Thionate ions

Deprotonation of heterocyclic thiones (157c) produces the corresponding thionate ion (157d) in which an electron pair on the heterocyclic trigonal nitrogen and three electron pairs on the thionate sulfur generate considerable coordination potential (158). 

All sulfur is shown to convert to sulfate ions in solution. Under the conditions or leaching, much of the suitor remains in solution as melastable soluble intermediates. Oxidation of sulfiir occurs in the sequence thiosulfate ions, S2Oj thionate ions, S Oj" sulfamale ious. SOjNHf and sulfate ions. SOj, The... 

Polythionates contain ions of type [8 Og] and may be prepared by condensation reactions such as those in scheme 15.114, but some ions must be made by specific routes. Poly-thionate ions are structurally similar and have two 8031-groups connected by a sulfur chain (15.56 shows [8505] ) solid state structures for a number of salts show chain conformations are variable. In aqueous solution, polythionates slowly decompose to H28O4, 8O2 and sulfur. 

The cis form occurs in cyanogen trisulfide, where the molecules lie across mirror planes of symmetry (94)- The trisulfide group of the penta-thionate ion occurs in the cis form in the three barium salts (115, 119, 124) for which structure determinations have been carried out, a mirror plane of symmetry being demanded by the space group in two of the salts. In the six- and seven-membered rings of 1,2,3-trithianes (202) and the one known 1,2,3,5,6-pentathiepane (125) the configuration of the trisulfide group is necessarily cis. 

Five studies are reported which describe the seleno- or telluro-penta-thionate ion or a derivative. The structure is represented schematically in... 

Note, however, that electron-transfer processes at inert electrodes are frequently not reversible. As a result, inert electrodes do not respond in a predictable way to many of the half-reactions found in a table of electrode potentials. For example, a platinum electrode immersed in a solution of thiosulfateaind telra-thionate ions does not exhibit reproducible potentials because the electron-transfer process... 

Diamino-6,6-dialkyl-7-oxo derivatives were converted with POCI3 (106°, 46 min) to 7-chloro analogs which were then 7-thionated with hydrosulfide ion. °... 

Thiosulfate ion is easily oxidized, especially by iodine, to tetra-thionate km, 840 — ... 

The reaction of azide ion with iodine is very greatly accelerated by the presence of inorganic " -or organic sulphides, thiocyanates , thiosulphate tri-, tetra- and pentathionates and carbon disulphide . Kinetic studies are most extensive for the carbon disulphide- and thionate-catalysed reactions. 

In this chapter, the term copper(I) thiolate is taken in its broadest sense of being any species in which a Cu1 ion is coordinated to one or more sulfur atoms of an SR unit. For comparative reasons, some examples of thione and thionate complexes (Scheme 2) are also included since in their deprotonated form thiones can be considered as anionic ligands ArS-. The coordination behavior of thione ligands toward metals was reviewed some years ago (Id). 

Triazanaphthalene3 (446) substituted with a single leaving group have been little studied. 4-Aminopyrido[3,2-d]pyrimidine and its 6-methyl derivative have been hydrolyzed with 5N acid (100°, 30 min) and ION alkali (95°, 3 hr, 10% yield).Attempted replacement of the 4-oxo group (via acyloxy intermediates) with phosphorus oxychloride or pentasulfide failed, in contrast to the successful replacement in the more activated 4-oxo-l,3,8-triaza analog discussed below. Similarly, the 2,4-dioxo derivative could not be thionated with the pentasulfide, and its reaction with the oxychloride was less facile than that of the 2,4-dioxo-l,3,8-triaza compound. 

Chloropyridopyrimidines readily undergo amination reactions with ammonia,9-11,13> 86>41, 48,50,78, 110,122,128,126,127aliphaticamines,9-11, i3,48,so,no,i2d, 127 and aromatic amines9, 11,48,50,110,122 to yield mono- or diaminopyridopyrimidines or 4-amino-2-ehloro derivatives. Selective replacement of chloro substituents, however, was not achieved with the reaction of dimethylamine and 2,4-dichloropyrido-[2,3-d]pyrimidine.110 Thionation reactions by means of thiourea,10, 36, no, 122 hydrosulfide ion, 9 13,48,°0,56 sodium ethyl sulfide,10 replacement by alkoxide,10,13,36,38,60 and hydrolysis9,10,13,60 to regenerate the pyridopyrimidone all take place readily. Reductive dehalogenation10 to yield pyrido[3,2-d]pyrimidine (2) has been claimed but disputed.33... 

Thiosulphates and Thionates. A neutron-diffraction study has shown that in barium thiosulphate monohydrate the tetrahedral 8203 anion has the bond lengths S—8=1.979 and 8—0= 1.472-1.483 A the Ba—8 distances are 3.355 and 3.424 A. A crystal structure determination of bis(ethylenethiourea)zinc(ii) thiosulphate has shown that each zinc atom is tetrahedrally surrounded by three sulphur atoms (two from etu and one from the thiosulphate group, with the mean distance Zn—8 = 2.320 A) and one oxygen atom from the 82O3 group. Crystalline Zn(NH3)3(8203),H20 and Cd(NH3)3(8203) have been prepared and characterized spectral data indicate that the 8203 ion is unidentate and is bonded to the metal through sulphur. 

Poly-4-vinylpyridine complexes of copper(II) catalyze the oxidation of thio salts such as sulfites (SO ), thiosulfates (S2C ), dithionates (8204"), disuintes (8205 ), tri-thionate (83O6"), tetrathionates (S4C ), by molecular oxygen to sulfate ions [84- 86]. 

Miura, Y. Watanabe, M. Ion-pair chromatography of poly-thionates and thiosulfate with detection based on their cat-al3ftic effects on the post-column azide-iodine reaction. J. Chromatogr. A, 2001,920, 163 171. 

A sensitive method for the determination of thiosulfate, thiocyanate and poly-thionates in a mixture with photometric detection at 230 nm illustrates further the applicability of ion-pair chromatography [9]. Excellent resolution of a complex mixture was obtained on a C18 column with a mobile phase of 6 mM tetrapropyl-ammonium acetate pH, 5.0, in 20-80% methanol-water (Figure 9.3). 

An interesting protocol for converting amides and lactams to their corresponding thio derivatives 1786, through in situ thionation of intermediate chloro imi-nium ions 1770 with hexamethyldisUathiane TMS2S, has been reported [1312]. 

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