Sulfur bonding chemistry

The importance of steric effects in determining the oxidation state of the product can be illustrated by a thioether linkage, eg (57). If a methyl group is forced to be adjacent to the sulfur bond, the planarity required for efficient electron donation by unshared electrons is prevented and oxidation is not observed (48). Similar chemistry is observed in the addition of organic nitrogen and oxygen nucleophiles as well as inorganic anions. 

In the reactions of arylsulfenyl chlorides with enamines one encounters an unusual result for enamine chemistry, in that the formation of 2,6-disubstituted cyclohexanone enamines predominates over the formation of monosubstitution products 474). A rationalization of this result suggests the formation of an intermediate which can act as an intramolecular electrophile in formation of the second carbon-sulfur bond. 

The sulfur-rich oxides S 0 and S 02 belong to the group of so-called lower oxides of sulfur named after the low oxidation state of the sulfur atom(s) compared to the best known oxide SO2 in which the sulfur is in the oxidation state +4. Sulfur monoxide SO is also a member of this class but is not subject of this review. The blue-green material of composition S2O3 described in the older literature has long been shown to be a mixture of salts with the cations S4 and Ss and polysulfate anions rather than a sulfur oxide [1,2]. Reliable reviews on the complex chemistry of the lower sulfur oxides have been published before [1, 3-6]. The present review deals with those sulfur oxides which contain at least one sulfur-sulfur bond and not more than two oxygen atoms. These species are important intermediates in a number of redox reactions of elemental sulfur and other sulfur compounds. 

Route b involves the formation of one carbon-carbon bond and one carbon-sulfur bond. It belongs to the category of sulfene chemistry. Sulfene intermediates react readily with diazoalkanes to produce, after the loss of nitrogen, thiirane dioxides. So far, this appears to be the method of choice for the preparation of thiirane dioxides of all types. 

In recent years, however, impressive progress has been made in the field of silicon- sulfur double-bond chemistry the first examples of kinetically stabilized and electronically stabilized silanethiones were successfully synthesized and fully characterized by spectroscopic and X-ray crystallographic data9,10. These results together with the theoretical studies have revealed the intrinsic nature of this unique double bond to silicon. 

Armstrong D, Sun Q, Schuler RH (1996) Reduction potentials and kinetics of electron transfer reactions of phenylthiyl radicals comparisons with phenoxyl radicals. J Phys Chem 100 9892-9899 Asmus K-D (1979) Stabilization of oxidized sulfur centers in organic sulfides. Radical cations and odd-electron sulfur-sulfur bonds. Acc Chem Res 12 436-442 Asmus K-D (1990a) Sulfur-centered free radicals. Methods Enzymol 186 168-180 Asmus K-D (1990b) Sulfur-centered three-electron bonded radical species. In Chatgilialoglu C, Asmus K-D (eds) Sulfur-centered reactive intermediates in chemistry and biology. Plenum, New York, pp 155-172... 

Sulfur occurs directly beneath oxygen in the periodic table, and, like oxygen, it often exhibits a valence of two. Therefore, sulfur analogs of alcohols and ethers are often encountered. However, because sulfur is in the third period of the periodic table, it can also have a higher valence. Structures with four or six bonds to a sulfur are common. In organic chemistry the most important of these expanded valence compounds have the sulfur bonded to one or two extra oxygens. 

The first aliphatic phosphenium cations involving a phosphorus-sulfur bond, e.g. (330) have been prepared and characterised. The stereochemistry, regioselectivity and mechanism of the insertion of the diisopropylamino (chloro) phosphenium cation into the phenylcyclopropane ring, to form phosphetanes, has been studied,Ligand-exchange processes involving mono- and bis-adducts of phosphenium ions have received a theoretical treatment. The coordination chemistry of the carbene adduct (331) of the... 

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