Sulfide Clusters Research Articles

Hydrogen evolution from water reactions with molybdenum sulfide cluster anions

A study of reactions between a distribution of 98MoxSy- clusters ranging from sub-sulfide (x ∼ y) to hypersulfide (y > 2x) is presented, compared with previous studies on homologous MoxOz- clusters, and analyzed with supporting computational studies of the reaction free energy pathways, giving insights into the molecular scale interactions involved in the electro- or photocatalytically driven hydrogen evolution reaction. First, reactions between MoxSy- clusters with water are approximately an order of magnitude slower than reactions between oxides with water, an effect attributed to longer-range repulsion between the cluster anions and water. However, sequential oxidation of the MoxSy- clusters, which generates oxosulfides and H2, is observed for several species. Evidence of oxidation of several hypersulfides with H2 evolution is also observed, indicating that oxidation of S2 groups is also possible. Based on the computational results on several of the bimetallic species, oxidation of the subsulfide Mo2S2− and Mo2S3− clusters is barrierless, while oxidation of the nascent Mo2S2O- cluster formed by oxidation of Mo2S2− is low-barrier. The stoichiometric Mo2S4- + H2O free energy path is predicted to have a modest barrier to the dissociative addition of water, which is consistent with the experimental observation of both oxidation (with H2 production) and water addition reactions. Calculations on the reaction free energy pathways of the oxosulfide species suggest that the formation of two dihydroxide groups, rather than a thiol and hydroxide group, is favored. Oxidation of the oxides is more thermodynamically favored than oxidation of sulfide analogs.

Macrocycle-Encircled Polynuclear Metal Clusters: Controllable Synthesis, Reactivity Studies, and Applications.

Macrocyclic ligands have been extensively applied to recognize single metal ions with high selectivity and good affinity based on the size-match principle. The resulting metal-macrocycle complexes play a significant role in mimicking the function of natural metal ion carriers and understanding and reproducing the catalytic activity of metalloenzymes. Because of the known macrocyclic effect, those single metal-macrocycle adducts often show an enhanced kinetic and thermodynamic stability in comparison with their open-chain analogues. By virtue of such extraordinary coordination properties of macrocyclic ligands, it is expected that larger macrocycles with multiple coordination sites could properly act as an outer scaffold to direct the formation of multiatom species inside, such as polynuclear metal cluster aggregates, whose assembly may largely depend on the template positioning of coordinative atoms in the macrocyclic ring. Thus, the employment of polydentate macrocyclic ligands may provide a convenient tool to access polynuclear metal clusters in a controllable way. In this Account, we review our studies of the metal ion binding process of a class of polydentate macrocyclic ligands, azacalixpyridines (Py[ n]s), and the application of Py[ n]s as an outer template to direct the controllable synthesis of polynuclear metal clusters. Our investigations revealed that Py[ n]s show a significant cooperative coordination effect in the metal ion binding process that facilitated the easy formation of a polymetallic assembled structure. Taking advantage of the cooperative coordination effect and the tunable and highly fluxional conformation of Py[ n]s, we laid our focus on control of the nuclearity number by tuning the size of Py[ n]s and the adoption of Py[ n]s with different anionic centers in metal cluster synthesis. As an important example for application, this new established macrocycle-directed method has been employed to achieve a variety of metal-cluster-centered capsule, rotaxane, catenane, polygon, and other supramolecular assemblies. Furthermore, a cluster-to-cluster transformation inside the cavity of Py[ n]s is presented to showcase the use of the acquired metal cluster-macrocycle complexes to achieve unconventional metal cluster entities. With regard to the application of the newly synthesized macrocycle-encircled metal clusters, examples of the fabrication of functional materials and catalysts are presented. With the assistance of Py[ n]s, a bulk-to-cluster-to-nanoparticle transformation of silver sulfide (Ag2S) and silver halides (AgX) has been conducted to produce a series of nonstoichiometric silver sulfide and halide nanoparticles. The resulting Ag-S nanoparticle material with a high Ag/S ratio, which is inherited from the Py[ n]-protected polysilver sulfide clusters, has a large energy gap relative to conventional Ag2S nanoparticles. Moreover, the nonstoichiometric silver halide nanoparticles can act as a new kind of electrocatalyst for the chlorine evolution reaction, showing excellent selectivity and high catalytic efficiency. Overall, in this Account we try to highlight the application of polydentate macrocycles as an outer template to guide the synthesis of polynuclear metal clusters in a controllable manner. This unique synthesis will provide a new avenue to access unconventional metal clusters of different metal kinds and diverse anionic centers, which are expected to have promising and significant applications in many interdisciplinary areas of chemistry.

Chalcogen Impact on Covalency within Molecular [Cu3(μ3-E)]3+ Clusters (E = O, S, Se): A Synthetic, Spectroscopic, and Computational Study.

Reaction of the tricopper(I)-dinitrogen tris(β-diketiminate) cyclophane, Cu3(N2)L, with O-atom-transfer reagents or elemental Se affords the oxido-bridged tricopper complex Cu3(μ3-O)L (2) or the corresponding Cu3(μ3-Se)L (4), respectively. For 2 and 4, incorporation of the bridging chalcogen donor was supported by electrospray ionization mass spectrometry and K-edge X-ray absorption spectroscopy (XAS) data. Cu L2,3-edge X-ray absorption data quantify 49.5% Cu 3d character in the lowest unoccupied molecular orbital of 2, with Cu 3d participation decreasing to 33.0% in 4 and 40.8% in the related sulfide cluster Cu3(μ3-S)L (3). Multiedge XAS and UV/visible/near-IR spectra are employed to benchmark density functional theory calculations, which describe the copper-chalcogen interactions as highly covalent across the series of [Cu3(μ-E)]3+ clusters. This result highlights that the metal-ligand covalency is not reserved for more formally oxidized metal centers (i.e., CuIII + O2- vs CuII + O-) but rather is a significant contributor even at more typical ligand-field cases (i.e., Cu3II/II/I + E2-). This bonding is reminiscent of that observed in p-block elements rather than in early-transition-metal complexes.

Stable Supersupertetrahedron with Infinite Order via the Assembly of Supertetrahedral T4 Zinc-Indium Sulfide Clusters.

A new family member of T p, q-based hierarchical chalcogenide architecture was created by assembling regular T4-ZnInS clusters into a periodically "hollowed-out" cubic ZnS-type structure framework (T4,∞) via the cross-linker of the tetracoordinated corner μ4-S2-. Ion-exchange and CO2 adsorption experiments suggest that such a structure with a corner μ4-S2- linker has structural stability superior to those of previously reported chalcogenide open frameworks composed of the same T4-ZnInS clusters with a bicoordinated (μ2-S2-) or a tricoordinated (μ3-S2-) cross-linker. Importantly, this case further demonstrates the feasibility of systematically engineering stable porous crystalline chalcogenide frameworks by a "hollow-out" strategy.

Tuning the Electron Acceptability of the [Mo6S8] Cluster Core by Decorating It with Methyl Groups on the Face‐Bridging µ3‐Sulfides

Methylation of the molybdenum sulfide cluster unit [Mo6S8(PEt3)6] (1) with CH3OTf resulted in the formation of mono‐ and dimethylated cluster units, [Mo6S8–x(SCH3)x(PEt3)6]OTf·yCH2Cl2 {[2]OTf·0.5CH2Cl2 (x = 1, y = 0.5) and [3]OTf·CH2Cl2 (x = 2, y = 1)}. Structural and electrochemical investigations revealed that the methylation of the µ3‐S ligand(s) induced a characteristic structural distortion of the [Mo6S8] cluster core and enhanced its ability to accept multiple electrons.

(PPh3)4Pt2S2(SnCl)]+: A Pt‐Sn‐S Cluster with a Ternary Trigonal Bipyramidal Cluster Core

By reaction of the organotin sulfide cluster [(R1Sn)4S6] (A) [R1 = CMe2CH2CMeN–N=CH(C11H8N2)] with [Pt(PPh3)2Cl2], a new heterobimetallic platinum‐tin chalcogenide cluster was synthesized with a ternary, trigonal bipyramidal cluster core. The structure of [(PPh3)4Pt2S2(SnCl)][SnCl3] (1) was determined by X‐ray diffraction, further characterization was done by means of electrospray ionization mass spectrometry (ESI‐MS) and nuclear magnetic resonance (NMR) spectroscopy.

Highly Photoluminescent Sulfide Clusters Confined in Zeolites

The design, synthesis and photoluminescence characterization of sulfide cluster-based zeolitic materials with the general formula Na8[SiAlO4]6SxCl2–2x is presented in this report. The employed experimental conditions, which included the thermal treatment of sodium Linde type A (Na-LTA) zeolites in the presence of Na2SO4 and NaCl, yielded highly photoluminescent sulfur-zeolites with remarkably large Stokes shifts. An emission band at 650 nm for samples with low sulfur contents is observed when excited at 380 nm, which is fully consistent with S2– clusters as light-emitting centers. These orange emitting materials display external quantum efficiencies (EQEs) reaching 53% with peculiar high temperature photoluminescence stability up to 450 °C. For higher S/Cl molar ratios, a gradual conversion to near-infrared (NIR) light-emitting centers is observed with a maximum at 780 nm. This novel NIR luminescent species with EQEs of about 10% are attributed to polysulfide clusters (tentatively S42– species). Given the...

White‐Light Generation through Nonlinear Optical Response of 1,3,5,7‐Tetraphenyladamantane: Amorphous versus Crystalline States

AbstractThe vast optical nonlinearity of 1,3,5,7‐tetraphenyladamantane (AdPh4) enables efficient frequency conversion. The observed spectrum depends heavily on the material's habitus. In particular, it shows nonlinear white‐light generation when its powder form is irradiated in the near‐infrared, similar to an analogous organotin sulfide cluster [(PhSn)4S6]. In contrast, single crystals of AdPh4 exclusively exhibit narrow‐band second‐harmonic generation, i.e., discrete conversion within the crystal, rather than spectrally broadband white‐light emission. This shows that crystallinity restricts the nonlinear response to the symmetry‐allowed higher‐harmonics, in this case the even‐numbered, second harmonic, and inhibits the quasi‐continuum white‐light emission. Using the diamondoid‐based material significantly enhances compatibility with conventional production techniques using photorefractive polymers and is thus an important step towards the fabrication of all‐integrated white‐light emitting devices.

Enhanced catalytic performance and promotional effect of molybdenum sulfide cluster-derived catalysts for higher alcohols synthesis from syngas

A series of catalysts were prepared using molybdenum sulfide clusters as precursors and their catalytic performance for higher alcohols synthesis was evaluated. It was found that the cluster precursors could provide well-dispersed MoS2 particles and a number of coordinated unsaturated Mo sites with all the catalysts in varying degrees, which were favorable for the formation of intermediate active phases thereby enhancing catalytic performance. In particular, K-NiMo3Sx catalyst obtained by using heterobimetallic cluster NiMo3S13 as precursor exhibited the highest activity with the space-time-yield (STY) of total alcohols (497 mg/g/h) and the selectivity of higher alcohols (59.71%), which could be attributed to the interaction effect of the Ni promoter and Mo species and the resultant formation of active phase NiMo3Sx. Thus, the most key factor for obtaining highly efficient molybdenum sulfide catalysts was to produce a number of coordinated unsaturated sites, on which abundant NiMoS active phase can be formed and the formation of bulk inactive phase should be avoided.

On the Reactivity and Stability of Iodide–Nitride–Sulfide Clusters of Neodymium and Dysprosium

The thermal decomposition of cluster Nd3I5(S2)(S2N2)(THF)10 (I) at 50–400°C affords a mixture of products among which tetrahydrofuran (THF), sulfur, diiodine, HI, H2S, CS2, S3N6, S3N5, MeI, thiophene, tetrahydrothiophene, diiodobutane, iodobutene, and NdI3 are identified. The treatment of Ln3I5(S2)(S2N2)(THF)10 (Ln = Nd (I), Dy (II)) with phenanthroline (Phen) in THF at room temperature results in the partial substitution of ТНF to form new complexes Ln3I5(S2)(S2N2)(THF)4(Phen)3. The dissolution of compound I in pyridine gives a pyridine (Py) complex Ln3I5(S2)(S2N2)(THF)3(Py)7. The dissolution of compounds I and II in acetonitrile at 20°C is accompanied by the fast rearrangement and fragmentation of the complexes to form LnI3(MeCN)6, [LnI(S2)(MeCN)], and [LnI(S2N2)(MeCN)]. Complex I in THF does not react with white phosphorus, carbon monoxide, fullerene C60, and chromium hexacarbonyl.

Towards atomically precise luminescent Ag2S clusters separable by thin layer chromatography

Synthesis of BBSH protected silver sulfide clusters.

Molybdenum sulfide clusters immobilized on defective graphene: a stable catalyst for the hydrogen evolution reaction

We design a composite catalyst composed of molybdenum sulfide clusters and defective graphene with high activity and good stability for hydrogen evolution.

Copper transport and sulphide sequestration during copper corrosion in anaerobic aqueous sulphide solutions

The corrosion of copper in aqueous solutions containing ≥5×10−4mol/L sulphide and the ensuing accumulation of corrosion product deposits (as chalcocite Cu2S) occurs non-uniformly indicating the occurrence of microgalvanic coupling between net anodic and net cathodic surface locations. A series of novel electrochemical experiments were designed to confirm the occurrence of this process and a series of analytical procedures used to identify the chemical nature of the transported Cu species. Transport was found to occur as copper sulphide complexes and clusters. It was also demonstrated that all the available sulphide was sequestered as deposited Cu2S.

A theoretical study on the geometry and spectroscopic properties of ground-state and local minima isomers of (CuS)n=2-6 clusters

Spectroscopic properties of gas-phase copper sulfide clusters (CuS)n (n = 2–6) are calculated using Density Functional Theory (DFT) and time-dependent (TD) DFT approaches. The energy landscape of the potential energy surface is explored through a basin-hopping DFT methodology. Ground-state and low-lying isomer structures are obtained. The global search was performed at the B3PW91/SDD level of theory. Normal modes are calculated to validate the existence of optimal cluster structures. Energetic properties are obtained for the ground-state and isomer clusters and their relative energies are evaluated for probing isomerization. This is a few tenths of an eV, except for (CuS)2 cluster, which presents energy differences of ∼1 eV. Notable differences in the infrared spectra exist between the ground-state and first isomer structures, even for the (CuS)5 cluster, which has in both configurations a core copper pyramid. TDDFT provides the simulated absorption spectrum, presenting a theoretical description of optical absorption bands in terms of electronic excitations in the UV and visible regions. Results exhibit a significant dependence of the calculated UV/vis spectra on clusters size and shape regarding the ground state structures. Optical absorption is strong in the UV region, and weak or forbidden in the visible region of the spectrum.

Syntheses and Properties of Gold-Organotin Sulfide Clusters.

We report that reactions of the binary organotin sulfide cluster [(R1Sn)3S4]Cl [A; R1 = CMe2CH2C(O)Me] with gold(I) phosphane complexes yield discrete ternary complexes [(R1Sn)2(AuPMe3)2S4] (1) and [(R2Sn)2(AuPMe3)2S4] [2; R2 = CMe2CH2C(NNH2)Me], which are related to recently published complexes [(R1,2Sn)2(AuPPh3)2S4] (B and C). Further, we present a binary tin sulfide cluster that cocrystallizes with a structure-directing salt of a gold phosphane complex in [Au(dppe)2][(R3Sn)4S6Cl] [3; R3 = CMe2CH2C(NNHPh)Me]. The nature of the product depends on the choice of the phosphane ligand as well as the addition of hydrazine hydrate or phenylhydrazine. Additionally, we report on the photophysical properties of 1, 2, B, and C, which indicate that the different phosphane ligands only have a slight influence on the optical responses. The structure, however, has a significant impact on the luminescence efficiency.

Structure-Directing Role of Phosphonate in the Synthesis of High-Nuclearity Silver(I) Sulfide-Ethynide-Thiolate Clusters.

Phosphonate ligands as structure-directing components have been employed to construct four new high-nuclearity silver(I) sulfide-ethynide-thiolate clusters, in which silver(I) aggregates tBuC≡C⊃Ag3, tBuC≡C⊃Ag4, and 2tBuC≡C⊃Ag7 are bridged by tBuS- ligands to engender respective silver(I) ethynide-thiolate clusters functioning as integral shell components, which are supported by phosphonate ligands. In each silver(I) sulfide-ethynide-thiolate cluster, a different encapsulated silver sulfide cluster serves as a core template.

Electron Transfer between Electrically Conductive Minerals and Quinones.

Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well-known, but the impact of abiotic currents across naturally occurring conductive and semiconductive minerals is poorly understood. In this paper I use cyclic voltammetry to explore electron transfer between electrodes made of common iron minerals (magnetite, hematite, pyrite, pyrrhotite, mackinawite, and greigite), and hydroquinones—a class of organic molecules found in carbon-rich sediments. Of all tested minerals, only pyrite and magnetite showed an increase in electric current in the presence of organic molecules, with pyrite showing excellent electrocatalytic performance. Pyrite electrodes performed better than commercially available glassy carbon electrodes and showed higher peak currents, lower overpotential values and a smaller separation between oxidation and reduction peaks for each tested quinone. Hydroquinone oxidation on pyrite surfaces was reversible, diffusion controlled, and stable over a large number of potential cycles. Given the ubiquity of both pyrite and quinones, abiotic electron transfer between minerals and organic molecules is likely widespread in Nature and may contribute to several different phenomena, including anaerobic respiration of a wide variety of microorganisms in temporally anoxic zones or in the proximity of hydrothermal vent chimneys, as well as quinone cycling and the propagation of anoxic zones in organic rich waters. Finally, interactions between pyrite and quinones make use of electrochemical gradients that have been suggested as an important source of energy for the origins of life on Earth. Ubiquinones and iron sulfide clusters are common redox cofactors found in electron transport chains across all domains of life and interactions between quinones and pyrite might have been an early analog of these ubiquitous systems.

Metal Trimethylsilylthiolates for the Synthesis of Trinuclear MnPd2 Complexes

The manganese(II)‐palladium(II)‐sulfide complex [MnCl2(μ3‐S)2Pd2(dppp)2] (2) was prepared from the reaction of [PdCl2(dppp)] with [Li(N,N'‐tmeda)]2[Mn(SSiMe3)4] (2) in a 2:1 ratio under mild conditions. The new trimethylsilylthiolate complex [Pd(dppp)(SSiMe3)2] (3) was synthesized from the reaction of [Pd(dppp)(OAc)2] with two equivalents of Li[SSiMe3]; this was then used in a reaction with [Mn(CH3CN)2(OTf)2] to form the manganese(II)‐palladium(II)‐sulfide cluster [Mn(OTf)(thf)2(μ3‐S)2Pd2(dppp)2]OTf (4).

Chemical Processes Involved in Atomic Layer Deposition of Gallium Sulfide: Insights from Theory

Growth characteristics of atomic layer deposition (ALD) of gallium sulfide (GaxS) from tris(dimethylamino)gallium (Ga(NMe2)3) and hydrogen sulfide (H2S) have been investigated by density functional theory. The steady-state film growth during one ALD cycle was modeled by studying the energetics of a large set of reactions taking place on a surface described as a SH-terminated gallium sulfide (Ga2S3) cluster. The opportunity of using gas-phase cluster calculations to compute entropic contributions is discussed. Detailed reaction mechanisms are provided, along with free energy profiles and a large reaction network emerges. It confirms a ligand loss/exchange mechanism, and various aspects of the growth are explored (fate of the precursor and co-reactant, self-saturation of the surface, crawling and cooperative effects, role of the amido ligand, of the impurities, etc.) and confronted to experimental observations. All the key reaction steps are facile and thermodynamically favorable, while undesired side react...

Chemoselective Hydrogenation of Nitroarenes Catalyzed by Molybdenum Sulphide Clusters

AbstractHerein, we describe an atom efficient and general protocol for the chemoselective hydrogenation of nitroarenes to anilines catalyzed by well‐defined diimino and diamino cubane‐type Mo3S4 clusters. The novel diimino [Mo3S4Cl3(dnbpy)3]+ ([5]+) (dnbpy=4,4′‐dinonyl‐2,2′‐dipyridyl, L1) trinuclear complex was synthesized in high yields by simple ligand substitution reactions starting from the thiourea (tu) [Mo3S4(tu)8(H2O)]Cl4⋅4 H2O (3) precursor. This strategy has also been successfully adapted for the isolation of the diamino [Mo3S4Cl3(dmen)3](BF4) ([6](BF4)), (dmen=N,N′‐dimethylethylenediamine) salt. Applying these catalysts, high selectivity in the hydrogenation of functionalized nitroarenes has been accomplished. Over thirty anilines bearing synthetically functional groups have been synthesized in 70 to 99 % yield. Notably, the integrity of the cluster core is preserved during catalysis. Based on kinetic studies on the hydrogenation of nitrobenzene and other potential reaction intermediates, the direct reduction to aniline is the preferential route.