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The coordination chemistry of the pentadentate 2,2,6,6-tetrakis(aminomethyl)-4-azaheptane (ditame)

Hegetschweiler, Kaspar; Maas, Oliver; Zimmer, Anja; Geue, Rodney; Sargeson, Alan; Harmer, Jeffrey; Schweiger, Arthur; Buder, Irmgard; Schwitzgebel, Gunter; Reiland, Vera; Frank, Walter

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The protonation and metal complex formation of the branched pentaamine ligand 2,2,6,6-tetrakis(aminomethyl)-4-azaheptane (ditame, L) with CoII, CoIII, NII, CuII, ZnII, and CDII have been studied. The crystal structures of [Ni(ditame)(EtOH)] Br2, [CO2(ditame)2(O2)Cl4 ·4H2O, and [Co2-(ditame)2(O2)]Cl2 [ZnCl4][ZnCl3(H2O)]·H2O were determined by X-ray diffraction analyses. The metal complexes showed octahedral coordination geometries with exclusive formation of six-membered chelate rings, the four...[Show more]

dc.contributor.authorHegetschweiler, Kaspar
dc.contributor.authorMaas, Oliver
dc.contributor.authorZimmer, Anja
dc.contributor.authorGeue, Rodney
dc.contributor.authorSargeson, Alan
dc.contributor.authorHarmer, Jeffrey
dc.contributor.authorSchweiger, Arthur
dc.contributor.authorBuder, Irmgard
dc.contributor.authorSchwitzgebel, Gunter
dc.contributor.authorReiland, Vera
dc.contributor.authorFrank, Walter
dc.date.accessioned2015-12-13T23:08:20Z
dc.date.available2015-12-13T23:08:20Z
dc.identifier.issn1434-1948
dc.identifier.urihttp://hdl.handle.net/1885/86631
dc.description.abstractThe protonation and metal complex formation of the branched pentaamine ligand 2,2,6,6-tetrakis(aminomethyl)-4-azaheptane (ditame, L) with CoII, CoIII, NII, CuII, ZnII, and CDII have been studied. The crystal structures of [Ni(ditame)(EtOH)] Br2, [CO2(ditame)2(O2)Cl4 ·4H2O, and [Co2-(ditame)2(O2)]Cl2 [ZnCl4][ZnCl3(H2O)]·H2O were determined by X-ray diffraction analyses. The metal complexes showed octahedral coordination geometries with exclusive formation of six-membered chelate rings, the four primary amino groups being in equatorial positions and the secondary amino group (Nsec) apical. This geometry enforces a relatively short M-Nsec bond. Complex formation in aqueous solution was evaluated by potentiometric titration. The ditame ligand forms a surprisingly stable NiII complex with logKNiL = 17.8 (25 °C, 0.1 M KNO3), and formation of protonated species [Ni(Hnditame)](n+2)+ (n = 1, 2) is not significant. Different behavior is evident for ZnII and CdII, with which protonated species are extensively formed, while the stability of [ML]2+ is relatively low. Complex formation between ditame and CuII in the range 3 < pH < 7 resulted in the formation of [Cu(H2ditame)]4+. In slightly alkaline solution, the dinuclear [Cu2(ditame)2]4+ appears to be formed. The structural assignment of this dimer is based on its UV/Vis and EPR characteristics, with the EPR data indicating a CuII···CuII separation of about 5.9 Å. The redox behavior of the Ni and Co complexes was investigated by cyclic voltammetry. The mononuclear species showed quasi-reversible electron transfer for the NiII/III and ColII/III couples. For the dinuclear peroxo/superoxo-bridged CoII/III complexes, quasi-reversible electron transfer corresponding to oxidation/reduction of the O22-/O2- bridge was observed. (
dc.publisherWiley-VCH Verlag GMBH
dc.sourceEuropean Journal of Inorganic Chemistry
dc.subjectKeywords: 2,2,6,6 tetrakis(aminomethyl) 4 azaheptane; alkaline earth metal; alkane derivative; amine; cadmium derivative; cobalt complex; nickel complex; unclassified drug; zinc complex; aqueous solution; article; carbon nuclear magnetic resonance; complex formatio Amine ligands; Chelates; Ligand design; Stability constants
dc.titleThe coordination chemistry of the pentadentate 2,2,6,6-tetrakis(aminomethyl)-4-azaheptane (ditame)
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
dc.date.issued2003
local.identifier.absfor030207 - Transition Metal Chemistry
local.identifier.ariespublicationMigratedxPub15553
local.type.statusPublished Version
local.contributor.affiliationHegetschweiler, Kaspar, Saarland University
local.contributor.affiliationMaas, Oliver, Saarland University
local.contributor.affiliationZimmer, Anja, Saarland University
local.contributor.affiliationGeue, Rodney, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationSargeson, Alan, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationHarmer, Jeffrey, Swiss Federal Institute of Technology (ETH)
local.contributor.affiliationSchweiger, Arthur, Eidgenossische Technische Hochschule (ETH)
local.contributor.affiliationBuder, Irmgard, Saarland University
local.contributor.affiliationSchwitzgebel, Gunter, Saarland University
local.contributor.affiliationReiland, Vera, Heinrich Heine University of Dusseldorf
local.contributor.affiliationFrank, Walter, Heinrich Heine University of Dusseldorf
local.bibliographicCitation.issue7
local.bibliographicCitation.startpage1340
local.bibliographicCitation.lastpage1354
dc.date.updated2015-12-12T08:13:10Z
local.identifier.scopusID2-s2.0-0037395127
CollectionsANU Research Publications

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