Complex sulfur halides

A variety of routes is available for the preparation of metal-thionitrosyl complexes. The most common of these are (a) reaction of nitride complexes with a sulfur source, e.g., elemental sulfur, propylene sulfide or sulfur halides, (b) reaction of (NSC1)3 with transition-metal complexes, and (c) reaction of [SN]" salts with transition-metal complexes. An example of each of these approaches is given in Eq. 7.1,... 

Other examples of this synthetic strategy are known for example, a recent zirconium polymer by Illingsworth and Burke (8), who joined amine side groups of a zirconium bis(quadridentate Schiff-base) with an acid dianhydride to give amide linkages. Once again, caution is necesary, as Jones and Power (2) learned when they attempted to link metal bisO-diketonates) with sulfur halides that is, they obtained insoluble metal sulfides because the p-diketone complexes which they used were fairly labile and the insolubility drove the reactions to completion in the wrong direction. 

Platinnm(TV) has a coordination number of 6. It forms complexes with halides, nitrogen and sulfur compounds, and other donors but to a lesser extent than plahnum(ll). 

The complexes of thiuram disulfide can be oxidized by an excess of halogens to products containing the bis(iminio)trithiolane dication (113).122 123 One of the sulfur atoms is removed as free sulfur or as sulfur halide. According to some reports the bis(iminio)tetrathiolane dication (114) also exists.124 In our investigations, however, we could not obtain any proof of this ion. The electrochemical literature about the oxidation of thiuram disulfide is also contradictory.125,126 Apart from the trithiolane ion a dithietane ion (115) is prepared by oxidation of dimethylformamide with bromine.127 As far as we know, no other disulfide can be oxidized to an analogous dication. 

Only S and Se are known to form well-defined oxo halides. These are of the three main types (a) the thionyl and selenyl halides, SOX2 and SeOX2 (b) the sulfuryl halides, SOzX2, and their one selenium analog, Se02F2 and (c) a number of more complex sulfur oxo chlorides and oxo fluorides. 

Silver Thiosulfate. Silver thiosulfate [23149-52-2], Ag2S203, is an insoluble precipitate formed when a soluble thiosulfate reacts with an excess of silver nitrate. In order to minimize the formation of silver sulfide, the silver ion can be complexed by halides before the addition of the thiosulfate solution. In the presence of excess thiosulfate, the very soluble Ag2(S203)4-3 and Ag2(S203)<5-5 complexes form. These soluble thiosulfate complexes, which are very stable, are the basis of photographic fixers. Silver thiosulfate complexes are oxidized to form silver sulfide, sulfate, and elemental sulfur (see Thiosulfates). 

We have also expanded our studies to include chromium(III) systems. However, for the chromium centers we have chosen the more volatile tri-fluoro (tfa") and hexafluoro (hfa ) derivatives of 2,4-pentanedione. Since the fluorinated derivatives are deactivated relative to the electrophilic attack used in these polymerizations, the Cr(acac)2(tfa) mixed ligand complex has been used initially to obtain polymeric products with sulfur halides. Whereas the intrinsic viscosity of one of the polymers so obtained was 0.17 dL/g, the GPC results suggest only oligomeric products. 

Fj with appropriate delocalization on the central atom and the ligands. Since would be a antibonding to ammonia and water, this may also explain the chemical fact that the s -family forms very strong complexes with halides, while amine (and cyanide) complexes are not known. OrgeF discusses the rather peculiar stereochemistry of the s -family and concludes that similar effects occur as in the hemiedric lone-pairs of nitrogen(III) in NO and sulfur(IV) in SO and SO2 (cf. also Gillespie and Nyholm ). 

Figure 5.27 Representative examples of NHC complexes with sulfur halides and oxides.

Silver Chloride. Silver chloride, AgCl, is a white precipitate that forms when chloride ion is added to a silver nitrate solution. The order of solubility of the three silver halides is Cl" > Br" > I. Because of the formation of complexes, silver chloride is soluble in solutions containing excess chloride and in solutions of cyanide, thiosulfate, and ammonia. Silver chloride is insoluble in nitric and dilute sulfuric acid. Treatment with concentrated sulfuric acid gives silver sulfate. 

Codeposition of silver vapor with perfluoroalkyl iodides at -196 °C provides an alternative route to nonsolvated primary perfluoroalkylsilvers [272] Phosphine complexes of trifluaromethylsilver are formed from the reaction of trimethyl-phosphme, silver acetate, and bis(trifluoromethyl)cadmium glyme [755] The per-fluoroalkylsilver compounds react with halogens [270], carbon dioxide [274], allyl halides [270, 274], mineral acids and water [275], and nitrosyl chloride [276] to give the expected products Oxidation with dioxygen gives ketones [270] or acyl halides [270] Sulfur reacts via insertion of sulfur into the carbon-silver bond [270] (equation 188)... 

Although the structure of [SsN] has not been established by X-ray crystallography, the vibrational spectra of 30% N-enriched [SsN] suggest an unbranched [SNSS] (5.22) arrangement of atoms in contrast to the branched structure (Dsh) of the isoelectronic [CSs] and the isovalent [NOs] ion (Section 1.2). Mass spectrometric experiments also support the SNSS connectivity in the gas phase.Many metal complexes are known in which the [SsN] ion is chelated to the metal by two sulfur atoms (Section 7.3.3). Indeed the first such complex, Ni(S3N)2, was reported more than twenty years before the discovery of the anion. It was isolated as a very minor product from the reaction of NiCl2 and S4N4 in methanol. However, some of these complexes, e.g., Cu and Ag complexes, may be obtained by metathetical reactions between the [S3N] ion and metal halides. 

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