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The reactivity of an electron-rich Ni-difluorocarbene complex, Ni=[CF.sub.2][(dppe)[P(OMe).sub.3]] (1), with a variety of fluorinated alkenes was investigated (dppe = 1,2-bis(diphenylphosphino)ethane). Reactions of 1 with perfluoro(methyl vinyl ether) and chlorotrifluoroethylene (CTFE) give regiospecific formation of metallacyclobutanes, in which the carbene C attacks the most electron-rich carbon of the fluoroalkene. Further reaction of the CTFE-derived metallacycle in the presence of tetrahydrofuran affords a single isomer of NiCl(r-[CF.sub.2]CF=CFH) (dppe), 8, proposed to be formed by Ni-mediated [C.sub.a]-Cl activation followed by hydride abstraction and loss of HF. Although 1 also undergoes a cyclization reaction with trifluoroethylene (TrFE), instability of the presumed nickelacyclobutane affords the C3 fluoroalkene, [F.sub.2]C=CH([CF.sub.3]), and subsequent formation of isomeric metallacyclopentanes from two additional TrFEs. Alternatively, reaction of 1 with hexafluoropropene forms an unexpected Ni--[CF.sub.3] r-perfluoroallyl complex. Key words: nickel difluorocarbene, fluoroalkene, cycloaddition, C--F bond activation. La reactivite d'un complexe de difluorocarbene-nickel riche en electrons, le Ni-[CF.sub.2](dppe)[P(OMe)] (1), avec une variete d'alcenes fluores a ete etudiee [dppe = 1,2-bis(diphenylphosphino)ethane]. Les reactions du complexe 1 avec le perfluoro(methylvinylether) et le chlorotrifluoroethylene (CTFE) donnent lieu a la formation regiospecifique de metallacyclobutanes, dans lesquels le C du carbene attaque le carbone le plus riche en electrons du fluoroalcene. La poursuite de la reaction du metallacycle derive du CTFE en presence de tetrahydrofurane produit un seul isomere de NiCl([sCF.sub.2]CF=CFH) (dppe), le complexe 8, dont la formation pourrait etre attribuable a l'activation de la liaison [C.sub.a]Cl catalysee par le Ni, suivie de l'abstraction de l'hydrure et de la perte d'une molecule de HF. Bien que le complexe 1 subisse egalement une reaction de cyclisation avec le trifluoroethylene (TrFE), l'instabilite du suppose nickelacyclobutane permettrait la formation du fluoroalcene en C3, le [F.sub.2]C=CH([CF.sub.3]), puis la formation subsequente de metallacyclopentanes isomeriques provenant de deux autres molecules de TrFE. Sinon, la reaction du complexe 1 avec l'hexafluoropropene forme un complexe inattendu de [CF.sub.3]sperfluoroallylNi. [Traduit par la Redaction] Mots-cles : difluorocarbene-nickel, fluoroalcene, cycloaddition, activation de liaisons C--F., Introduction Reactions involving metal alkylidenes and carbenes are some of the most valuable and desired catalytic transformations. (1-4) Although the reactivity of metal carbenes has been thoroughly studied and established, [...]

The correlations between stimulated Brillouin scattering (SBS) characteristics of perfluoro-compound (PFC) and perfluoropolyether (PFPE) and their chemical structure are analyzed in detail and a series of new PFC and PFPE are reported. In the Nd:YAG laser system, the absorption coefficient, optical breakdown threshold (OBT), SBS threshold, and Brillouin frequency shift of new media such as FC-87, FC-43, HT-55, and DET are measured. Parameters such as gain coefficient, Brillouin linewidth, and phonon lifetime are calculated. The results demonstrate their good SBS properties: the absorption coefficients are below [10.sup.-3][cm.sup.-1] and OBTs are above 100 GW/[cm.sup.2]. These media also exhibit a series of unique physicochemical properties, i.e., high heat-resistance, high oxidation stability, good chemical inertness, and insulation properties. The discovery of new media not only diversifies SBS medium, but also improves the performance of the SBS system, thereby laying a good foundation for the application of a SBS phase conjugation mirror in a high-power laser system. OCIS codes: 190.0190, 290.5830, 190.2640.

Density functional calculations for the structure and magnetic parameters of the perfluorinated ethyl and n-propyl radicals are described. It is seen that fluorine substitution leads not only to nonplanarity at the radical center but to delocalization of spin density onto the [F.sup.alpha] atoms and to spin polarization effects that lead to anomalies.

The comparison results of the standard molar enthalpies of formation of fluoromethylaniline in gaseous state with the Cox scheme and the G3MP2/B3LYP calculations are presented.

The interactions between the aromatic portion of the fluorinated n-(4-sulfamylbenzoyl)benzylamine (SBB) inhibitors and two residues of Human Carbonic Anhydrase II (HCAII)- Phe-131 and Pro-202 are studied. The structure of proteins is determined by the interactions between aromatic rings.

A systematic density functional theory (DFT) calculations is performed on the stabilities and electronic properties of two different structures [Csub.58][X.sub.18] and [C.sub.58][X.sub.1], where X = H, F, and Cl. It is seen that the large energy gaps between the highest occupied molecular orbitals and the lowest unoccupied molecular orbital and the aromatic character possess high stabilities.

The investigation of the circular differential transmission in thick films of poly{9.9-bis[(3S)-3,7-dimethyloctyl}-2,7-fluorene} is presented. A specifically designed chiroptical setup is used to show that the circular selective reflection of light, in which the circular polarization of the light is retained after reflection, makes a negligible contribution to the differential transmission.

An analytical potential energy surface (PES-2006) was developed and quasi-classical trajectory (QCT) calculations were used to analyze the F + C[D.sub.4] gas-phase abstraction reaction. The state-specific scattering distributions at different collision energies were found to reproduce the experimental behavior with a clear propensity toward forward scattering.

Reaction free energetics and dynamics of unimolecular electron-transfer processes in ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate are investigated using a model diatomic solute. It is found that the overall characteristics of electron transfer free energetics are similar between two solvents.

Vertical excitation energies of the C[F.sub.3]Cl molecule are determined from a response function approach with a coupled cluster (CC) reference function in order to examine the absolute photoabsorption oscillator strengths in the molecular-adapted quantum defect orbital formalism (MQDO). The results for the molecular Rydberg transitions have provided better f-values of the isolated Cl atom than the MQDO results.

The synthesis of new cyclam derivatives with diametrically disubstituted pyrene fluorophores is described and their fluoroionophoric properties towards transition metal ions [Cu.sup.2} - and [Hg.sup.2} are studied. It is demonstrated that the diametrically disubstituted pyrene derivatives of cyclam exhibited a selective fluorescence quenching attitude towards [Cu.sup.2}- and [Hg.sup.2} ions in switching-off type responses in aqueous methanol or acetonitrile solution.

The systematic investigation of in-plane hydrogen-bonded complexes of ammonia with partially substituted fluorobenzenes has shown that fluorobenzene, difluorobenzene and trifluorobenzene have favored the formation of cyclic complexes with a C-H...N-H...F-C binding motif. The tendency with which fluorobenzenes adapt to the C-H...N-H...F-C binding motif has decreased with the progressive fluorination of the benzene ring and has disappeared completely when benzene ring is substituted with five or more fluorine atoms.

Ab initio quantum chemistry calculations of the decarbonylation kinetics of [C.sub.n][F.sub.2n+1]CO radicals are reported. The results have shown that [C.sub.n][F.sub.2n+1]CO radicals have a strong tendency to decompose in order to give [C.sub.n][F.sub.2n+1] and CO under atmospheric conditions.

The chemical activation techniques coupled with electronic structure calculations were used to investigate the unimolecular reactions of a series of chlorofluoropropane molecules. Fully halogenated fluorochloroethanes and propanes seem to have high threshold energies for ClF interchange, and other decomposition pathways are favored over ClF interchange.

The structure, spectra, and rearrangement mechanisms of P[H.sub.2][F.sub.3], the first member of the P[H.sub.n][F.sub.5-n] series and a prototype for molecules that undergo rotational isomerism, are analyzed. The results have identified the spectral fingerprints that could distinguish various rotational isomers that could form a powerful basis for the characterization of various rotational isomers of P[H.sub.2][F.sub.3] when used along with high resolution measurements.

Conformational equilibria in formic acid and, adduct of formic acid and hexafluoroacetone, HC[O.sub.2]C[(C[F.sub.3]).sub.2]OH were investigated. Formic acid showed separate signals for the E and Z conformations in solvents containing hydrogen and acceptor with peaks for E and Z conformations found at low temperatures for both formic acid and hexafluoroacetone.

Treatment of the hydrazone of 2H-perfluoro-2-methyl-3-pentanone with trietylamine at increased temperature has yielded a methylenecyclobutene via degradation to acetylene followed by dimerization. The finding suggests that the acidity and the conformational dynamics of the methylenecyclobutene are influenced by buttressing effects in this crowed molecule.

The properties of the low-sensitivity explosive trans-1,4,5,8-tetranitro-1,4,5,8-tetraazadecalin (TNAD)-based polymer-bonded explosives (PBXs) with four typical fluorine polymers are studied by using the molecular dynamics simulations. The results reveal that the addition of small amounts of fluorine polymers improves the mechanical properties of TNAD, whereas the detonation performances of the PBXs decrease.

The structures, electron ionization and excitation energies and electron density distribution of symmetrical five-membered heterocycle derivatives of carbazole and fluorene are analyzed. The results have shown that the properties of consecutive oligomers have indicated their fast convergence to values characterizing polymers.

The interactions of nitrous oxide with fluorinated liquids was investigated by reporting original experimental results on gas solubility and interpreting them using molecular simulation. Nitrous oxide was found to be highly soluble in the three fluorinated liquids studied, with mole fraction solubilities on the order of 0.03 under ambient conditions.

The degradation of polyfluorenes (PFs) and fluorene oligomers with alkyl and aromatic substitutions under ultraviolet (UV)-light irradiation is studied. The experiments have concluded that the degradation of fluorene is a radical chain process propagated by alkyl side chains and the different stability between alkyl and aromatic substitution can be well described.

Experimental vibrational spectroscopy in conjunction with DFT quantum chemical calculations is applied to characterize two fluorofullerenes, C60F48 and C60F36. The study reveals that vibrational spectroscopy, supplemented with reliable theoretical modeling could provide a powerful structural tool to meet the challenges of the structure determination for fullerene derivatives when other method, such as X-ray or NMR are unable to provide unambiguous solutions to the problem.

Helix induction in melitting and beta-lactoglobulin A is enhanced by fluorinated diols with the order to efficiency 2,2,3,3-tetrafluoro-1,4-butanediol (TFBD) < 2,2,3,3,4,4-hexafluoro-1,6-pentanediol (HFPD) < 2,2,3,3,4,4,5,5,-octafluoro-1,6-hexanediol (OFHD). The negligible red-edge excitation shift in the fluorescence of melittin has shown that the fluorinated diol/water solvent shell surrounding the tryptophan chromophore is less immobilized than is molecules in a lamellar vesicle.

An investigation is conducted of the heterogenous uptake of 8-2 fluorotelomer alcohol (FTOH) on liquid water surfaces and on 1-octanol surfaces with a droplet of train flow reactor. The larger uptake coefficient measured for 1-octanol surfaces indicates that FTOH partitioning to organic-containing cloud/fog droplets and aerosol particles may be an atmospheric loss mechanism.

The double bond of 2,3-dimethyl-2-butene (DMB) was very receptive to addition and even at -15degrees C instead of being inhibited to addition of Th+ by its four attached methyl groups. The reaction of Th+ with DMB was followed with cyclic voltammetry and was found to exhibit redox catalysis in which Th was generated.

Syntheses of fluorinated mucin core 2 tri- and tetrasaccharides modified at the C-3 or C-4 position of the pertinent galactose residue is discussed. The results revealed that the activities of only Gal 3-O-sulfotransferases and not sialyltransferases were adversely affected by a C-3 fluoro substituting at the other Gal terminal of mucin core 2.

Fluorescence excitation, multiphoton ionization and dispersed fluorescence spectra of bare and hydrogen-bonded 2-fluoropyridine with water are calculated in a supersonic free jet. The appearance of low frequency vibronic bands, which are seen for bare 2-fluoropyridine, is attributed to the existence of closely lying (n,pi(super star)) state.

A study was conducted about triplet-state formation and intersystem crossing in an A-alt-B series of fluorene copolymers using flash photolysis and pulse radiolysis-energy transfer. Fluorene-thiophene copolymers PFaT and PF3T, the triplet energies are closer to those of thiophene oligomers, indicating that there is significant conjugation between fluorene and thiophene units but also that there is a more localized triplet state than with the homopolymers.

The structure of bis(trifluoromethanesulfonyl) imide(TFSI(super minus)) in the liquid state was studied by means of Raman spectroscopy and DFL Calculations. The results concluded that a conformational equilibrium was established between the C(sub 1) and C(sub 2) conformers of TFSI(super minus) in the liquid EMI(super plus)TFSI(super -) and the C2 conformer is more favorable than the C1 one.

A significantly improved procedure that provides efficient access to a highly congested 1,8-diacridylnaphthalene fluorosensor is reported. Screening of palladium-catalyzed Negishi, Kumada, Suzuki, Hiyama, and Stille coupling methods showed that the latter affords highly congested 1,8-diarylnapthalenes in superior yields.

A convenient route for the total synthesis of a number of hydrofluorene natural products and their analogues is developed. The protocol is followed to realize the total synthesis of (plusmn)-dichroanal B, (plusmn)-dichroanone, (plusmn)-taiwaniaqunol B and (plismn)-taiwaniaquinones D and H.

An investigation is conducted of the relative importance of hydrogen bonding versus pie stacking interactions in DNA where the hydrogen-bonded complexes of the nucleobase mimic 2-pyridone (2PY) with seven different fluorinated benzenes. Ab initio studies are performed on the individual hydrogen bonds occurring between nucleobases and fluronated isomers.

A study conducted on modified DNA oligomers and polymerase reactions have demonstrated that canonical nucleobases can exhibit stable and even selective pairing with shape-complementary fluorobenzene nucleotides. Hydrogen bonds are believed to be absent because of the fluorination of the pairing edges and the local DNA stability is attributed pie-stacking and shape complementarity.

A description is provided on the photochemistry of O-chlorooxyalyl and O-fluoroformyl-9-fluorenone oxime. Time-resolved step/scan FTIR spectroscopy investigations on fluoroformyl oxide gave evidence of the formation of fluoroformyl radical FCO(super .) which rapidly adds to the solvent acetonitrile, yielding a fluoroformyl-functionalized iminyl radical.

The carbon 1s ionization energies for all of the carbon atoms in benzene molecules are measured by high-resolution photoelectron spectroscopy. A comparison of the ionization energies and proton affinities gives insight into the effects of fluorine as an electron-withdrawing group and as a pi donor, both in the neutral molecular and in response to an added positive charge.

The ARS-E model was used for calculating the intermolecular interaction energy of hexafluorobenzene-benzene. The largest and most negative energy of -5.38 kcal/mol was observed in the slipped-parallel complex.

The collective electronic oscillator (CEO) approach was adopted for calculating the linear absorption and florescence spectra and the oscillator strengths of 2,2',7,7'-tetraphenyl-9,9'-spirobifluorene, 2,2',7,7'-tetrakis(biphenyl-4-yl)-9,9'-spirobifluorene and 2,2',7,7'-tetrakis(9,9'-spirobifluoren-2-yl)-9,9'spirobifluorene. The higher CEO modes with significant oscillator strengths are corresponding to different spiro-centers, intra-branch and inter-branch neutral electronic delocalization.

Quantum scattering calculations for the reaction F + HCI --> HF + CI are performed on ab initio potential energy surface. The shape of the adiabatic potential surface yields to a simple and intuitive interpretation for the rotational enhancement of the rate.

Hydrolysis and condensation of simple trifluorosilanes, HSiF(sub 3) and MeSiF(sub 3), is studied by quantum mechanical methods. The results suggest that the activation energy for hydrolysis by a water dimer is significantly lower than that for hydrolysis by a water monomer.

Photogeneration of C(sub 6)F(sub 5)-C(sub 6)F(sub 4)H from HO-B(C(sub 6)F(sub 5))(sub 3)- and of C(sub 6)H(sub 5)-C(sub 6)F(sub 4)H from C(sub 6)H(sub 5)-B(C(sub 6)F(sub 5))(sub 3)- was studied. The photogeneration of H(sub 2)O.B(C(sub 6)F(sub 5))(sub 3) resulted from irradiation of isoquinolinium hydroxytris(pentafluorophenyl)borate.

A simple spirobifluorene molecule with pseudotetrahedral structure was investigated for its supposed conformational resilience upon adsorption. The molecule stays 'rigid' by keeping one of the original symmetry elements in the two physisorbed states while in an unexpected state, a strong deformation destroyed definitively any symmetry of the molecule.

The study of ionization and double ionization spectra of (H(sub 2)O)(sub1-3)F(super -) calculated by ab initio methods with microsolvation of F(super -) is conducted. Results show that the ionization spectrum of the isomer A with C(sub 3) symmetric ground-state geometry is rather similar from the energetical point of view to that of the isomer B with one H-donor-bound second solvation shell water molecule.

The dynamics of the photoinduced reaction producing electronically excited CaF when 1:1 Ca.CH(sub 3)F complexes are deposited at the surface of large argon clusters are examined using the 'cluster isolated chemical reactions' technique. The observations suggest that a profound alteration of the calcium electronic structure and a control of the reaction by the CF stretch in CH(sub 3)F.

The 1(super 2)A', 1(super 2)A', 2(super 2)A', 2(super 2)A', and 3(super 2)A' states of the CH3F(super +) ion are studied. The 1(super 2)A' state is predicted to be the ground state, and the C(sub s)-state energy levels are different from those of the CH3F(super +) ion.

The ubiquity of the fluorine-fluorine bonding interaction for a systematic examination is reported. Teh bond path is shown to persist for a range of internuclear distances (2.3-2.8 angstrom) and a range of relative orientations of the two C-F internuclear axes.

The infrared and ultraviolet-visible absorption cross sections, effective quantum yield of photolysis, and OH, Cl, and NO(sub 3) reaction rate coefficients of CHF(sub 2)CHO are reported. The photolysis of CHF(sub 2)CHO was investigated under pseudonatural tropospheric conditions and an effective quantum yield of photolysis equal to 0.30 plusmn 0.05 over the wavelength range 290-500 nm was extracted.

A study of the dynamics and kinetics of reactions between ions of known recombination energy and CHCl(sub 2)F, CHCIF(sub 2) and CH(sub 2)CIF using the well-established selected ion flow tube (SHIFT) technique is presented. It is concluded that the H(sub 3)O(super +) ion only reacts with CHCl(sub 2)F, even though all of the observed channels are apparently endothermic.

Theoretical investigation on the chemical addition patterns governing the fluorination of single wall carbon nanotubes is presented. Ab initio analysis of the fluorination of small nanotubes concluded that fluorine addition along the nanotube axis direction is favored by a mechanism of carbon framework distortion.

An investigation of the mid-infrared spectra of mixed solutions in liquid xenon containing fluoroform and either ammonia or pyridine is conducted at temperatures between 173 and 213 K. For both Lewis bases, a new band is found in the CH stretching region at a frequency 5 cm(super -1) higher than that of monomer fluoroform, which is assigned to a complex between fluoroform and the Lewis base.