Mixed donor macrocycles

Related to the crown ethers are compounds, such as hexamethyl-[14]-4,ll-diene (6), which differ by the replacement of one or more of the oxygen atoms by other kinds of donor atoms, particularly N or S. MacrocycHc amine and thioether compounds have been synthesized. Compounds having more than one kind of heteroatom in the ring are called mixed-donor macrocycles. The naturally occurring metaboUtes nonactin [6833-84-7] and monactin [7182-54-9] have both ether and ester groups incorporated in the macrocyclic stmcture. 

Figure 16 Some examples of silver(I) complexes with mixed donor macrocyclic ligands.

L. F. Lindoy, in Mixed-donor macrocycles solution and structural aspects of their complexation with transition and post-transition ions, Cation Binding by Macrocycles (Y. Inoue and G. W. Gokel, eds.), p. 599, Marcel Dekker, New York (1990). 

Mixed donor macrocycles have been employed in a number of applications involving the separation or analysis of manganesetll). These include examples of use of such a ligand as the extractant in solvent extraction processes " and as the ionophore in membrane transport studies. 

Bi sfethylenedithio)tetrathioful valene (BEDT-TTF), synthesis, 29 254-256 Bis(ferrocenecarbonyl)-diazatetrathia mixed-donor macrocyclic ligands, 39 125-126 Bis(ferrtx enyl)-diazatetrathia mixed-donor macrocyclic ligands, 39 125-126 Bis(fluorosulfonyl)amides, 19 197 Bisfluorosulfonylamidourea, synthesis of, 14 364... 

Complexes with mixed-donor macrocycles and with all-phosphorus and all-sulfur macrocycles 257... 

The subject matter of this chapter will be subdivided into sections concerning template synthesis of the complexes structural and thermodynamic properties of the complexes with synthetic cyclic polyamines complexes with mixed-donor macrocycles reactivity of the complexes cryptates and complexes with phthalocyanines and porphyrins. 

In Table 108 significant examples of nickel(II) complexes with mixed-donor macrocycles of various denticity are reported. Apart from the nitrogen atoms, the heteroatoms in the macrocyclic rings are usually either O or S, or in a few cases P. Few examples of nickel complexes with macrocycles containing all-sulfur or all-phosphorus donor atoms have been reported to date they are also included in Table 108. In nickel(II) complexes formed by mixed-donor penta- and hexa-dentate ligands the oxygen atoms of the macrocycle are often only weakly coordinated or are not coordinated at all. 

Tei, L., Blake, A.J., Cooke, P.A., Caltagirone, C., Demartin, F., Lippolis, V., Morale, F., Wilson, C., and Schroder, M. Nitrile functionalised pendant arm derivatives of aza- and mixed donor macrocyclic ligands as new building blocks for inorganic crystal engineering, Dalton Trans. (2002), 1662-1670. 

Co-condensation of 2,6-bis(bromomethyl)pyridine, 4, with a variety of dithiols, 5, yields not only the [1+1] cyclisation product, e.g. 6, but also—by working at higher concentration—the [2+2] cyclised ligand.9,10 An example of this is provided by the formation of the tetradentate ligand 7 and the mixed donor macrocycle 8. 

Efforts have also been made to improve the methodology used to prepare various mixed donor macrocycles especially applicable to binding transition metal cations <2006POL599>. Various approaches were tried including amide formation followed by reduction (see Figure 4). Activated leaving groups such as tosylate were employed and... 

Tanaka and co-workers have also prepared a variety of mixed donor macrocycles, albeit by more traditional methods <2001JOC7008>. They surveyed the complexation ability of the macrocycles obtained with a range of alkali and transition metal cations. 

The simple mixed donor macrocycles (14) at one time were the major sonrce of study of the influence of the incorporation of soft phosphorus and arsenic donors into macrocycles. Mixed oxygennitrogen macrocycles have been studied quite extensively, since they serve as bridges for examining the coordination tendencies of the aza macrocycles and the oxa crown ethers. 

Simple mixed donor macrocycles, such as aza oxa, aza thia, oxa thia, and analogous phospha and arsa analogs are generally achieved via combinations of the routes used for synthesis of the pure donor analogs. Since the possibilities are so extensive they will not be treated here, but are found elsewhere. New mixed donor phosphorus techniques have been devised for phospha-thia and phospha-aza macrocycles. ... 

Examples of the use of synthetic mixed donor macrocycles in heavy metal ion separations are found in the discrimination of silver from lead. A number of studies indicate that the inclusion of sulfur in macrocyclic sequestering agents shifts the discrimination to silver. An example of this is seen with (57) and (58). For the aza-oxa macrocycle (57) the log K is 5.9 for both silver and lead ions, while the thia-incorporated ligand (58) complexes silver more efficiently (log K = 9.9) compared to lead (log K = 5.7). ... 

For the purposes of this review we will restrict macrocycles to those cyclic compounds with at least three heteroatoms within the ring and with at least two carbon atoms between each adjacent pair of heteroatoms. The following discussion will concentrate on macrocycles containing only S or Se or Te donor atoms, with occasional reference to mixed-donor macrocycles containing one or more of these donor types as appropriate. 

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