Fluorine-induced chemiluminescence detection of biologically methylated tellurium,selenium, and sulfur compounds

Summary The sensitive detection of volatile, methylated selenium and tellurium compounds based on capillary gas chromatography coupled to fluorine-induced chemiluminescence detection is described. The method requires no sample derivatization, and the detection limits for selenides and tellurides (low pg range) are the lowest reported to date. This technique can resolve and speciate complex mixtures of methylated tellurium, selenium, and sulfur gases and is useful for analysis of selenium and tellurium gases in environmental samples that also contain usually interfering reduced sulfur gases. Applications of the technique for analysis of bacterial and fungal headspace samples are presented.     

Telluration and de-telluration: New ways for the cleavage and formation of P-P bonds

Abstract

Phosphanes react with tellurium much more selectively than with oxygen, sulfur and selenium. Tertiary phosphanes give “phosphane tellurides” that can equivalently be described as coordination compounds of the phosphanes with Te(O); these are kinetically labile to (phosphane) ligand substitution reactions in the nmr time scale.¹     

Low-temperature 1H, 13C, 77Se,and 125Te NMR studies on the apical-apical ligand exchange via the hypervalent tellurium and selenium ate complexes [10-M-3(C3); M = Se,Te] in the reactions of diaryl tellurides and selenides with aryllithium reagents

Pentafluorophenyl phenyl telluride ( 1 ) and 3,5-dichloro-2,4,6-trifluorophenyl phenyl telluride ( 2 ) react with pentafluorophenyllithium or 3,5-dichloro-2,4,6-trifluorophenyllithium in THF at low temperatures to form the corresponding tellurium ate complexes ( A ) and ( B ) as sole intermediates in the ligand exchange on the hypervalent tellurium atom. The corresponding selenides ( 3 ) and ( 4 ) also react with identical aryllithium reagents in THF to form the discrete intermediates, selenium ate complexes ( C ) and ( D ), in the exchange reactions. In these ligand exchange reactions of tellurides and selenides, electron-withdrawing ligands occupy the apical positions and the exchange takes place between these apical-oriented groups. The low-temperature ¹H, ¹³C, ⁷⁷Se, and ¹²⁵Te NMR spectroscopic techniques are effective methods for detection of unstable tellurium and selenium ate complexes.     

Titrimetric determination of selenium in anodic slimes

The determination of selenium in the presence of tellurium and copper has been studied, to allow analysis of anodic slimes from electrolytic copper refining. Three methods have been developed for the determination of selenium in these slimes. They are based on the extraction of selenium with sodium sulphite, reduction of selenite with sodium sulphite, and separation of selenium and tellurium by adjustment of pH. Selenium (10(-3)-10(-2)M) is determined in the presence of tellurium, copper, iron, silver and lead. The methods are fast and simple, do not need expensive reagents, and give satisfactory results.     

Solution‐Phase Conversion of Bulk Metal Oxides to Metal Chalcogenides Using a Simple Thiol–Amine Solvent Mixture

A thiol–amine solvent mixture is used to dissolve ten inexpensive bulk oxides (Cu₂O, ZnO, GeO₂, As₂O₃, Ag₂O, CdO, SnO, Sb₂O₃, PbO, and Bi₂O₃) under ambient conditions. Dissolved oxides can be converted to the corresponding sulfides using the thiol as the sulfur source, while selenides and tellurides can be accessed upon mixing with a stoichiometric amount of dissolved selenium or tellurium. The practicality of this method is illustrated by solution depositing Sb₂Se₃ thin films from compound inks of dissolved Sb₂O₃ and selenium that give high photoelectrochemical current response. The direct band gap of the resulting material can be tuned from 1.2–1.6 eV by modulating the ink formulation to give compositionally controlled Sb₂Se_3?xS_x alloys.     

Free radical telluroacylative addition of telluroesters to terminal alkynes

Vinyl selenides and tellurides are important precursors of many kinds of organic compounds, particular the substituted alkenes that occurred in many biologically active compounds as skeleton structures. Thus the study of vinyl selenides and tellurides has attracted considerable attention in recent years. The bifunctional addition reactions involving selenium and tellurium moieties are the latest methods for preparation of vinyl selenides with various functional groups. Recently we have reported the selenocarbonylation of alkynes with selenoesters catalyzed by cuprous halides. Nevertheless the similar bifunctional addition involving tellurium atoms has not been reported. Considering the C-Te bonds are easier to be broken than corresponding C-Se bonds, the vinyl tellurides containing electron-withdrawing groups may have particular reactivity and application in the preparation of substituted alkenes. Herein we describe the synthesis of β-aryltelluro-α,β-unsaturated ketones via bifunctional addition.     

Correlated ab initio calculations of one-bond 31P?77Se and 31P?125Te spin–spin coupling constants in a series of PSe and PTe systems accounting for relativistic effects (part 2)

Synthetic chalcogen–phosphorus chemistry permanently makes new challenges to computational Nuclear Magnetic Resonance (NMR) spectroscopy, which has proven to be a powerful tool of structural analysis of chalcogen–phosphorus compounds. This paper reports on the calculations of one-bond ³¹P ⁷⁷Se and ³¹P ¹²⁵Te NMR spin–spin coupling constants (SSCCs) in the series of phosphine selenides and tellurides. The applicability of the combined computational approach to the one-bond ³¹P ⁷⁷Se and ³¹P ¹²⁵Te SSCCs, incorporating the composite nonrelativistic scheme, built of high-accuracy correlated SOPPA (CC2) and Coupled Cluster Single and Double (CCSD) methods and the Density Functional Theory (DFT) relativistic corrections (four-component level), was examined against the experiment and another scheme based on the four-component relativistic DFT method. A special J-oriented basis set (acv3z-J) for selenium and tellurium atoms, developed previously by the authors, was used throughout the NMR calculations in this work at the first time. The proposed computational methodologies (combined and ‘pure’) provided a reasonable accuracy for ³¹P ⁷⁷Se and ³¹P ¹²⁵Te SSCCs against experimental data, characterizing by the mean absolute percentage errors of about 4% and 1%, and 12% and 8% for selenium and tellurium species, respectively. The present study reports typical relativistic corrections to ⁷⁷Se ³¹P and ¹²⁵Te ³¹P SSCCs, calculated within the four-component DFT formalism for a broad series of tertiary phosphine selenides and tellurides with different substituents at phosphorus.     

Application of organic selenides and tellurides in organic synthesis

This paper describes the progress on the synthesis of organic selenides and tellurides and their application in organic synthesis.Low valent selenium and telluronium compounds having high reducing selectivity can be used to form carbon-hydrogen bonds as special reducing reagents.Telluronium ylides can react with aldehydes and ketones by Wittig-type condensation to produce (E)-configuration alkenes stereoselectively.α-Phenylselanyl arsonium ylides were prepared by transyl-idation reaction of arsonium ylides with phenylselanyl halides which can undergo Wittig-type reactions with carbonyl compounds to give (Z)-α-selanyl-α,β-unsaturated compounds with high stereoselectiv-ity.Zirconium,tin,boron,halogen,metal or hetero-atom were introduced in organoselenium and telluronium compounds as new difunctional group reagents.Under transition metal catalysis,the corresponding cross coupling reactions provide new methods of formation of carbon-carbon double bonds,which were used in the stereoselective synthesis of     

Determination of the hydride concentration in alkyldiboranes(6) by 11B NMR spectroscopy – Reduction of inorganic selenium and tellurium compounds

As an alternative to volumetric analysis, ¹¹B NMR spectroscopy can be used to determine the hydride concentration and the relative amount of different active hydride species in mixtures of alkyldiboranes(6) (alkyl = Et, Pr). Inorganic selenium(IV) compounds react with propyldiboranes(6) at first to give elemental selenium (hydride number HN = 4) and after prolonged heating at 130?°C to selenides (HN = 6). In contrast, tellurium(IV) and tellurium(VI) compounds are reduced only to elemental tellurium.     

Amidoselenation and Amidotelluration of Alkenes using Oxygen as Terminal Oxidant

A protocol has been established for oxygen‐mediated amidoselenation and amidotelluration of alkenes under mild conditions. This method provides a simple route to a series of structurally diverse β‐amido selenides and β‐amido tellurides in moderate to high yields. The wide substrate scope, good functional group tolerance, ease of large‐scale preparation and potential for product derivatization make this reaction attractive for the synthesis of nitrogen‐, selenium‐ and tellurium‐containing molecules.     

Determination of the hydride concentration in alkyldiboranes(6) by 11B NMR spectroscopy – Reduction of inorganic selenium and tellurium compounds

As an alternative to volumetric analysis, ¹¹B NMR spectroscopy can be used to determine the hydride concentration and the relative amount of different active hydride species in mixtures of alkyldiboranes(6) (alkyl = Et, Pr). Inorganic selenium(IV) compounds react with propyldiboranes(6) at first to give elemental selenium (hydride number HN = 4) and after prolonged heating at 130 °C to selenides (HN = 6). In contrast, tellurium(IV) and tellurium(VI) compounds are reduced only to elemental tellurium. Received: 31 March 1998 / Accepted: 26 April 1998     

A Regioselective Synthesis of Novel Functionalized Organochalcogen Compounds by Chalcogenocyclofunctionalization Reactions Based on Chalcogen Halides and Natural Products

The regioselective synthesis of novel functionalized condensed organochalcogen compounds by chalcogenocyclofunctionalization reactions based on chalcogen halides and the natural products thymol and carvacrol has been developed. The reactions of selenium dibromide with allyl thymol and allyl carvacrol proceeded in methylene chloride at room temperature in the presence of NaHCO₃ affording bis[(7-isopropyl-4-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] and bis[(4-isopropyl-7-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] selenides in 90–92% yield. Similar sulfides were obtained in 70–72% yields by the reaction of sulfur dichloride in chloroform under reflux. Trihalotellanes containing the same organic moieties were synthesized from allyl thymol, allyl carvacrol and tellurium tetrachloride or tetrabromide in quantitative yields. Corresponding functionalized ditellurides were prepared in 91–92% yields by the reduction of the trichlorotellanes with sodium metabisulfite in two-phase solvent system. The comparison of reactivity of sulfur, selenium and tellurium halides in chalcogenocyclofunctionalization and distinguishing features of each reaction were discussed.     

Dialkynyl selenides: Synthesis, 13C NMR spectra,and molecular orbital calculations

Reactions of SeCl₄ with lithium bis(trimethylsilyl)amide and terminal acetylenes in the presence of BuLi or AIBN afforded the corresponding dialkynyl selenides in moderate to high yields. The reaction may proceed via a selenium amide 7 and an alkynyl selenium amide 8 . The comparison of ¹³C NMR spectra of dialkynyl selenides and tellurides has disclosed that the differences of the chemical shift of acetylenic carbons between Se and Te derivatives are consistent regardless of their substitution patterns. Ab initio molecular orbital calculations are reported for dialkynyl ether and chalcogenides. The calculated structures, charge distributions, and orbital energies are discussed.     

Retrospect of Se and Te Chemistry

Retrospect of organoselenium and tellurium chemistry for these 30 years is described focusing on our novel findings in this field: (1) telluroxide elimination leading to alkenes and allylic compounds, (2) Pd-catalyzed or –mediated carbodetelluration for a new C–C bond formation, (3) synthesis of chiral diferrocenyl dichalcogenides and their use as chiral auxiliaries, (4) asymmetric selenoxide elimination for making optically active allenes and alkenes, (5) meta chloroperbenzoic acid (MCPBA) oxidation of organic selenides and tellurides leading to a substitution of a PhSe or PhTe moiety, as well as (6) preparation of chalcogen-bridged diruthenium complexes and their catalytic use for propargylic substitution reactions.     

Contributions to the Chemistry of the Binary Compounds of the Transition Elements

Phase and structural relationships of the sulfur, selenium, and tellurium compounds of the 4d and 5d transition elements of groups IV to VII of the periodic system are discussed. Homologous elements behave very similarly with respect to the chalcogens, and this is particularly the case for niobium and tantalum, and for molybdenum and tungsten. However, zirconium, niobium, and molybdenum have a greater tendency towards formation of chalcogen-poor phases than their homologues hafnium, tantalum, and tungsten. Subchalcogenides are known only for zirconium and niobium. The number of phases and the tendency towards formation of solid solutions are considerably smaller among the tellurides than among the sulfides and selenides. The crystal structures of the telluride phases also differ from those of the sulfide and selenide phases of analogous composition. In addition, a review of the phase and structural relationships of the arsenic and antimony compounds of the 4d and 5d transition elements of groups V to VII is given.     

Synthesis of tris(organylthioethyl)phosphines and their derivatives on the basis of the reaction of phosphine with vinyl sulfides

Phosphine generated from the red phosphorus in the system KOH-H₂O-toluene adds regio- and chemoselectively to vinyl sulfides under radical initiation conditions with the formation of tris(2-organylthioethyl)phosphines, which are easily oxidized by elemental sulfur and selenium to the corresponding phosphine sulfides and phosphine selenides in 54–78% yield. The obtained adducts are split when treated with sodium amide in THF to give trivinylphosphine and trivinylphosphine chalcogenides.     

The analysis of copper refinery slimes

Methods are reviewed for the determination of the following constituents of copper refinery slimes: aluminium, antimony, arsenic, barium, bismuth, calcium, cobalt, copper, gold, iron, lead, magnesium, manganese, molybdenum, nickel, platinum metals, selenium, silicon, silver, sulphur, tellurium, tin and zinc.     

Regiospecific Functionalization of Dimetalated (1-Naphthyl)acetylene. Efficient Synthetic Procedures for Naphtho[2,1-b]chalcophenes

Treatment of (1-naphthyl)acetylene (1) with two mol equivalents of the BuLi-t-BuOK reagent in tetrahydrofuran/hexane, followed by successive addition of anhydrous lithium bromide, sulfur, selenium, or tellurium and t-butylalcohol gives naphtho[2,1-b]thiophene, -selenophene and -tellurophene in good yields. Reaction of dimetalated 1 with iodine or dimethyldisulfide afforded 2-iodo-, and 2-thiomethyl(1-ethylnyl)naphthalene.     

The reaction of hydrogen chloride with bis (p-ethoxyphenyl)telluride,a possible route to pure tellurium

The reaction of hydrogen chloride with bis(p-ethoxyphenyl)telluride is investigated and shown to give essentially phenetole (C₆H₅COEt), tellurium, and bis(p-ethoxyphenyl)tellurium dichloride. Spectroscopic methods (UV–visible, ¹²⁵Te NMR) show that some bis(p-ethoxyphenyl)ditelluride is produced. This is believed to arise from a side reaction of organic telluride with an intermediate organyltellurenyl chloride which is considered to arise from initial proton attack at the Te–C bond of the telluride. The ditelluride reacts with HCl to deposit 80% of its tellurium content as the element; phenetole is the other major product. Use of a spin-trap reagent gave no evidence of radical intermediates. An attempt to develop a reaction sequence to prepare high-purity tellurium is described. Although a purity of 99.985% could be achieved, overall yields are not economic, unless very highpurity tellurium is required. The method described is, however, very effective for the removal of traces of tin, lead, arsenic and antimony and can significantly reduce the copper, iron and selenium content; for example, one treatment of an alloy (Te, 75%; Se, 25%) gave a sample of tellurium containing 40 ppm selenium.     

CHALCOGENIDE PHOTOVOLTAIC SOLAR CELLS OF SPECIAL INTEREST

Abstract

A brief review is given of those semiconducting selenides and tellurides that appear suitable for the absorber layer of a photovoltaic solar cell, with energy gaps in the range 1 to 2 eV. Furthermore, to obtain a lower cost cell, the semiconductor is also required to be used in the form of a thin polycrystalline film, necessitating a high optical absorption coefficient in the material. At the present time the two best chalcogenides meeting these requirements are the compounds CuInSe ₂ and CdTe, both of which have been used in polycrystalline thin film structures with CdS, as the window layer, yielding conversion efficiencies of over 10%. They have also demonstrated very good chemical stability.