Site directed synthesis of mono and disubstituted SF5-polyfluoroalkyl benzenes

A novel method for the preparation of o-, m-, p-SF₅CF₂CFYC₆H₄X (Y = Br, F and X = m-Br, p-Br, Cl, CH₃, CF₃, NO₂, o-NO₂, F, CF₃, CH(CH₃)₂) derivatives was devised by a two-step reaction: SF₅Br-addition to o-, m-, p-CF₂CFC₆H₄X followed by reaction of AgBF₄ with the o-, m-, p-SF₅CF₂CFBrC₆H₄X adducts. Additional studies have been carried out with several derivatives and includes the preparation of SF₅CF₂C(O)C₆H₅, p-CF₃CFBrC₆H₄NO₂, SF₅CF₂CF₂C₆H₃(NO₂)₂, SF₅CF₂CF₂C₆H₃(NH₂)₂, and an SF₅CF₂CF₂-containing polyimide and dye. The complete characterization (IR, NMR, and MS) of these compounds is given.     

Synthesis of SF5benzene (SF5C6H5) by the SF5halide method

Several significant and useful syntheses of pentafluorothiobenzene (SF₅C₆H₅) from SF₅halides (SF₅X, X=Cl, Br) and cyclohexene or derivatives of cyclohexene are presented.     

Halogen displacement chemistry with silver and alkali metal salts: Preparation of SF5-esters, alcohols, aliphatic olefins, acids and an iodide

It has been found that treatment of SF₅-alkyl halides, especially SF₅(CH₂)₂Br, with silver salts such as CH₃C(O)OAg, p-CH₃C₆H₄SO₃Ag, CF₃SO₃Ag and AgNO₃ provides convenient pathways for preparing the following ester compounds: SF₅CH₂CH₂R (R = CH₃COO, TosO, CF₃SO₃, NO₃), SF₅(CH₂)₃OTos, and SF₅(CF₂)₄(CH₂)₂OAc. Important derivatives prepared from these esters include SF₅(CH₂)₂OH; SF₅(CF₂)₄(CH₂)₂OH. Several alkenes SF₅C(Br)CH₂ and SF₅CH₂(COOCH₃)CCHC(O)OCH₃ are obtained using silver salts. The use of alkali metals salts with SF₅(CH₂)₃Br is studied and yields SF₅(CH₂)₃I; also, a pathway has been developed that extends for SF₅(CH₂)₃₋ the chain by two-carbon atoms and also produces the first SF₅-containing malonic acid.     

New acrylate systems: derivatives of β-SF5-acrylic acid

Addition of pentafluorothio bromide, SF₅Br, to ethyl propiolate results in an 1:1 adduct, SF₅CHCBrC(O)OC₂H₅, and a small amount of a 1:2 adduct. The former is converted by reduction to the corresponding β-SF₅-acrylic ester, SF₅CHCHC(O)OC₂H₅. Treatment of SF₅CH₂CBr(CH₃)C(O)OCH₃ with base produces methyl-β-SF₅-methacrylate, SF₅CHC(CH₃)C(O)OCH₃. The preparation and characterization of these new compounds are described.     

Pentafluoro-λ-sulfanyl (SF5) perfluoroalkyl iodides-synthesis and reaction with ethylene and tetrafluoroethylene : Crystal structure of SF5(CF2)4CH2CH2I

A series of reactions between SF₅CF₂CF₂I and SF₅(CF₂)₄I with F₂CCF₂ was carried out in an effort to find the most effective methods for chain-extension. Also, for the first time, SF₅(CF₂)₈I and SF₅(CF₂)₁₀I have been prepared and isolated. The reaction conditions for the addition of H₂CCH₂ were also investigated. A determination of the crystal structure of the SF₅(CF₂)₄CH₂CH₂I has been carried out: the crystal system is monoclinic, with space group P2(1)/n and a=23.465(5) Å; b=6.0971(12) Å; c=44.892(9) Å; α=90°; β=99.38(3)°; γ=90°; Z=20.     

The reaction of SF5Br with select 1,2-dihaloethylenes

SF₅Br reacts with 1,2-haloethylenes (F, Cl, Br) in distinct ways. In the case of F- and Cl-olefins, the expected addition occurs while with 1,2-dibromoethylene a metathetical reaction yielding in a clean reaction a 1:1 mixture of SF₅CHCHBr and CHBr₂CHBr₂ is found. The mechanism for this reaction is discussed.     

A convenient and efficient method for incorporation of pentafluorosulfanyl (SF5) substituents into aliphatic compounds

Both SF₅Cl and SF₅Br undergo smooth, high yield addition to alkenes and alkynes under the mild free radical chain reaction conditions of triethylborane initiation at low temperature, although the SF₅Br chemistry is somewhat limited by its competing high electrophilic reactivity with electron rich alkenes. The SF₅Cl addition reaction is relatively insensitive to a wide variety of non-allylic functionalities.     

S 2p photoabsorption of the SF5CF3 molecule: Experiment,theory and comparison with SF6

The S 2p core excitation spectrum of the SF₅CF₃ molecule has been measured in the total ion yield mode. It resembles a lot the analogous spectrum of SF₆, also recorded in this study, displaying intense transitions to the empty molecular orbitals both below and above the S 2p ionization potential (IP) and weak transitions to the Rydberg orbitals. The S 2p photoabsorption spectra of SF₆ and SF₅CF₃ have been calculated using time-dependent density functional theory, whereby the spin–orbit coupling was included for the transitions below the S 2p IP. The agreement between experiment and theory is good for both molecules, which allows us to assign the main S 2p absorption features in SF₅CF₃.     

Infrared spectra of p-, m- and o-fluorobenzaldehyde in low temperature argon matrices

Three structural isomers of fluorobenzaldehyde (p-, m- and o-forms) have been investigated in detail with matrix-isolation infrared spectroscopy, in the 700-3000 cm⁻¹ region, combined with the UV photoexcitation and the density functional calculations. Two rotamers (syn and anti) were identified for m- and o-fluorobenzaldehyde upon the photoexcitation and most of the bands of each rotamer were assigned. It is shown that the formation of the intramolecular C-H?F hydrogen bond for the anti rotamer of o-FB results in the shortening of the aldehyde C-H bond length and that the C-F and/or CO bond lengths are shortened for the syn rotamer of o-FB presumably due to the repulsion between the aldehyde O and F atoms.     

Synthesis and reactions of 2-SF5-butadiene

A stable and storable precursor of 2-SF₅-butadiene, 3-SF₅-3-sulfolene, has been synthesized and its reactivity studied with several olefinic compounds. When SF₅Br is added to sulfolene, 3-bromo-4-SF₅-sulfolane is formed and when reacted further with silver tosylate forms 4-SF₅-2-sulfolene. The 4-SF₅-2-sulfolene undergoes rearrangement with silicic acid to give 3-SF₅-3-sulfolene and when heated forms 2-SF₅-butadiene; in the absence of a dienophile, dimerization does occur. The new 2-SF₅-butadiene is a reactive diene undergoing a Diels-Alder reaction with olefinic sytems such as maleic anhydride, p-naphthoquinone, and methyl acrylate.     

New pentafluoro-λ-sulfanyl (SF5) perfluoroalkyl benzene derivatives

Preparation of the following new SF₅-perfluoroalkyl benzene derivatives, m-SF₅CF₂CF₂C₆H₄X (X=NO₂, NH₂, OH, I, NHCOCH₃, SO₂Cl, SO₃H, SO₃K) has been achieved. The new compounds were characterized by their respective IR, NMR and HRMS or elemental analysis.     

Diode laser spectroscopy of the ν8 band of the SF5Cl molecule

Diode laser spectra of SF(5)Cl have been recorded in the nu(8) band region at a temperature of ca. 240 K, a pressure of 0.25 mbar and an instrumental bandwidth of ca. 0.001 cm(-1). Four regions have been studied: a first one in the P-branch (906.849-907.687 cm(-1)), a second one in the Q-branch (910.407-910.944 cm(-1)), and two other ones in the R-branch (913.957-914.556 and 917.853-918.705 cm(-1) ). The whole nu(1)/nu(8) dyad of SF(5)35Cl has been previously recorded in the group of Professor H. Burger in Wuppertal, thanks to a Fourier transform infrared spectrometer. These data have thus been combined with our diode laser ones in the aim of refining the analysis. We used an effective Hamiltonian developed up to the fourth order and a set of programs called C(4nu)TDS. One thousand three hundred and forty-six transitions for nu(1), 495 (FTIR: 351; diode laser: 144) transitions for nu(8), and 406 ground state combination differences have been assigned and fitted. A global fit has been obtained with a rms of 0.00081 cm(-1) for the nu(1) band, 0.0012 cm(-1) for the FTIR data of the nu(8) band, 0.00055 cm(-1) for the diode laser data of this same band, and 0.00064 cm(-1) for the ground state. It appears that more data (for instance, using a supersonic jet) are still necessary to obtain a completely satisfactory analysis of the nu(8) region.     

Carbon nanotube field-effect transistor detector associated to gas chromatography for speciation of benzene,toluene, ethylbenzene, (o-, m- and p-)xylene

An analytical methodology based on a field-effect transistor detector using carbon nanotubes (NTFET) coupled to a gas chromatograph has been developed for the speciation of the following aromatic compounds: benzene, toluene, ethylbenzene, m-xylene, p-xylene and o-xylene (BTEX). This methodology combines the proven separation capability of gas chromatography (GC) with the potential for detection of a NTFET. The developed analyzer shows a high and stable analytical response upon repeated analysis of BTEX during 4 weeks, with detection limit less than 4 μg/L. The GC–NTFET system also shows a great suitability for actual monitoring of indoor atmospheres and no significant difference was observed between the results obtained by the developed analyzer and a more classical analytical methodology, namely gas chromatography–flame ionization detection (GC–FID).     

Use of 1,3-dipolar reactions for the preparation of SF5-substituted five-membered ring heterocycles. Pyrroles and thiophenes

In situ-generated unsubstituted, “parent” azomethine and thiocarbonyl ylides are used to prepare a large variety of 3-aryl- and alkyl-substituted, 4-pentafluorosulfanylpyrroles and 3-aryl-substituted, 4-pentafluorosulfanylthiophenes, the latter of which are to our knowledge the first reported SF₅-substituted thiophenes. The 1,3-cycloadditions of these ylides with aryl and alkyl, SF₅-alkynes produce dihydro-pyrroles and thiophenes, which without isolation can then be oxidatively aromatized to the respective pentafluorosulfanylpyrroles and thiophenes in good yield.     

AuBr3-catalyzed cyclization of o-(alkynyl)nitrobenzenes. Efficient synthesis of isatogens and anthranils

The cyclization of o-(arylalkynyl)nitrobenzenes was catalyzed by AuBr₃ to produce the corresponding isatogens in good to high yields together with small amounts of anthranils. On the other hand, anthranils were obtained selectively when the AuBr₃-catalyzed reaction was carried out using o-(alkylalkynyl)nitrobenzenes.     

The synthesis and structural characterization of the new ternary nitrides: Ca4TiN4 and Ca5NbN5

The ternary nitrides, Ca₄TiN₄ and Ca₅NbN₅, were synthesized in sealed niobium tubes using lithium nitride as a flux at 900 and 1050 °C, respectively. The structures of both compounds were solved from single-crystal X-ray diffraction data. Ca₄TiN₄ is the first example of a calcium group IV nitride; it crystallizes in the triclinic space group (No. 2) with cell parameters a=5.9757(5) Å, b=6.0129(5) Å, c=6.0116(12) Å, α=71.565(4)°, β=79.471(4)°, γ=68.258(4)° and Z=2. Ca₄TiN₄ is isostructural with Na₄TiO₄ and contains tetrahedral TiN₄ units connected through edges and corners to CaN₄ tetrahedra and CaN₅ square pyramids. Ca₅NbN₅ crystallizes in the monoclinic space group C2/m (No. 12) with cell parameters a=11.922(7) Å, b=6.878(5) Å, c=8.936(7) Å, β=101.22(3)° and Z=4. Ca₅NbN₅ is isostructural with Ba₅NbN₅; the structure contains NbN₄ tetrahedra that share vertices with CaN₅ trigonal bipyramids.     

(C5H5FeS1,55)4: Ein neuartiger vierkerniger Fe-S-Cluster in einer (C5H5FeS)4-Matrix

Ohne Zusammenfassung

---

(C₅H₅FeSi_1.5)₄: A new quadrinuclear Fe-S cluster in a (C₅H₅FeS)₄ matrix

     

The synthesis and characterisation of novel o-substituted benzyldi-t-butylphosphine-boranes

The novel compounds o-(chloromethyl)benzyldi-t-butylphosphine-borane and o-(methoxymethyl)benzyldi-t-butylphosphine-borane have been synthesised in 54% and 51% yields, respectively, and have been fully characterised. An improved method for the synthesis of α-chloro-α′-methoxy-o-xylene is also reported.     

Hydrothermal synthesis and magnetic properties of RMn2O5 (R=La, Pr, Nd, Tb, Bi) and LaMn2O5+δ

RMn₂O₅ (R=La, Pr, Nd, Tb, Bi) crystallites were prepared by a mild hydrothermal method and characterized by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and magnetic measurement. The formation of manganates was sensitive to the alkalinities and Mn-containing precursors of the reaction mixtures. This family of manganates is isostructural and has a space group of Pbam. The magnetic measurements for RMn₂O₅ showed an antiferromagnetic transition. The strong irreversibility between the ZFC and FC curves indicated a helicoidally magnetic structure below 40 K. The max d.c. susceptibilities of LaMn₂O_5+δ (δ=0.01, 0.06, 0.08, 0.16, 0.17) were found to be variable and the excess oxygen (δ) in the compounds was influenced by the alkalinity used in the hydrothermal synthesis.