Synthesis, characterization, and substitution chemistry of [Bu4N]2[W6Cl8(OSO2CF3)6]. A versatile precursor for axially substituted clusters containing the (W6Cl8)4+ core

The new cluster [Bu4N]2[W6Cl8(OSO2CF3)6] (1) has been prepared and structurally characterized. This material is an effective precursor for the generation of cluster ions with the general formula [W6C18L6]n (L = Cl-, Br-, I-, NCS-, NCO-, NCSe-, and O=PPh3; n = 2- or 4+). The last three clusters are new. The products have been characterized by IR spectroscopy, NMR spectroscopy, and FAB mass spectrometry. In addition to 1, the products [Bu4N]2[W6C18(NCS)6] (5) and [Bu4N]2[W6C18(NCO)6] (7) were structurally characterized. Crystal data for 1: space group, P2(1/c) (No. 14); a = 11.116(5) A; b = 27.952(1) A; c = 24.516(1) A; beta = 95.182(9) degrees; V = 7586.3(5) A3; Z = 4. Crystal data for 5: space group, P2(1/n) (No. 14); a = 11.3323(9) A; b = 12.3404(9) A; c = 44.583(3) A; beta = 97.089(1) degrees ; V = 6187.1(7) A3; Z = 4. Crystal data for 7: space group, P1 (No. 2); a = 11.8009(8) A; b = 11.9332(8) A; c = 11.9522(8) A; alpha = 77.904(1) degrees; beta = 95.182(9) degrees; gamma = 62.574(1) degrees V = 1450.5(2) A3; Z = 1.     

Selective separation of uranium from other elements by cation-exchange chromatography in hydrobromic acid and hydrochloric acid-acetone mixtures

U(VI) can be separated from Ga, Fe(III), Bi, Pb, Cd, Zn, Cu(II) and Au(III) by quantitative elution with 0.50M HBr in 86% acetone or with 0.35M HBr in 90% acetone from a column of AG50W-X4 cation-exchange resin of 200-400 mesh particle size. U(VI) and many other ions are retained. U(VI) then can be eluted selectively with 0.50M HCl in 83% acetone or with 0.35M HCl in 85% acetone. Co(II), Mn(II), Mg, Ca, Ti(IV), Al, Zr, Th and La are quantitatively retained by the column. These elements then can be eluted with 5M HNO(3). At the higher acid concentration (0.50M) the separation between U(VI) and Li is not satisfactory but is excellent at the lower acid concentration; the U(VI) peak is sharper at the higher acid concentration. Separations are sharp and quantitative, as is demonstrated by results for some synthetic mixtures. Distribution coefficients and elution curves are presented.     

X-Ray Structure and Proton NMR Study of a Hexacoordinated Lithium Complex

The structure of the lithium complex with1,3,5-tris[oxymethylene(N,N-dicyclohexyl)carboxyamido]cyclohexanehas been determined by the X-ray method.The compound is triclinic, space group P¯1,a = 15.623(3), b = 19.279(4),c = 19.295(4)Å = 102.32(3), = 92.45(3), = 105.67(3)0, V = 5436(2)Å3, Z = 4. Itscomposition is represented by the formulaC48H82N3O6LiI 0.5H2O. The lithium cationis encapsulated in a polar pseudo-cavity of six oxygen atoms of the ligandmolecule and displays a distorted trigonal prism coordination. The conformationof the ligand in the solid state complex has been compared with the conformationof the complex in solution determined by 1H-NMR measurements.Supplementary data relevant to this publication have been deposited with the British Library, No. SUP 82224 (21 pages).     

High‐efficiency polymer solar cells based on phenylenevinylene copolymer with BF2‐azopyrrole complex and CN‐PC70BM with solvent additive

Power conversion efficiency (PCE) of phenylenevinylene‐based copolymer with BF₂ azopyrrole complex (PB)/modified PC₇₀BM, that is, CN‐PC₇₀BM bulk heterojunction solar cells improves from 2.16 to 4.90% using a processing additive and drying condition. The results demonstrate that a processing additive and drying condition provides an effective means to control both the surface roughness and finer interpenetrating networks to enhance the exciton dissociation into free charge carriers, charge transportation, and collection. Taking into the account of simple device fabrication process without thermal annealing, the PCE of the polymer solar cell can further improved by chloronapthalene (CN) additive under the fast drying condition. The average carrier lifetimes extracted from the impedance spectra and found to correlate with measured PCEs. At short circuit conditions and illumination, the average charge carrier lifetime was found vary from 16.8 to 32 μs with power conversion efficiencies ranging from 3.0 to 4.9%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Origin and Location of Electrons and Protons during the Formation of Intermetalloid Clusters [Sm@Ga3−xH3−2xBi10+x]3− (x=0, 1)

Reaction of [GaBi₃]^2? with [Sm(C₅Me₄H)₃] yielded the first protonated ternary intermetalloid clusters [Sm@Ga_3?xH_3?2xBi_10+x]^3? ( 1 ; x=0,1). The presence of the Ga? H bonds and the transfer of electrons and protons during the formation of 1 were elucidated by a combination of experimental and quantum chemical methods, thereby rationalizing the role of the solvent ethane‐1,2‐diamine as a Brønsted acid. As an organic by‐product, we observed the previously unknown octamethylfulvene ( 2 ) upon C? C coupling of (C₅Me₄H)^?.     

Ligand Effects on the Electronic Structure of Heteroleptic Antimony-Centered Radicals

We report on the structures of three unprecedented heteroleptic Sb-centered radicals [L(Cl)Ga](R)Sb^. ( 2-R , R=B[N(Dip)CH]₂ 2-B , 2,6-Mes₂C₆H₃ 2-C , N(SiMe₃)Dip 2-N ) stabilized by one electropositive metal fragment [L(Cl)Ga] (L=HC[C(Me)N(Dip)]₂, Dip=2,6-i-Pr₂C₆H₃) and one bulky B- ( 2-B ), C- ( 2-C ), or N-based ( 2-N ) substituent. Compounds 2-R are predominantly metal-centered radicals. Their electronic properties are largely influenced by the electronic nature of the ligands R, and significant delocalization of unpaired-spin density onto the ligands was observed in 2-B and 2-N . Cyclic voltammetry (CV) studies showed that 2-B undergoes a quasi-reversible one-electron reduction, which was confirmed by the synthesis of [K([2.2.2]crypt)][L(Cl)GaSbB[N(Dip)CH]₂] ([K([2.2.2]crypt)][ 2-B ]) containing the stibanyl anion [ 2-B ]⁻, which was shown to possess significant Sb−B multiple-bonding character.     

Polymer coatings on steel substrates: An infrared spectroscopic study of temperature effects

Polymer coatings on steel substrates were analyzed by reflectance/absorbance infrared spectroscopy. Initial studies were performed ex-situ on samples which had been cured at a variety of temperatures on two different substrates. Further studies were done in-situ under both air and nitrogen atmospheres. The two substrates studied were untreated cold-rolled steel and cold-rolled steel with a conversion coating of zinc phosphate. Changes in the spectra of the phosphate conversion layer correlated well with anti-corrosion properties. Mechanisms of degradation and cure could be determined from the in-situ studies (1).     

The Bounded Axiom A Forcing Axiom

We introduce the Bounded Axiom A Forcing Axiom (BAAFA). It turns out that it is equiconsistent with the existence of a regular ∑₂‐correct cardinal and hence also equiconsistent with BPFA. Furthermore we show that, if consistent, it does not imply the Bounded Proper Forcing Axiom (BPFA) (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)