New bis(ferrocenecarbonyl)- and bis(ferrocenyl)-appended diazatetrathia mixed-donor macrocyclic ligands and their copper-(II) and -(I) complexes

New bis(ferrocenecarbonyl)-, bis(ferrocenyl)- and dibenzyl-appended diazatetrathia mixed-donor macrocyclic ligands L1, L2 and L3 have been prepared. Copper-(II) and -(I) complexes of these ligands have been isolated and characterised. Single-crystal X-ray structures of 7,16-bis(ferrocenemethyl)-1,4,10,13-tetrathia-7,16-diazacyclooctadecane (L2) and of its copper(I) complex [CuL2]PF6 have also been determined. Electrochemical investigations reveal the respective ferrocene–ferrocenium redox couples of ligands L1 and L2 are perturbed to more positive potentials on co-ordination of the copper(II) ion. These copper(II) complexes also exhibit quasi-reversible copper(II)–copper(I) redox couples at negative potentials (versus saturated calomel electrode).