An Organogold(III) Difluoride with a trans Arrangement

The trans isomer of the organogold(III) difluoride complex [PPh₄][(CF₃)₂AuF₂] has been obtained in a stereoselective way and in excellent yield by reaction of [PPh₄][CF₃AuCF₃] with XeF₂ under mild conditions. The compound is both thermally stable and reactive. Thus, the fluoride ligands are stereospecifically replaced by any heavier halide or by cyanide, the cyanide affording [PPh₄][trans‐(CF₃)₂Au(CN)₂]. The organogold fluoride complexes [CF₃AuF_x]^? (x=1, 2, 3) have been experimentally detected to arise upon collision‐induced dissociation of the [trans‐(CF₃)₂AuF₂]^? anion in the gas phase. Their structures have been calculated by DFT methods. In the isomeric forms identified for the open‐shell species [CF₃AuF₂]^?, the spin density residing on the metal center is found to strongly depend on the precise stereochemistry. Based on crystallographic evidence, it is concluded that Auⁱⁱⁱ and Agⁱⁱⁱ have similar covalent radii, at least in their most common square‐planar geometry.     

NMR Study of the Reactions of Tin(II) Difluoride and Antimony(III) Trifluoride with Niobium Pentachloride

The reactions of SnF₂and SbF₃with NbCl₅in acetonitrile or dimethyl sulfoxide were studied by ¹⁹F, ⁹³Nb, and ¹¹⁹Sn NMR spectroscopy. The products of reaction in acetonitrile are anionic, while those in di-methyl sulfoxide are neutral octahedral niobium chlorofluoride complexes. Tin(II) difluoride and antimony(III) trifluoride are powerful sources of fluoride ions in the preparation of metal chlorofluoride and fluoro complexes.     

Near-Infrared Boron Difluoride Formazanate Dyes

Near-infrared (NIR) dyes are sought after for their utility in light harvesting, bioimaging, and light-mediated therapies. Since long-wavelength photoluminescence typically involves extensive π-conjugated systems of double bonds and aromatic rings, it is often assumed that NIR dyes have to be large molecules that require complex syntheses. We challenge this assumption by demonstrating that facile incorporation of tertiary amine groups into readily available 3-cyanoformazans affords efficient production of relatively simple NIR-active BF₂ formazanate dyes (λ_abs=691–760 nm, λ_PL=834–904 nm in toluene). Cyclic voltammetry experiments on these compounds reveal multiple reversible redox waves linked to the interplay between the tertiary amine and BF₂ formazanate moieties. Density-functional calculations indicate that the NIR electronic transitions in BF₂ formazanates are of π→π*-type, but do not always involve strong charge transfer.     

Isocyanate-Terminated Poly(ethylene Oxide)

Isocyanate-terminated polyethylene oxide (PEO) was prepared by reaction of hydroxyl-terminated PEO of different molecular weights and toluene diisocyanate (TDI), at a molar ratio of 1:2. Reaction was carried out with and without catalyst (dibutyltin dilaurate). When catalyst was used, some chain extension accompanied the endcapping reaction. When endcapping reaction was carried out without catalyst, chain extension was minimal as determined from endgroup analysis and viscosity measurements. It was also found that secondary reactions of the terminal isocyanate groups led to further increase in solution viscosity after completion of the endcapping reaction.     

Tin(II) Difluoride and Antimony(III) Trifluoride as Fluorine Donors in Reactions with Tantalum Halides in Various Solvents

Reactions of SnF₂and SbF₃with TaF₅and TaCl₅in acetonitrile and dimethyl sulfoxide were studied by ¹⁹F and ¹¹⁹Sn NMR. It was found that SnF₂and SbF₃behave as fluorine donors for tantalum(V). The anionic and cationic tantalum fluorochloride complexes form in acetonitrile, while [TaF₆]^–predominates in dimethyl sulfoxide. Tin(II) occurs in solution in the form of fluorine-containing polymeric cations.     

Block Polymers Derived from Poly(ethylene Oxide) and Carboxyl-Terminated Polybutadiene

The use of preformed poly(ethylene oxide) (PEO) and carboxyl-terminated polybutadiene (CTPB) for the preparation of block polymers is reported. Block polymerization was carried out by esterification and by coupling of equimolar amounts of these polymers with 2,4-toluene diisocyanate (TDI). When esterification was carried out, conversion of the two preformed polymers and block polymer composition varied with reaction temperature, catalyst used, and molecular weight of the PEO. Full conversions were not obtained. Better results were achieved when the preformed polymers were coupled with TDI. Tensile properties and water absorption capability of these block polymers were determined. Hydrogels with high water content up to 82% were obtained.     

Solvent and Zn2+ Binding Effects on the Photo-physical Properties of (Dibenzoylmethanato)boron Difluoride

Absorption and emission spectroscopic studies of (dibenzoylmethanato)boron difluoride (1bf) in various polar and non-polar, protic and aprotic solvents are reported. The solvatochromic shifts of the spectral bands were examined in terms of solvent properties, including donor and acceptor numbers, followed by multilinear regression in which several solvent parameters were simultaneously analyzed. This π-conjugated positively charged system exhibits excellent solvatochromism. Variations in the electronic absorption spectral characteristics of 1bf were studied in solution in the presence of zinc perchlorate. Absorption spectral studies indicate stable complex formation between the zinc ion and 1bf in the ground state in aprotic dipolar benzonitrile rather than in protic polar solvent methanol. Zinc ion binding of 1bf was theoretically rationalized through frontier molecular orbital interaction.     

Synthesis and Structure of Triphenylbismuth Difluoride

The reaction of triphenylbismuth dichloride with sodium fluoride in acetone leads to formation of triphenylbismuth difluoride in 73% yield. The X-ray diffraction data show that the bismuth atom in the two symmetrically independent molecules of bismuth difluoride has a trigonal-bipyramidal coordination with equatorial fluorine atoms. The Bi-F and Bi-C distances are 2.53(1)-2.59(1) and 2.10(3)-2.22(2) Å, respectively, and the FBiF angle is 175.1(5)°.     

Adsorption of A Multifunctional Additive (ZnDTC) Onto Iron and Iron(III) Oxide from n-Decane

The adsorption of zinc diisooctylodithiocarbamate (ZnDTC) onto iron and iron(III) oxide from n-decane solution was studied. The adsorption isotherms were determined together with the variation of the apparent differential molar enthalpy of displacement for ZnDTC on both adsorbents at 298 K. The shapes of the iostherms for the adsorption of dithiocarbamate on iron and iron(III) oxide are quite different, especially in the low coverage ratio. The corresponding differential molar enthalpies of displacement for the two studied systems are exothermic. On iron, the very high exothermic values indicate a process of ZnDTC chemisorption, while on iron(III) oxide, the much lower enthalpic effects are characteristic of physisorption.