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Macrocycles based on magnetically functionalized zirconium oxide clusters

TitleMacrocycles based on magnetically functionalized zirconium oxide clusters
Publication TypeJournal Article
Year of Publication2012
AuthorsMalaestean IL, Kutluca M, Speldrich M, Ellern A, Kogerler P
Journal TitleInorganica Chimica Acta
Volume380
Pages72-77
Date Published01
Type of ArticleArticle
ISBN Number0020-1693
Accession NumberWOS:000300180100010
Keywordschemistry, complex, core, crystal-structure, Heterometallic complexes, ions, ligands, macrocycles, magnetic properties, Zirconium compounds, zr6o4(oh)(4)(oocr)(12)
Abstract

In the presence of 4,4'-bipyridine and Co(II) or Ni(II) groups, which are coordinatively constrained by bis-alkoxyamine chelating groups, dimeric [(Zr6O4)-O-IV(OH)(4)(RCOO)(12)](2) clusters rearrange to {Zr12O11(OH)(11)(RCOO)(16)} frameworks featuring highly condensed zirconium oxide cores. These {Zr-12} groups subsequently each coordinate to three M(II) groups and self-assemble via two bridging 4,4'-bpy into 2.6 nm {M6Zr24}type macrocycles of composition [M6Zr24O22(OH)(22)(C2H5COO)(40)(Hmdea)(2)(H(2)mdea)(4)(4,4'-bpy)(2)]. Surprisingly, two M(II) sites peripherally attached to the {Zr-12} frameworks adopt a rare eightfold coordination mode where the M2+ ions reside in a distorted square antiprismatic O7N environment. Magnetic measurements reveal that the zirconium oxide fragments efficiently mediate antiferromagnetic exchange between Ni2+ spin centers, whereas in case of the virtually isostructural Co2+ derivative pronounced ligand field asymmetry causes single-ion effects to significantly influence the low-field susceptibility data. (C) 2011 Elsevier B. V. All rights reserved.
URL<Go to ISI>://WOS:000300180100010
DOI10.1016/j.ica.2011.08.061
Alternate JournalInorg. Chim. Acta