Sulfur tervalent

Compounds with o-tervalent sulfur atoms are considered as a special group in Section II, E the parent skeleton is derived by substituting the sulfur atoms with tertiary carbon atoms. 

These compounds, at present hypothetical, contain a cr-tervalent sulfur atom. Theoretical studies were performed16 for models of compounds 122-126 the first two are, in a sense, analogues of bicyclic compounds. In view of their formal similarity with the cyclazines,133 and their positive charge, the tricyclic compounds 124-126 shall be called cyclothiolia. ... 

K. N. Reddy, K. R. Reddy, K. C. Rajanna, and P. K. Saiprakash, Oxidation of epimeric aldo-, and D-, L-ketohexoses by tervalent manganese in sulfuric acid media a kinetic approach, Oxid. Commun., 19 (1996) 381-389. 

Reaction of phenylphosphonic dianilide with tris-(diethylamino)phosphane yields colorless crystals of compound X (m.p. 156-157 °C). Reaction of N,N -di-phenylsulfamide with the same reagent leads to compound XI, which is the first member of the class of thiadiazaphosphetidines containing tervalent phosphorus. The colorless crystals melt at 94-95 °C. With elemental sulfur the corresponding sulfide is obtained. 

Ruthenium, the homologue of iron in this group, was also shown to form complexes quite early. Ruthenocene, Ru( 5H5)2, is obtained by treatment of the acetylacetonate of tervalent ruthenium with five times the theoretical quantity of the Grignard reagent (206), or, better, by the action of cyclopentadienyl sodium on ruthenium trichloride in tetrahydrofuran (47). It forms pale yellow scales which sublime at 120° and melt at 200°. Its properties are closely similar to those of ferrocene it is soluble in organic solvents, and in the absence of air is not attacked by bases or by sulfuric or hydrochloric acid. Oxidation converts it into the pale yellow [Ru( 5H6)2] + ion. 

In spite of its highly strained Dewar structure 1 is stable and may be kept in a refrigerator for several years. It isomerizes to the aromatic isomer at high temperature (half-life in benzene at 160 C was 5.1 h). The treatment of the Dewar thiophene with triphenylphosphine did not cause the elimination of sulfur, but instead accelerated the isomerization to the aromatic isomer. This catalytic acceleration is limited to tervalent phosphorus compounds but phosphorous trichloride or phenyldichlorophosphine are ineffective. An adduct of diphenylchlorophosphine with the Dewar thiophene was postulated to be a ff-complex with a P—S bond. It decomposed spontaneously to the thiophene and the phosphine as shown in Eq. (9).15 Recently,... 

Rule 2. Tervalent Sulfur Atoms—i.e.. Sulfur Atoms Bonded to Three Other Atoms—Cannot Engage in pir-pir Bonding. This rule is reasonable in view of Rule 1. The lone pair of a tervalent sulfur atom is essentially in a 3s orbital, and extensive hybridization is required to use it in 7T bonding. 

The tervalent sulfur atoms prohibit pw bonding, and the ring has a non-planar conformation, analogous to the chair conformation of cyclohexane (8). However, the ring is nearly planar (the average distance of the nitrogen atoms from the plane of the sulfur atoms is only 0.2 A), and the... 

The structure of SaNsNPPha is shown in Figure 6 (23). Because the tervalent sulfur atom cannot engage in n bonding, the ir bonding is re-... 

New quinolizidines containing phosphine chalcogenide side arms were prepared from the vinyl ether of enantiomerically pure lupinine by the radical addition of R2PH followed by blocking the tervalent phosphorus atom with oxygen, sulfur or selenium (Scheme 13). ... 

The chelate compounds, produced as shown in (2), are not decomposed at once by even (1 1) sulfuric acid and therefore a sensitive test for aluminum has been developed on this basis. (Tervalent chromium salts exhibit an analogous behavior.) The color reactions are selective if the test solution is treated with a shght excess of magnesium carbonate before the reagent is introduced. It is essential that sulfuric acid be used for the acidification if hydrochloric acid is employed the zirconimn compounds formed at the same time remain unchanged. The sulfuric acid probably decomposes the colored zirconium compounds through formation of complex zirconium sulfuric acids. Chrome Fast Pure Blue B is the best reagent because its dye acid can be completely extracted by ether, which is not true of some of the related dyes. 

A drop of the test solution is placed on filter paper and spotted with a (hrop of a saturated water solution of sodium azide. The fleck is exposed to the vapors of a saturated aqueous solution of sulfurous acid. A yellow color appears which changes to blue on treatment with a drop of a 2 % acetic acid solution of a-tolidine Idn, Limit 0.5 y Co). The test is based on the fact that the oxidation of complex Co azide to complex cobalt azide is catalyzed by the autoxidation of sulfurous acid. The color reaction with o-tolidine is due to the action of the tervalent cobalt formed. Copper and iron ions interfere and should be previously removed or masked. The test can be carried out in the presence of as much as 200 times the amount of nickel. 

On adding an excess of sodium azide to neutral or slightly acid solutions of cobalt salts, a violet color appears which is due to complex cobalt -azide anions. In contact with air an oxidation to anionic azide-complexes of tervalent cobalt takes place, shown by a change of color from violet to yellow. This very slow autoxidation is enormously accelerated by sulfurous acid or sulfite ions. Probably the autoxidation of sulfite to sulfate induces the oxidation of the complex bounded cobalt. However, the color change violet yellow is not sufficiently sensitive to serve as a test for this induction effect and therefore, for sulfite. It is better to identify the tervalent cobalt through a color reaction with an acetic acid solution of o-tolidine (formation of a blue quinoidal oxidation product of the base). Compare page 209. 

If magnesium or zinc salts are to be tested for iron, and the latter is in the tervalent state, reduction is necessary before the a, a -dipyridyl reagent is applied. Metallic zinc or magnesium may not be used, because these metals usually contain traces of iron. Hydroxylamine hydrochloride or sulfurous acid should be used. After adding the a,a -dipyridyl-hydrochloric acid reagent solution, the system should be made basic with ammonium hydroxide. 

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