Macrocycles inorganic

A rack-like arrangement schematically represented by 160, would be formed by the complexation of several metal ions to rigid, linear sequences of binding sites. Thus, binding of bipy or phen units to 155 and to its extended tri- and tetratopic analogues present in 157 and in 158 via metal ions of tetrahedral coordination such as Cu(l) and Ag(l) should yield rack structures of type 160. With the bipy or phen unit included in a macrocycle, inorganic rotaxane-type structures (see also Section 9.6) such as 159 have been obtained [9.97a]. A linear sequence of connected terpy sites such as 161 yields racks with individual terpy units and metal ions of octahedral coordination [9.97b]. 

Crown-ethers are macrocyclic polyethers capable of forming host-guest complexes, especially with inorganic and organic cations. Modification of the crown-ether by the introduction of four carboxylic groups makes it possible to use this class of compounds as chiral selectors in CE. ... 

A molecule that contains one or more binding sites that can accommodate inorganic or organic ions referred to as guests. The binding site could even be a cavity within a crystal structure. Although enzymes clearly qualify as examples of host molecules, the term is usually restricted to structures such as crown ethers, macrocycles, and cyclodextrins. Nevertheless, these hosts do serve as models for molecular recognition. See also Crown Ethers Macrocycles Inclusion Complexes... 

Anion effects have been observed especially in relation to dissolution of the cation complexes in media of low polarity. Soft organic and inorganic anions (phenates, thiocyanate, permanganate etc) generally allow ready dissolution the pier ate anion has been much used (62, 66). The interaction between the anion and the complexed cation may affect the stability of the complex. Ion pairing may occur when the anion can contact the complexed cation, as in the case of macrocyclic complexes, where approach of the anion from top and bottom is possible. This is observed in the RbNCS complex of IS, but not in its NaNCS complex, as shown by the crystal structure data (100). With bromide as anion both a complexed ion pair and a complexed sodium cation are found in the solid state for (15, NaBr) (118). 

The metal complexing properties of macrocyclic compounds, coupled with the solubilities of their metal complexes in a variety of organic solvents, make them especially useful as reagents in organic syntheses. They provide a unique method for solubilizing inorganic salts such as KC1 in organic solvents. Despite their promise and the favorable results obtained thus far, it has been observed that few synthetic applications of these compounds have been reported (53). 

Mechanisms of oxidations of inorganic and organic substrates by macrocyclic complexes containing the trans-Ru KO) unit have been reviewed [48]. 

Recently, two related bis-tren type macrocycles, 21 and 22 have been shown to complex CIO4 and SiF anions in the solid state, highlighting the potential of these types of hosts for inorganic anion complexation. ... 

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