Perfluoralkyljod-verbindungen: das trifluormethyljod-bis-trifluoracetat CF3J(OCOCF3)2

CF₃I(OCOCF₃)₂ is formed from the reactions of CF₃IF₂ or CF₃IO with trifluoroacetic anhydride at low temperature. During the reaction of CF₃IF₂ with (CF₃CO)₂O CF₃IF(OCOCF₃) is formed as an intermediate product. The preparation, the ¹⁹F-nmr spectra and the thermal decomposition are described.     

Perfluoralkyljod-verbindungen: Darstellungen und eigenschaften von CF3JO,CF3JOF2 und CF3JO2

Perfluoroalkyl iodine compounds: preparations and properties of CF₃IO, CF₃IOF₂, and CF₃IO₂. The trifluoromethyl iodine compounds CF₃IO, CF₃IOF₂, and CF₃IO₂ are formed from the reactions of CF₃I, CF₃IF₂ or CF₃IF₄ with ozone or silicon dioxide respectively. Their preparartions, properties, ¹⁹F-nmr spectra, and ir spectra are described.     

Vergleich der trifluormethylierungseigenschaften von(CF3)Hg,CF3I und (CF3)2te am beispiel der reaktionen mit cyclohexen,benzol und pyridin

The trifluoromethylation reactions of (CF₃)₂Hg, CF₃I and (CF₃)₂Te with cyclohexene, benzene and pyridine are compared under similar conditions. Photochemical as well as thermal reactions result in an increase of the reactivity in the series (CF₃)₂Hg < CF₃I ? (CF₃)2Te. The yields and the kind of products vary depending on the time of irradiation and the temperature. In all cases the best yields are obtained from the thermal reactions with (CF₃)₂Te. With cyclohexene only trifluoromethylated addition products are observed. The substitution reactions with pyridine yield a mixture of isomeric trifluoromethylpyridines. (CF₃)₂Hg and CF₃I react with benzene to yield only benzotrifluoride C₆H₅CF₃. The main product of the reaction of (CF₃)2Te with benzene is also benzotrifluoride; in addition to this the disubstituted bis(trifluoromethyl)benzene isomers and trifluoromethyl- cyclohexadienes are formed. ¹H, ¹⁹F n.m.r. and mass spectra are described.     

Explored routes to unknown polyfluoroorganyliodine hexafluorides, RFIF6

Two routes to R_FIF₆ compounds were investigated: (a) the substitution of F by R_F in IF₇ and (b) the fluorine addition to iodine in R_FIF₄ precursors. For route (a) the reagents C₆F₅SiMe₃, C₆F₅SiF₃, [NMe₄][C₆F₅SiF₄], C₆F₅BF₂, and 1,4-C₆F₄(BF₂)₂ were tested. C₆F₅IF₄ and CF₃CH₂IF₄ were used in route (b) and treated with the fluoro-oxidizers IF₇, [O₂][SbF₆]/KF, and K₂[NiF₆]/KF. The observed sidestep reactions in case of routes (a) and (b) are discussed. Interaction of C₆F₅SiX₃ (X = Me, F), C₆F₅BF₂, 1,4-C₆F₄(BF₂)₂ with IF₇ gave exclusively the corresponding ring fluorination products, perfluorinated cyclohexadiene and cyclohexene derivatives, whereas [NMe₄][C₆F₅SiF₄] and IF₇ formed mixtures of C₆F_nIF₄ and C₆F_nH compounds (n = 7 and 9). CF₃CH₂IF₄ was not reactive towards the fluoro-oxidizer IF₇, whereas C₆F₅IF₄ formed C₆F_nIF₄ compounds (n = 7 and 9). C₆F₅IF₄ and CF₃CH₂IF₄ were inert towards [O₂][SbF₆] in anhydrous HF. CF₃CH₂IF₄ underwent C-H fluorination and C-I bond cleavage when treated with K₂[NiF₆]/KF in HF. The fluorine addition property of IF₇ was independently demonstrated in case of perfluorohexenes. C₄F₉CFCF₂ and IF₇ underwent oxidative fluorine addition at −30 °C, and the isomers (CF₃)₂CFCFCFCF₃ (cis and trans) formed very slowly perfluoroisohexanes even at 25 °C. The compatibility of IF₇ and selected organic solvents was investigated. The polyfluoroalkanes CF₃CH₂CHF₂ (PFP), CF₃CH₂CF₂CH₃ (PFB), and C₄F₉Br are inert towards iodine heptafluoride at 25 °C while CF₃CH₂Br was slowly converted to CF₃CH₂F. Especially PFP and PFB are new suitable organic solvents for IF₇.     

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.     

Reactions of the (CF3)2NO radical with strong oxidizers

The reactions of (CF₃)₂NO with PtF₆, MoF₆, ReF₆, O⁺₂SbF^?₆ and O⁺₂AsF^?₆ have been studied. The reaction of (CF₃)₂NO with O⁺₂SbF^?₆ presents a new method of producing CF₃ radicals chemically at low temperature. This was demonstrated by a new and high yield synthesis of (CF₃)₂NOCF₃. In addition, the novel compound [(CF₃)₂NO]₂CF₂ has been isolated as a by-product from this reaction and was characterized.     

Substitution reactions of IF5

Using silyl protected organic hydroxo compounds substitution of fluorine in IF₅ is successful.Reacting IF₅ with Si(OCH₃)₄ in CH₃CN or SO₂ using different molar ratios it was shown that in the series IF_5?n(OCH₃)_n only the first member IF₄(OCH₃) (n=1) is stable enough to be isolated. The product in solution with n=2 bismutates to products with n=1 and n=3 if isolated as solids. The last one decomposes to the new oxo compound IF₂O(OCH₃) under elimination of CH₃OCH₃. With n=4,5 only redox reaction products could be isolated.IF₂O(OCH₃) can also be obtained by treating IF₄(OCH₃) with (CH₃)₆Si₂O. Similarly reaction of IF₅ with the disiloxane represents a new method to win IOF₃. Excess of the oxygen transfer reagent leads to formation of IO₂F and I₂O₅. An other oxo compound, IO(CH₃COO)₃, can be prepared by disolving IF₅, IOF₃ or IO₂F in acetic acid anhydride.Reactions of IF₅ with trimethylsilyl protected fluorinated benzoic acids R_fCOOSi(CH₃)₃ (R_f = C₆F₅, 4HC₆F₄) appeared to be independent of the educts molar ratios because the only products are IF(R_fCOO)₄.In order to stabilize iodine (V) derivates with bifunctional chelating oxo ligands we applicated bis(trimethylsilyl) pinacolate, and in smooth reactions we yielded IF₃[OC(CH₃)₂C(CH₃)₂O] and IF[OC(CH₃)₂  C(CH₃)₂O]₂, in which iodine is part of five membered heterocyclic rings. The ¹⁹F-nmr-spectra are consistent with the diolate occupying the axiale and equatorial positions.An extension of the silyl method is the new synthesis of C₆F₅IF₄ which could be obtained in the smooth reaction of IF₅ with stochiometric amounts of Si(C₆F₅)₄.     

Die NMR-Spektren von CF3I,CF3IF2 und CF3IF4

The NMR Spectra of CF₃I, CF₃IF₂, and CF₃IF₄ The ¹⁹F-NMR and ¹³C-NMR spectra of CF₃I, CF₃IF₂ and CF₃IF₄ were recorded in acetonitrile solution. The chemical shifts of the CF₃-groups are strongly dependent on the oxidation state of the iodine atom. With increasing oxidation state the resonances of the CF₃-groups in the ¹⁹F-NMR spectra are characteristically shifted to high field, whereas in the ¹³C-NMR spectra a characteristic shift to low field is measured. The absolute value of the coupling constants ¹J(¹⁹F? ¹³C) increases with increasing oxidation state from 344 Hz (CF₃I) via 354 Hz (CF₃IF₂) to 359 Hz (CF₃IF₄).     

TEA CO2 laser-induced reaction of CH3NO2 with CF2HCl: A mechanistic study

Dissociation of nitromethane has been observed when a mixture of CF₂HCl and CH₃NO₂ is irradiated using pulsed TEA CO₂ laser at 9R (24) line (1081 cm^-1), which is strongly absorbed by CF₂HCl but not by CH₃NO₂. Under low laser fluence conditions, only nitromethane dissociates, whereas at high fluence CF₂HCl also undergoes dissociation, showing that dissociation occurs via the vibrational energy transfer processes from the TEA CO₂ laser-excited CF₂HCl to CH₃NO₂. Time-resolved infrared fluorescence from vibrationally excited CF₂HCl and CH₃NO₂ molecules as well as UV absorption of CF₂ radicals are carried out to elucidate the dynamics of excitation/dissociation and the chemical reactions of the dissociation products.     

Synthesis and properties of pentamethylmetallocene derivatives Cp*MCp (M = Ru, Fe). Crystal structure of the salt [CpRuC5Me4CH2+OC6H2(NO2)3-]

Photolysis of a solution of Cp*RuCp (1) in CF₃CO₂H generates salt [CpRu(C₅Me₄CH₂)]-(O₂CCF₃)(2 • O₂CCF₃). The reaction of compound 1 with oleum at 20 °C through the intermediate dication [η⁵-(CH₂C₅Me₄)Ru(μ:η⁵,ν⁵-C₅H₄C₅H₅)Ru(C₅Me₄CH₂)-η⁶]²⁺ leads to the triply charged cation η⁷CH₂)₂C₅Me₃Ru(μη⁵,η⁵-C₅H₄C₅H₄)Ru(C₅Me₄CH₂)-η⁶]³⁺. Synthesis of pentamethylmetallocene derivatives CpMC₅Me₄X (M = Ru, Fe; X = CHO, CH₂OH, CH₂An) has been accomplished. The reactions of 1-hydroxymethyl-2,3,4,5-tetramethylruthenocene with acids CF₃CO₂H, HBF₄, CF₃CO₂H/NaB[C₆H₃(CF₃)₂]₄, and picric acid C₆H₂(NO₂)₃OH afforded salts 2•X (X = CF₃CO₂, BF₄, B[C₆H₃(CF₃)₂]₄), and (2,3,4,5-tetram ethylruthenocenyl)methyl picrate [CpRu(C₅Me₄CH₂)-η⁶][(C₆H₂(NO₂)₃O] (2•C₆H₂(NO₂)₃O). Structure of the latter was characterized by single crystal X-ray diffraction.     

AB initio molecular orbital studies of CF3O2H,CF3O2F and CF2(OF)2

Ab initio calculations employing an extended 4-31G basis set have been applied to the highly fluorinated molecules, CF₃O₂H, CF₃O₂F and CF₂(OF)₂. Partial geometry optimizations have also been carried out on these molecules allowing a comparison between theory and the recently completed gas-phase electron diffraction results. The O-O bond distance in CF₃O₂ H is found to be longer (by 0.02 Å) than the corresponding bond in CF₃O₂F while the CO bond is found to be shorter (by 0.02 Å) in CF₃O₂H. The OF bond in CF₃O₂F is found to be longer (by 0.03–0.04 Å) than the corresponding bond in CF₃OF or F₂O. Torsional barriers have been computed for CF₃O₂H and CF₃O₂F with the aid of Fourier analysis of the potential curves. CF₃O₂H is found to have a torsional potential about the peroxide bond rather similar to that found for H₂O₂ while in CF₃O₂F the cis and trans barriers are predicted to be much larger (14.6 and 8.4 kcal mol^?1, respectively). The threefold barrier to rotation of the CF₃ group in CF₃O₂F is predicted to be 4.4 kcal mol^?1. Various conformations of CF₂(OF)₂ have also been studied with conformations consistent with the operation of the gauche-effect being most stable. Bond separation energies and molecular properties have also been computed for these molecules.     

Trifluoromethylsilane,CF3SiH3

CF₃SiH₃ (I) has been obtained in ～90 % yield from the reaction of CF₃SiF₃ or CF₃SiF₂I with LiAlH₄ in dibutyl ether at ?78°. (I) has been characterized by its ¹H, ¹⁹F, ¹³C and ²⁹Si NMR-, mass-, IR- and Raman spectra. It is thermally stable up to 180° and not attacked by O₂, H₂O and H₃PO₄, but cleaved by aqueous alkali. From a rovibrational analysis, B_o = 0.09769(2) cm^?1 is deduced, and a long SiC bond, 1.95(1)Å, is predicted.     

Fragmentation of μ4-oxohexa-μ-nitratotetraberyllium, Be4O(NO)3)6, under electron impact

The behaviour of Be₄O(NO₃)₆ under electron impact is similar to that of its carboxylato analogues, Be₄O(RCO₂)₆ where R is H, alkyl or halogenated alkyl. In all these systems, the dissociation of the molecular ions is dominated by steric interactions. The major fragmentations involve the elimination of N₂O₅ or (RCO)₂O and Be(NO₃)₂ or Be(RCO₂)₂ from the ions [M-NO₃]⁺ or [M-RCO₂]⁺. The results obtained confirm the structural similarity of the nitrato complex to tetra-nuclear beryllium oxocarboxylates.     

Novel ammonium hexafluoroarsenate salts from reaction of (CF3)2NH,CF3N(OCF3)H,CF3N[OCF(CF3)2]H,CF3NHF and SF5NHF with the strong acid HF/ASF5.

Reactions of the fluorinated amines (CF₃)₂NH, CF₃N(OCF₃)H, CF₃N[OCF(CF₃)₂]H, CF₃NHF and SF₅NHF with the strong acid HF/AsF₅ form the corresponding ammonium salts R_f¹R_f²NH₂⁺AsF₆^? and R_fNFH₂⁺ AsF₆^? in high yield. [R_f¹=CF₃, R_f²=CF₃, CF₃O, (CF₃)₂CFO; R_f=CF₃, SF₅] The colorless crystalline solids are stable for prolonged periods at 22°C in sealed FEP containers. They have dissociation pressures at 22°C ranging from ～5 torr (R_fNFH₂⁺ AsF₆^?) to ～50 torr [CF₃N(OCF₃)H₂⁺AsF₆^?]. ¹⁹F NMR and Raman spectroscopy were used to identify the compounds.     

C(CF3)2OH → OCH(CF3)2 Isomerism in some sulfur and phosphorus compounds

The insertion of (CF₃)₂CO into the PH bond of Me_nH_3?nP yields Me_nH_2?nPC(CF₃)₂OH and Me_nH_1?nP[C(CF₃)₂OH]₂ (n=O, 1), respectively [1]. MeP[C(CF₃)₂OH]₂ rearranges giving the diphosphine [MePOCH(CF₃)₂]₂ and the phosphorane MeP[OCH(CF₃)₂]₄. Me₂PH reacts with (CF₃)₂CO forming several products, e.g. MePF[OCH(CF₃)₂]₂ and Me₂PPMe₂ [1]. The phosphines tBu(R)PH(R=Me, tBu), however, add (CF₃)₂CO giving rise to the phosphinites tBu(R)POCH(CF₃)₂, which furnish stable phosphonium salts upon treating with MeI. (CF₃)₂CO inserts into the SH bond of RSH to yield RSC(CF₃)₂OH (R=H,Me,Ph), which were reacted with MeI, too. Reacting SCl₂ with LiOCH(CF₃)₂ gives S[OCH(CF₃)₂]₂ which is oxidised by chlorine to the sulfurane ClS[OCH(CF₃)₂]₃ [2]. The sulfurane is able to transfer (CF₃)₂CHO groups to phosphorus (III) compounds, e.g. P[OCH(CF₃)₂]₃ and Me₃P yielding P[OCH(CF₃)₂]₅ and [Me₃POCH(CF₃)₂]⁺Cl^?. ClS[OCH(CF₃)₂]₃ gives a stable salt upon reaction with SbCl₅, like ClP[OCH(CF₃)₂]₄. The mechanisms for these reactions are discussed.     

Untersuchungen zum reaktiven verhalten von (CF3)2PPH2 und (CF3)2AsPH2

Cleavage of the E-P bond in compounds of the type (CF₃)₂EPh₂(E = P, As) is achieved by polar [HBr, (CF₃)₂EI, (CH₃)₃SnH, (CF₃)₂AsH] and non-polar [Br₂, Mn₂(CO)₁₀] substances. Exchange reactions are possible with (CF₃₄)E₂ and P₂F₄ leading to the unsymmetrical compounds (CF₃)₂PPF₂, (CF₃)₂AsPF₂, (CF₃)₂PAs(CF₃)₂, F₂PPH₂, (CF₃)₂AsPH₂. The reaction of (CF₃)₂PPH₂ with Mn₂(CO)₁₀ gives the new binuclear complex Mn₂(CO)₈PH₂P(CF₃)₂ and Mn₂(CO)₈[P(CF₃)₂]₂. The hitherto unknown compound (CF₃)₂AsPF₂ is obtained by the reaction of (CF₃)₂AsPH₂ with P₂F₄. Adducts of (CF₃)₂PPH₂ with B₂H₆ and (CH₃)₃N, respectively, are discussed. Investigation of the reaction route and characterization of most of the reaction product is based on ¹H and ¹⁹F NMR spectral data.     

The rate coefficients for the thermal decomposition of CCl3O2NO2

The thermal decomposition of CCl₃O₂NO₂ has been reevaluated based on new rate data for the reaction of Cl + NO₂. The revised rate coefficient for CCl₃O₂NO₂ thermal decay at about 1 atm total pressure (mainly N₂) is 1.42 × 10¹⁶ × exp(?11500/T) s^?1 from 268–298 K.     

Darstellung von Trifluormethylhalogen-Iodaten(I) des Typs (CH3)4N+CF3IX− (X = F,Cl, Br) und Trifluormethyltrifluormethoxyiodat(I) (CH3)4N+CF3IOCF3−

Preparation of Trifluormethylhalogen Iodate(I) Salts (CH₃)₄N⁺CF₃IX^? (X = F, Cl, Br) and Trifluormethyltrifluormethoxy Iodate(I) (CH₃)₄N⁺CF₃IOCF₃^? We describe the preparation of new trifluormethyliodate(I) salts CF₃IX^? (X = F, Cl, Br, OCF₃). (CH₃)₄N⁺CF₃ICl^? and (CH₃)₄N⁺CF₃IBr^? are obtained via addition of CF₃I with the corresponded tetramethylammonium halogenide. (CH₃)₄N⁺CF₃IOCF₃^? is synthesized by comproportionation of (CH₃)₄N⁺CF₃ICl^? with CF₃OCl under formation of Cl₂ at ?78°C. (CH₃)₄N⁺CF₃IF^? is formed either, through thermolysis of (CH₃)₄N⁺ CF₃IOCF₃^? under separation of COF₂, or reaction of CF₃I with (CH₃)₄N⁺ OCF₃^?. The thermolabile compounds have been characterized by i.r., Raman, ¹⁹F-, ¹³C NMR spectroscopy.     

Three-coordinate RhX[P(C6H11)3]2, their reactions with N2 and O2, and the trans-influence in RhX[P(C6H11)3]2L (X = anionic,L = neutral ligand)

Three-coordinate RhX(PCy₃)₂ complexes (X = F, Cl, Br, I; Cy = cyclohexyl) have been prepared from rhodium(I) cyclooctene compounds. RhCl(PCy₃)₂ is in equilibrium with its dimer. The complexes RhX(PCy₃)₂ (X = Cl, Br, I) form the adducts RhX(PCy₃)₂(N₂) with dinitrogen, the times for N₂-fixation being 4 days, 3 hours and 15 minutes respectively. The three-coordinate complexes form four-coordinate dioxygen adducts RhX(PCy₃)₂(O₂) which have unusually high ν(OO) at about 990 cm^?1. This high frequency is attributed to the four-coordination, which is exceptional for dioxygen complexes. From RhF(PCy₃)₂ carbonyl, ethene, and diphenylacetylene complexes RhX(PCy₃)₂L (X = F, Cl, Br, I, N₃, NCO, NCS; L = CO, C₂H₄, C₂Ph₂) (X = CN, NO₃, acetate; L = CO) have been prepared. The trans-influence of the anionic ligands on the infrared frequencies of the neutral ligands is discussed in terms of the different π-bonding properties of the X- and L-ligands.     

Cover Feature: Effects of Microhydration on the Mechanisms of Hydrolysis and Cl− Substitution in Reactions of N2O5 and Seawater (ChemPhysChem 5/2023)

The reaction of N₂O₅ at atmospheric interfaces has recently received considerable attention due to its importance in atmospheric chemistry. N₂O₅ reacts preferentially with Cl⁻ to form ClNO₂/NO₃⁻ (Cl⁻ substitution), but can also react with H₂O to form 2HNO₃ (hydrolysis). In this paper, we explore these competing reactions in a theoretical study of the clusters N₂O₅/Cl⁻/nH₂O (n=2–5), resulting in the identification of three reaction motifs. First, we uncovered an S_N2-type Cl⁻ substitution reaction of N₂O₅ that occurs very quickly due to low barriers to reaction. Second, we found a low-lying pathway to hydrolysis via a ClNO₂ intermediate (two-step hydrolysis). Finally, we found a direct hydrolysis pathway where H₂O attacks N₂O₅ (one-step hydrolysis). We find that Cl⁻ substitution is the fastest reaction in every cluster. Between one-step and two-step hydrolysis, we find that one-step hydrolysis barriers are lower, making two-step hydrolysis (via ClNO₂ intermediate) likely only when concentrations of Cl⁻ are high.