CF3 SO3 Research Articles

Synthesis of polyfluorinated 4-phenyl-3,4-dihydroquinolin-2-ones and quinolin-2-ones via superacidic activation of N-(polyfluorophenyl)cinnamamides

The cyclization reactions of a series of polyfluorocinnamanilides in triflic acid (CF 3SO 3H) yield 4-phenyl-3,4-dihydroquinolin-2-ones, which include a polyfluorinated benzene moiety as a part of the quinoline scaffold. These compounds undergo dehydrophenylation in the presence of AlCl 3 to give the corresponding polyfluoroquinolin-2-ones which are converted into polyfluorinated 2-chloroquinolines on treatment with POCl 3. A mechanism for the cyclization reaction presuming the intermediacy of a superelectrophilic O,C-diprotonated form of the starting material is suggested.

Mg 2+-doped poly(ɛ-caprolactone)/siloxane biohybrids

Ionically conducting materials based on a poly(ɛ-caprolactone) (PCL)/siloxane organic/inorganic host framework doped with magnesium triflate (Mg(CF 3SO 3) 2) were synthesized by the sol–gel process. In this matrix short PCL chains are covalently bonded to the siliceous network via urethane linkages. In this study the salt content of samples was identified using the conventional notation n, where n indicates the number of (C( O)(CH 2) 5O) PCL repeat units per Mg 2+ ion. Xerogels with compositions ranging from n = ∞ to 1 were prepared. The only composition studied that was not entirely amorphous was that prepared with n = 1. Xerogels with n ≥ 7 are thermally stable up to at least 200 °C. The composition with the highest conductivity of the series is that with n = 34 (5.9 × 10 −9 and 9.8 × 10 −7 S cm −1 at 24 and 104 °C, respectively).

CH…O hydrogen bond in the crystal structure of a pyrazine-based ligand and determination of the amplitude of the ligand conformational change induced by Cu(II) coordination

The crystallographic structural features of the ditopic ligand pyrazine-2,5-dicarbaldehyde-bis(propionyl-N-methylhydrazone) 1, as well as their comparison with related ligands are herein reported. CH…O short contacts (2.46 and 2.55 Å) supporting network formation were observed. The amplitude of the conformational switch induced by the formation of the dinuclear rack-like complex [Cu 2 1(terpy) 2](CF 3SO 3) 4 of ligand 1 (synthesized by reaction of 2,5-pyrazine-dicarboxaldehyde with two equivalents of N-methyl-propionohydrazide), has been determined on the basis of the X-ray structures and it was found to be of 3 Å. Moreover, the correlation between the structural data and the data obtained by 2D NMR spectroscopy, is confirmed by the mean of the structural analysis herein discussed that concerns the protons involved in the NOE effects observed by NOESY spectroscopy.

Oxidation of activated methylene groups to ketones catalyzed by new iron phosphinooxazoline complexes and by iron(II) triflate

The study describes the first catalytic application of iron phosphinooxazoline complexes and Fe(OTf) 2 in oxidation reactions. New iron phosphinooxazoline (PHOX) complexes of the general formulation [Fe(PHOX) 2] 2+[OTf] 2 ( 3, OTf = CF 3SO 3 −) were synthesized in virtually quantitative yield from anhydrous Fe(OTf) 2 and the corresponding PHOX ligands. The new complexes 3 as well as previously synthesized iron PHOX complexes of the general formula [Fe(Cp)(CO)(PHOX)] +[I] − ( 2) were employed as catalysts in the oxidation of benzylic CH 2 groups to the corresponding ketones. Whereas 3 showed catalytic activity at room temperature (about two equivalents t-BuOOH as the oxidant, 2 mol% catalyst, pyridine solvent, 12 h, 38–93% isolated yields), complexes of 2 were only active at elevated temperatures. The product profile is in accordance with a mechanism previously described as “oxygenated Fenton chemistry”, which is further corroborated by UV–vis investigations. They showed that an iron alkylperoxo species [Fe–OO tBu] might be involved in the catalytic cycle. The reaction follows a pseudo zero order rate law in substrate.

Secondary ligand–metal interactions in rhodium(III) and iridium(III) phosphoramidite complexes

The synthesis, characterization, and application in asymmetric catalytic cyclopropanation of Rh(III) and Ir(III) complexes containing ( S a,R C,R C )-O,O′-[1,1′-binaphthyl-2,2′-diyl]-N,N′-bis[1-phenyl-ethyl]phosphoramidite ( 1) are reported. The X-ray structures of the half-sandwich complexes [MCl 2(C 5Me 5)( 1,κ P)] (M = Rh, 2a; M = Ir, 2b) show that the metal–phosphoramidite bond is significantly shorter in the Ir(III) analog. Chloride abstraction from 2a (with CF 3SO 3SiMe 3 or with CF 3SO 3Me) and from 2b (with AgSbF 6) gives the cationic species [MCl(C 5Me 5)(1,2-η- 1,κ P)] + (M = Rh, 3a; M = Ir, 3b), which display a secondary interaction between the metal and a dangling phenethyl group (NCH(CH 3)Ph) of the phosphoramidite ligand, as indicated by NMR spectroscopic studies. Complexes 3a and 3b slowly decompose in solution. In the case of 3b, the binuclear species [Ir 2Cl 3(C 5Me 5) 2] + is slowly formed, as indicated by an X-ray study. Preliminary catalytic tests showed that 3a cyclopropanates styrene with moderate yield (35%) and diastereoselectivity (70:30 trans: cis ratio) and with 32% ee (for the trans isomer).

Preparation, characterization and crystal structures of three salts of the quaterpyridine ligand

As a result of a reaction between 6,6′′′-dimethyl-2,2′:6′,2′′:6′′,2′′′-quaterpyridine C 22H 18N 4 and lanthanide(III) salts, compounds, [C 22H 20N 4] 2+·2(CF 3SO 3) − ( 1) and [C 22H 20N 4] 2+·2(ClO 4) − ( 2), have been obtained. They were characterized by spectroscopic techniques (ESI-MS, NMR, IR), elemental analysis, and their formulae were confirmed on the basis of X-ray crystallography. It turned out that the perchlorate crystallizes as two solvates: with acetonitrile and disordered water molecules. These are the first structural characterization of a 6,6′″-dimethyl-2,2′:6′,2″:6″,2′″-quaterpyridinium dication. Due to the intramolecular hydrogen bond it adopts the previously unobserved cis/trans/cis conformation. In all three crystals the dications have C i symmetry, they occupy the special positions in their respective space groups. In the crystal structures the π–π stacking and weak hydrogen bonds add directionality to the dominating electrostatic interactions between cations and anions.

Syntheses and structural analyses of chiral rhenium containing amines of the formula (η 5-C 5H 5)Re(NO)(PPh 3)((CH 2) nNRR′) ( n = 0, 1)

The reaction of the racemic chiral methyl complex (η 5-C 5H 5)Re(NO)(PPh 3)(CH 3) ( 1) with CF 3SO 3H and then NH 2CH 2C 6H 5 gives [(η 5-C 5H 5)Re(NO)(PPh 3)(NH 2CH 2C 6H 5)] + CF 3 SO 3 - ([ 4a-H] + CF 3 SO 3 - ; 73%), and deprotonation with t-BuOK affords the amido complex (η 5-C 5H 5)Re(NO)(PPh 3)(NHCH 2C 6H 5) (76%). Reactions of 1 with Ph 3C + X − and then primary or secondary amines give [(η 5-C 5H 5)Re(NO)(PPh 3)(CH 2NHRR′)] + X − ([ 6-H] + X −; R/R′/X = a, H/NH 2CH 2C 6H 5/BF 4; a′, H/NH 2CH 2C 6H 5/PF 6; b, H/NH 2CH 2(CH 2) 2CH 3/PF 6; c, H/( S)-NH 2CH(CH 3)C 6H 5/BF 4); d, CH 2CH 3/CH 2CH 3/PF 6; e, CH 2(CH 2) 2CH 3/CH 2(CH 2) 2CH 3/PF 6; f, CH 2C 6H 5/CH 2C 6H 5/PF 6; g, -CH 2(CH 2) 2CH 2-/PF 6; h, –CH 2(CH 2) 3CH 2–/PF 6; i, CH 3/CH 2CH 2OH/PF 6 (62–99%). Deprotonations with t-BuOK afford the amines (η 5-C 5H 5)Re(NO)(PPh 3)(CH 2NRR′) ( 6a– i; 99–40%), which are more stable and isolated in analytically pure form when R ≠ H. Enantiopure 1 is used to prepare ( R Re S C)-[ 6c-H] + BF 4 - , ( R Re S C)- 6c, ( S)-[ 6g-H] + PF 6 - , and ( S)- 6g. The crystal structures of [ 4a-H] + CF 3 SO 3 - , a previously prepared NH 2CH 2Si(CH 3) 3 analog, [ 6a′, d, f, h-H] + PF 6 - , ( R Re S C)- 6c, and 6f are determined and analyzed in detail, particularly with respect to cation/anion hydrogen bonding and conformation. In contrast to analogous rhenium containing phosphines, 6a– i show poor activities in reactions that are catalyzed by organic amines.

Electrochemical preparation of graphite intercalation compounds containing a cyclic amide, [CF 2(CF 2SO 2) 2N] −

Graphite intercalation compounds (GICs) containing the cyclo-hexafluoropropane-1,3-bis(sulfonyl)amide anion, [CF 2(CF 2SO 2) 2N] −, are prepared for the first time. Stages 2 and 3 GICs are obtained by electrochemical oxidation of graphite in a nitromethane electrolyte. Gallery heights of 0.85–0.86 nm are determined by powder X-ray diffraction, and the intercalate anion orientation within the intercalate galleries is modeled using an energy minimized anion structure. GIC compositions are determined by thermogravimetric, fluorine and nitrogen analyses. The chemical preparation and bifluoride displacement reactions are compared with a GIC containing the linear bis(trifluoromethanesulfonyl)amide anion, [(CF 3SO 2) 2N] −.

An imidazolidin-1-ol, nitrone and oxadiazinane ring-chain-ring tautomeric dynamic combinatorial library

A dynamic combinatorial library (DCL) based on benzylidene exchange reactions between imidazolidin-1-ol, nitrone and oxadiazinane (INO) ring-chain-ring tautomers at room temperature is created. The probable mechanism of the reaction is discussed based on Hammett type correlation analyses. The equilibria in the DCL are defined as interconversion of INOAr-X to INOAr-Y as a result of reactions with the corresponding aldehydes Y-ArCHO and X-ArCHO and are shown to depend on the σ constants of the substituents and are described by a simple equation log K XY = ρσ dif + log K XY(X = Y). The prediction of K XY for any INOAr-X and INOAr-Y interconversion requires only the experimental values of ρ and the known Hammett σ constants of the substituents. The effect of Zn(II) and CF 3SO 3H on the DCL equilibria is also reported.

Development of biosensors containing laccase and imidazolium bis(trifluoromethylsulfonyl)imide ionic liquid for the determination of rutin

Biosensors based on hydrophobic ionic liquids (ILs) derived from the bis(trifluoromethylsulfonyl)imide [(CF 3SO 2) 2N − = Tf 2N −] anion associated with three different imidazolium cations: 1-butyl-3-methylimidazolium (BMI·Tf 2N), 1-decyl-3-methylimidazolium (DMI·Tf 2N) and 1-tetradecyl-3-methylimidazolium (TDMI·Tf 2N), along with laccase from Aspergillus oryzae, were constructed and optimized for determination of rutin. The laccase catalyzes the oxidation of rutin to the corresponding o-quinone, which is electrochemically reduced back to rutin. The best performance was obtained with 50:20:15:15% (w/w/w/w) as the graphite powder:laccase:Nujol:ILs composition in 0.1 mol L −1 acetate buffer solution (pH 5.0). The parameters for the square-wave voltammetry experiments and scanning electron microscopy images of the biosensors were studied. Under the selected conditions, the cathodic peak current increased linearly in the rutin concentration ranges of 4.77 × 10 −6 to 4.62 × 10 −5 mol L −1, 5.84 × 10 −6 to 5.36 × 10 −5 mol L −1 and 5.84 × 10 −6 to 5.36 × 10 −5 mol L −1 using the (I) BMI·Tf 2N-laccase, (II) DMI·Tf 2N-laccase and (III) TDMI·Tf 2N-laccase, respectively. The rutin contents of commercial samples of pharmaceuticals were successfully determined by the biosensors and the results compared well with those obtained using the official method. The studies on rutin recovery from these samples gave values of 96.9–104.6%.

Copper(II) complexes with 2,5-bis(2-pyridyl)pyrazine and 1,1,3,3-tetracyano-2-ethoxypropenide anion: Syntheses, crystal structures and magnetic properties

The copper(II) complexes of formula [Cu 2(2,5-dpp)(H 2O) 4(CF 3SO 3) 4] · 2H 2O ( 1) and [Cu 2(2,5-dpp)(H 2O) 2(tcnoet) 4] n ( 2) [2,5-dpp = 2,5-bis(2-pyridyl)pyrazine and tcnoet − = 1,1,3,3-tetracyano-2-ethoxypropenide anion] have been prepared and their structures determined by X-ray crystallographic methods. Compound 1 is a dinuclear complex where the 2,5-dpp molecule acts as a bis-bidentate bridge between the two copper centers, the electroneutrality being achieved by four terminally bound triflate anions. Each copper(II) ion presents an elongated octahedral CuN 2O 4 environment with two nitrogen atoms from 2,5-dpp and two water molecules in the basal plane and two triflate-oxygen atoms in the axial positions. Compound 2 is a zigzag chain of copper(II) ions with regular alternating 2,5-dpp and double tcnoet groups as bridges. Each copper(II) ion exhibits an elongated octahedral CuN 5O surrounding with four nitrogen atoms, two from 2,5-dpp, one from a terminally bound tcnoet and the other from a bridging tcnoet occupying the equatorial positions and a water oxygen and a nitrogen from a monodentate tcnoet in the axial sites. The values of the copper–copper separation across 2,5-dpp are 6.763(1) ( 1) and 6.754(1) Å ( 2) whereas that through the double tcnoet bridge is 9.559(1) Å ( 2). The investigation of the magnetic properties of 1 and 2 in the temperature range 1.9–295 K reveal a Curie law behaviour for 1 and a very weak ferromagnetic interaction for 2. The poor ability of the 2,5-dpp ligand to mediate magnetic interactions between the copper(II) ions in the 2,5-dpp-bridged copper(II) complexes contrast with the somewhat better ability of the pyrazine ring in related pyrazine-bridged copper(II) complexes.

Coordination environment of [UO 2Br 4] 2− in ionic liquids and crystal structure of [Bmim] 2[UO 2Br 4

The complex formed by the reaction of the uranyl ion, UO 2 2+, with bromide ions in the ionic liquids 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][Tf 2N]) and methyl-tributylammonium bis(trifluoromethylsulfonyl)imide ([MeBu 3N][Tf 2N]) has been investigated by UV–Vis and U L III-edge EXAFS spectroscopy and compared to the crystal structure of [Bmim] 2[UO 2Br 4]. The solid state reveals a classical tetragonal bipyramid geometry for [UO 2Br 4] 2− with hydrogen bonds between the Bmim + and the coordinated bromides. The UV–Vis spectroscopy reveals the quantitative formation of [UO 2Br 4] 2− when a stoichiometric amount of bromide ions is added to UO 2(CF 3SO 3) 2 in both Tf 2N-based ionic liquids. The absorption spectrum also suggests a D 4h symmetry for [UO 2Br 4] 2− in ionic liquids, as previously observed for the [UO 2Cl 4] 2− congener. EXAFS analysis supports this conclusion and demonstrates that the [UO 2Br 4] 2− coordination polyhedron is maintained in the ionic liquids without any coordinating solvent or water molecules. The mean U–O and U–Br distances in the solutions, determined by EXAFS, are, respectively, 1.766(2) and 2.821(2) Å in [Bmim][Tf 2N], and, respectively, 1.768(2) and 2.827(2) Å, in [MeBu 3N][Tf 2N]. Similar results are obtained in both ionic liquids indicating no significant influence of the ionic liquid cation either on the complexation reaction or on the structure of the uranyl species.

Magnetostructural examination of Mn(III) complexes [Mn(cyclam)X 2] + with strong axial ligands

Three novel Mn(III) cyclam complexes, [Mn(cyclam)(NCBH 3) 2](CF 3SO 3), [Mn(cyclam)(NCBPh 3) 2](CF 3SO 3), and [Mn(cyclam)(NCSe) 2](CF 3SO 3) · H 2O, have been synthesized. These complexes are in the high-spin state between 4 and 350 K, and show large zero-field splittings. The crystal structure of [Mn(cyclam)(NCBH 3) 2](CF 3SO 3) was determined where the axial elongation of Mn–N bonds is found to be the largest among the homologue complexes. Ligand field in the [Mn(cyclam)X 2] + complex series was examined by angular-overlap model calculation.

Triflic acid promoted synthesis of polycyclic aromatic compounds

The triflic acid (CF 3SO 3H) promoted cyclizations of 2-styrylbiaryls are found to be useful for the synthesis of polycyclic aromatic compounds, including functionalized derivatives of polycyclic aromatic compounds and heterocyclic systems. The reaction involves cationic cyclization followed by an elimination of benzene from the intermediate product.

The interaction between inorganic Li salts (LiTf, LiNTf 2) and the surface of alumina particles as studied with solid state nuclear magnetic resonance

The interaction between Li salts {LiTf (Tf = CF 3SO 3) and LiNTf 2 (NTf 2 = N(SO 2CF 3) 2)} with surface modified alumina particles (basic, neutral or acidic) is investigated employing a range of advanced solid state NMR methodologies. Utilizing 7Li MAS NMR, a new signal – in addition to the signal of the pure salt – could be identified in the composite samples, increasing with increasing basicity of the alumina surface. Employing 7Li–{ 1H} CPMAS NMR and 7Li–{ 1H}–CPMAS–{ 27Al} REAPDOR NMR spectroscopy, this new signal could be unequivocally assigned to an alumina-surface bound Li species. For the anions, 19F MAS NMR spectra clearly prove the existence of new anion sites. Employing 19F–{ 7Li} REDOR spectroscopy and 19F–{ 27Al} TRAPDOR NMR spectroscopy, the identified signals could be safely assigned to anions within the pristine Li salt and anions attached to the alumina surface. These results present direct evidence for the anion∙∙∙alumina surface and cation∙∙∙alumina surface interaction, suggested by several authors to aid in the interpretation of the effect of the ceramic additive on the ionic conductivity.

Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate using GLC

Activity coefficients at infinite dilution, γ 13 ∞ , for 32 organic compounds: alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran, tert-butyl methyl ether and water in the ionic liquid 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate [BMPYR][CF 3SO 3] were determined by gas–liquid chromatography at the temperatures ranging from 298.15 to 368.15 K. The partial molar excess enthalpies at infinite dilution Δ H 1 E , ∞ were calculated from the experimental γ 13 ∞ values obtained over the temperature range. The selectivities for the n-hexane/benzene, cyclohexane/benzene, n-hexane/thiophene, cyclohexane/thiophene, benzene/thiophene and hexen-1-ene/ n-hexane separation problems were calculated from the γ 13 ∞ and compared to the literature values for other ionic liquids, NMP and sulfolane.

Permeability and Selectivity of Sulfur Dioxide and Carbon Dioxide in Supported Ionic Liquid Membranes

Permeabilities and selectivities of gases such as carbon dioxide (CO 2), sulfur dioxide (SO 2), nitrogen (N 2) and methane (CH 4) in six imidazolium-based ionic liquids ([emim][BF 4], [bmim][BF 4], [bmim][PF 6], [hmim][BF 4], [bmim][Tf 2N] and [emim][CF 3SO 3]) supported on polyethersulfone microfiltration membranes are investigated in a single gas feed system using nitrogen as the environment and reference component at temperature from 25 to 45°C and pressure of N 2 from 100 to 400 kPa. It is found that SO 2 has the highest permeability in the tested supported ionic liquid membranes, being an order of magnitude higher than that of CO 2, and about 2 to 3 orders of magnitude larger than those of N 2 and CH 4. The observed selectivity of SO 2 over the two ordinary gas components is also striking. It is shown experimentally that the dissolution and transport of gas components in the supported ionic liquid membranes, as well as the nature of ionic liquids play important roles in the gas permeation. A nonlinear increase of permeation rate with temperature and operation pressure is also observed for all sample gases. By considering the factors that influence the permeabilities and selectivities of CO 2 and SO 2, it is expected to develop an optimal supported ionic liquid membrane technology for the isolation of acidic gases in the near future.

Infinite dilution diffusion coefficients of [Bmim]-based ionic liquids in water and its molar conductivities

In this work, we presented new experimental data of diffusion coefficients of four [Bmim (1-butyl-3-methylimidazolium)]-based ionic liquids in water at infinite dilution for temperatures ranging from 303.2 to 323.2 K using Taylor dispersion technique. The investigated ILs were [Bmim][BF 4 (tetrafluoroborate)], [Bmim][MeSO 4 (methylsulfate)], [Bmim][PF 6 (hexafluorophosphate)], and [Bmim][CF 3SO 3 (trifluoromethanesulfonate)]. The molar conductivities of these ionic liquids were also measured and the infinite dilution conductances were determined. The present experimental diffusion coefficients were represented using three correlations; namely, Wilke–Chang, modified Wilke–Chang, and Nernst–Haskell equation. The Wilke–Chang equation underestimated the diffusion coefficient while the Nernst–Haskell equation overestimated the diffusion coefficient. Only the modified Wilke–Chang equation satisfactorily represented the present experimental data.

Coordination of bistriflimide and triflate to the uranyl bis(diphenylphosphino)methane dication, {UO 2(DPPMO 2) 2} 2+

The {UO 2(DPPMO 2) 2} 2+ dication (where DPPMO 2 = bis(diphenylphosphino)methane) contains the linear uranyl group, {UO 2} 2+, with two bidentate P O donor ligands. Previously, we have shown that the weakly coordinating oxoanions [ReO 4] − and [TcO 4] − (as well as Cl −) will fill a fifth equatorial coordination site yielding complexes of general formula [UO 2(DPPMO 2) 2X][X] (where X = [ReO 4] −, [TcO 4] − and Cl −), with the X − anion acting in both monodentate coordinated and uncoordinated modes. Seven coordinate pentagonal bipyramidal uranyl complexes with the same general formula have now also been prepared with both the bistriflimide, ((CF 3SO 2) 2N −, NTf 2 - ) and triflate ( CF 3 SO 3 - OTf −) anions and we report the structural characterisation of both [UO 2(NTf 2)(DPPMO 2) 2][NTf 2] ( 1) and [UO 2(OTf)(DPPMO 2) 2][OTf] ( 2). In the case of 1 the anion is coordinated through a terminal oxygen, representing the first structural characterization of an actinide-bistriflimide complex. Both the solid state uranium-anion bond lengths (for O-donor ligands only) and 31P{ 1H} NMR solution competition studies indicate that the strength of the uranyl-anion bond decreases along the series Cl − > [ReO 4] − > [OTf] − > [NTf 2] −. In addition, 31P{ 1H} NMR competition studies show that both nitrate and excess DPPMO 2 will readily displace the weakly coordinating X − anions.

Conversion of novel palladacycles into oxopyrrolo[3,4-b]quinolines

The quinolinylcyclopalladated complexes 3a– b were synthesised in good yields (81% and 77%) by the insertion reaction of the prepared dinuclear palladium complexes [Pd( C,N-2-C 9H 4N-CHO-3-R-6)Cl(PPh 3)] 2 [(R = H ( 2a), R = OMe ( 2b)] with isonitrile XyNC (Xy = 2,6-Me 2C 6H 3). The cyclopalladated complexes 3a– b were also obtained in low yields (39% and 33.5%) via a one pot oxidative addition reaction of quinoline chloride 1a– b with isonitrile XyNC:Pd(dba) 2 (4:1). The reactions of 3a– b with Tl(TfO) (TfO = triflate, CF 3SO 3) in the presence of H 2O or EtOH causes depalladation reactions of the complexes to provide the corresponding organic compounds 4a– b, 5a– b and 6a– b in yields (41%, 27% and 18–19%). The products were characterized by satisfactory elemental analyses and spectral studies (IR, 1H, 13C and 31P NMR). The crystal structures of 2a, 3a and 3b were determined by X-ray diffraction studies.