Synthesis, characterization and complexation studies of a cage ligand bearing a tris(bipyridyl)iron(II) capping group

Reaction between 5-(4-amino-2-thiabutyl)-5-methyl-3,7-dithianonane-1,9-diamine (N3S3) and 5-methyl-2,2-bipyridine-5-carbaldehyde and subsequent reduction of the resulting imine with sodium borohydride results in a potentially ditopic ligand (L). Treatment of L with one equivalent of an iron(II) salt led to the monoprotonated complex [Fe(HL)], isolated as the hexafluorophosphate salt. The presence of characteristic bands for the tris(bipyridyl)iron(II) chromophore in the UV/vis spectrum indicated that the iron(II) atom is coordinated octahedrally by the three bipyridyl (bipy) groups. The [Fe(bipy)] moiety encloses a cavity composed of the N3S3 portion of the ditopic ligand. The mononuclear and monomeric nature of the complex [Fe(HL)] has been established also by accurate mass analysis. [Fe(HL)] displays reduced stability to base compared with the complex [Fe(bipy)]. In aqueous solution [Fe(HL)] exhibits irreversible electrochemical behaviour with an oxidation wave ca. 60 mV to more positive potential than [Fe(bipy)]. Investigations of the interaction of [Fe(L)] with copper(II), iron(II), and mercury(II) using mass spectroscopic and potentiometric methods suggested that where complexation occurred, fewer than six of the N3S3 cavity donors were involved. The high affinity of the complex [Fe(L)] for protons is one reason suggested to contribute to the reluctance to coordinate a second metal ion

Application of the shrinking core model to the kinetics of extraction of gold(I), silver(I) and nickel(II) cyanide complexes by novel anion exchange resins

This paper describes an investigation of the kinetics of loading of gold(I), silver(I), and nickel(II) cyanide complexes onto two novel anion exchange resins with high selectivity for the linear dicyanoaurate(I) and dicyanoargentate(I) complexes. The kinetic data fit well to a shrinking core theoretical model, and indicate that in all three complexes, the loading is controlled by the rate of diffusion of the ions penetrating the reacted layer, Diffusion coefficients were determined and those of Au(I) and Ag(I) cyano complexes are similar to one another but much higher (30 to 60 times) those of the Ni(II) cyano complex on these two resins. (C) 2000 Elsevier Science B.V. All rights reserved

Synthesis and X-ray structural characterization of an iron(III) complex of the fluoroquinolone antimicrobial ciprofloxacin, [Fe(CIP)(NTA)]3·5H2O (NTA=Nitrilotriacetato)

Reaction of the fluoroquinolone antimicrobial ciprofloxacin (cip) with iron(III) in the presence of nitrilotriacetate (nta) results in the isolation of yellow crystals of the complex [Fe(cip)(nta)]3 . 5H(2)O. The X-ray structural studies establish that, in the solid state, coordination of the iron(III) occurs through the keto and the carboxylic acid oxygen of the ciprofloxacin ligand to form a six-membered ring