Directed Dehydration of Na4Sn2S6 ⋅ 5H2O Generates the New Compound Na4Sn2S6: Crystal Structure and Selected Properties

The new thiostannate Na₄Sn₂S₆ was prepared by directed crystal water removal from the hydrate Na₄Sn₂S₆ ⋅ 5H₂O at moderate temperatures. While the structure of the hydrate comprises isolated [Sn₂S₆]⁴⁻ anions, that of the anhydrate contains linear chains composed of corner-sharing SnS₄ tetrahedra, a structural motif not known in thiostannate chemistry. This structural rearrangement requires bond-breakage in the [Sn₂S₆]⁴⁻ anion, movements of the fragments of the opened [Sn₂S₆]⁴⁻ anion and Sn−S−Sn bond formation. Simultaneously, the coordination environment of the Na⁺ cations is significantly altered and the in situ formed NaS₅ polyhedra are joined by corner- and edge-sharing to form a six-membered ring. Time-dependent in situ X-ray powder diffraction evidences very fast rehydration into Na₄Sn₂S₆ ⋅ 5H₂O during storage in air atmosphere, but recovery of the initial crystallinity requires several days. Impedance spectroscopy demonstrates a mediocre room-temperature Na⁺ ion conductivity of 0.31 μS cm⁻¹ and an activation energy for ionic transport of E_a=0.75 eV.     

Vibration spectrum and normal coordinate analysis of the pyrothiophosphates Na4P2S7, Na2FeP2S7, and Ag4P2S7

Na₄P₂S₇, Na₂FeP₂S₇, and Ag₄P₂S₇ were prepared by elemental synthesis at high temperatures and were characterized by vibration spectra and differential thermal analysis (DTA). A normal coordinate analysis was performed for P₂S⁴⁻₇. Additional vibration frequencies indicate the presence of the decathiotriphosphate anion P₃S⁵⁻₁₀. The formation of higher thiophosphates of the type P_nS^(n+2)-_3n+1 with n ≥ 4 cannot be excluded.     

An unusual two‐dimensional hydrogen‐bonding network in bis(2,9‐dimethyl‐1,10‐phenanthrolin‐1‐ium) peroxodisulfate dihydrate

The title compound, 2C₁₄H₁₃N₂⁺·S₂O₈²⁻·2H₂O, is a protonated amine salt which is formed from two rather uncommon ionic species, namely a peroxodisulfate (pds²⁻) anion, which lies across a crystallographic inversion centre, and a 2,9‐dimethyl‐1,10‐phenanthrolin‐1‐ium (Hdmph⁺) cation lying in a general position. Each pds²⁻ anion binds to two water molecules through strong water–peroxo O—H...O interactions, giving rise to an unprecedented planar network of hydrogen‐bonded macrocycles which run parallel to (100). The atoms of the large R₈⁸(30) rings are provided by four water molecules bridging in fully extended form (...H—O—H...) and four pds²⁻ anions alternately acting as long (...O—S—O—O—S—O...) and short (...O—S—O...) bridges. The Hdmph⁺ cations, in turn, bind to these units through hydrogen bonds involving their protonated N atoms. In addition, the crystal structure also contains π–π and aromatic–peroxo C—H...O interactions.     

On the Flexibility of Thioantimonate Networks: Solvothermal Syntheses and Crystal Structures of Six New Thioantimonates(III) with the [Sb4S7]2− Anion

Six new thioantimonates(III) with the [Sb₄S₇]²⁻ anion were obtained under solvothermal conditions with in‐situ formed transition metal complexes as structure directors. In the two isostructural compounds [Fe(dien)₂]Sb₄S₇·H₂O ( 1 ) and [Co(dien)₂]Sb₄S₇·0.5 H₂O ( 2 ) (dien = diethylenetriamine; space group: P2₁/c) the layered [Sb₄S₇]²⁻ anion is characterized by Sb₈S₈ rings with a diameter of about 9.6·7.6Å. The cation complexes are located above and below the pores of the rings. Despite the larger size of the cation complex the network topology of the third thioantimonate [Ni(dien)(tren)]Sb₄S₇ ( 3 ) (tren = tris(2‐aminoethyl)amine; space group: P2₁/n) is similar to that of the first two compounds. In the isostructural thioantimonates [M(trien)]Sb₄S₇ (M = Zn ( 4 ); M = Mn ( 5 ); trien = triethylenetetramine; space group: ) the M²⁺ ions are fivefold coordinated by four N atoms of the amine molecule and by one S atom of the thioantimonate anion forming a MN₄S trigonal bipyramid. Sb₈S₁₆ building blocks are the central structural motifs of the anion. Two of the terminal S atoms at the periphery of the Sb₈S₁₆ units are bound to M²⁺ ions and the four remaining terminal S atoms connect adjacent Sb₈S₁₆ groups into the final [Sb₄S₇]²⁻ chain. [Ni(tren)]Sb₄S₇ ( 6 ) (space group: ) contains a one‐dimensional anionic chain. The Ni²⁺ ion has two bonds to the [Sb₄S₇]²⁻ anion which is a unique feature in the thioantimonate(III) chemistry. The NiN₄S₂ octahedron is severly distorted with one very long Ni‐S bond of 2.782(2) Å. In all compounds several short S···H distances indicate hydrogen bonding interactions.     

An investigation of the sulphur(−II)/sulphur(0) system on bold electrodes

Sulphur deposited on gold by the anodic oxidation of sulphur(−II) species in solution has been studied by X-ray photoelectron spectroscopy. The initial layer behaved as gold sulphide. Multilayers of sulphur had a lower volatility and a smaller electron binding energy than bulk elemental sulphur, indicating that there is interaction with the underlying gold or gold sulphide.The anodic oxidation of sulphur(−II) to sulphur, and the reverse process, has been investigated on gold using the rotating ring disc electrode technique. Polysulphide ions were formed as intermediates in both processes. Polysulphides were also produced by chemical reaction of deposited sulphur with sulphur(−II) species in solution. The polysulphide intermediates were identified as S²⁻₅ at pH 13, a mixture of species with average stoichiometry S²⁻_3.3 at pH 9.2 and S²⁻₂, possibly HS⁻₂, at pH 6.8.     

Pd0-Catalyzed Asymmetric Carbonitratation Reaction Featuring an H-Bonding-Driven Alkyl−PdII−ONO2 Reductive Elimination

Reductive elimination of alkyl−Pd^II−O is a synthetically useful yet underdeveloped elementary reaction. Here we report that the combination of an H-bonding donor [PyH][BF₄] and AgNO₃ additive under toluene/H₂O biphasic system can enable such elementary step to form alkyl nitrate. This results in the Pd⁰-catalyzed asymmetric carbonitratations of (Z)-1-iodo-1,6-dienes with (R)-BINAP as the chiral ligand, affording alkyl nitrates up to 96 % ee. Mechanistic studies disclose that the reaction consists of oxidative addition of Pd⁰ catalyst to vinyl iodide, anion ligand exchange between I⁻ and NO₃⁻, alkene insertion and S_N2-type alkyl−Pd^II−ONO₂ reductive elimination. Evidences suggest that H-bonding interaction of PyH⋅⋅⋅ONO₂ can facilitate dissociation of O₂NO⁻ ligand from the alkyl−Pd^II−ONO₂ species, thus enabling the challenging alkyl−Pd^II−ONO₂ reductive elimination to be feasible.     

The Unprecedented [S4N2O10]2− Anion in the Molecular Gold Complexes [Au2Br2(S4N2O10)2] and [Au2Cl2(S4N2O10)2](S2O5Cl2)

The reaction of hexachlorophosphazene, P₃N₃Cl₆, with SO₃ and the gold halides AuCl₃ and AuBr₃, respectively, leads to the new cyclic anionic tetramer, [S₄N₂O₁₀]²⁻, which is coordinated to Au³⁺ in the dimeric complexes [Au₂X₂(S₄N₂O₁₀)₂] (X=Cl, Br). The [S₄N₂O₁₀]²⁻ anion can be seen as the condensation product of two sulfate anions, [SO₄]²⁻_, and two amidosulfate anions, [NH₂SO₃]⁻.     

FeIII in a low‐spin state in caesium bis[3‐ethoxysalicylaldehyde 4‐methylthiosemicarbazonato(2–)‐κ3O2,N1,S]ferrate(III) methanol monosolvate

The synthesis and crystal structure (at 100 K) of the title compound, Cs[Fe(C₁₁H₁₃N₃O₂S₂)₂]·CH₃OH, is reported. The asymmetric unit consists of an octahedral [Fe^III(L)₂]⁻ fragment, where L²⁻ is 3‐ethoxysalicylaldehyde 4‐methylthiosemicarbazonate(2−) {systematic name: [2‐(3‐ethoxy‐2‐oxidobenzylidene)hydrazin‐1‐ylidene](methylamino)methanethiolate}, a caesium cation and a methanol solvent molecule. Each L²⁻ ligand binds through the thiolate S, the imine N and the phenolate O atoms as donors, resulting in an Fe^IIIS₂N₂O₂ chromophore. The O,N,S‐coordinating ligands are orientated in two perpendicular planes, with the O and S atoms in cis positions and the N atoms in trans positions. The Fe^III cation is in the low‐spin state at 100 K.     

The Sulfur Rich Fluorothiophosphate Dianions [S5P2F2]2− and [S3PF]2− : Cluster and Chelation Control of P-S Heterolysis

The sulfur rich difluoropentathiodiphosphate dianion [S₅P₂F₂]²⁻, from fluoride addition to P₄S₁₀, has a somewhat checkered history and proves to be the main product of the reaction in acetonitrile. Its optimized synthesis, and structural characterization, as either a tetraphenylphosphonium or a tetrapropylammonium salt, [NⁿPr₄]₂[S₅P₂F₂] allows for the first coordination chemistry for this dianion. Reactions of [S₅P₂F₂]²⁻ with d¹⁰ metal ions of zinc(II), and cadmium(II), and d⁹ copper(II) resulted in a surprising diverse array of binding modes and structural motifs. In addition to the simple bis-chelate coordination of [S₅P₂F₂]²⁻ with zinc, cleavage of the P−S bond resulted in complexes with the unusual [S₃PF]²⁻ fluorotrithiophosphate dianion. This was observed in two cluster complexes: a trinuclear cadmium complex with mixed [S₅P₂F₂]²⁻/[S₃PF]²⁻ ligands, [Cd₃(S₅P₂F₂)₃(S₃PF)₂]⁴⁻ as well as an octanuclear copper cluster, [Cu₈(S₃PF)₆]⁴⁻ which form rapidly at room temperature. These new metal/sulfur/ligand clusters are of relevance to understanding multimetal binding to metallothionines, and to potential capping strategies for the condensed nanoparticulate cadmium chalcogenide semiconductors CdS and CdSe.     

Negative Ion Formation by Thermal Surface Ionization of Sulfur Dioxide

The generation of negative ions from SO₂ in the gas phase was studied using the thermal surface ionization method. Six anion types were measured: O⁻, S⁻, SO⁻, and SO₂⁻ and anions with m/z=96 and m/z=128. The most abundant anion formed was S⁻ and the formation routes are discussed for each of the six anions. O⁻, S⁻, and SO⁻ are formed via dissociative electron attachment to the molecule, whereas the generation of SO₂⁻ and anions with m/z=96 and m/z=128 are probably associated with the formation of H₂SO₄ in the gas inlet system and the ion source. Using statistical thermodynamics the dissociation temperatures of SO₂ and SO in the gas phase are calculated and values of above 1800 °C are obtained for both molecules. We also estimated the optimal filament temperatures for the formation of all anions measured, indicating that for SO₂ the optimal temperature is related to the electron affinity of the molecules: the optimal temperature increases with decreasing value of the electron affinity for the molecule corresponding to the respective anion.     

Room-Temperature Solid-State Transformation of Na4SnS4 ⋅ 14H2O into Na4Sn2S6 ⋅ 5H2O: An Unusual Epitaxial Reaction Including Bond Formation,Mass Transport,and Ionic Conductivity

A highly unusual solid-state epitaxy-induced phase transformation of Na₄SnS₄ ⋅ 14H₂O ( I ) into Na₄Sn₂S₆ ⋅ 5H₂O ( II ) occurs at room temperature. Ab initio molecular dynamics (AIMD) simulations indicate an internal acid-base reaction to form [SnS₃SH]³⁻ which condensates to [Sn₂S₆]⁴⁻. The reaction involves a complex sequence of O−H bond cleavage, S²⁻ protonation, Sn−S bond formation and diffusion of various species while preserving the crystal morphology. In situ Raman and IR spectroscopy evidence the formation of [Sn₂S₆]⁴⁻. DFT calculations allowed assignment of all bands appearing during the transformation. X-ray diffraction and in situ ¹H NMR demonstrate a transformation within several days and yield a reaction turnover of ≈0.38 %/h. AIMD and experimental ionic conductivity data closely follow a Vogel-Fulcher-Tammann type T dependence with D(Na)=6×10⁻¹⁴ m² s⁻¹ at T=300 K with values increasing by three orders of magnitude from −20 to +25 °C.     

O-atom transfer biomimetic oxidation of benzoin in the presence of monooxomolybdenum(IV) thiolate complexes

Novel catalytically active monooxomolybdenum(IV) species containing four thiolate ligands obtainable in solution by NaBH₄ reduction of [Mo^vO(SC₆H₅)₄]⁻, [Mo^vO(Z-cys-Val-OMe)₄]⁻, (Z=benzyloxycarbonyl), or [Mo^vO(S₂C₆H₄)₂]⁻ perform the pyridine-N-oxide oxidation of benzoin in N,N-dimethylformamide at 30 °C. The order of catalytic activity is [Mo^vO(Z-cys-Val-OMe)₄]⁻ > [Mo^vO(S₂C₆H₄)₂]⁻ > [Mo^vO(SC₆H₅)₄]⁻ ([benzoin]/[oxidant]/[catalyst]= 20/20/1), while the oxidation by air under the same catalytic conditions gives a different order, [Mo^vO(Z-cys-Val-OMe)₄]⁻> [Mo^vO(SC₆H₅)₄]⁻ >[Mo^vO(S₂C₆H₄)₂]⁻. During the catalytic cycle in the amine-N-oxide oxidation, two intermediate species, [Mo^IVOL₄]²⁻ and [Mo^VIO₂L₄]²⁻, were detected by ¹H NMR, while in the air oxidation an unidentified Mo(VT) species is involved.     

Metal Binding Ability of Small Peptides Containing Cysteine Residues

The Cd(II)-, Pb(II)-, Ni(II)- and Zn(II)-complexes of small terminally protected peptides containing CXXX, XXXC, XCCX, CX_nC (n=1–3) sequences have been studied with potentiometric, UV/Vis and CD spectroscopic techniques. The cysteine thiolate group is the primary binding site for all studied metal ions, but the presence of a histidyl or aspartyl side chain in the molecule contributes to the stability of the complexes. For two-cysteine containing peptides the (S⁻,S⁻) coordinated species are formed in the physiological pH range and the stability increases in the Ni(II)<Zn(II)<Pb(II)<Cd(II) order. As a conclusion, the inserting of −CXXC− sequence into the peptide makes the synthesis of peptides with high selectivity to toxic Cd(II) or Pb(II) ion possible. In addition, the spectroscopic characterization of these complexes can contribute to the discovery of the exact binding site and binding mode of longer peptides mimicking the biologically important proteins.     

Electrocatalysis of hydrogen evolution by synthetic diiron units using weak acids as the proton source: Pathways of doubtful relevance to enzymic catalysis by the diiron subsite of [FeFe] hydrogenase

IR spectroelectrochemical studies of bis(thiolate) and dithiolate-bridged diiron carbonyl compounds, [Fe₂(μ-SR)₂(CO)₆], show that the primary reduction process results in rapid chemical reaction, leading to two-electron reduced products. When the reaction is conducted under an inert atmosphere, the major product is [Fe₂(μ-SR)(μ-CO)(CO)₆]¹⁻, where in the case of dithiolate-bridged neutral compounds the product has one bridging and one non-bound sulfur atom. This product is formed in near-quantitative yield for solutions saturated with CO. Reduction of [Fe₂(μ-SR)(μ-CO)(CO)₆]¹⁻ occurs at potentials near −2.0 V vs. SCE to give a range of products including [Fe(CO)₄]²⁻. Reduction of thiolate-bridged diiron compounds at mild potentials in the presence of CH₃COOH leads to formation of [Fe₂(μ-SR)(μ-CO)(CO)₆]¹⁻ and this is accompanied by an acid-base reaction with the dissociated thiolate. The reaction is largely reversible with recovery of ca. 90% of the starting diiron compound and CH₃COOH. In the presence of acid, reduction of [Fe₂(μ-SR)₂(CO)₆] proceeds without generation of observable concentrations of the structurally related one-electron reduced compound. Electrocatalytic proton reduction is achieved when the potential is stepped sufficiently negative to reduce [Fe₂(μ-SR)(μ-CO)(CO)₆]¹⁻, an observation in keeping with the cyclic voltammetry of the system. Since the catalytic species involved in the weak-acid reactions is structurally distinct from the starting material, and the diiron subsite of the hydrogenase H-cluster, these experiments are of dubious relevance to the biological system.     

Kinetic evidence for the reaction of O•− radical ions and peroxodisulfate in alkaline aqueous solutions

Photolysis of S₂O₈⁼ in strong alkaline solutions (pH>13) in the presence of molecular oxygen yields ozonide radical ions, . These radicals show a complex decay rate sensitive to the peroxodisulfate concentration. A reaction mechanism, which includes the reaction of O^•− and S₂O₈⁼ with a rate constant k=(3−6)×10⁶M⁻¹s⁻¹ and accounts for the experimental results is discussed. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 491–496, 1998     

A three‐dimensional metal–organic polymer: poly[bis(μ2‐pyrimidine‐2‐thiolato‐κ4N1,S:S,N3)lead(II)]

The title compound, [Pb(C₄H₃N₂S)₂]_n, was prepared by the reaction of [Pb(OAc)₂]·3H₂O (OAc is acetate) with pyrimidine‐2‐thione in the presence of triethylamine in methanol. In the crystal structure, the Pb^II atom has an N₄S₄ coordination environment with four ligands coordinated by N‐ and S‐donor atoms. This compound shows that the pyrimidine‐2‐thiolate anion can lead to a three‐dimensional network when the coordination number of the metal ion can be higher than 6, as is the case with the Pb^II ion. This compound presents only covalent bonds, showing that despite the possibility of the hemidirected geometries of Pb^II, the eight‐coordinated ion does not allow the formation of an isolated molecular structure with pyrimidine‐2‐thiolate as the ligand.     

Products of the interaction of (1‐diaminomethylene)thiourea with hydrofluoric acid

The salts 1‐(diaminomethylene)thiouron‐1‐ium hydrogen difluoride, C₂H₇N₄S⁺·HF₂⁻, (I), and bis[1‐(diaminomethylene)thiouron‐1‐ium] hexafluoridosilicate, 2C₂H₇N₄S⁺·SiF₆²⁻, (II), have both been obtained from the reaction of (1‐diaminomethylene)thiourea (HATU) with hydrofluoric acid. Both compounds contain extensive networks of N—H...F hydrogen bonds. The hydrogen difluoride salt contains four independent asymmetric [HF₂]⁻ anions. In the hexafluoridosilicate salt, the centrosymmetric [SiF₆]²⁻ anion is distorted, although this distortion is not clearly correlated with the N—H...F hydrogen‐bonding network.     

Réactivité du bromure de 5-thioxylopyranosyle et du 1,5-dithioxylopyranoside vis-à-vis d’anions thiolate

Reactivity of 5-thioxylopyranosyl bromide and 1,5-dithioxylopyranoside towards thiolate anions. Reactivity of thiolate anion RS^– 2′ (C₆H₅–S^–) and 3′ (p-CH₃–C₆H₄–S^–) towards 5-thioxylopyranosyl bromide Xyl–Br yields to the corresponding 1,5-dithioxylopyranoside Xyl–SR 7 R = C₆H₅– and 8 R = p-CH₃–C₆H₄, respectively. In the presence of 4′ (C₆H₅–CH₂–S^–) or 5′ (CH₃–S^–), the reaction gives the 5-thioxylopyranose 9. Anions 5′ and 4′ react with 1,5-dithioxylopyranoside 10 Xyl–SR′ (R′ = –C₆H₄–CO–C₆H₄–CN) to give sulphide derivative 11 (CH₃–S–C₆H₄–CO–C₆H₄– CN) and 13 (C₆H₅–CH₂–S–C₆H₄–CO–C₆H₄–CN), respectively, and the 1,5–dithioxylose 12. These differences in terms of reactivity could be explained by the nucleophilic behaviour of the formed thiolate anion. To cite this article: D. Brevet et al., C. R. Chimie 6 (2003).     

On the reaction of P4S10 with hexamethyldisilazane

P₄S₁₀ reacts with (Me₃Si)₂NH, to give SP(NHSi-Me₃)_x(SSiMe₃)_3−x, where x = 0–3. These species were shown by ³¹P NMR spectroscopy to subsequently form cyclic and linear condensation products. The molecular structure of a linear trimer (Me₃SiNH)P(S)[(μ-NH)P(S)(NHSiMe₃)₂]₂, 12 , was authenticated by an X-ray diffraction study. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:115–121, 1998     

Synthesis and structural characterization of sulfur rich iron (II) carbonyl dimers: Facile reversible reaction with carbon monoxide

The sulfur-rich iron carbonyl dimer complexes [Fe(CO)₂(S′^SiS₂)]₂ (2), and [Fe(CO)(S′^SiS₂)]₂ (3) have been prepared. The [2Fe-2S] cores of the new complexes are planar. The binding mode of the tridentate sulfur ligand in complex 2 is facial with a S(thiolate)-Fe-S(thiolate) angle of 92°, while in complex 3, the S′^SiS₂ ligand binds the metal with a S(thiolate)-M-S(thiolate) angle of 120°. The Fe-Fe distance is reduced from 3.45 Å in complex 2 to 2.78 Å in the 32 electron dimer complex 3. Complexes 2 and 3 are at equilibrium in solution and can be readily interconverted by addition or removal of CO.