Bridging Fluorine Atoms Research Articles

The effect of nitrogen addition on certain properties and structure of fluorozirconate glasses

The effect of nitrogen on the properties and structure of fluorozirconate glasses in the system ZrF4-BaF2-LaF3-AlF3 (ZBLA) was investigated. Nitrogen was introduced by means of aluminium nitride. The substitution of fluorine by nitrogen in ZBLA glasses resulted in a considerable increase of microhardness, reduction of the linear expansion coefficient, and a small increase in characteristic temperatures. Structural investigations comprised RDF and Fourier transform-infrared (FT-IR) examinations. From radial distribution function (RDF) it followed that the introduction of nitrogen caused an increase of the mean distances Zr-F(N), Ba-F(N), La-F(N). From FT-IR spectra, it followed that nitrogen became incorporated into the bridging fluorine atoms which was evinced by a shifting of bands deriving from the bending vibrations between the [ZrF6]2− octahedra towards higher wave numbers.

Vibrational spectra of solid CrF4 and of three new fluorochromate(IV) complexes with Xe fluorides, XeF2·CrF4, (XeF+5CrF−5)4·XeF4 and XeF+5CrF−5

Abstract Spectra of solid CrF 4 show bands assigned to stretching vibrations of terminal and bridging fluorine atoms, indicating a polymeric structure. The beginning of ionization of XeF 2 is revealed in the spectra of XeF 2 ·CrF 4 . The number of CrF terminal and bridging stretching bands tallies with the known X-ray diffraction structure. Spectra of (XeF + 5 CrF − 5 ) 4 ·XeF 4 disclose slight interactions of XeF 4 in the lattice and are characteristic for deformed XeF + 5 ions in structures with polymeric fluorometallate anions. Similar spectra, but with XeF 4 bands absent, indicate distorted XeF + 5 and polymeric chains of deformed fluorochromate(IV) octahedral in the structure of XeF + 5 CrF − 5 .

Hydrolysis of tin(II) fluoride and crystal structure of Sn4OF6

The hydrolysis of SnF2 in concentrated aqueous solution resulted in the formation of the tin(II) fluoride oxide, Sn4OF6. This is the first evidence for the formation of a basic tin(II) fluoride from an aqueous system. The crystal structure of Sn4OF6 has been determined using single-crystal X-ray diffraction and refined by full-matrix least-squares analysis to R= 0.0199. The compound crystallises in the orthorhombic space group P212121 with a= 16.088(3), b= 10.681 (2), c= 4.940(1)A and Z= 4. The structure consists of a three-dimensional polymeric network of bridging fluorine and oxygen atoms. Tin is present in four distinct sites one showing tetragonal-based pyramidal geometry while the others all show trigonal-pyramidal geometry with a fourth bridging fluorine atom at 2.4–2.5 A. The non-bonding electrons are stereochemically active and appear to point into irregular channels which run parallel to the c axis.

An unusual complex derived from MoCl 3(THF) 3 and AgBF 4 in acetonitrile: Synthesis and structure of [MO 2(μ-F)(NCCH 3) 8O 2][BF 4] 3

Reaction of MoCl 3(THF) 3 with 3 equiv of AgBF 4 in refluxing acetonitrile produces the unusual solvated Mo IV-oxo complex [Mo 2(μ-F)(NCCH 3) 8O 2[BF 4] 3 ( 1) as a result of oxidation by silver(I), as well as abstraction of both a fluoride ion from [BF 4] − and an oxygen atom from THF or adventitious water. Compound 1 has been investigated by 1H and 19F NMR, IR and UV-vis spectroscopy, electrochemistry and X-ray crystallography. Single crystal X-ray data collected at − 92 ± 2°C revealed that 1 is monoclinic, space group P2/ n with a = 11.776(4), b = 12.293(7), c = 12.497(7) Å, β = 100.90(4)°, V = 1776(1) Å 3 and Z = 2. Final refinement led to R = 0.038 and R w = 0.059. The structural core of the molecule consists of the unusual group [OMoFMoO] 3+ for which the angle MoFMo is 165.0°. The pyramidal MoN 4 units around each molybdenum(IV) centre are staggered with respect to one another, and as a result of the basal N plane being 0.27 Å from the molybdenum centre, the acetonitriles are canted towards the centre of the molecule forming a “cupped” central region around the bridging fluorine atom. This fluoride-bridged structure is unique among molybdenum(IV) dimers, and is one of only several documented examples in molybdenum chemistry.

The X-ray structure of bis-2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionatolead(II): an eight-coordinate dimer with bridging fluorine atoms

The title complex, a useful precursor for a range of lead oxides, has an unusual structure involving dimeric, eight-coordinate lead units bridged by the fluorine atoms of the ligand; the compound is unusually volatile which may in part be explained by the structure.

ChemInform Abstract: The Gas‐Phase Structures of Perfluoroquinolizidine and Perfluorotripropylamine

Abstract The geometric structures of perfluoroquinolizidine (PFQ) and perfluorotripropylamine (PFTA) have been studied by gas electron diffraction. For PFQ only the configuration with the nitrogen lone pair trans to the bridging fluorine atom was observed. Fluorination causes lengthening of the CC bonds and shortening of the NC bonds relative to those in piperidine and flattening of the six-membered rings. For PFTA a large number of rotational isomers has been considered. A structure with C 3 symmetry and planar configuration at the nitrogen atom best reproduces the experimental electron-diffraction intensities. Strong steric interactions in this molecule are further indicated by the increase in the NC and (CC) mean bond lengths [about 0.03 A relative to N (CF 3 ) 3 and C 2 F 6 ] and by opening of the NC 1 C 2 angle to 118.1(12)°.

The gas-phase structures of perfluoroquinolizidine and perfluorotripropylamine

The geometric structures of perfluoroquinolizidine (PFQ) and perfluorotripropylamine (PFTA) have been studied by gas electron diffraction. For PFQ only the configuration with the nitrogen lone pair trans to the bridging fluorine atom was observed. Fluorination causes lengthening of the CC bonds and shortening of the NC bonds relative to those in piperidine and flattening of the six-membered rings. For PFTA a large number of rotational isomers has been considered. A structure with C 3 symmetry and planar configuration at the nitrogen atom best reproduces the experimental electron-diffraction intensities. Strong steric interactions in this molecule are further indicated by the increase in the NC and (CC) mean bond lengths [about 0.03 Å relative to N (CF 3) 3 and C 2F 6] and by opening of the NC 1C 2 angle to 118.1(12)°.

Studies on peroxomolybdates. XVI: A new fluoro-bridged tetraperoxodimolybdate. Crystal structure of ammonium μ-fluoro-bis(fluorooxodiperoxomolybdate(VI)), (NH4)3[F{MoFO(02)2}2

Abstract The crystal structure of ammonium μ-fluoro-bis(fluorooxodiperoxomolybdate(VI)), (NH4)3[F{MoFO(O2)2}2], was determined by single-crystal X-ray diffraction methods. The yellow compound crystallizes in the mono-clinic space group P2/n with a = 10.686(7) A , b = 6.604(5) A , c = 8.338(7) A , β = 106.39° (at 170 K) and Z = 2. Two data sets were collected, one at 170 K (1797 reflections; R = 0.025) and one at 290 K (2757 reflections; R = 0.042). The complex anion is composed of two identical corner-sharing pentagonal bipyramids. Each molydenum atom is surrounded by a pentagonal bipyramidal arrangement of ligand atoms. Two side-on bonded peroxo groups and a fluorine atom form the equatorial plane, and the bridging fluorine atom and a double-bonded oxygen atom occupy the apical positions. The molybdenum atom is displaced by 0.324(1) A from the equatorial plane towards the double-bonded oxygen atom. Bond distances at 170 K are MoO peroxo = 1.934(2)–1.972(2) A , MoO apical = 1.670(2) A , MoF equatorial = 1.964(2) A , MoF apical = 2.196(1) A and (OO) peroxo = 1.473(2)–1.487(2) A . The angle MoFMo is 146.2(1)°.

Mössbauer resonance investigation of α-Sn 3F 8

Mössbauer resonance investigation have been performed on the mixed tin fluoride Sn 3F 8 over the temperature range 4.2 ⩽ T ⩽ 473 K. The effective vibrating masses M eff have been deduced from the temperature dependence of the isomer shift. The lattice temperatures calculated from the thermal evolution of the area of the resonance peak are θ M[Sn(II)] = 181 K and θ M[Sn(IV)] = 230 K. Using M eff, leads to lattice temperatures θ′ M[Sn(II)]=199K and θ′ M[Sn(IV)] = 164 K. The recoilless fractions obtained for Sn 3F 8 are relatively high in comparison with those of other tin compounds. Such a result is certainly due to the bridging fluorine atoms which give rise to a strong lattice rigidity.

Ab initio calculations on (SiH 3) 2F +: stability in the gas phase and model for bridging fluorine atom in ion-implanted amorphous silicon

Ab initio calculations have been performed on model molecular clusters simulating bridging fluorine configurations in fluorinated amorphous silicon. Optimized geometries, total energies and vibrational frequencies have been computed for (SiH 3) 2F + clusters with the terminal SiH 3 groups eclipsed or staggered. The stable minimum on the potential energy surface corresponds to a linear, but very flexible, Si-F-Si bridging configuration. (SiH 3) 2F + appears to be stable with respect to unimolecular decomposition. The calculated vibrational frequencies include a strongly infrared-active antisymmetric stretch mode at 740 cm −1, similar to the metastable “ Bband” experimentally observed at 750 cm −1 in the ion-implanted samples. These results are compared with calculated geometries and vibrational frequencies of SiH 3F, SiH 3F +, SiH 2F + and Si 2H 5F.

The preparation of bis(perfluoroethyl) tellurium difluoride and dichloride, trans perfluoroethyl tellurium monochloride tetrafluoride, trans bis(perfluoroethyl) tellurium tetrafluoride; and the preparation and X-ray crystal structure of perfluoroethyl tellurium trifluoride

The reaction of (C2F5)2Te and XeF2 in a slurry of SO2ClF yielded (C2F5)2TeF2 essentially quantitatively. Chlorine and (C2F5)2Te gave (C2F5)2TeCl2. Both (C2F5)2TeF2 and (C2F5)2TeCl2 were assigned a trigonal bipyramidal geometry, on the basis of their 19F nmr and vibrational spectra, with the lone pair and C2F5 groups in equatorial, and the halogens in the axial positions. Perfluoroethyl tellurium trifluoride was prepared essentially quantitatively by the reaction of C2F5TeTeC2F5 and XeF2 in liquid SO2F2. The generally inert SO2ClF was found to react with C2F5TeTeC2F5 to give C2F5TeClxF3−x, and sulphur dioxide. The structure of C2F5TeF3 was determined by X-ray diffraction. The crystals are tetragonal with a = 10.129(4), c = 25.561(6) Å, and Z = 16. The structure was refined in space group I41/a to a conventional R factor of 0.051 for 901 observed reflections with I ≥ 3σ(I). Each tellurium atom is surrounded by two terminal fluorine atoms and two bridging fluorine atoms and a C2F5 group in an axial position around the apex of a distorted square pyramid. The square-pyramidal units are linked by symmetrical cis bridging atoms into endless chains with bridging angles of 180° and 177°. The geometry of the (C2F5TeF4) group is consistent with steric activity of the non-bonded electron pair. The 19F nmr and Raman spectra of C2F5TeF3 were recorded and the Raman spectrum assigned. Trans-C2F5TeClF4 was prepared by the reaction of C2F5TeTeC2F5, and an excess of ClF. The trans octahedral geometry of C2F5TeClF4 was unambiguously assigned from its 19F nmr and vibrational spectra. A mixture of trans-(C2F5)2TeF4 and trans-C2F5TeClF4 was obtained from the reaction of (C2F5)2Te and an excess of ClF. Trans geometry of (C2F5)2TeF4 was unambiguously assigned from its 19F nmr spectrum.

ReNF4 · ReF5(NCl), ein Nitrido-Nitrenokomplex von Rhenium(VII)/ ReNF4 · ReF5(NCl), a Nitrido Nitrene Complex of Rhenium (VII)

Abstract ReNF4 · ReF5(NCl) is prepared by direct fluorination of ReNCl4 with fluorine between 80 °C and 130 °C. The red crystals are extremely sensitive to moisture. The complex is characterized by the IR spectrum and by an X-ray structural investigation. ReNF4 · ReF5(NCl) crystallizes orthorhombically in the space group Pnma with 4 formula units per unit cell and with the cell dimensions a = 1440, b = 848, c = 776 pm (419 observed, independent reflexions, R = 13.9%). The complex consists of the molecules ReNF4 and ReF5(NCl), which are linked by a linear asymmetric fluorine bridge. The bridging fluorine atom is in trans-position to the nitrido ligand Re -F - 228 pm) and to the nitreno ligand (Re -F = 159 pm and Re= N - Cl 164 pm) correspond to triple 188 pm). The Re ≡ N bond lengths Re= N bonds.

Crystal structure of fluoroxenon(1+) hexafluoroarsenate(1-)

Crystals of XeF/sup +/AsF/sub 6//sup -/ are monoclinic, space group P2/sub 1//n, a = 6.308 (3) A, b = 6.275 (3) A, c = 16.023 (5) A, ..beta.. = 99.97 (5)/sup 0/, V = 624.66 A/sup 3/, Z = 4, and d/sub x/ = 3.61 g cm/sup -3/, at 24/sup 0/C. X-ray diffraction data were measured with counter methods and Mo K..cap alpha.. radiation. With anisotropic temperature factors for all atoms, R = 0.033 for 777 independent reflections (I greater than 3 sigma). The structure consists of ion pairs connected by a bridging fluorine atom into FXeFAsF/sub 5/ units. The FXeF portion of the molecule is linear (angle = 178.9 (7)/sup 0/) with Xe--F = 1.873 (6) A (terminal) and 2.212 (5) A (bridging). The FAsF/sub 5/ portion of the molecule is roughly octahedral with cis F--As--F angles ranging from 85.3 (3) to 94.6 (5)/sup 0/; the five terminal As--F distances range from 1.676 (5) to 1.690 (8) A and the bridging As--F distance is 1.813 (6) A. The bridge Xe--F--As angle is 134.8 (2)/sup 0/. 6 tables, 4 figures, 24 references.

ChemInform Abstract: FLUORIDE CRYSTAL STRUCTURES. PART 32. TRIANTIMONY NONACHLORIDE TETRAFLUORIDE OXIDE

AbstractSb3Cl9F4O entsteht als Nebenprodukt der Reaktion von C12 mit SbF3.

Fluoride crystal structures. Part 32. Triantimony nonachloride tetrafluoride oxide

The title compound has been prepared as a minor component in the reaction of chlorine with antimony trifluoride. Its structure has been determined from X-ray diffractometer data and refined by full-matrix least-squares methods to R 0.067 for 3 379 reflections. Crystals are triclinic, space group P, a= 9.79, b= 13.24, c= 6.94 A, α= 93.1, β= 105.3, γ= 91.1°. In the structure each antimony atom has octahedral co-ordination, two with three terminal chlorine atoms, two bridging fluorine atoms, and a bridging oxygen atom, and the third with three terminal chlorine atoms and two bridging and one terminal fluorine atoms. Two antimony atoms are linked together by a double bridge, consisting of an oxygen and a fluorine atom, and are also linked to the third antimony atom by single fluorine bridges.

Fluoride crystal structures. Part XXI. Trifluorotellurium(IV)µ-fluorobis[pentafluoroantimonate(V)

The interaction of tellurium tetrafluoride and antimony pentafluoride gives the title compound as a minor product. Crystals are monoclinic, space group P21/c, a= 7·48 ± 0·01, b= 14·29 ± 0·02, c= 9·72 ± 0·01 A, β= 91·0°± 0·2°. The structure was solved by Patterson and Fourier methods and refined by three-dimensional least-squares methods to R 0·095 for 824 reflections measured photographically. Although the atomic arrangement is consistent with the ionic formulation [TeF3]+[Sb2F11]– there is considerable interaction between the ions through fluorine bridging. The cation has C3v symmetry, with a mean Te–F distance of 1·84 A, and there are three long contacts of 2·54, 2·55, and 2·69 A to bridging fluorine atoms to give a much distorted octahedral co-ordination for tellurium, very similar to that found for selenium in [SeF3]+[Nb2F11]–.

Preparation and crystal structure of osmium pentaluoride

The preparation of osmium pentafluoride is described. Crystal of the solid are monoclinic, space group P21/c, a= 5·53, b= 9·91, c= 12·59 A, β= 99·5°. The structure was refined by three-dimensional least-squares methods, the final R being 0·106 for 642 independent reflections. The compound is isostructural with ruthenium pentafluoride. The structural unit is a tetramer with osmium atoms at the corners of a rhombus, non-linearly linked by bridging fluorine atoms. The fluorine atoms have been shown to form an approximately hexagonal closepacked lattice.

The crystal structure of ammonium dioxotrifluoromolybdate

An X-ray crystal study of NH4MoO2F3 has shown that MoO2F3–1 anions exist in infinite chains formed by fluorine bridging atoms; in each MoO2F4 octahedron two terminal oxygen atoms are cis-related and the bridging fluorine atoms are trans to the oxygen atoms.

Fluoride crystal structures. Part XVII. Dipotassium pentafluoro-manganate(III) hydrate

Crystals of dipotassium pentafluoromanganate(III) hydrate are monoclinic, space group P21/m, a= 6·04, b= 8·20, c= 5·94 A, β= 96·5°, Z= 2. The structure was refined by three-dimensional least squares methods to R 0·093 for 663 reflections. In the crystal the water molecule is not co-ordinated to manganese, and the manganese atoms are linked through trans bridging fluorine atoms to give endless kinked chains parallel to b, with a distorted octahedral co-ordination of the manganese atoms. Mn–F distances are 1·82, 1·84, and 2·07 A. The potassium ions and water molecule, together with the fluorine atoms, are arranged in a distorted cubic close packed arrangement, where the distortion can be correlated with a hydrogen bonding network.

Fluoride crystal structures. Part IV. Tellurium tetrafluoride

Crystals of tellurium tetrafluoride are orthorhombic, space group P212121, a= 5·36, b= 6·22, c= 9·64 A. The structure was refined by three-dimensional least-squares methods, the final R being 0·084 for 376 reflections. Each tellurium atom in the structure is surrounded by three terminal and two bridging fluorine atoms arranged at the apices of a distorted square pyramid. The square-pyramidal units are linked by cis bridging atoms into endless chains with a bridge angle of 159°. The geometry of the [TeF5] group is consistent with steric activity of the non-bonding electron pair and the arrangement can be described as a distorted octahedral co-ordination of the tellurium atom by five fluorine ligands and the electron pair.