Number Of Fluorine Atoms Research Articles

High-speed Processing with Reactive Cluster Ion Beams

ABSTRACTCluster ion beam processes can produce high rate sputtering with low damage in comparison with monomer ion beam processes. Especially, it is expected that extreme high rate sputtering can be obtained using reactive cluster ion beams. Reactive cluster ion beams, such as SF6, CF4, CHF3, and CH2F2, were generated and their cluster size distributions were measured using Time-of-Flight (TOF) method. Si substrates were irradiated with the reactive cluster ions at the acceleration energy of 5–65 keV. Each sputtering yield was increased with acceleration energy and was about 1000 times higher than that of Ar monomer ions. The sputtering yield of SF6 cluster ions was about 4600 atoms/ion at 65 keV. With this beam, 12 inches wafers can be etched 0.5 μm per minute at 1 mA of beam current. The TOF measurement showed that the size of SF6 cluster was about 550 molecules and the number of fluorine atoms in a SF6 cluster was about 3300. If the sputtered product was SiF, the yield has to be less than 3300 atoms/ion. These results indicate that the reactive cluster ions etch targets not only chemically, but also physically. This high-speed processing with reactive cluster ion beam can be applied to fabricate nano-devices.

A Theoretical Study of Substituted Stepwise Fluorinated Cyclopropanone Keto-Enol System

MINDO-Forces calculations have been performed with complete optimization of the geometries on stepwise fluorinated cyclopropanones and their enols. Increase in the number of fluorine atoms causes destabilization of cyclopropanone. Perfluorinated enol was found to be present in substantial concentration, as was mentioned in previous work. This is supported by calculations of Gibbs free energies and isodesmic reactions. Geometrical parameters, heats of formation, electron densities, dipole moments and orbital energies (HOMO-LUMO) are reported.

Nonaqueous Lithium Battery Electrolytes Based on Bis(polyfluorodiolato)borates

Ten lithium salts recently reported by our laboratory have been studied for their potential use as battery electrolytes. The parent compound is One derivative had a t-butyl and a methyl group on each of the two phenyl rings of the borate anion, and the other eight derivatives had one, two, or three fluorine atoms in various positions on each of the phenyl rings. Except for the t-butyl/methyl derivative, all of the borates were oxidized at potentials more positive than 4.2 vs. in 1,2-dimethoxyethane (DME) and in 50:50 mol % ethylene carbonate:dimethylcarbonate (EC:DMC). None of the anions was reduced at vs. in either solvent, and, in contrast to none caused significant corrosion of an aluminum electrode at 4.2 V vs. Except for the t-butyl/methyl derivative, the DME values occurred for 0.5 M solutions and ranged from 5.39 to The DME and EC:DMC values for were 5.88 and respectively. For a given number of phenyl-ring fluorine atoms (one, two, or three), the conductivity and the potential to passivate platinum or stainless steel electrodes depended strongly on the fluorine-atom substitution pattern. The potential at which the borate was oxidized only depended on the number of fluorine atoms and not on their substitution pattern. © 2003 The Electrochemical Society. All rights reserved.

N‐Isopropyl enols of carboxylic acid amides

AbstractEight N‐isopropyl compounds of the formal structure YY′CHCONHPr‐i (6), Y,Y′ = CO2Me, CO2CH2CF3, CN; YY′ = Meldrum′s acid residue; Y = CO2Me, Y′ = CO2CH2CF3, CN; Y = CO2CH2CF3, CO2CH(CF3)2, Y′ = CN, and the N‐t‐butyl derivative of Meldrum's acid were prepared and their structures were investigated in the solid state and in solution. The x‐ray diffraction data indicate that in the solid state the structure is that of the amide 6, when Y = Y′ = CO2Me, whereas when Y = CO2Me, Y′ = CN or YY′ = Meldrum′s acid residue the structure is that of the enol (5) YY′C=C(OH)NHPr‐i. The solid‐state 13C spectra indicate structure 6 when Y = CO2Me, Y′ = CO2R, R = Me, CH2CF3 and an enol structure for the other compounds studied. 1H, 13C and when available 19F NMR spectra showed that the enol/amide composition in solution is structure and solvent dependent, in analogy with the previously investigated N‐Ph analogs. The percentage of enol (and KEnol) decrease in the order of solvents CCl4 > CDCl3 > THF‐d8 > CD3CN > DMSO‐d6, DMF‐d7. For Y,Y′ the percentage of enol increases when the number of fluorine atoms in R of the CO2R increases, when CN replaces a CO2R group or for the cyclic Meldrum's acid derivative. Both E‐ and Z‐enols were observed when Y ≠ Y′, mostly at low temperature. The δ(OH) values increase with increased polarity of the medium and with increased strength of the hydrogen bonds in which they are involved. In THF‐d8 and DMF‐d7 the Z‐enol/E‐enol and the amide/enol ratios increase with increase in temperature. A main conclusion from the work is that the percentage of the enol increases, but not drastically, when the N‐substituent is changed from Ph to i‐Pr. Copyright © 2003 John Wiley & Sons, Ltd.

Aggregation feature of fluorine-substituted benzene rings and intermolecular C-H.F interaction: crystal structure analyses of mono- and trifluoro-L-phenylalanines.

X-Ray crystal structures of four different fluorine-substituted phenylalanines (two mono- and two tri-substitutions) were analyzed to investigate the effect of fluorine atom on the association pattern of benzene rings. Although respective structures showed similar molecular packing in such a way that the layers of hydrophobic benzene rings and hydrophilic amino/carboxyl groups were alternately running along a crystallographic axis, the association patterns of benzene rings were different depending on the substitution position and number of fluorine atoms. The general features could be that the partially displaced face-to-face interactions are increased with increase in the number of fluorine atoms, whereas the edge-to-face interactions are decreased. The C-H bond next to a fluorine-substituted carbon atom could serve as a donor of an intermolecular C-H.F hydrogen bond.

New Titanium Complexes Bearing Two Indolide−Imine Chelate Ligands for the Polymerization of Ethylene

New titanium complexes 5−8 with two indolide−imine chelate ligands [7-(RNCH)C8H5N]2TiCl2 (R: 5, phenyl; 6, 2,6-difluorophenyl; 7, 2,4,6-trifluorophenyl; 8, pentafluorophenyl) were synthesized and investigated as ethylene polymerization catalysts. On activation with methylalumoxane (MAO), all of the complexes were active ethylene polymerization catalysts at 25 °C to produce linear polyethylenes. The catalytic activity (TOF) increased sharply with the number of fluorine atom in the ligand. In addition, complexes 5−8 potentially exhibit the characteristics of a living ethylene polymerization. Complexes 6 and 7 promoted room temperature living ethylene polymerization to produce polyethylenes having extremely narrow molecular weight distributions (6, Mw/Mn 1.09−1.14; 7, Mw/Mn 1.05−1.23). On the other hand, at −10 °C complex 8 afforded monodisperse polyethylenes (Mw/Mn 1.12−1.25), with exceptionally high activities for a living ethylene polymerization (TOF: maximum 1155 min-1 atm-1). Using complex 7/MAO catal...

Influence of F and CF3 Groups at the C=C Double Bond on the Structure and Properties of Protonated Forms of Olefin‐Series Compounds: an MP2 ab initio Study

The ab initio MP2 method using the 6−31G* basis set with full geometry optimization was employed to calculate the protonated fluoroolefin molecules (F)i(H)jC=C(F)k(H)l (A) and (CF3)i(F)jC=C(CF3)k×(F)l (B), where i + j = k + l = 2. It is shown that a proton is attached to a carbon atom that is linked to fewer fluorine atoms as substituents. In series A, the proton affinity (PA:rpar; passes through a maximum as the number of fluorine atoms in the molecule increases. The highest PA is found for the 1,1′‐difluoroethylene molecule (182.6 kcal/mole). In series B, the PA decreases monotonically, assuming an anomalously low value for the tetra(trifluoromethyl)ethylene molecule (114.7 kcal/mole). The obtained results are compared with Hartree–Fock calculations; the Hartree–Fock method is inadequate for predicting the structures of the carbocations examined.

Enols of Amides. The Effect of Fluorine Substituents in the Ester Groups of Dicarboalkoxyanilidomethanes on the Enol/Amide and E-Enol/Z-Enol Ratios. A Multinuclei NMR Study1

Condensation of phenyl isocyanate substituted by 4-MeO, 4-Me, 4-H, 4-Br, and 2,4-(MeO)(2) with esters CH(2)(CO(2)R)CO(2)R', R = CH(2)CF(3), R' = CH(3), CH(2)CF(3), CH(CF(3))(2), or R = CH(3), R' = CH(CF(3))(2) gave 17 "amides" ArNHCOCH(CO(2)R)CO(2)R' containing three, six, or nine fluorines in the ester groups. X-ray crystallography of six of them revealed that compounds with > or =6 fluorine atoms exist in the solid state as the enols of amides ArNHC(OH)=C(CO(2)R)CO(2)R' whereas the ester with R = R' = CH(3) was shown previously to have the amide structure. In the solid enols, the OH is cis and hydrogen bonded to the better electron-donating (i.e., with fewer fluorine atoms) ester group. X-ray diffraction could not be obtained for compounds with only three fluorine atoms, i.e., R = CH(2)CF(3), R' = CH(3) but the (13)C CP-MAS spectra indicate that they have the amide structure in the solid state, whereas esters with six and nine fluorine atoms display spectra assigned to the enols. The solid enols show unsymmetrical hydrogen bonds and the expected features of push-pull alkenes, e.g., long C(alpha)=C(beta) bonds. The structure in solution depends on the number of fluorine atoms and the solvent, but only slightly on the substituents. The symmetrical systems (R = R' = CH(2)CF(3)) show signals for the amide and the enol, but all systems with R not equal R' displayed signals for the amide and for two enols, presumably the E- and Z-isomers. The [Enol I]/[Enol II] ratio is 1.6-2.9 when R = CH(2)CF(3), R' = CH(3), CH(CF(3))(2) and 4.5-5.3 when R = CH(3), R' = CH(CF(3))(2). The most abundant enol display a lower field delta(OH) and a higher field delta(NH) and assigned the E-structure with a stronger O-H.O=C(OR) hydrogen bond than in the Z-isomer. delta(OH) and delta(NH) values are nearly the same for all systems with the same cis CO(2)R group. The [Enols]/[Amide] ratio in various solvents follows the order CCl(4) > CDCl(3) > CD(3)CN > DMSO-d(6). The enols always predominate in CCl(4) and the amide is the exclusive isomer in DMSO-d(6) and the major one in CD(3)CN. In CDCl(3) the major tautomer depends on the number of fluorines. For example, in CDCl(3,) for Ar = Ph, the % enol (K(Enol)) is 35% (0.54) for R = CH(2)CF(3,) R' = CH(3), 87% (6.7) for R = R' = CH(2)CF(3), 79% (3.8) for R = CH(3), R' = CH(CF(3))(2) and 100% (> or =50) for R = CH(2)CF(3), R' = CH(CF(3))(2). (17)O and (15)N NMR spectra measured for nine of the enols are consistent with the suggested assignments. The data indicate the importance of electron withdrawal at C(beta), of intramolecular hydrogen bonding, and of low polarity solvents in stabilizing the enols. The enols of amides should no longer be regarded as esoteric species.

Influence of the position and number of fluorine atoms and of the chiral moiety on a newly synthesized series with anticlinic properties

A series of trifluoro-substituted benzoate derivatives: (S)-1-ethylheptyl 4-[4-(4-alkyloxy-3- fluorobenzoyloxy)-3-fluorobenzoyloxy]-2-fluorobenzoates is reported. The short chain members (n = 8 to n = 11) display a direct SmC*A-SmA transition, whereas for longer chains a SmC* phase appears, but no ferrielectric phases are present, and a direct SmCA*-SmC* transition is obtained. The mesomorphic properties were studied by optical microscopy and DSC, and by electro-optical, helical pitch and optical rotatory power measurements. The effect of the number and position of the fluoro substituents, and the influence of the chiral moiety on the mesomorphic behaviour are discussed.

Fluorinated phosphorus compounds: Part 5. The boiling points of fluoroalkyl phosphoryl compounds

The relationship between structure and boiling point for several classes of phosphoryl compounds having fluorinated or hydrocarbon ester groups is discussed, i.e. phosphoramidates (R 2N) 2P(O)OCH 2R F and (R FCH 2O) 2P(O)NR 2, phosphates (RO) 2P(O)OR F, (R FCH 2O) 2P(O)OR, (R FO) 3PO and (R FCH 2O) 2P(O)OCH 2R F′, and phosphonates (R FO) 2P(O)R, where R= alkyl and R F= fluoroalkyl. Fluorination generally produces compounds of similar or lower boiling point than the unfluorinated parent compounds. A key factor governing the boiling point of a fluorinated phosphoryl compound relative to its hydrocarbon analogue is not its molecular weight, but the position and number of fluorine atoms in the ester linkage(s). Molecules with an umbrella of fluorine atoms repel each other, leading to low intermolecular forces: the boiling points of (C 3F 7CH 2O) 3PO and (C 3H 7CH 2O) 3PO are close despite a molecular weight difference of 378. Molecules with protons capable of intermolecular hydrogen-fluorine bonding (i.e. those containing NHR or CF 2H groups) have higher boiling points than those without, due to attractive forces in the liquid state. Synthetic procedures for four unfluorinated phosphates — (MeO) 2P(O)O- i-Pr, (MeO) 2P(O)O- n-Bu, (EtO) 2P(O)O- i-Pr and ( s-BuO) 3PO are outlined.

Synthesis, electronic spectra, and crystal structural properties of fluorinated [3(3)](1,3,5)cyclophanes.

[structure: see text] Trifluoro- and hexafluoro[3(3)](1,3,5)cyclophanes 3 and 4 were synthesized with TosMIC coupling as a key reaction. The pi-pi absorption bands show blue shifts as the number of fluorine atoms is increased. In the crystalline state, characteristic stacking with the fluorinated benzene rings facing each other is observed in both cases.

Structural Characterization of Clusters Formed from Alkyl Nitriles and the Methyl Cation

Cluster ions composed of the alkyl nitriles, acetonitrile (CH3CN) and butyronitrile (C3H7CN), and the methyl cation (CH3+) have been examined in an effort to study methyl cation affinities and the intrinsic nucleophilicity of these bases. Structural characterization of the gas-phase dimeric adduct ions was achieved via multiple stage mass spectrometry (MSn) experiments and by quantum mechanical calculations. The kinetic method was used as a diagnostic tool in determining the structure of the dimeric adduct: the results of tandem mass spectrometry (MS2) experiments are found to provide ratios which exclude loosely bonded dimers based on the thermochemistry of the constituent monomers, and which are consistent with a mixture of noninterconverting covalently bonded structures predicted by ab initio calculations. These clusters are bound such that one nitrile is N-methylated and the second nitrile is bound covalently to the carbon of the methylated cyano group. Collision-induced dissociation of this cluster ion results in the loss of a single neutral nitrile whereas both N-methylated nitriles should be formed upon dissociation of a loosely bound dimer with the greater fragment ion abundance corresponding to the nitrile having the higher CH3+ affinity. Ab initio calculations show a large barrier between the two isomeric forms of the dimeric cluster and this precludes intramolecular methyl cation transfer between the nitriles. The effects of fluorine substitution at the methyl cation, i.e., CH2F+ and CF3+, on the adducts of the nitriles greatly affects the stability order of the methylated nitrile monomers and dimeric adducts, and thus the abundance ratios of the MS/MS fragments. As the number of fluorine atoms in the cation is increased, the methylated nitrile becomes less stable relative to the dimeric cluster ion.

Vacuum ultraviolet spectra of fluorocompounds for 157 nm lithography

The optical characteristics in the vacuum ultraviolet region were studied using the molecular orbital method. A model molecule, p-ethylphenol, was used to represent poly(p-hydroxystyrene), and its spectrum was calculated by the semiempirical molecular orbital calculations. The theoretical results were compared with the experimental ones. The wavelengths of the absorption peaks showed good agreement in both results, though the intensities of the absorption did not agree. The fluorination of p-ethylphenol was investigated and it was found that the increase in the number of fluorine atoms became more transparent in the compound. The cause was explained by two factors. One was the redshift of the π–π* electronic transition of the aromatic molecules, of which the oscillator strength did not depend upon the fluorination number. The other was the decrease in the oscillator strength of the peak at 157 nm, of which the wavelength did not significantly shift.

A Density Functional Study of Ion-Pair Formation and Dissociation in the Reaction between Boron- and Aluminum-Based Lewis Acids with (1,2-Me2Cp)2ZrMe2

Calculations have been carried out on the reaction between the olefin polymerization precatalyst (1,2-Me2Cp)2ZrMe2 (P) and a number of Lewis acids (A) to form the methide-bridged (contact) ion pair (1,2-Me2Cp)2ZrMe(μ-Me)A (I; P + A → I + ΔHipf). This is the first step in the activation of P to becoming an olefin polymerization catalyst. The calculated enthalpies of formation (ΔHipf) for I were as follows (A, ΔHipf in kcal/mol): B(C6F5)3 (1a), −23.8; B(C6F5)2(C6H3F2) (1b), −21.5; B(C6F5)2(C6H5) (1c), −18.3; B(C6F5)2(C6H3(CH3)2 (1d), −18.0; B(C6H5)3 (1e), −6.7; B(C10F7)3 (1f), −25.8; (MeAlO)6 (2a), −15.9; (MeBO)6 (2b), −22.3; AlMe3 (2c), −8.1; Al(C6F5)3 (2d), −30.8. The charge separation between the (1,2-Me2Cp)2ZrMe+ and AMe- fragments in I was calculated for all A, and it was found that the charge separation as well as −ΔHipf increases through the series 1e, 1c, 1b, and 1a with the number of fluorine atoms. A good activating Lewis acid (A) has the equilibrium shifted strongly from P and A toward I, and this is the case for all A except 1e and 2c. Also considered was the complete dissociation in solution (toluene) of I into the counterions [(1,2-Me2Cp)2ZrMe]+ and AMe- with the dissociating enthalpy ΔHips as well as the formation from I of the solvent-separated ion pair (S = toluene) [(1,2-Me2Cp)2ZrMe]+−S−[AMe]- with the reaction enthalpy ΔHss. The two types of separation processes have both been postulated as the second and final steps in the activation of P. The calculated values are as follows (A, ΔHips and ΔHss in kcal/mol): 1a, 38.0, 18.7; 1f, 43.6, 18.9; 2a, 57.0, 32.4; 2b, 46.9, 35.3; 2c, 69.2, 35.3; 2d, 48.3, 20.6. It is concluded that the formation of [(1,2-Me2Cp)2ZrMe]+−S−[AMe]- is the more likely separation process. Consideration has also been given to the influence of solvent polarity on the separation process, with S = toluene, chlorobenzene, and 1,2-dichlorobenzene. Finally discussed are ΔHips and ΔHss for the ion pair [(1,2-Me2Cp)2ZrMe]+[A]- (III‘); A- = B(C6F5)4- (3a), Al(C6F5)4- (3b), [(C2B9H11)2Co]- (3c), and {tBuCH2CH[B(C6F5)2]H}- (3d)), where III‘ is formed from the reaction of P with the activator [CPh3+][A-]. Here the calculated values are as follows (A-, ΔHips and ΔHss in kcal/mol): 3a, 22.1, −4.2; 3b, 26.2, 0.7; 3c, 34.9, 7.5; 3d, 26.7, −0.5. It is found that III type ion pairs are easier to dissociate than I held together by a methide bridge.

Analysis of Cross-Polarization Dynamics between Two Abundant Nuclei, 19F and 1H, Based on Spin Thermodynamics Theory

The phenomenological theory of spin thermodynamics based on the spin temperature hypothesis was employed to describe the cross-polarization (CP) dynamics between two abundant nuclei, 19F and 1H, when the number of fluorine atoms is not substantially less than the number of hydrogens. The influence of T1ρ's of both nuclei and the relative magnitude (heat capacity) of the two spin baths must be incorporated explicitly into the analysis in order to derive values for the parameters involved in the CP dynamics. Numerical calculations were performed to clarify the difference in the evolution of magnetization in variable contact time CP experiments between the 1H → 13C and 1H → 19F cases. A new type of CP-drain experiment was developed for observing the residual 1H magnetization after 1H → 19F CP. 19F direct polarization magic-angle spinning (MAS), 1H → 19F CP, and 1H → 19F CP-drain MAS NMR spectra have been measured for a fluorinated polyimide, 6FDA/ODA. The CP dynamics between 1H and 19F for the polyimide were analyzed on the basis of the spin thermodynamics theory. The constant for polarization transfer (THF) was determined by the analysis using the effective CP parameters, which were directly obtained from the CP and CP-drain experiments, together with independently measured values of TH1ρ and TF1ρ.

Separation Behavior of Various Organic Compounds on Branched-Polyfluoroalkylsilane Coated SilicaGel Columns

Fluorinated compounds are separated using fluorinated columns. The elution order depends on the number of fluorine atoms in the solutes. The addition of a masking agent of adsorption point to the mobile phase improves the separation of nitrogen-containing compounds, giving rise to symmetric peaks. Better recognition of geometrical isomers and epimers is achieved on fluorinated packings, which is attributed to the less solvophobic interaction than on an octadecyl siloxane column and the rigid molecular structure of the fluorocarbon chain. Using 2,2,2-trifluoroethanol as a mobile phase, cresol isomers are separated on fluorinated columns.

Influence of the introduction of fluorine atoms on the13C NMR spectra of acrylic esters

The effect of progressive introduction of fluorine atoms on the 13C chemical shifts in the β,β-dimethylacrylic ester series is examined. The main perturbation is located at the olefinic carbons positions. Comparison of the various data allows the calculation of increments corresponding to the substitution of methyl groups by CH2F, CHF2 or CF3 groups. The perturbation induced on the vinylic carbons increases roughly with the number of fluorine atoms. However, an influence of the stereochemistry is observed in the CH2F and CF3 series. The increments are not additive for compounds bearing two highly fluorinated groups at the β-positions. Copyright © 1999 John Wiley & Sons, Ltd.

Reactions of aromatic and heteroaromatic β-amino-β-polyfluoroalkylvinyl ketones with ethylenediamine. A new synthesis ofN,N′-unsubstituted imidazolidines

The reactions of aromatic and heteroaromatic β-amino-β-polyfluoroalkylvinyl ketones with ethylenediamine results in the formation of 2,3-dihydro-1H-1,4-diazepines,N,N′-unsubstituted imidazolidines, orN,N′-ethylenebis(aminovinyl ketones). The reaction route depends on the reaction conditions, the nature of the substituent at the carbonyl group, and the number of fluorine atoms in the polyfluoroalkyl radical.

DETERMINATION OF PARTITION COEFFICIENTS FOR SEVERAL PROPRANOLOL ANALOGUES BY REVERSED PHASE HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

The partition coefficients, log P oct app, for a series of propranolol analogues have been obtained by reversed phase-high performance liquid chromatography (RP-HPLC). A Collander type equation was set for 22 different standards that have the same trend as their H-bond capability. Fluorinated propranolol analogues are known to possess enhanced pharmacological properties and thus they were also investigated according to their capability offorming H–bonding. It was found that these fluorinated analogues do behave differently from their H–substituted counterparts. The results suggest that this behaviour may not be related to the number of fluorine atoms in the side chain, but rather to the strong polarisation of the molecules.

The application of the Deiters equation of state to the estimation of the solubility of solidified substances in liquid nitrogen by the Preston–Prausnitz method

The solubility of selected halogenhydrocarbons in liquid nitrogen has been measured at 77.4 K 1–5 and on the basis of this measurement the parameter I 12 in the Scatchard–Hildebrand equation has been calculated. The properties of the pure halogenhydrocarbons (necessary for the calculation of the solubility by the Preston–Prausnitz method) collected from various experimental sources were verified by the Deiters equation of state. It was shown that the values of the parameters in the Deiters equation of state decrease when the number of fluorine atoms in the molecule of the halogen derivatives of methane increase.