Sulfides anionic, tetra

In the polymerization of propylene sulfide and 1,2-butylene sulfide mainly tetra-mers were observed. Cycles were formed mostly during the slow degradation process that followed rapid polymerizations. Degradation can also be induced by adding cationic initiators to polymer prepared by other mechanisms, e.g. by anionic processes. Thus, poly(trans-2,3-butene sulfide) is rapidly degraded to equimolar amounts of 3,5,6,7-tetramethyl-l,2,5-trithiacycloheptane and trans-butene 47). Poly(cis-2,3-butene sulfide) forms, however, a mixture of tetramer, trithiacycloheptane derivative and cis-butene 47 . If one is forced to use cationic processes for the synthesis of poly-sulfides, the reaction conditions should be controlled to avoid macrocyclization. If cyclic products are desired, the kinetics of their formation should be studied to determine optimum yields. 

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. ... 

On oxidation the alkali metals are converted into oxides to which the formula R2O4 and the name alkali tetroxide were assigned until recently, in the belief that the substances were analogous to the tetra-sulfides and contained the O anion with structure... 

A new class of nucleophiles have been introduced for sulfur addition. Degl Innocenti and his group [145, 146] have shown that allyl or benzylsi-lanes, in the presence of tetra-n-butylammonium fluoride, reacted in a thiophilic fashion and led to allyl sulfides or dithioacetals. It is remarkable that this selective reaction is general for a large variety of thiocarbonyl compounds thioketones [145], dithioesters [146], and even with the normally sluggish trithiocarbonates [145]. With substituted allyl silanes retention of configuration of the allyl chain is observed. It is noteworthy that the possible [2,3] sigmatropic shift of the intermediate anionic species was not observed. 

SCN anions are most often detected by the formation of the ferrithiocyanate complex (see earlier). This reaction is very sensitive and is specific. It is also used to detect hydrocyanic acid. In the presence of hydrogen sulfide and sulfur, it is readily converted into thiocyanate anion. Let s recall that thiocanate anions yield numerous, often colored, complexes with diverse metallic ions Fe +, Ca +, and Hg +. Mercuric cations, in the presence of thiocyanate anions, precipitate as mercuric thiocyanate, which is not a salt but rather the dicyanomercury(II) complex [Hg(CN)2]. It is soluble in an excess of thiocyanates by formation of the tri(thiocyano) and tetra(thiocyano) mercurate(II) complexes [Hg(SCN)3] and [Hg(SCN)4]. The cation dichlorodimercury(I) ( mercurous ) Hg2 + yields a white precipitate of mercurous thiocyanate Hg2(SCN)2. The reaction is not simple. It involves the anion complex [Hg(SCN)3] as the intermediary. Hence, a disproportionation reaction occurs simultaneously with the complexation reaction... 

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