Thioether 9 aneS

Cyclic thioethers involving rigid linkages are also known. Examples include a range of derivatives of [14]aneS4 incorporating 1,2-benzene and/or 1,2-cyclohex-ane units 79 TTOB, TTMB 80 tetrathia and hexathia cyclophane derivatives.81 84... 

A range of compounds with only S atoms as ligands are those of cyclic thioethers such as the octahedral cation [Os([9]ane S3)2]2+.79 Finally, OsVI complexes of WS4" (as well as Re04 , Cr04 , W04") are known, e.g., [Os(N)(CH2S2Me3)2-... 

The remarkable complexing properties of cyclic thioethers, in particular, those exploited by Schroder s and Yoshida s groups, have stimulated a great interest in metal thioether chemistry. These cyclic ligands bind preferentially to soft metal ions and have allowed the preparation of complexes displaying unusual stereochemistry and/or oxidation states. The most common thioethers involved are [9]ane-S3,... 

SYNS DIETHYLSULFID (CZECH) DIETHYL SULFIDE (DOT) DIETHYLTHIOETHER ETHYL MONOSULFIDE ETHYLTHIOETHANE ETHYL THIOETHER SULFODOR (CZECH) 3-THIAPENT-ANE 1,1 -THI0BISETHANE THIOETHYL ETHER... 

The silicon-halogen, silicon-oxygen, and silicon-sulfur bonds of the haiogenosil-anes, siiyl ethers, and siiyi thioethers are cleaved by reaction with LAH, AIH3, or DIBAH, and the corresponding siiyl hydrides are obtained [CGI, CG2]. Ultrasound activation can be applied [LG2] (Figure 5.9), Anionic pentacoordinated silicon compounds are reduced to hydrogenosilanes by LAH or DIBAH [BC6]. 

It is of interest now to consider the kinetics of complex formation (kf) and dissociation (kd) of chelate, macrocyclic, and cryptate complexes and how these are related to the type of ligand stmcture. Table 10 lists kf and kj valnes for chelating ( 1-3), macrocyclic ( 4 and 5), and cryptand ( 6-8) ligands and the appropriate reference compounds. For the chelate effect, the reactions of Ni " with py, bipy, and terpy show very little difference in kf values. On the other hand, the valnes of kj decrease by factors of 2 x 10 and 2 X 10, for bipy and terpy, respectively. A similar effect is seen in a comparison of the reactions of Cn + ion with the thioether macrocycle [14]aneS4 (ane denoting a saturated carbon macrocycle and S4 (he four sulfur donor atoms) and its acyclic... 

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