Redox-responsive crown ethers containing a direct link between the ferrocene redox-active centre and a benzo-crown ether. Crystal structures of a ferrocene benzo-15-crown-5 ligand and of its sodium complex

Abstract

benzopentaoxacyclopentadecine (L') and N-(4-ferrocenylphenyl) -lr4,7,10-tetraoxa-13azacyclopentadecane ( L2), containing a direct link between the ferrocene redox centre and respectively benzo-15-crown-5 and N-phenylaza-15-crown-5, have been prepared. The sodium cation forms 1 1 stoicheiometric complexes with both ionophores whereas the larger potassium cation produces 1 : 2 intermolecular sandwich complexes w i t h the same ligands, which were also observed b y fast-atom-bombardment mass spectrometry. Single-crystal X-ray structures of L1 and of its sodium complex [NaL'] PF, have also been determined. Electrochemical investigations reveal that the binding of Na', K', and Mg2+ guest cations by L' and L2 results in shifts of the respective ferrocene-ferrocenium redox couple to more positive potentials. The magnitude of these one-wave anodic shifts is related to the charge: radius ratio of the cationic guest species.

Alkali-metal binding properties of simple ferrocenyl- and ruthenocenyl-substituted aza-crown ethers

“…2). Behaviour of this kind has previously been noted with other metallocene monocrowns, especially those derived from 15-crown-5 (1,4,7,10,13-pentaoxacyclopentadecane), 29 a crown ether which has a well documented ability to form 2 : 1 sandwich type complexes with potassium salts. No appreciable shifts of the ferrocenyl resonances would be expected for a complex of this type since, unlike cryptand 4 where the binding site is 'tied' to both ferrocene rings, no conformational reorganisation involving the ferrocene unit is required.…”

Effect of metal ion complexation and chalcogen donor identity on the antiproliferative activity of 2-acetylpyridine N,N-dimethyl(chalcogen)semicarbazones

“…3) along with the presence of the PF À 6 counter anion are in agreement with the monodeprotonated nature of the coordinated ligands and formal oxidation state 3+ of ruthenium in 7. The hexafluorophosphate anion was found to be disordered over two positions with P-F bond lengths typical for this species [32].…”

Reactivity of the Acyclic Diazadioxa Redox Active Ligand [(C5H5)Fe(C5H4CH2N(CH3)(CH2)2OCH2−)]2: NMR, Electrochemical, and Mössbauer Studies. Crystal Structure of Its Copper Complex

“…Na + presents a good affinity for N and O atoms in diazacrown ether compounds. 8b, In 6 additional coordination could be provided from the PF 6 counteranion through its F atoms . However, 31 P{ 1 H} (161.98 MHz, CD 2 Cl 2 ) variable temperature NMR experiments down to 183 K do not show significant variation of the spectra, thus lending no support to this proposal (the heptuplet at −141.72 ppm is not modified). Yellow crystals of the pure compound were obtained, but they were not suitable for X-ray diffraction studies.…”