Sulfur—antimony bonds

A one-pot synthesis of alkyl perfluoroalkyl ketones has been developed. Phosphoranes, generated in situ, are acylated with a perfluoroacyl anhydnde, and the resultmg phosphonium salts are hydrolyzed with alkali [4S (equation 48) Hydrolysis of a carbon-sulfur bond in 2-chloro-2,4,4-trifluoro-1,3-dithietane-S-trioxide, which can be obtained from 2,2,4,4-tetrachloro-l,3-dithietane by fluor-mation with antimony trifluoride followed by selective oxidations, opens the nng to produce 2-chloro-1,1,2-trifluorodimethyl sulfone [49] (equation 49)... 

The SRN1 process has proven to be a versatile mechanism for replacing a suitable leaving group by a nucleophile at the ipso position. This reaction affords substitution in nonactivated aromatic (ArX) compounds, with an extensive variety of nucleophiles ( u ) derived from carbon, nitrogen, and oxygen to form new C—C bonds, and from tin, phosphorus, arsenic, antimony, sulfur, selenium, and tellurium to afford new C-heteroatom bonds. 

Anions derived from tin, phosphorus, arsenic, antimony, sulfur, selenium, and tellurium are known to react at the heteroatom to form a new carbon-heteroatom bond in good yields. 

Arsenic, Antimony and Bismuth Table 25 Bismuth-Sulfur Bond Lengths and Angles... 

These are cis-[Mn(CO) L SCN], cis-[Mn(CO) L2 SCN] and trans-[Mn(CO) L2 NCS]. The compounds cis-[Mn(CO) L SCN] and cis-[Mn(CO) L2SCN] contain sulfur-bonded thiocyanate. The fact that the latter has not been isolated with P(C Hg) may be due to the small size of phosphorus, relative to arsenic and antimony, " which considerably crowds the phenyls around the metal. This explanation is supported by molecular models (Stewart) of the compounds. The different modes of Mn-CNS attachment in the cis- and trans-disubstituted complexes may be due to a greater steric hindrance in the former. Molecular models... 

The eight-membered rings 13.14 normally adopt boat conformations in the solid state with short S=N bond distances (1.51-1.52 A) that are typical of sulfur diimides. There are no transannular S S contacts. The sole exception is the antimony derivative BuSb(NSN)2Sb Bu, which is a planar eight-membered ring. 

The ylides have been classified on the basis of the heteroalom covalently bonded to the carbanion. Accordingly, they can be differentiated into nitrogen ylide (Scheme 2), sulfur ylide Scheme 3, phosphorus ylide Scheme 4, arsenic ylide Scheme 5, antimony ylide (Scheme 6), bismuth ylide (Scheme 7) and thallium ylide (Scheme 8). 

The magnetic criterion is particularly valuable because it provides a basis for differentiating sharply between essentially ionic and essentially electron-pair bonds Experimental data have as yet been obtained for only a few of the interesting compounds, but these indicate that oxides and fluorides of most metals are ionic. Electron-pair bonds are formed by most of the transition elements with sulfur, selenium, tellurium, phosphorus, arsenic and antimony, as in the sulfide minerals (pyrite, molybdenite, skutterudite, etc.). The halogens other than fluorine form electron-pair bonds with metals of the palladium and platinum groups and sometimes, but not always, with iron-group metals. 

The monoxide SgO forms the 0-bonded adduct SgO SbCl5 upon treatment with antimony pentachloride in CSy adduct formation results in pyramidal inversion at the three-coordinate sulfur atom. In contrast, the treatment of 850 with antimony pentachloride induces dimerisation to give the 2 1 adduct of SbCls with the cyclic dioxide SiyOy. The chair form of the two S O constituents of this dimerisation process are evident in the conformation of the 12-membered S12 ring in the adduct. 

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