Sulfide Complex Research Articles

Copper-Complexed Hydrogen Sulfide in Wine: Measurement by Gas Detection Tubes and Comparison of Release Approaches

Recent work suggests that copper complexes may serve as a latent source of free hydrogen sulfide (H2S) and other malodorous volatile thiols during wine storage. However, measurements of these complexes require analytical tools that are unavailable to most wineries. To facilitate additional studies of these compounds, we developed an inexpensive and convenient method for detecting copper-complexed H2S in wine with commercially available colorimetric gas detection tubes. Using brine dilution as a pretreatment, we observed that this approach showed acceptable detection limits (0.34 μg/L) and excellent H2S recovery from both model and real wines. Alternative approaches to H2S release from copper sulfide complexes were also investigated, including ethylenediaminetetraacetic acid (EDTA), neocuproine, ascorbic acid, and tris(2-carboxyethyl)phosphine (TCEP), alone and in combination. EDTA resulted in loss of free H2S. Partial recovery (35 to 70%) of H2S from model wines was achieved with the other reagents, with the release induced by ascorbic acid being of particular interest to winemakers. In a survey of seven commercial wines, the fraction of complexed H2S released by the brine was 80 to 95% of the total H2S pool, with lower releases observed for neocuproine and ascorbic acid. However, in several wines, TCEP treatment released higher concentrations of H2S from unknown precursors.

Oxidative Addition of Disulfides, Alkyl Sulfides, and Diphosphides to an Aluminum(I) Center.

The aluminum(I) compound NacNacAl (1) reacts with diphenyl disulfide and diethyl sulfide to form the respective four-coordinate bis(phenyl sulfide) complex NacNacAl(SPh)2 (2) and alkyl thiolate aluminum complex NacNacAlEt(SEt) (3). As well, reaction of 1 with tetraphenyl diphosphine furnishes the bis(diphenyl phosphido) complex NacNacAl(PPh2)2 (4). Production of 3 and 4 are the first examples of C(sp(3))-S and R2P-PR2 activation by a main-group element complex. All three complexes were characterized by multinuclear NMR spectroscopy and X-ray crystal structure analysis. Furthermore, a variable-temperature NMR spectroscopic study was undertaken on 4 to study its dynamic behavior in solution.

Effects of major ions in recycled water on sulfide minerals flotation

The use of recycled water in flotation has significant effects on flotation and selectivity because the recycled water contains many dissolved compounds and ions that alter the chemistry of the system. In this study, the effects of calcium, magnesium and sulfate, which are abundant components in recycled water, were investigated on galena, sphalerite and pyrite flotation using pure minerals and a complex sulfide ore by conducting bench-scale flotation, microflotation and zeta potential measurements. The bench-scale flotation tests indicated that higher recoveries of galena and sphalerite are obtained when water is recycled, due to higher concentrations of ions in recycled water. However, there was a critical ion concentration for galena recovery. The microflotation tests showed that galena recoveries at different pHs in recycled water are lower than in tap and distilled water. Pure sphalerite recoveries improved in recycled water in the bench-scale test with ore. Pure pyrite was depressed with recycled water as well. Zeta potentials became less negative with increased calcium and magnesium ion concentrations due to their adsorptions, and the presence of sulfate ions was seen to increase the negative charges of sphalerite and pyrite, conversely for galena.

Sc2S3–Cu2S phase diagram

A phase diagram is constructed for the Sc2S3–Cu2S system. The system forms two incongruently melting complex sulfides: hexagonal CuScS2 (1Cu2S: 1Sc2S3): a = 0.3734 nm, c = 0.6102 nm, space group P3m1, Т m = 1635 K, ΔH m = 1670 kJ/mol; and cubic CuSc3S5 (1Cu2S: 3Sc2S3), a = 1.0481 nm, space group Fd3m, Т m = 1835 K. In the 45–62 mol % Cu2S solid solution (ss) range, there is a singular point corresponding to the composition of compound CuScS2 (50 mol % Cu2S). The Sc2S3-based solubility at 1070 K is 14 mol % Cu2S. In the γ-Cu2S-based solid solution range, there is a peritectic point at 7 mol % Sc2S3, 1423 K.

Simultaneous Extraction of Selenium from Indermediate Products of Extraction Reprocessing of Washing Acid of Copper Production

Background: In pyroprocessing sulphide complex copper ores, considerable amount of selenium along with radio genic osmium and rhenium concentrated in the solid-phase products of acid wash is disappearing with waste chromium containing solutions. Methods: Studying the peculiarities of selenium recovery in sulfuric acid chromium-containing medium is an important task, which will prevent channel losses of selenium with intermediates of sulphate production at complex processing of sulfide polymetallic raw materials and thereby increase up the production. On the basis of analysis of the literature and patent data as the most promising methods for the extraction of selenium and selenium from sulfuric acid solutions, recovery methods were chosen. Results: The thermodynamic evaluation of the possibility of extracting selenium from sulfuric acid solutions at the temperatures of 298-348 K, with the use of sulfur dioxide and sodium sulfite proved a high probability of recovering selenite-ions SeO 3 2- and to a lesser extent, selenate-ions SeO 4 2- . The experiment on precipitation of selenium were carried out on the basis of synthetic sulfuric solutions, containing, (g/l): 5-15 Se (IV), 5 Se (VI), 60 Cr (III), 5 Cr (VI), 100-250 H 2 SO 4 . It has been found that the temperature increase adversely affects the process of recovering selenium with sulfur dioxide, which is caused by reduction of the solubility of sulfur dioxide. The selenium selection process using sodium sulfate is characterized by significantly higher recovery rate due to removal of the diffusion constraints associated with the dissolution of sulfur dioxide. By using all studied reducing agents in the optimum conditions, almost complete recovery of selenium is ensured, selenium is at that recovered with not more than 60%. Conclusion: Taking into account high rates of extraction of selenium from sulphate chrome-bearing solutions, sulfur dioxide and sodium sulfite, choice of selenium recovery, largely determined by specific features of an enterprise.

Combined effect of carbon dioxide and sulfur on vapor–liquid partitioning of metals in hydrothermal systems

Although CO2 is a ubiquitous volatile in geological fluids typically ranging from a few to more than 50wt%, its effect on metal vapor–liquid fractionation during fluid boiling and immiscibility phenomena in the Earth’s crust remains virtually unknown. Here we conducted first experiments to quantify the influence of CO2 on the partition of different metals in model water+salt+sulfur+CO2 systems at 350°C and CO2 pressures up to 100bar, which are typical conditions of formation of many hydrothermal ore deposits. In addition, we performed in situ Raman spectroscopy measurements on these two-phase systems, to determine sulfur and carbon speciation in the liquid and vapor phases. Results show that, in S-free systems and across a CO2 concentration range of 0–50wt% in the vapor phase, the absolute vapor–liquid partitioning coefficients of metals (Kvap/liq=Cvap/Cliq, where C is the mass concentration of the metal in the corresponding vapor and liquid phase) are in the range 10−6–10−5 for Mo; 10−4–10−3 for Na, K, Cu, Fe, Zn, Au; 10−3–10−2 for Si; and 10−4–10−1 for Pt. With increasing CO2 from 0 to 50wt%, Kvap/liq values decrease for Fe, Cu and Si by less than one order of magnitude, remain constant within errors (±0.2 log unit) for Na, K and Zn, and increase by 0.5 and 2 orders of magnitude, respectively for Au and Pt. The negative effect of CO2 on the partitioning of some metals is due to weakening of hydration of chloride complexes of some metals (Cu, Fe) in the vapor phase and/or salting-in effects in the liquid phase (Si), whereas both phenomena are negligible for complexes of other metals (Na, K, Zn, Mo). The only exception is Pt (and in a lesser extent Au), which partitions significantly more to the vapor of S-free systems in the presence of CO2, likely due to formation of volatile carbonyl (CO) complexes. In the S-bearing system, with H2S content of 0.1–1.0wt% in the vapor, Kvap/liq values of Cu, Fe, Mo, and Au are in the range 0.01–0.1, those of Pt 0.5–2.0, those of alkali metals are similar to the S-free system, and the partitioning of none of the studied metals is influenced by the presence of CO2 (up to 50wt% in the vapor). Our data thus confirm the large enhancement of volatility in the presence of reduced sulfur (H2S) due to formation of sulfide complexes for chalcophile metals such as Au, Pt, Mo and, to a lesser extent, Cu and Fe, as reported in previous studies of CO2-free water-salt systems. The negligible effect of CO2 on vapor–liquid partitioning of the studied metals in S-bearing systems is due to the lack of hydration of metal sulfide species making them little sensitive to changes in water activity and solvation power of CO2–H2O vapor. Our findings, combined with existing data over a wide range of temperature on vapor–liquid partitioning of metals in H2O-dominated systems, suggest that CO2 exerts mostly an indirect impact on metal fractionation, by extending vapor–liquid immiscibility to higher temperatures and pressures or depth compared to a CO2-free H2O-S-salt system. The deeper vapor–liquid separation, in particular in S-bearing systems, is expected to cause more significant partitioning of precious metals and molybdenum (Au, Pt, Mo) into the vapor phase while base metals (Fe, Zn, Cu) remain concentrated in the salt-rich (NaCl, KCl) liquid phase. In addition, irrespective of the presence of sulfur, an expansion of the immiscibility domain to higher temperature and pressure conditions in the presence of CO2 will also increase the depth of ore deposition and affect the vertical metal zonation in hydrothermal systems.

Bioleaching of a Complex Co-Ni-Cu Sulfide Flotation Concentrate by Bacillus megaterium QM B1551 at Neutral pH

ABSTRACTBioleaching of sulfide minerals at neutral pH has been rarely reported. In this study, a bacterium, Bacillus megaterium QM B1551, was isolated from Jinchuan sulfide tailings and used to leach a complex sulfide flotation concentrate for the extraction of Co2+, Ni2+ and Cu2+ at near neutral pH. A total of 38.2% Co, 44.7% Ni and 3.6% Cu were extracted from the sulfide concentrate in 5 days with an initial pH of 6. An enhanced Co2+, Ni2+ and Cu2+ extraction extent was achieved by first bioleaching the concentrate with Bacillus megaterium QM B1551 at 35°C and then followed by chemical leaching with 4 M sulfuric acid at 90°C. As a result, a total of 60.7% Co2+, 76.3% Ni2+ and 39.8% Cu2+ were extracted. On an industrial scale, the profits from the metal recovery by such a combined leaching procedure are optimum if considering the cost-benefit ratio.

Thermodynamics of Complex Sulfide Inclusion Formation in Ca-Treated Al-Killed Structural Steel

Controlling the morphology of the sulfide inclusion is of vital importance in enhancing the properties of structural steel. Long strip-shaped sulfides in hot-rolled steel can spherize when, instead of the inclusion of pure single-phase MnS, the guest is a complex sulfide, such as an oxide-sulfide duplex and a solid-solution sulfide particle. In this study, the inclusions in a commercial rolled structural steel were investigated. Spherical and elongated oxide-sulfide duplex as well as single-phase (Mn,Ca)S solid solution inclusions were observed in the steel. A thermodynamic equilibrium between the oxide and sulfide inclusions was proposed to understand the oxide-sulfide duplex inclusion formation. Based on the equilibrium solidification principle, thermodynamic discussions on inclusion precipitation during the solidification process were performed for both general and resulfurized structural steel. The predicted results of the present study agreed well with the experimental ones.

Gaseous complex sulfides

Gaseous complex sulfides

Crystal Structures of α- and β-SrCeCuS3

The crystal structure of SrCeCuS3, a complex sulfide synthesized for the first time, has been solved using X-ray powder diffraction data. The crystals are orthorhombic, space group Pnma. SrCeCuS3 has two polymorphs: the high-temperature phase of Ba2MnS3 structural type (a = 8.1393(3) A, b = 4.0587(2) A, c = 15.9661(2) A) and the low-temperature phase isostructural to BaLaCuS3 (a = 11.1626(2) A, b = 4.0970(2) A, c = 11.5307(1) A). The incongruent melting temperature and enthalpy of SrCeCuS3 are, respectively, 1486 ± 3 K and 13.4 ± 1.5 J/g.

Stable -ESiMe3 Complexes of Cu(I) and Ag(I) (E=S, Se) with NHCs: Synthons in Ternary Nanocluster Assembly.

As a part of efforts to prepare new "metallachalcogenolate" precursors and develop their chemistry for the formation of ternary mixed-metal chalcogenide nanoclusters, two sets of thermally stable, N-heterocyclic carbene metal-chalcogenolate complexes of the general formula [(IPr)Ag-ESiMe3] (IPr=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene; E=S, 1; Se, 2) and [(iPr2-bimy)Cu-ESiMe3]2 (iPr2-bimy=1,3-diisopropylbenzimidazolin-2-ylidene; E=S, 4; Se, 5) are reported. These are prepared from the reaction between the corresponding carbene metal acetate, [(IPr)AgOAc] and [(iPr-bimy)CuOAc] respectively, and E(SiMe3 )2 at low temperature. The reaction of [(IPr)Ag-ESiMe3] 1 with mercury(II) acetate affords the heterometallic complex [{(IPr)AgS}2Hg] 3 containing two (IPr)Ag-S(-) fragments bonded to a central Hg(II), representing a mixed mercury-silver sulfide complex. The reaction of [(iPr2-bimy)Cu-SSiMe3]2, which contains a smaller N-heterocyclic-carbene, with mercuric(II) acetate affords the high nuclearity cluster, [(iPr2-bimy)6Cu10S8Hg3]6. The new N-heterocyclic carbene metal-chalcogenolate complexes 1, 2, 4, 5 and the ternary mixed-metal chalcogenolate complex 3 and cluster 6 have been characterized by multinuclear NMR spectroscopy ((1)H and (13)C), elemental analysis and single-crystal X-ray diffraction.

錯体水素化物固体電解質と硫化物ガラス固体電解質のハイブリッド利用による室温動作可能な 4 V 級バルク型全固体リチウム二次電池の開発

錯体水素化物固体電解質と硫化物ガラス固体電解質のハイブリッド利用による室温動作可能な 4 V 級バルク型全固体リチウム二次電池の開発

Hydrogen bonding in alcohol–ethylene oxide and alcohol–ethylene sulfide complexes

The O–H⋯O and O–H⋯S hydrogen bonds are of similar strength in the corresponding alcohol–EO and alcohol–ES complexes.

Structural studies on tribenzylphosphane sulfide complexes of copper(I) and silver(I)

Tribenzylphosphane sulfide (SPBn3) reacts with [Cu(CH3CN)4]PF6 in a 2:1 ratio to give [Cu(CH3CN)(SPBn3)2]PF6 whereas with [Ag(CH3CN)4]PF6 in the same ratio it forms [Ag2(SPBn3)3](PF6)2. The crystal structure of the Cu(I) complex shows it to contain discrete 3-coordinate [Cu(CH3CN)(SPBn3)2]+ cations and [PF6]− anions with the Cu atom lying in the plane formed by the two coordinated sulfur atoms and the nitrogen from the coordinated acetonitrile molecule. The Ag complex is a dinuclear species with the one silver atom being 3-coordinate and the other 4-coordinate. Each of the SPBn3 molecules forms a Ag–C η1-bond with one of the aromatic rings thus blocking the coordination of further SPBn3 ligands. The two Ag centers are linked by a bridging sulfur and a weaker interaction with carbon from the aromatic ring of the same tribenzylphosphane sulfide.

Synthesis and spectral properties of colloidal solutions of metal sulfides

Cadmium, lead, and zinc sulfides as well as cadmium and lead (cadmium and zinc) complex sulfides have been synthesized in the colloidal state by reaction of metal trifluoroacetates with thioacetamide in ethyl acetate and methylmethacrylate. Synthesis products have been isolated from the reaction solutions and studied by X-ray diffraction, vibrational and electronic spectroscopy, and electronic microscopy. The effect of the composition on spectral properties of formulations has been discussed. The formation of colloidal particles and the stability of solutions are related to the complexation.

Occurrence of gold in hydrothermal pyrite, western Taupo Volcanic Zone, New Zealand

The Taupo Volcanic Zone (TVZ) on the North Island of New Zealand is located above the subducting Pacific slab and hosts hydrothermal systems related to subduction, arc magmatism and crustal extension. In these systems, gold is transported primarily as sulphide complexes, with gold being deposited in response to boiling and mixing of the deep geothermal fluids. Conglomerate cobbles and hydrothermal fumaroles from the upper Retaruke River in the western TVZ are mineralised deposits that have been eroded from the nearby Miocene alluvial sedimentary plateau. Abundant gold-bearing pyrite was precipitated in the conglomerates and fumaroles by late hydrothermal process, primarily occurring as veinlets, disseminations and fine-grained aggregates which consists discrete euhedral microcrystals. Scanning electron microscopy combined with X-ray energy disperses spectroscopy shows that pyrites are commendably affected by late hydrothermal fluids, possibly by the carbonate fluid. Electron probe microanalysis revealed that the pyrite contains 20–120 ppm Au (averaging 60 ppm). Wavelength dispersive spectral elemental mapping suggests that gold is distributed uniformly in pyrite, indicating structurally bound gold (solid solution) in pyrite. Gold mineralisation recognised in the conglomerates and fumaroles demonstrates that the upper Retaruke River is a promising target for future gold exploration.

Sulfur isotope values in the sulfidic Frasassi cave system, central Italy: A case study of a chemolithotrophic S-based ecosystem

Sulfide oxidation forms a critical step in the global sulfur cycle, although this process is notoriously difficult to constrain due to the multiple pathways and highly reactive intermediates involved. Multiple sulfur isotopes (δ34S and Δ33S) can provide a powerful tool for unravelling sulfur cycling processes in modern (and ancient) environments, although they have had limited application to systems with well-resolved oxidative S cycling. In this study, we report the major (δ34S) and minor (Δ33S) isotope values of sulfur compounds in streams and sediments from the sulfidic Frasassi cave system, Marche Region, Italy. These microaerophilic cave streams host prominent white biofilms dominated by chemolithotrophic organisms that oxidize sulfide to S0, allowing us to estimate S isotope fractionations associated with in situ sulfide oxidation and to evaluate any resulting isotope biosignatures. Our results demonstrate that chemolithotrophic sulfide oxidation produces 34S enrichments in the S0 products that are larger than those previously measured in laboratory experiments, with 34εS0–H2S of up to 8‰ calculated. These small reverse isotope effects are similar to those produced during phototrophic sulfide oxidation (⩽7‰), but distinct from the small normal isotope effects previously calculated for abiotic oxidation of sulfide with O2 (∼−5‰). An inverse correlation between the magnitude of 34εS0–H2S effects and sulfide availability, along with substantial differences in Δ33S, both support complex sulfide oxidation pathways and intracellular recycling of S intermediates by organisms inhabiting the biofilms. At the ecosystem level, we calculate fractionations of less than 40‰ between sulfide and sulfate in the water column and in the sediments. These fractionations are smaller than those typically calculated for systems dominated by sulfate reduction (>50‰), and contrast with the commonly held assumption that oxidative recycling of sulfide generally increases overall fractionations. The relatively small fractionations appear to be related to the sequestration of S0 in the biofilms (either intra- or extra-cellularly), which removes this intermediate substrate from fractionation by further disproportionation or oxidation reactions. In addition, the net 33λH2S–SO4 values calculated in this system are larger than data published for systems dominated by reductive sulfur cycling, partially due to the isotopic imprint of chemolithotrophic sulfide oxidation on the aqueous sulfide pool. These distinct isotopic relationships are retained in the sedimentary sulfur pool, suggesting that trends in 34S and 33S values could provide an isotopic fingerprint of such chemolithotrophic ecosystems in modern and ancient environments.

Crystallographic analysis of modular structures of cupromakopavonite Cu8Ag3Pb4Bi19S38 and heyrovskyite Pb6Bi2S9 minerals

The well-known “modular” concept of the structure of two complex sulfides has been supplemented by crystallographic analysis fixing specific features of ordering atomic sites in crystal structures. Regular ordering of cations (formation of F sublattices with close parameters) and independent, less regular ordering of anions is established. It is shown that local ordering of atoms in contacting modular layers gives rise to a unified sublattice for the structures and forms a long-range order.

Synthesis, Characterization, and Nitrogenase-Relevant Reactions of an Iron Sulfide Complex with a Bridging Hydride.

The FeMoco of nitrogenase is an iron–sulfur cluster with exceptional bond-reducing abilities. ENDOR studies have suggested that E4, the state that binds and reduces N2, contains bridging hydrides as part of the active-site iron-sulfide cluster. However, there are no examples of any isolable iron-sulfide cluster with a hydride, which would test the feasibility of such a species. Here, we describe a diiron sulfide hydride complex that is prepared using a mild method involving C–S cleavage of added thiolate. Its reactions with nitrogenase substrates show that the hydride can act as a base or nucleophile and that reduction can cause the iron atoms to bind N2. These results add experimental support to hydride-based pathways for nitrogenase.

Dimethyl Sulfide-Dimethyl Ether and Ethylene Oxide-Ethylene Sulfide Complexes Investigated by Fourier Transform Microwave Spectroscopy and Ab Initio Calculation.

The ground-state rotational spectra of the dimethyl sulfide-dimethyl ether (DMS-DME) and the ethylene oxide-ethylene sulfide (EO-ES) complexes were observed by Fourier transform microwave spectroscopy, and a-type and c-type transitions were assigned for the normal, (34)S, and three (13)C species of the DMS-DME and a-type and b-type transitions for the normal, (34)S, and two (13)C species of the EO-ES complexes. The transition frequencies measured for both the complexes were analyzed by using an S-reduced asymmetric-top rotational Hamiltonian. The rotational parameters thus derived for the DMS-DME were found to be consistent with a structure of Cs symmetry with the DMS bound to the DME by two C-H(DMS)···O and one S···H-C(DME) hydrogen bonds. Some high-Ka lines were found to be split, and we have interpreted these splittings in terms of internal rotations of the two methyl groups of the DMS and of the "free", i.e., outer group, of the DME. Some forbidden transitions were also observed in cases where Ka = 3 levels were involved, for the DMS-DME complex in the internal-rotation E state. The barrier height, V3, to internal rotation of the CH3 in the DME thus derived is smaller than that of the DME monomer, while the V3 of the CH3 groups in the DMS is nearly the same as that of the DMS monomer. For the EO-ES complex, the observed data were interpreted in terms of an antiparallel structure of Cs symmetry with the EO bound to the ES by two C-H(ES)···O and two S···H-C(EO) hydrogen bonds. An attempt was also made to observe a-type transitions of the DMS dimer without success. We have applied a natural bond orbital analysis to the DMS-DME and EO-ES to calculate the stabilization energy CT (= ΔEσσ*), which was correlated closely with the binding energy as found for other related complexes.