Electrochemical Oxidations ofp-Doped Semiconducting Single-Walled Carbon Nanotubes

Two oxidation peaks at 0.99, 1.48 V versus Fc/Fc+appear in the cyclic voltammograms of a series of defect-site functionalized SWNTs in methylene chloride solution in the presence of ferrocenes. These two peaks are demonstrated to be the electrochemical responses to the independent oxidation of v1and v2valence bands ofp-doped semiconducting SWNTs.

Electrochemical preparation of poly(vinylferrocenium)perchlorate-polyaniline composite-modified platinium electrode in methylene chloride

A new surface based on poly(vinylferrocenium)perchlorate-polyaniline (PVF+ClO4–-PANI) composite-modified platinum electrode was prepared electrochemically to combine the electrocatalytic properties of an intrinsically conducting polymer and a redox polymer. The composite film was synthesized as a bilayer from individual polymerization solutions. Furthermore, PVF+ClO4– and PANI polymers were simultaneously deposited as a mixture from a methylene chloride solution containing PVF polymer and aniline monomer on Pt electrode. When PVF+ClO4– and PANI were codeposited by cycling the potential between 0.20 and 1.80 V vs Ag|AgCl, these polymers were encapsulated within each other. The encapsulation of PVF+ClO4– inside the growing PANI polymer provided the retainment of PVF+ClO4– on the electrode surface even if it was in dedoped form (PVF). This composite film was characterized by cyclic voltammetry, FTIR, SEM and conductivity measurements. The response of the composite film to catechol and hydroquinone was investigated by chronocoulometry in aqueous medium. It was found that the increase in charge consumption for catechol and hydroquinone was observed up to 7.5 and 5.0 times, respectively, when compared to that of PANI film. This might be due to the presence of PVF+ClO4– in the composite film, which played an important role in accelerating the electron transfer.

Synthese und Kristallstruktur des Bromdifluormethyl-triphenyl- phosphoniumbromids, [(C6H5)3PCF2Br]+ Br- / Synthesis and Crystal Structure of Bromodifluoromethyl-triphenylphosphonium Bromide, [(C6H5)3PCF2Br]+ Br-

Difluorobromomethyl-triphenylphosphonium bromide [(C6H5)3PCF2Br]+ Br- (1) has been prepared by the reaction of triphenylphosphine with dibromodifluoro-methane in acetonitrile or methylene chloride. The colorless crystals are monoclinic, space group P 21/n, Z=4, a = 1067.1(2), b = 1488,5(2), c = 1178,2(2) pm, β = 95,67(3)°. The lattice contains Br- anions and [(C6H5)3PCF2Br]+ cations with a Br-Br distance of 322,33(11) pm.. For the title compound the results of AM 1, PM 3 ,and MNDO calculations are in good agreement with corresponding values determined by the X-ray analysis only in the case of PM 3.The yellow-red [(C6H5)3PCF2Br]+ Br3- (2) has been obtained by treating 1 with equimolar quantities of elemental bromine in methylene chloride solution.

Synthesen und Kristallstrukturen von Tris(di-n-propylamino)-p-brombenzylphosphonium-bromiden: [(C3H7)2N]3PCH2C6H4Br+Br- und [(C3H7)2N]3PCH2C6H4Br+Br3-/Syntheses and Crystal Structures of Tris(di-n-propylamino)-p-bromobenzyl-phosphonium Bromides: [(C3H7)2N]3PCH2C6H4Br+Br- and [(C3H7)2N]3PCH2C6H4Br+Br3-

Tris(di-n-propylamino)-p-bromobenzylphosphonium bromide [(C3H7)2N]3PCH2C6H4Br+- Br- (1) has been prepared by the reaction of tris(di-n-propylamino)phosphine with p-bromobenzylbromide in methylene chloride. The colorless crystals are monoclinic, space group P21, Z = 2, a = 930.2(3), b = 1501.2(3), c = 1093.5(2) pm, β = 105,97(4)°. The lattice contains Br- anions and [(C3H7)2N]3PCH2C6H4Br+ cations. [(C3H7)2N]3PCH2C6H4Br+Br- (2) has been obtained by treating 1 with equimolar quantities of elemental bromine in methylene chloride solution. The yellow-red crystals of 2 are triclinic, space group P1̄, Z = 2, a = 1069.5(3), b = 1267.7(7), c = 1273.7(3) pm, α= 87.27(3), β = 82,67, γ = 67.15°, and consist of [(C3H7)2N]3PCH2C6H4Br+ cations and linear Br3- anions. The three N atoms in the cations of 2 are planar.

Synthese und Kristallstruktur der Benzyltriphenylphosphonium-bromide: [C6H5-CH2P(C6H5)3]+Br-CH2Cl2 und [C6H5-CH2P(C6H5)3]+Br3- / Synthesis and Crystal Structures of (Benzyl)triphenylphosphonium Bromides, [C6H5-CH2P(C6H5)3]+Br-CH2Cl2 and [C6H5-CH2P(C6H5)3]+Br3-

(Benzyl)triphenylphosphonium bromide, [C6H5-CH2P(C6H5)3]+Br- (CH2Cl2) (1) has been prepared by the reaction of triphenylphosphine with benzylbromide and its structure determined. The colorless crystals are triclinic, space group P1̄, Z = 2, a = 976.0(3), b = 1069.0(3), c = 1226.1(4) pm, α = 94.13(3), β = 104.70(3), γ = 100.14(3)°. The lattice contains Br- anions and [C6H5-CH2P(C6H5)3]+ cations. [C6H5-CH2P(C6H5)3]Br3 (2) has been obtained by treating compound 1 with equimolar quantities of elemental bromine in methylene chloride solution. The red crystals of 2 are monoclinic, space group P21/c, Z = 4, a = 917.9(2), b = 1022.6(2), c = 2573.6(5) pm, β = 99.11(2)°, and comprise[C6H5-CH2P(C6H5)3]+ cations and linear, slightly asymmetrical Br3- anions with bromine-bromine distances of 246.19(11) and 263.69(11) pm.

The reactions of [Pd2Cl2(μ-PP)2] (PP = dppm, dmpm) with Et2NC≡CNEt2 in methylene chloride solution: X-ray crystal structures of [Pd2Cl2(μ-CH2)(μ-dppm)2] and hexakis(diethylamino)benzene, C6(NEt2)6

The binuciear palladium(I) complex, [Pd2Cl2(μ-dppm)2] (dppm = bis(diphenylphosphino)methane), has been shown to react with bis(diethylamino)acetylene, Et2NC≡CNEt2, in methylene chloride solution to yield two isolable products, the known methylene-bridged complex, [Pd2Cl2(μ-CH2)(μ-dppm)2], and hexakis(diethylamino)benzene, C6(NEt2)6, both of which have been characterized crystallographically. The source of the bridging methylene group in [Pd2Cl2(μ-CH2)(μ-dppm)2] has been shown to be the methylene chloride solvent. A mechanism that accounts for the formation of the two isolable products is proposed. The complex, [Pd2Cl2(μdmpm)2] (dmpm = bis(dimethylphosphino)methane), was similarly found to react with Et2NC≡NEt2 in methylene chloride solution to yield [Pd2Cl2(μ-CH2)(μ-dmpm)2], which was identified spectroscopically. Key words: acetylene, palladium, cyclooligomerization, aminoacetylene, hexakis(diethylamino)benzene.