%0 Journal Article
%A Malaestean, I.L.
%A Kutluca, M.
%A Speldrich, M.
%A Ellern, A.
%A Kögerler, P.
%T Macrocycles based on magnetically functionalized zirconium oxide clusters
%J Inorganica chimica acta
%V 380
%@ 0020-1693
%C New York, NY [u.a.]
%I Elsevier
%M PreJuSER-22478
%P 72 - 77
%D 2012
%Z Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358.
%X 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.
%K J (WoSType)
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000300180100010
%R 10.1016/j.ica.2011.08.061
%U https://juser.fz-juelich.de/record/22478