Thioether macrocycles

A small number of template mediated reactions which afford thioether macrocycles are also known, e.g. the small trithia [9]aneS3 is also obtained in good yield using Mo(CO)3 as a template.73,74 The crown trithioether is readily demetallated by addition of a further equivalent of [NMe4]2[S(CH2)2S(CH2)2S]. Also, dibenzo-[18]aneS6 and dibenzo-[15]aneS5 have been prepared via an iron dicarbonyl template.75,76 Metal-induced cyclo-oligomerization reactions of... 

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... 

High-performance liquid chromatography, thioether macrocyclic complexes separation, 35 7... 

The soft donor atoms, phosphorus, arsenic and sulfur, potentially act as stabilizing influences to more polarizable substrates. These heteroatoms have been less extensively studied than the nitrogen and oxygen analogs. Of the three, the thioether macrocycles are the most common, and complexes of many of the first row as well as the heavier transition metals have been reported.43... 

The value of log K for the copper complex of 6.24 is 4.3, whilst for that of 6.23 it is 1.97. The macrocyclic complex is thus about 100 times more stable than the open-chain complex, and this is presumably due to the macrocyclic effect. In this case, thermodynamic measurements have shown that Afor the macrocyclic and open-chain complexes are almost identical, and so the macrocyclic effect is due almost entirely to the entropy term. However, even with these ligands the involvement of solvation may not be neglected entirely. The stability values given above are for the complexes in aqueous solution if the measurements are repeated in 80 % aqueous methanol, the value of log K for the formation of the macrocyclic complex is only 3.5. A hole-size effect (section 6.6) is also apparent if we move to the larger thioether macrocycle 6.26. For the formation of the copper complex of 6.26 (again in 80 % aqueous methanol) log K is found to be 0.95. 

Shaw, J. L., Wolowska, J., Collison, D., etal., Redox non-innocence of thioether macrocycles Elucidation of the electronic structures of mononuclear complexes of gold (II) and silver(II). J Am. Chem. Soc. 2006, 128, 13827-13839. 

The charge-transfer complex of 1,4,7-trithiacyclononane 10 and I2 has been prepared by slow evaporation of solutions containing I2 and thioether macrocycle in CH2CI2. The structure of the complex showed two independent macrocycles in the asymmetric unit which are linked by a diiodine bridge. Asymmetric units are linked by iodine-iodine and sulfur-iodine interactions to form an extended array of linked macrocycles. The formation enthalpy ( AH = 35.0 kj mob1) and formation constant (K= 169 dm3 mol-1) of 1 1 adduct have been determined by electronic spectroscopy and compared to other polythia macrocycles of different sizes <1997JCD1337>. 

In recent years, thioethereal macrocycles have attracted considerable interest in the chemical community. A variety of ring sizes have been prepared and their metal ion chemistry studied, yielding a diverse range of structures and unexpected electronic and redox responses. 

The coordination chemistry of thioether macrocycles has expanded greatly only since the mid-1980s, as seen by a number of reviews. The macrocychc effect is also noted for... 

Thioether coordination chemistry has undergone a renaissance with the development of general syntheses of poly-thioether macrocyclic hgands. Scheme 29 illustrates some of the ligands that have been reported. The tridentate ligand... 

The aim of this chapter is to summarize critically the coordination chemistry of homoleptic thioether macrocycles, with emphasis on likely future developments and uses. The chemistry of mixed-donor ligands is not included. The literature is reviewed up to mid-1989 with particular emphasis on the literature since 1980. Some unpublished results, mainly crystallographic data from our own laboratories, are included. Recent reviews on aspects of thioether chemistry include those by Murray and Hartley (149), Kuehn and Isied (125), Cooper (74), Schroder (188), and Muller and Diemann (148). 

Buter and Kellogg 62, 63), large-scale synthesis of thioether macrocycles can now be achieved in good yields (2 77,223,224,226). Octathia Ss-donor macrocycles have been synthesized as 2 -t- 2 products from the cyclization reactions employed to form tetrathia S4-donor ligands 59, 61,83,147,209). 

A range of mixed-donor thia macrocycles have also been prepared using related techniques (5, 57, 58, 59, 60, 62, 63, 93,123,150, 213) water-soluble thioether macrocycles incorporating hydroxy-groups on the carbon back-bone have also been reported (163). 

Mass spectroscopic (136,191) and NMR spectroscopic (83) studies on thioether macrocyclic ligands and related open-chain systems have been reported. The synthesis of thioether macrocyclic compounds incorporating the cycloheptatriene and tropylium ion moieties has been described (152). 

Very recently, a series of thioether macrocycles containing the thiophene unit was synthesized by Lucas and co-workers (Fig. 2) (137, 138,139). 

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