Ferrocene polyoxa coronands

Other types include crown ether (coronands) modified by ferrocene units attached as side groups. These are illustrated by compounds in which the ferrocene is sepa- 

The ferrocene coronands 31 undergo reversible one-electron oxidation [72] and the redox potential is usually sensitive to metal-ion complexation by the crown ether part of the molecule. Such complexes have been prepared in reactions with thiocyanates, MSCN (M = Li, Na, K) [71]. The macrocyclic ligands extract thal- 

The aryl- and arylalkenyl ferroceno-coronands also form 1 1 complexes with Na+ and 2 1 complexes with K+ and are redox-responsive. Thus, coordination of K , Na , and shifts the ferrocene oxidation half-wave potential to more positive values [75, 76]. 

Selective complexation of alkali metals by metalloceno-coronands has also been observed some have strong selectivity for potassium relative to both Na+ and Cs+ [77]. 

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