Thioethers, crown

Irregular 6- and 7-fold coordination of Sb occurs in the complexes of SbCl3 with crown thioethers, and 8-fold coordination has been established in its complex with the j -ether... 

Scheme 2.35 Zn-catalysed 1,4-addition of /-PrMgCI to cyclohexenone with crown thioether ligands.

Henry reactions 317-20 hydrosilylations 333 organozinc reagents, addition to ketones 156-80 PrMgCl to cyclohexenone with crown thioether ligands 100-1 see also specific ZnEt2 and ZnR2 addition reactions... 

The chemistry of silver(I) with crown thioethers has developed in the last years,1094,1095 but now numerous examples with a great variety of ligands have been reported. The first homoleptic silver compounds have been described with 1,4,7-trithiacyclononane ([9]aneS3), [Ag([9]aneS3)2]OTf (168), which is octahedral and shows a reversible oxidation assigned to the Ag1/Ag11 couple,1096,1097 and the trimeric species [Ag3([9]aneS3)3]3+ (169).1097 The complexes... 

The ability of thioether macrocyclic complexes (and especially those of [9]aneS3) to support multi-redox behaviour at the coordinated metal centre is particularly notable. This allows a series of reversible stepwise one-electron oxidation and/or reduction processes, and stabilization of highly unusual transition metal oxidation states e.g. mononuclear [Pd([9]aneS3)2]2+/3+/4+,149 [Au([9]aneS3)2]+/2+/3+,150 [Ni([9]aneS3)2]2+/3+,151 and [Rh([9]aneS3)2]+/2+/3+.152 It appears to be the ability of the crown thioethers to readily adjust their... 

In certain systems the crown thioether ligand itself may undergo some chemical transformation when coordinated to a metal ion. For example, in mildly basic conditions the Rh(III) species [Rh([9]aneS3)2]3+ and [Rh([18]aneS6)]3+... 

See Table VI.) Crown thioethers of various sizes ([12]aneS4 = 1,4,7,10-tetrathiacyclododecane, [15]aneSs = 1,4,7,10,13-pentathia-... 

Fig. 2.9 Chemical formulas of crown thioether complexes and Cu(I I)bis-thiosemicarbazone. 

Crowns, 76 773. See also Crown compounds Crown thioether complexes, 23 707 Crucibles, in fused quartz manufacture, 22 413... 

Crown thioethers, coordination chemistry, 35 3 (CIO4), 43 226 Crude oil, vanadium in, 35 99 Crustaceans, arsenic in, 44 150, 167, 168, 170 Cryoscopic measurements, sulfuric acid and, 1 390-391... 

The chemistry of crown thioethers and thioether cages is a fast-developing field [23], and their synthesis involves a caesium carbonate ring closure [24,25],... 

Wolf, R. E., Hartman, J. A. R., Storey, J. M. E., Foxman, B. M., Cooper, S. R., Crown thioether chemistry - structural and conformational studies ofTetrathia-12-Crown-4, Pentathia-15-Crown-5, and HexathiaT8-Crown-6 - implications for ligand design , J. Am. Chem. Soc. 1987,109, 4328-4335. 

The higher affinity of U(III) also for S- donor ligands comparing to trivalent lanthanides can be well appreciated during the complexation with crown thioethers. Again, a comparative study among the crystal structures of trivalent... 

Thioacetamide as Starting Material in Crown Thioether Formation 788... 

Troyansky etal. reported that homolytic cycloaddition of dithiols derived from trans- and r-l,2-cyclohexanediols to alkynes, induced by Pr3B-02, offered an extremely simple approach to trans- and m-cyclohexano-fused 12-membered crown thioethers <1995TL11431>. The reaction of 22 (A,A) proceeded with a pronounced remote 1,6-asymmetric induction to give predominantly 23 (1A, 6R, 12A), while 25 (A, R) reacted nonstereoselectively (Scheme 2). 

Considerable effort has been made with regard to conformation analysis of crown thioethers. It has been found that ligand strain is most evident in torsion angles, whereby an examination of the deviations from the optimum values of... 

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