Sulfur-containing macrocycles

Bradshaw and Hui, in their review of sulfur-containing macrocycles, have included the analog of compound 7 (this chapter) in which each carbon bridge is replaced by a dimethylsilyl bridge. Nevertheless, silicon-containing crown relatives remain rare. 

Macrocyclic thioethers which contain a carborane backbone have also been prepared and the silver(I) complexes obtained. The reaction of AgN03 with the sulfur-containing macrocyclic ligand... 

These sulfur-containing macrocycles had been prepared under pseudo-high dilution conditions, but Hay and coworkers demonstrated that the cyclodepolymerization of aromatic disulfide polymers was an efficient and easier... 

Table 2 Synthetic methods for sulfur-containing macrocycles in order of ring size, number of sulfur atoms, and substitution grade (the method code is specified at the end)... 

The sulfonamide cyclization method has been used to prepare not only aza- and peraza-crowns but also sulfur-containing macrocycles as shown (Boe-yens et al., 1985 Gahan et al., 1982 Hart et al., 1983). 

The reaction of a diester with a diamine can also be used to prepare these sulfur-containing macrocycles. Several thiaaza macrocycles were prepared in 15-40% yields from the reaction of sulfur-containing diesters and polyamines (method Z-8) (Kodama et al., 1984 Tabushi et al., 1976). Again, the cyclic... 

Oxygen- and sulfur-containing macrocyclic compounds show much of the same functional group chemistry expressed in the simple acyclic systems. For example, as shown in Scheme 4, the macroring... 

In addition to Scheme 8, Schemes 9-16 contain general methods for the preparation of the various classes of oxygen- and sulfur-containing macrocycles mentioned in this chapter as follows ... 

Most of the applications of the oxygen- and sulfur-containing macrocycles center on the interactions of those compounds with various cations. Since ring size, substituents, number and type of... 

Sulfur-containing macrocycles bound to silica gel are highly selective concentration and purification ligands for Pd", Hg" and Ag. These immobilized macrocycles efficiently removed Au " and Pd" from solutions of HCl and FeCls. Similarly, Ag+, Au" and Pd" were separated by these columns and selectively eluted from the columns with purities of 99.9%. It was also shown that Pd" can be removed from industrial silver electrolyte solutions with 99.9% purity in one pass through these columns <91ANC1014>. 

Sulfur-containing macrocyclic compounds as complexing reagents and extragents for transition and heavy metals 05RKZ(6)47. 

Supramolecular networking of sulfur-containing macrocycles based on exo-coordination 12ACR391. 

The sulfur-containing receptors have little affinity for hard cations but can form extractable host-guest complexes with soft cations such as Ag+, Hg +, T1+, Pd +, and Pt +. Silver is found to interact strongly with sulfur [138, 139]. It was even possible to isolate 1 1 host-guest silver and mercury complexes in a large sulfur-containing macrocycle a linear HgC molecule is hosted in the cavity, but in the 1 2 complex a second mercury atom is externally attached to the ruthenium atom [140-142]. Palladium and platinum are also selectively complexed by polythia-coronands [143-148]. Some X-ray diffraction studies on palladium [147, 148] and platinum [143, 145] complexes established that the coordination of the metal occurs by interaction with the sulfur sites. 

The sulfur-containing macrocycle 18-thiacrown-6 forms a pentamethylcyclo-pentadienylrhodium complex, 105, with two ( / -C5Me5)Rh groups externally coordinated to the ring acting as an exo receptor [433], i.e. more like a traditional... 

Larger rhenium complexes are also the subject of a number of publications. Reaction of an excess of thietane with the thietane complex fRe3(CX))jQ(p-H)3(p-cyclo-SCH2CH2CH2)] affords a number of ring-opening oligomerisation products from which sulfur containing macrocycles such as 12-S-4, 16-S-4 and 24-S-6 can be eliminated upon addition of pyridine . Addition of... 

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