Sulfides anionic polysulfides

In solution this reaction is rather rapid but in the solid state autoxidation takes place much slower. Nevertheless, commercial sulfides and polysulfides of the alkali and alkali earth metals usually contain thiosulfate (and anions of other sulfur oxoacids) as impurities [6]. For all these reasons the chemistry of polysulfides is rather complex, and some of the earlier studies on polysulfides (prior to ca. 1960) are not very rehable experimentally and/or describe erroneous interpretations of the experimental results. 

Upon discharge sodium ions diffuse through the sodium-conducting /J- or -alumina or NASICON -> solid electrolyte. On the outer surface of the solid electrolyte they react with molten sulfur and/or low valency sulfide anions forming negatively charged polysulfide anions. The rather low electric conductivity of molten sulfur is improved by addition of tetracyanoethylene... 

Copper(I) Sulfido Anions. There is a remarkable array of polynuclear anions containing sulfur rings or chains that can be isolated as salts of large cations. They are formed by dissolution of copper sulfides in polysulfide solutions or by the action of sulfur and H2S on ethanolic solutions of Cu11 acetate. Examples are ions such as [Cu2S20]4-, [Cu3Si2]3, and [Cu4Si8]4-. Many of the structures are quite complex, for example, (17-H-VII) and (17-H-VIII). 

From the reaction of Au with alkali metal polysulfide liquids, LiAuS and NaAuS were discovered. Both compounds contain infinite one-dimensional (AuS) chains, featuring alternating sulfide anions and linear coordinated Au centers. In LiAu8, the chains are zigzag and fully extended and they pack in mutually perpendicular sets. In NaAuS, the same chains coil in an unusual fashion so that they become interwoven to form layers reminiscent of chicken-wire (Figure 17). This novel coiling mode allows Au Au contacts to form, which help to stabilize the structure. 

There is a range of polysulfide dianions 8 that can be obtained by reaction of sulfur with simple sulfides, by high-temperature reaction of an alkali metal with sulfur, or by reaction of alkali metals with sulfur in liquid ammonia. Often, once formed, the anions are in equilibrium in solution, but individual anions can be complexed successfully. 8tructures of the free poly sulfide anions are shown in Figure 31. 

There are three principal species of reduced sulfur (i) H2S that is produced mainly by SRB as earlier discussed. At pH above 7 the sulfide anion (HS ) is quantitatively the dominant species (SCHWARZENBACH and Fisher, 1960 Boulegue and Michard, 1978 Boulegue, 1978). In order to simplify, we will use the term sulfide for both species (ii) elemental sulfur (S°) produced from bacterial or chemical oxidation of sulfide (Jorgensen, 1988) (iii) polysulfides (S ) produced from bacterial or chemical oxidation of H2S (Fossing and Jorgensen, 1990) or by reaction between H2S or HS and elemental sulfur according to Eq. (2) ... 

A great variety of binary Mo-S complex anions is formed and can be isolated in reactions of the tetrathiomolybdate anion [Mo 4] with various sulfide and polysulfide anions. The nature of the anionic products that can be isolated from these reactions depends on (a) the amount of excess sulfur used (and the types of ligands present in the reaction mixtures), (b) the type of counterion used in the isolation of the complex anions, and (c) the type of solvent employed in the synthetic procedure. In a recent article, we described a scheme that interrelates the various [Mo2(S)n(S2)6.n] anions. In this scheme (Fig. 1), any of the six homologs can hypothetically be obtained from any other by either the addition of sulfur, or the abstraction of sulfur by triphenylphosphine. Experimentally, the correctness of this scheme has been verified by the successful synthesis of most of the [Mo2(S),(S2)6-,] complexes, or of their internal redox isomers. In the [Mo2(S), (S2)6-,] series, the homologs with = 4, 5, and 6 have been characterized structurally. Those with n — 2 and 3 have been characterized structurally as the internal-redox isomers, [(S4)Mo(S)(/i-S)2(S)Mo(S2)] " (ref. 3) and... 

Since an aqueous solution of inorganic polysulfide ions is an equilibrium mixture of monosulfide to pentasulfide ions, it is very difficult to study the relative reactivity of the individual polysulfide ions since they cannot be isolated to permit kinetic studies [19]. Regarding the reactivity, the nucleophilicity of the sulfide anions increases with the rank [20]. The equilibration is effected by the nucleophilic displacement interchange at the organic polysulfide bond ... 

The aqueous solutions of sodium polysulfide, NajS, prepared according to the above procedures contain a distribution of sulfide anions ranging from S to S " and possibly higher [17] ... 

Batsanov et al. 23) reacted sulfur with PtCU and PtBr2 by heating mixtures of the reactants in evacuated, sealed ampoules. At 100 -200°C after 12-24 h, sulfide chlorides PtCljS (1.70 < x < 2 0.6 s y < 3.35) and sulfide bromides PtBr S (1.87 < x 2.06 0.84 y s 1.80) were formed. The compositions depended on the initial PtX2 S ratio, and the temperature. At 320-350°C, loss of chlorine led to the compounds PtClS (1.7 y 1.9). According to their X-ray powder patterns, all of these products retained the main structural features of the original platinum halides. From considerations of molar volumes, the authors deduced the presence of polysulfide anions. 

Important results and a detailed insight into aqueous chemical deposition processes have been reported and discussed elsewhere for CdSe [248, 249] and ZnS [250, 251] target products. We should note also the work of Davies et al. [252] who described an alternative method for the chemical growth of metal sulfides and selenides on the basis of polysulfide or polyselenide solutions (containing hexa- and tetra-chalcogen anions) formed by the dissolution of sulfur or selenium in hydrazine monohydrate. ... 

Sulfide ions in solution react with sulfur to produce polyatomic anions known as the polysulfides. When... 

The aqueous solution of barium sulfide oxidizes slowly in the air forming elemental sulfur and various anions of sulfur including sulfite, thiosulfate, polysulfides and sulfate. The yellow color of barium sulfide solution is attributed to the presence of dissolved elemental sulfur that results from its slow oxidation in the air. In the presence of an oxidizing agent, barium sulfate is formed. Violent to explosive oxidation may occur when heated with strong oxidants such as phosphorus pentoxide or potassium chlorate. 

Copper(I) sulfide reacts with polysulfide anions in aqueous solutions forming soluble copper polysulfides. 

Sulfur-rich binary P-S anions of the type [S2P(p-S )2PS2] form monocyclic structures with sulfide or disulfide bridging units ( = 1, 2) (11.39). Another type of cyclic P-S anion with the general formula [(PS2) ] is formed in the reaction of white phosphorus with polysulfides in a non-aqueous medium these anions have homocyclic structures with two exocyclic sulfur atoms attached to each phosphorus atom, e.g. [P4Ss] (11.40). ... 

There is a series of analogous cyclic thiuphosphoric acids with the formula (HS2P) thal may be prepared by the oxidation of red or white phosphorus with polysulfides under a variety of conditions. For example, the reaction of white phosphorus with a mixture of sulfur and hydrogen sulfide dissolved in triethylamine (which acts as a base) and chloroform opens the phosphorus cage to form the tectamerre cyclic anion ... 

Tne question of the source molecule occurrence must be addressed. The coincidence in anaerobic environments of ammonia and reduced divalent sulfur species, which includes hydrogen sulfide, bisulfide anion and sulfide dianion, has been given adequate recognition. (See for example references 36,37.) The coincidence of polysulfide and ammonia has already been noted in an earlier part of this report (1). Polysulfide has been found in tidal and salt marsh sediments as well (38). 

Related investigations on polysulfide and polyselenide anions with iron carbonyl reveal that there is an equally rich chemistry of sulfides and selenides, but it is substantially different from that of the tellurides. For instance, attempts to obtain lighter analogs of 51 under similar... 

Most macroscale experiments run with C/S sacrificial cathode were conducted at a potential of —0.9 V (vs. SCE). Obviously, transients species coming from the fragmentation of sulfur (radical ions or anions) can act as reducing species and nucleophiles. Very often, it appeared difficult to discriminate between different chemical (and electrochemical) pathways. Preliminary experiments based on the nucleophilicity of reduced products of dissolved sulfur led with poor selectivity to dipropionitrile sulfide (Tomilov [285]) and to alkyl polysulfides (Paris [286]). 

The sulfur particles are fed to the gas absorber by the liquid recycle due to an incomplete separation of solid sulfur in the separation step of the process. In the bioreactor, the polysulfide anions either decompose into sulfide and sulfur (Eq. 28), or are oxidized to thiosulfate (Eq. 29). Sulfate can also be formed by oxidation of HS (Eq. 30) ... 

---