of water produced mainly trans-CHFCHF. The metallation of C₃F₇OCFCFH (cis:trans=45:55) to C₃F₇OCFCFLi and its subsequent reaction with B(OMe)₃ and K[HF₂] gave the salt K[C₃F₇OCFCFBF₃] in a different cis to trans ratio (25:75) with satisfactory yield.     

Intramolecular nucleophilic substitution in C6F5 moiety. The fluoride-dialkylamino exchange in decafluorodiphenlamino moiety

The reactions of [In(NEt₂)₃]₂ and Sb(NEt₂)₃ with an equimolar amount of decafluorodiphenylamine (DFDPA, LH) lead to the indium or antimony amides [(C₆F₅)₂NIn(NEt₂)₂]₂ (1) and (C₆F₅)₂NSb(NEt₂)₂ (2). Compound 2 rearranged further to give monofluoride Et₂NSb(F)[N(o-Et₂N-C₆F₄)(C₆F₅)] (3) and then difluoride F₂Sb[N(o-Et₂N-C₆F₄)₂] (4). The hydrolysis of 4 gave free ligand HN(o-Et₂N-C₆F₄)₂ (5). Closely related HN(o-Me₂N-C₆F₄)₂ (6) was prepared from the reaction of Bi(NMe₂)₃ with DFDPA. The reactions of LiN(C₆F₅)₂·THF with metal halides gave Sb[N(C₆F₅)₂]₃ (7), Me₃Sb(Br)[N(C₆F₅)₂] (8), Me₃Sb(Cl)[N(C₆F₅)₂] (9), Me₃Sb[N(C₆F₅)₂]₂ (10), [Li(THF)₂][In{N(C₆F₅)₂}₃Cl] (11). The X-ray structural investigations of 2 and 8 are presented.     

Reactions of Alk‐1‐enylxenonium(II) and Alk‐1‐ynylxenonium(II) Salts [RXe]Y with Bromides and Iodides in Anhydrous HF

The replacement of xenon(+) by iodine in reactions of alkenylxenonium(II) salts [RCF=CFXe]Y (R = cis-C₂F₅, trans-H) and alkynylxenonium(II) salt [C₃F₇C≡CXe][BF₄] with NaI in anhydrous HF (aHF) occurred regiospecifically. At −60 °C the substitution of xenon(+) by bromine in the perfluorinated salts [cis-CF₃CF=CFXe]Y and [trans-C₄F₉CF=CFXe]Y proceeded regio- and stereospecifically with NaBr in aHF, but at a higher temperature and after a longer time the treatment of [cis-C₂F₅CF=CFXe]Y with NaBr, KBr, or [NBu₄]Br in aHF gave mixtures of cisand trans-perfluorobut-1-enyl bromides. The reaction of [C₃F₇C≡CXe][BF₄] with NaBr in aHF at −65 °C gave only 48 %, of C₃F₇C≡CBr and was accompanied by a mixture of bromine-containing related olefins. Reaction pathways to the main product are discussed.     

Formation of perfluorinated polyphenylenes by multiple pentafluorophenylation using C6F5Si(CH3)3

Pentafluorophenylation of perfluoroarenes with C₆F₅Si(CH₃)₃ was investigated by using NMR and MALDI-TOF-MS techniques. Successive multiple pentafluorophenylation easily occurred not only on the para-position but also on the ortho-positions to provide perfluorinated p-phenylene and m-phenylene compounds. The perfluoroarenes having electron-withdrawing substituents provided oligo- to poly-(phenylene)s depending on the added amounts of C₆F₅Si(CH₃)₃, while the perfluoroarenes having electron-donor substituents gave H(C₆F₄)_nF polymers produced from C₆F₅H, which was the decomposed product of C₆F₅Si(CH₃)₃.     

Reactions of methyl(pentafluorophenyl)- and methyl(pentafluorophenyl)phenylsilanes with electrophiles. A convenient preparative route to halogeno(methyl)pentafluorophenylsilanes C6F5SiMe2X and C6F5SiMeX2 (X=F, Cl and Br)

Halogeno(methyl)pentafluorophenylsilanes C₆F₅SiMe_nX_3−n (n=1, 2) (X=F, Cl, Br) were prepared in good yields from the corresponding phenylsilanes C₆F₅SiMe_nPh_3−n by reactions with the electrophiles aHF, HCl–AlCl₃, Br₂–AlBr₃ or AlX₃ (X=Cl, Br) halogenated hydrocarbons. Additionally, reactions of C₆F₅SiMe₃ and (C₆F₅)₂SiMe₂ with selected electrophiles were studied.     

Dehalogenative aromatization of perchlorofluoroalicyclic compounds C6Cl6F6, C10Cl8F8 and C5Cl4F5N in the vapour phase or in solution

Dehalogenation of perhalogenated cyclohexanes C₆Cl₆F₆, 1-azacyclohexenes C₅Cl₄F₅N and bicyclo[4.4.0]dec-1(6)-enes C₁₀Cl₈F₈ in the vapour phase over iron filings at 350-500 °C and in solution with Zn and additivities (Cu, NiCl₂·6H₂O + bpy) at 80 °C (heterogeneous reaction) or with P(NEt₂)₃ at 20 °C (homogeneous reaction) was studied. In all cases, perfluoroarenes, chloroperfluoroarenes and dichloroperfluoroarenes (benzenes, naphthalenes and pyridines) were obtained in good overall yield.     

Reactions of pentafluorophenylxenon(II) hexafluoroarsenate [C6F5Ze] [AsF6] with halide anions in acetonitrile

Reactions of [C₆F₅Xe]⁺ [AsF₆]⁻ in acetonitrile with halide anions X⁻ show different results depending on X. If X = I, Br or Cl, then C₆F₅X is obtained. If X = F, then C₆F₅H and C₆F₅---C₆F₅ are produced, and if X = HF₂, then C₆F₆, C₆F₅H and C₆F₅---C₆F₅ are formed.     

Study of selective dissociation in C6F5H?C6F5D mixtures induced by intense CO2 laser pulses

Irradiation of a C₆F₅H–C₆F₅D mixture at 1 Torr by a tunable CO₂ pulse laser brings about chiefly dissociation of one component depending on the frequency of emission absorbed by the proper molecules. The addition of radical acceptors increases the selectivity by suppressing secondary reactions.

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C₆F₅H C₆F₅D 1 CO₂-, , . .

     

Influence of secondary chemical reactions on the selectivity of the multiphoton dissociation process in C6F5H?C6F5D mixtures

Radical acceptors significantly increasing the dissociation selectivity in C₆F₅H–C₆F₅D mixtures have been selected by studying the mechanism of C₆F₅H dissociation in the field of a pulsed CO₂-laser. The contribution of secondary chemical reactions to the total rate of consumption of the initial molecules has been determined.

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C₆F₅H CO₂- , C₆F₅H C₆F₅D. .

     

Syntesis and Crystal Structure of Cs2Nb6Br5F12: A Nb6 Cluster Compound with a One-Dimensional Nb6Br5F7F6 Unit Connection

The synthesis and the crystal structure of Cs₂Nb₆Br₅F₁₂ containing octahedral niobium clusters are presented in this work. This bromofluoride is based on a Nb₆Lⁱ₁₂F^a₆ (L=Br and F) unit and crystallizes in the orthorhombic system (space group, Cccm; Z=4; a=9.2446(2) Å, b=13.6256(3) Å, and c=17.1665(4) Å; R=0.0241). Fluorine and bromine are randomly distributed on the inner ligand positions, Lⁱ, that edge-bridge the Nb₆ cluster whereas fluorine fully occupies the apical positions (L^a). The units are linked to each other by apical ligands leading to an original one-dimensional unit connection. The cesium atoms are statistically distributed on several sites that describe parallel channels along the [1 0 0] direction. The influence of fluorine ligands upon the stabilization of this structure type as well as the structural relationships with Ba₂Zr₆Cl₁₇(B), Nb₆F₁₅, and NaMo₆Cl₁₃ will be evidenced and discussed.     

Tieftemperatur-flüssigphase-fluorierung von (C6F5)2Te: Bildung von (C6F5)2TeF2, (C6F5)2TeF4 und (C6F11)2TeF4 [1]

(C₆F₅)₂Te reacts with elemental fluorine step by step to form the tellurium fluorides (C₆F₅)₂TeF₂, (C₆F₅)₂TeF₄ and (C₆F₁₁)₂TeF₄, which can be isolated in pure states. The intermediates (C₆F_11?2n)₂TeF₄ (n = 1,2) are detected spectroscopically. (C₆F₅)₂TeF₂ is also formed from the reaction of (C₆F₅)₂Te with XeF₂. The preparations, properties and ¹⁹F n.m.r. spectra of these new compounds are discussed, the mass and vibrational spectra are described.     

X-ray crystal structures and solution dynamics of sodium organofluorotitanates [Na{Ti2(C5Me5)2F7}] and [NaTi6(C5Me5)5F20(H2O)]·(THF)

[Na{Ti₂(C₅Me₅)₂F₇}] (1) was prepared from sodium fluoride and [{Ti(C₅Me₅)F₃}₂] [H.W. Roesky, et al., Angew. Chem. Int. Ed. Engl. 31 (1992) 864-866]. The solid-state 1 consists of a polymeric chain of two rows of dititanate anions [Ti₂(C₅Me₅)₂F₇]⁻ connected by sodium ions in the middle of the chain. Each sodium ion is coordinated by five fluorine atoms from three [Ti₂(C₅Me₅)₂F₇]⁻ anions. The variable-temperature ¹⁹F NMR of CD₃CN solution of 1 revealed interconversions of monomeric species [Na(CD₃CN)_n{Ti₂(C₅Me₅)₂F₇}] (1solv) with different number of CD₃CN ligands on the sodium ion. The addition of HMPA to the CD₃CN solution of 1 allows ¹⁹F NMR observation of 1·HMPA (1a) and 1·HMPA·CD₃CN (1b) in the slow exchange. The solid-state structure of [NaTi₆(C₅Me₅)₅F₂₀(H₂O)]·(THF) (2·THF) reveals the sodium ion coordinated by four fluorine atoms from the anion [Ti₂(C₅Me₅)₂F₇]⁻ and by three fluorine atoms from the cluster [Ti₄(C₅Me₅)₃F₁₃(H₂O)].     

C60F14OFPh3, a fluoroxy derivative of C60F15Ph3; evidence for the presence of ‘missing’ fluorine through restricted rotation of a phenyl group

From the reaction of C₆₀F₁₈ with benzene in the presence of SbCl₅ we have isolated a compound of 1252 amu indicated to be C₆₀F₁₄OFPh₃, a fluoroxyfullerene. Temperature-variable ¹H NMR shows that one phenyl group suffers restricted rotation on cooling to 218 K, attributed to the presence of the OF group which, as in the case of the recently characterised C₆₀F₁₇OF, fails to give a signal for this group in the ¹⁹F NMR. We have isolated also, C₆₀F₁₄O₂FPh₃ (1268 amu) a mixture of oxahomo derivatives of C₆₀F₁₄OFPh₃ arising from oxygen insertion into FCCF bonds. Theoretical calculations for C₆₀F₁₄OFPh₃ indicate that the phenyl group nearest to the OF group is twisted out of the plane containing the other two.     

Perfluororganozink-verbindungen: darstellung und eigenschaften von (Rf)2Zn-komplexen (Rf = CF3, C2F5, C3F7, C6F5) [1]

A new method for the preparation of bis(perfluoroorgano) zinc compounds is described: CF₃I and C₆F₅I react with dialkylzinc in the presence of a Lewis base quantitatively to give (CF₃)₂Zn and (C₆F₅)₂Zn complexes, while the analogous reactions with C₂F₅I and iC₃F₇I do not yield the pure compounds. ¹H, ¹⁹F n.m.r, i.r. and Raman spectra are presented.     

NMR evidence for B(C6F5)3 attack on the inward position of a highly hindered meso ansa-zirconocene

The reaction of the ansa-zirconocene meso-[C₂H₄(4,7-Me₂Indenyl)₂]ZrMe₂ with B(C₆F₅)₃ afforded, besides the expected ion pair with outward anion, also a minor isomer (molar fraction 0.043) with the bulky methylborate anion in the inward site. 2D ¹H EXSY experiments revealed exchange between the two isomers, at T > 320 K, through the migration of the anion between outward and inward sites. The presence of free B(C₆F₅)₃ fastened the exchange, suggesting B(C₆F₅)₃ attack on the zirconium bound methyl ligand of the two ion pairs.     

The Reaction of 2‐X‐1, 2‐Difluoroalk‐1‐enyldifluoroboranes with Xenon Difluoride. A Methodical Approach to 1, 2‐Difluoroalk‐1‐enylxenon(II) Salts

2‐X‐1, 2‐Difluoroalk‐1‐enylxenon(II) salts were prepared by the reaction of XeF₂ with XCF=CFBF₂ (X = F, trans‐H, cis‐Cl, trans‐Cl, cis‐CF₃, cis‐C₂F₅) but no organoxenon(II) compounds were obtained when the trans‐isomers of boranes, trans‐XCF=CFBF₂ (X = CF₃, C₄F₉, C₄H₉, Et₃Si), were used under similar conditions.     

Preparation of 1‐X‐2, 2‐Difluoroethenylxenon(II) Tetrafluoroborates [CF2=CXXe][BF4]

The new type of alkenylxenon(II) salts [CF₂=CXXe] [BF₄] (X = H, Cl, CF₃) was prepared by reacting the corresponding alkenyldifluoroboranes CF₂=CXBF₂ with XeF₂ in 1, 1, 1, 3, 3‐pentafluoropropane (PFP) at —60 °C. The alkenylxenon(II) salts were characterised by multinuclear NMR spectroscopy. The influence of the substituent X at C‐1 on the stability of alkenylxenon(II) salts is discussed. Additionally the preparation of the potassium alkenyltrifluoroborate salts K [CF₂=CXBF₃] and their transformation into the boranes CF₂=CXBF₂ by fluoride abstraction in PFP is reported.