Reactions of triphenylarsine oxide with aqueous hydrogen fluoride: Crystal structure of bis(triphenylarsine oxide)hydrogen(I) tetrafluoroborate

Fluorination of triphenylarsine oxide by aqueous hydrogen fluoride (1–40%) in the absence of glass readily gives triphenylarsine difluoride. When the reaction with dilute (1%) aqueous hydrogen fluoride is carried out in borosilicate glass apparatus, the glass participates in the reaction resulting in the formation of the crystalline 2:1 adduct 2Ph₃AsO·HBF₄. Crystals of this compound are monoclinic, $\text{P}$2₁/$\text{c}$, $\text{a}$ = 12.926(4), $\text{b}$ = 17.819(6), $\text{c}$ = 14.994(4) Å, β = 98.97(3)°, Z = 4. The structure contains cations [(Ph₃AsO)₂H]⁺ in which $\text{O}\text{?}$O is 2.44(2)Å, and anions BF₄^?.     

Some reactions of 1,2,3,4,7,7-hexafluorobicyclo[2,2,1]hepta-2,5-diene: Thermolysis and attack by methoxide ion and by bistrifluoromethyl nitroxide

1,2,3,4,7,7-Hexafluorobicyclo[2,2,1]hepta-2,5-diene gave 1,2,3,4-tetrafluorebenzene in at least 73% yield when heated to 450°C in a sealed tube; the CF₂ bridge appeared, in part, as octafluorocyclobutane. Nucleophilic attack by sodium methoxide- methanol on the diene occurred exclusively at the CFCF bond, causing the formation of 1,2,4,7,7-pentafluoro-3-methoxybicyclo- [2,2,1]hepta-2,5-diene and a 1,4,5,6,7,7-hexafluoro-5-methoxybicyclo [2,2,1]hept-2-ene thought, on the basis of ¹⁹F nmr data, to be the 6-$\text{endo}$-F,5-$\text{exo}$-MeO isomer. Radical attack on 1,2,3,- 4,7,7-hexafluorobicyclo[2,2,1]hepta-2,5-diene by bistrifluoromethyl nitroxide took place at both olefinic sites, with a $\text{ca}$. 10:1 preference for the CFCF linkage; all three geometrical isomers of 5,6-bis(bistrifluoromethylamino-oxy)-1,4,5,6,7,7- hexafluorobicyclo[2,2,1]hept-2-ene were formed.     

Crystal structures of V3S4 and V5S8

Crystal structures of the ordered phases of V₃S₄ and V₅S₈ were refined with single crystal data. Both are monoclinic. Chemical compositions, space groups and lattice constants are as follows: VS_1.47, $\text{I2}\text{m}$ (No. 12), a = 5.831(1), b = 3.267(1), c = 11.317(2)Å, β = 91.78(1)° and VS_1.64, $\text{F}\text{2}\text{m}$ (No. 12), a = 11.396(11), b = 6.645(7), c = 11.293(4), Å, β = 91.45(6)°. In both structures, short metal-metal bonds were found between the layers as well as within them. In comparison with the structure of Fe₇S₈, the stability of NiAs-type structure was discussed based on the detailed metal-sulfur distances.     

Preparation of some highly halogenated derivative of furan

Direct chlorination of 2-(2H-hexafluoropropyl)-tetra- hydrofuran $\text{1}$ gave high yield of 2-(2-chlorohexafluoropropyl)- pentachloro-2,5-dihydrofuran $\text{2}$. Bromination of $\text{1}$ gave very complex mixture of products, from which three compounds, $\text{viz}$. 2-bromo-5-(2H-hexafluoropropyl)-furan $\text{3}$, 3-bromo-5-(2H-hexafluoropropyl)-furan $\text{4}$, and 2,4-dibromo-5-(2H-hexafluoropropyl)furan $\text{5}$ were isolated. Exchange fluorination of $\text{2}$ with dry KF at 240 – 300° led to a stepwise substitution of fluorines for chlorines to give mixtures of chloro-fluoro-2-(2-chlorohexafluoropropyl)-dihydrofurans $\text{7}$,$\text{8}$,$\text{9}$ and $\text{10}$, together with small amounts of 2-(2-chlorohexafluoropropyl)-3,4,5-trichlorofuran $\text{6}$.Exchange fluorination of 3,4-dihalo-2,2,5,5-tetrafluoro- 2,5-dihydrofurans $\text{11a}$ and $\text{11b}$ led to a substitution of fluorine for one vinylic halogen to give 3-halo-2,2,4,5,5-pentafluoro-2,5-dihydrofurans $\text{12a}$ and $\text{12b}$ in good yields.Compounds $\text{2}$ – $\text{12}$ were characterised by n.m.r., m.s., and i.r. spectroscopy and elemental analysis.     

Darstellung und eigenschaften von bis(μ-fumarato)bis[di(π-cyclopentadienyl)titan(IV)]; strukturuntersuchungen der reinen und der kristall-chloroform enthaltenden phase

The reaction of titanocene dichloride with disodium fumarate in the two-phase system H₂O/CHCl₃ yields bis(μ-fumarato)bis[di(π-cyclopentadienyl)titamum(IV)]. Crystal data for the pure compound (IIIa): monoclinic, P2₁/n, a 18.558(5), b 9.076(5), c 7.559(2) Å, β 101.69(2)°; Z = 2. Crystal data for a phase containing chloroform of crystallization (CHCl₃/Ti = $\text{1}\text{1}$) (IIIb): triclinic, P$\text{1}$, a 20.439(11), b 10.269(5), c 8.858(3) Å, α 112.18(3), β 93.93(5), γ 91.63(7)°; Z = 2 × 1. The three independent [(π-C₅H₅)₂TiOCOCHHOCO]₂ molecules differ in the puckering of their 14-membered rings and the geometry of their TiOC units.     

Comparative reactions between aziridines and F2, COF2, CF3OF

In CFCl₃, aziridines $\text{I}$ react with F₂(6 %/N₂,  20°C), COF₂ (20 %/N₂,  40°C) and CF₃OF [1] (20 %/N₂,  40°C).Substitution products are obtained : l-(aziridine)carbonyl fluorides $\text{II}$ and l-Fluoroaziridines $\text{III}$

In (Et)₂O, aziridines $\text{I}$ react with COF₂ (20 %/N₂, 10°C) and we have the carbonyl fluorides $\text{IV}$.

Products IV can be thermally decomposed into β fluoro isocyanates.In CFCl₃, N substituted aziridines $\text{V}$ react with F₂(6%/N₂, 20°C) and with CF₃OF [2] (20%/N₂, 40°C). No reaction is observed with COF₂in our conditions (5% to 25%/N₂, 80°C to + 40°C).Addition products are obtained : N Fluoro amines β fluorinated $\text{VI}$, N Fluoro and NN difluoro amines β trifluoro methoxylated $\text{VII}$ and $\text{VIII}$.

with R = SO₂Ø, COØNO₂, Cl.     

Metal—metal bonding in dinuclear complexes of platinum(I). The crystal and molecular structure of carbonyl(chloro)-bis-μ-[bis(diphenylphosphino)methane]diplatinum hexafluorophosphate

The structure of [Pt₂Cl(CO) (μ-Ph₂PCH₂PPh₂)₂] [PF₆] was determined by $\text{X}$-ray methods and refined to $\text{R}$ = 0.082, using diffractometric intensities of 5646 independent reflections. The crystals are monoclinic, space group $\text{P}$2₁/$\text{n}$, $\text{a}$ = 12.919(3), $\text{b}$ = 15.576(6), $\text{c}$ = 25.151(5)Å, β = 94.82(3)°, $\text{Z}$ = 4. They are built of octahedral hexafluorophosphate anions and dinuclear platinum(I) cations. The latter contain PtCl and PtCO fragments linked to one another by a PtPt σ-bond and by two bridging bis(diphenylphosphino)methane ligands. The platinum atoms are in square planar environments and the dihedral angle between the two coordination planes is 40.1°. Selected bond lengths are: PtPt 2.620(1), PtCl 2.384(5), PtC 1.89(3) and PtP 2.291(5) – 2.308(5)Å.     

Nuclear magnetic resonance spectra of polyfluorobuta-1,3-dienes. Part II [1]. Variable temperature study of two 2-azabutadienes

The two perfluoro-azadienes CF₂N.CRCF₂ (R = CF₃ or CF₂Cl) show temperature dependent ¹⁹F n.m.r. spectra, with non-equivalent fluorine nuclei of the CF₂N portion at low temperatures, which coalesce due to inversion at the nitrogen at higher temperatures (ΔG3 = 60 kJ mol^?1). N.m.r. parameters have been obtained. One of the five-bond FF coupling constants is much larger ($\text{ca}$. 24 Hz) than the remainder (0·5–5·5 Hz), possibly due to ‘through-space’ coupling of fluorines in the $\text{cis}$-skew conformation.     

Synthesis and crystal structure of 1,1,1,5,5,5-hexafluoro-2-aminopentan-4-one (HFAP)

The vapour phase reaction of ammonia and hexafluoroacetylacetone leads to the formation of the new β-keto-amine C₅H₃F₆NO. Crystals of the compound are monoclinic, space group $\text{P}$2₁/$\text{n}$, $\text{a}$ = 10.01(2), $\text{b}$ = 19.33(3), $\text{c}$ = 8.40(1) Å, β = 82.27(6)°; final R = 0.044.     

The structures of 5-methyl-5-phenyl-5H-dibenzo[b,f] silepin and its saturated analog

The structures of 5-methyl-5-phenyl-5H-dibenzo[b,f] silepin (I) and 5-methyl- 5-phenyl-1O,11-dihydro-5H-dibenzo [b,f] silepin (II) have been determined from three-dimensional X-ray data collected by counter methods. I crystallizes in the orthorhombic space group Pnam with a 7.596(3), b 18.102(5) and c 12.190(2) Å; observed and calculated densities (Z = 4) are 1.17 and 1.18 g cm^?3, respectively. II crystallizes in the monoclinic space group $\text{P}\text{2}{}_1\text{c}$ with a 11.115(3), b 7.920(3), c 20.765(5) Å and β 111.71(2)°; observed and calculated densities (Z = 4) are 1.17 g cm^?3. Anisotropic refinement of nonhydrogen atoms, with hydrogen atoms included at fixed ideal locations, gave conventional R-factors of 4.5% (I) and 5.0% (II). Compound I exhibits the boat conformation for the tricyclic framework and is located on a crystallographically required mirror plane. Com- pound II has the expected folded boat conformation. The torsion angle about the 10,11-bond is 0.0° for I, a crystallographic symmetry requirement, and 89.9° for II. Mean SiC bond distances are 1.863 Å(I) and 1.875 Å(II). The dihedral angles between the planar benzo groups are 129.7° (I) and 137.2° (II); introduc- tion of unsaturation at the 10,11-position decreases the dihedral angle in the tri- cyclic system, i.e., the tricyclic system is more bent.     

The crystal structure of N-sodiohexamethyldisilazane,Na[N{Si(CH3)3}2]

The crystal structure of Na[N{Si(CH₃)₃}₂] has been determined from single-crystal x-ray diffraction data collected by counter methods. N-sodiohexamethyldisilazane crystallizes in the mono-clinic space group p21/n with unit cell parameters $\text{a}$ = 9.426(3), $\text{b}$ = 6.921(3), c = 17.974(5)Å, β = 93.83(2)°, and ?_calc = 1.04 g cm^?3 for z = 4 formula units. Least-squares refinement gave a final conventional R value of 0.034 for 1244 independent observed reflections. In the solid state the compound exists in a polymeric arrangement with an average Na-N distance of 2.355(4)Å. The methyl group are configured such that the angle of rotation of the trimethylsilyl moiety about the Si-N bond is 30° from the eclipsed position. The Si-N bond length is 1.690(5)Å, and the Si-N-Si bond angle is 125.6(1)°.     

Organothiometallate - alkyne addition products. The crystal and molecular structure of [(η5-C5H5)W{C(CO2Me)C(CO2Me)C(O)SMe} (CO)2]

The title compound is the final product of the reaction between dimethylacetylene dicarboxylate and [(η⁵-C₅H₅)W(SMe) (CO)₃ ]. Its molecular structure has been established by an $\text{x}$-ray analysis based on 3301 diffractometric intensities. The crystals are monoclinic, space group $\text{P}$2₁/$\text{a}$, with four molecules in a cell of dimensions $\text{a}$ = 10.323(2), $\text{b}$ = 16.016(2), $\text{c}$ = 10.437(2)», β = 103.56(2)°. After least-squares refinement $\text{R}$ = 0.036. The tungsten co-ordination is square-pyramidal, the apical site being occupied by the centroid of the cyclopentadienyl ring. The basal co-ordination sites contain two carbonyl groups and also the sulphur and σ-bonded carbon atoms of a chelating carbothiolic methyl ester ligand derived from the incoming alkyne and CO and SMe groups of the original complex. The W-S and σ-W-C bond lengths are 2.440(2) and 2.194(7)».     

Poly(hexamethylene terephthalate)—II. The crystal structure of forms I and II,from electron and x-ray diffraction,and packing analyses

Form I of poly(hexamethylene terephthalate), poly(6GT), has been shown, through electron diffraction of micro-single crystals, and fibre X-ray diffraction to belong to the triclinic system. The unit cell containing only one chain has dimensions $\text{a = 5.217(8), b = 5.284(12), c = 15.738(16)}\text{A}\text{?}\text{(}\text{fibre axis}\text{), α = 129.4(2), β = 97.6(2)}\text{and}\text{γ = 95.6(2)°}$. The space group is PT. The crystal structure of poly(6GT) form I has been established by the model compound approach and confirmed using 19 independent electron diffraction intensities. Upon refinement of the scale and temperature factors, the agreement index R reaches 0.172, with an overall isotropic temperature factor $\text{B = 3.0}\text{A}\text{?}{}_2$. Calculation of dynamical amplitudes, and also of structure amplitudes which allow for crystal bending, confirms that the electron diffraction data are suitable for a conventional structure analysis. The chain of the polyester has the same fully extended conformation as its related model compound hexamethylene glycol dibenzoate. The planar chain in the single cell is at 35° to the α-axis. The unit-cell dimensions of poly(6GT) form II differ from those of form I by the doubling of the b-dimension. The two chains in the double unit-cell are at 31 and 39° respectively from the a-axis. The agreement index R is 0.161 for the 19 reflections of the single cell and R = 0.196 when the 10 reflections causing the doubling of b are included.     

Vacuum flash pyrolysis (VFP) of malonyl peroxides: decarboxylation versus decarbonylation of the intermediary α-lactones

Vacuum Flash Pyrolysis (VFP) at ca. 450–500°C and ca. 0.1–0.3 Torr of the spirocyclic malonyl peroxides ($\text{2a,b}$) affords high yields of allenes ($\text{5a,b}$), while the simple malonyl peroxide ($\text{2c}$) leads to ketone ($\text{4}$), derived respectively from decarboxylation and decarbonylation of the intermediary α-lactones ($\text{3}$).     

The crystal and molecular structure of μ-μ-dichlorobis(hexafluorobut-2-enyl)-bis(cycloocta-1,5-dienyl)diiridium(III).

The title compound is isolated from reaction of hexafluorobut-2-yne with μ-μ-Dichlorobis(cycloocta-1,5-diene)diiridium(I) at 90°C. Crystals of the complex, solvated with deuterobenzene, are monoclinic, space group $\text{P}$2₁/$\text{n}$ with $\text{a}$ = 10.97 $\text{+}$ 0.02, $\text{b}$ = 17.96 $\text{+}$ 0.03, $\text{c}$ = 11.63 $\text{+}$ 0.02 », β = 127.4 $\text{+}$ 0.60°. The acetylene has abstracted a hydrogen atom forming a σ-bonded $\text{cis}$-vinylic group and the original cyclooctadiene, having lost a proton, is coordinated as the cycloocta-1,5-dienyl ligand. Mean bond lengths are IrCl 2.467, IrC (allylic) 2.17, IC (olefinic) 2.36 and IrC (vinylic) 2.09 ».     

H3N·PF5 and H2NPF5−, new compounds in the system H3N/PF5

Phosphorus pentafluoride was reported long ago to give adducts 2 PF₅ ·5 NH₃ (1) and nNH₃·PF₅ (n= 1 ? 4) (2). None of the compounds was characterised in detail. Repeating the reaction of PF₅ and NH₃ we found the adduct H₃N·PF₅, $\text{1}$, in 8% yield besides (H₂N) ₂PF₃ (3) and NH₄PF₆. However, HF and (F₂P=N)₃ gave $\text{1}$ in 41% yield. The ¹H, ¹⁹F, and ³¹P n.m.r. spectra of $\text{1}$ exhibit ¹⁴NH, ¹⁴NPF(cis), and ¹⁴NP coupling. The x-ray structure determination shows almost perfect octahedral geometry at phosphorus with a PN bond length of 1.842 ā. Compound $\text{1}$ is soluble in water without decomposition. Treatment with NH₃ leads to the anion H₂NPF₅^?. Upon heating $\text{1}$ forms in good yield H₂NPF₄ and NH₄PF₆. Without a solvent $\text{1}$ and NH₃ react to give (H₂N) ₂PF₃. A mechanism for the ammonolysis of PF₅ is proposed.     

Übergangsmetall-silyl-komplexe: IV. Bildung eines ring-substituierten wolframocen dihydrid derivats durch reaktion von Cp2WCl2 MIT Li[Si(SiMe3)3]

In the reaction of Cp₂WGl₂ with Li[Si(SiMe₃)₃] the dihydrid tungstenocene derivative [(Me₃Si)₃SiC₅H₄]WH₂ (3) is formed with a 56% yield. 3 crystallizes in space group P$\text{1}$, with a 918.0(4), b 1580.9(4), c 1621.2(7) pm, α 117.63(2), β 89.95(3), γ 94.39(3)° at ?40° C. The dihedral angle between the Cp planes is 140.9°.     

X-ray molecular structure of the 1:1 adduct of [FeH(CO)4]− and dimethyl acetylenedicarboxylate. η3-[trans-2,3-bis(methoxycarbonyl)acryloyl]tricarbonylferrate

The crystal structure of a bis(triphenylphosphine)iminium salt of the 1:1 adduct of [FeH(CO)₄]^? and dimethyl acetylenecarboxylate has been determined from three-dimensional X-ray data collected by the counter method. Single crystals belong to the triclinic space space group P$\text{1}$, with two units of [C₃₆H₃₀NP₂]⁺[C₁₀H₇FeO₈]^? in a cell of dimensions: $\text{a}$ = 13.918(2), $\text{b}$ = 15.669(5), $\text{c}$ = 9.909(2) Å, $\text{α}$ = 91.22(3), $\text{β}$ = 94.83(2), and $\text{γ}$ = 77.62(2)°. The structure was refined to a conventional $\text{R}$ of 0.068 for 5373 observed

reflections. The resulting structure indicates that the complex anion is η³-[$\text{trans}$-2,3-bis(methoxycarbonyl)acryloyl]tricarbonylferrate, the coordination around the iron atom being described as a considerably distorted trigonal bipyramid. A comparison of the present structure with the structures of related complexes suggests that the η³-acryloyl portion is best represented as an intermediate of (η³-allyl) with the oxygen atom and (η²-olefin + η¹-acyl). The short Fe-C(acyl) length of 1.897(5) Å implies an enhanced back-donation of electrons from the iron atom to the acyl group.