Über Chalkogenidhalogenide des Rheniums: Synthese und Kristallstrukturen der Dreieckscluster Re3E7X7 (E = S,Se; X = Cl,Br)

On Chalcogenide Halogenides of Rhenium: Synthesis and Crystal Structures of the Triangular Clusters Re₃E₇X₇ (E = S, Se; X = Cl, Br) The compounds Re₃E₇X₇ are obtained from rhenium tetrahalides ReX₄, elemental chalcogens and the respective chalcogen halides E₂X₂ or SeX₄ (E = S, Se; X = Cl, Br). Re₃S₇Cl₇, Re₃S₇Br₇ and Re₃Se₇Br₇ are formed in solutions of sulfur or selenium halides or SiBr₄ in form of black crystals and crystallize isotypically in the trigonal space group P31c. Re₃Se₇Cl₇ is formed by solid state reaction of ReCl₄, Se and SeCl₄ or by thermal decomposition of Se₄[ReCl₆], crystallizing as red, in thin layers transparent crystals in the orthorhombic space group Pbcm. The crystal structures consist of discrete positively charged cluster units and halide ions according to the formula [Re₃(μ₃-E)(μ₂-E₂)₃X₆]⁺X^–. In the rhenium triangular clusters the Re–Re distances range from 269,0 to 270,4 pm for the sulfur and from 273,3 to 275,3 pm for the selenium containing compounds. The Re₃ units are capped by chalcogen atoms, three E₂ groups form bridges over the edges of the Re₃ triangles. The trigonal and the orthorhombic structure type show differences in the site symmetry of the clusters (C₃ vs. C_s) and in the stacking sequence of the molecules, which are packed in the motif of a closest packing of spheres.     

Ion pairing between dissolved poly(o-phenylenediamine) and halogenide ions

An electrically conductive polymer, poly(o-phenylenediamine) (PoPD), is soluble in dimethylsulfoxide (DMSO) without any pretreatment. Cyclic voltammograms of dissolved PoPD were measured in DMSO solutions containing halogenide ions and two reversible redox peak currents were evident. The redox potential shifted with the concentration of the dissolved halogenide ion. The relationship between the potential shift and the concentration determined the relative association constant of PoPD for four halogenide ions: 104 mol⁻¹ dm⁻³ for F⁻; 32 mol⁻¹ dm⁻³ for Cl⁻; 29 mol⁻¹ dm⁻³ for Br⁻ and 9 mol⁻¹ dm⁻³ for I⁻.     

Contribution to Halo‐Chalcogenates Chemistry

Abstract. By direct reactions of selenium with halogen and trimethylphenylammonium halogenide and tetraphenylphosphonium, ethyltriphenylphosphonium, and methyltriphenylphosphonium bromides, the tetrahalogenidoselenates(II) – bis(trimethylphenylammonium)tetrabromidoselenate(II) bromide, [NPhMe₃]₂[SeBr₄] · [NPhMe₃]Br, a mixed bis(trimethylphenylammonium) tetra(bromido/chlorido)selenate(II), [NPhMe₃]₂[SeBr_4–xCl_x] · [NPhMe₃]₂SeBr_1–yCl_y], [NPhMe₃]₂[SeBr_4–xCl_x],the haxahalogenidodiselenates(II) – bis(trimethylphenylammonium) hexabromidodiselenate(II), [NPhMe₃]₂[Se₂Br₆], bis(trimethylphenylammonium) hexachloridodiselenate(II), [NPhMe₃]₂[Se₂Cl₆], a mixed bis(trimethylphenylammonium) bromido/chlorido‐diselenate(II), [NPhMe₃]₂[Se₂Br₅Cl], bis(tetraphenylphosphonium) hexabromidodiselenate(II), [PPh₄]₂[Se₂Br₆], bis(ethyltriphenylphosphonium) hexabromidodiselenate(II), [PEtPh₃]₂[Se₂Br₆], and bis(methyltriphenylphosphonium) hexabromidodiselenate(II), [PMePh₃]₂[Se₂Br₆], were prepared. By the reaction of selenium with bromine in acetonitrile in the presence of trimethylphenylammonium, benzyltrimethylammonium, and tetramethylammonium bromides, the salts of the unique bromidoselenate(I) anions – bis(trimethylphenylammonium) hexabromidotetraselenate(I), [NPhMe₃]₂[Se₄Br₆], bis(benzyltrimethylammonium) hexabromidotetraselenate(I), [NBzMe₃]₂[Se₄Br₆], and bis(tetramethylammonium) octadecabromidohexadecaselenate(I), [NMe₄]₂[Se₁₆Br₁₈], were isolated. First mixed‐valence bromidoselenates(II/I) – bis(tetraethylammonium) octabromidotriselenate(II){dibromidodiselenate(I)}, [NEt₄]₂[Se₃Br₈(Se₂Br₂)], bis(tetraphenylphosphonium) hexabromidodiselenate(II)‐bis{dibromidodiselenate(I)}, [PPh₄]₂[Se₂Br₆(Se₂Br₂)₂], and tetrakis(tetramethylammonium) bis{decabromidotetraselenate(II)}‐bis{dibromidodiselenate(I)}, [(CH₃)₄N]₄[(Se₄Br₁₀)₂(Se₂Br₂)₂] – were synthesized. Mixed bis(trimethylphenylammonium) hexabromidoselenate/tellurate(IV), [NPhMe₃]₂[Se_0.75Te_0.25Br₆], catena‐poly[(di‐μ‐bromidobis‐{tetrabromidoselenate/tellurate(IV)})‐ μ‐bromine], [NPhMe₃]_2n[Se_1.5Te_0.5Br₁₀ · Br₂]_n were isolated. First mixed‐valence bromidoselenate(IV/I)‐bis(trimethylphenylammonium) hexabromidoselenate(IV)‐bis{dibromidodiselenate(I)}, [NPhMe₃]₂[SeBr₆(Se₂Br₂)₂], a number of mixed bromidochalcogenates(IV/I) – bis(trimethylphenylammonium), bis(tetraethylphosphonium), bis(ethyltriphenylphosphonium) hexabromidotellurates(IV)‐bis{dibromidodiselenates(I)}, [NPhMe₃]₂[TeBr₆(Se₂Br₂)₂], [PEt₄]₂[TeBr₆(Se₂Br₂)₂], [PEtPh₃]₂[TeBr₆(Se₂Br₂)₂], bis(triethylmethylammonium) hexabromidotellurate(IV)‐tris{dibromidodiselenate(I)}, [NMeEt₃]_2n[TeBr₆(Se₂Br₂)₃]_n, were synthesized. Mixed‐valence bromidoselenate(IV/II) – bis(methyltriphenylphosphonium) hexabromidoselenate(IV)‐bis{dibromidoselenate(II)},[PMePh₃]₂[SeBr₆(SeBr₂)₂], received by direct synthesis and two mixed‐valence bromidochalcogenates(IV/II) – bis(methyltriphenylphosphonium) and bis(tetrapropylammonium) hexabromidotellurates(IV)‐selenates(II), [PMePh₃]₂[TeBr₆(SeBr₂)₂] and [NⁿPr₄]₂[TeBr₆(SeBr₂)₂], were synthesized from elemental selenium, tellurium dioxide, and corresponding onium bromide. The structures of all compounds were determined by X‐ray diffraction.     

Speciation of halogenides and oxyhalogens by ion chromatography-inductively coupled plasma mass spectrometry

A speciation method utilizing ion chromatography coupled with inductively coupled plasma mass spectrometry is described for simultaneous analysis of eight halogenides and oxyhalogens: chloride, chlorite, chlorate, perchlorate, bromide, bromate, iodide and iodate. The method was applied for the analysis of drinking water samples collected from water treatment plants in areas in Finland, which are known to have high bromine concentrations in ground water. Water samples collected before and after disinfection were analyzed to get information about potential species conversion as a result of purification. Chloride and chlorate were the chlorine species found in these water samples, and iodine existed as both iodate and iodide. In the case of bromine, species conversion had taken place, since total bromine concentrations were increased during disinfection but bromide concentrations were decreased. No bromate was observed in the samples. The detection limits for all the chlorine species studied were 500 μg/l, for bromine species studied 10 μg/l, for iodide 0.1 μg/l and for iodate 0.2 μg/l.     

From an Impurity to the Pure Compound – an Electron Microscopy Study

The power of electron microscopy techniques for the determination of structure and composition of marginal byproducts is demonstrated for rare earth metal cluster compounds. Small amounts of the new phase Gd₄GaI₆ in samples with the nominal composition Gd₇GaI₁₂ could only be identified by a combined approach of EDX, electron diffraction and HRTEM. The structure of Gd₄GaI₆ can be assigned to the Y₄BBr₆‐type containing chains of Gd₆ octahedra which are centered by Ga atoms. The results of the electron microscopy study initiated the synthesis of homogeneous samples of the new compound Gd₄GaI₆ by applying the correct ratio of the starting materials.