科研之友
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摘要
Two hexanuclear Co-II clusters, NHEt3[Co-6(phendc)(6) superset of X]center dot MeOH center dot 3H(2)O (X = Cl- (1) or F- (2)), were obtained accidently by the in situ formation of the coordinating ligand 1-12phendc (1,10phenanthroline-2,9-dicarboxylate) from the precursor ligand H(2)phenox (1,1 0-phenanthroline-2,9dicarbaldehyde dioxime). Halides among the reactants used become the template around which a highly symmetric cluster is generated which display spin-glass magnetic behavior as a consequence of the severe magnetic frustration due to geometrical arrangement of the moments. Different aniontemplate effects were demonstrated by ES I-M S studies. Interestingly, 1 exists in solution; in its solid state, a rare and unique single-crystal to single-crystal transformation is observed upon desolvation, which is accompanied by the departure of NEt3. Both dc and ac magnetization data suggest the spinglass behavior for 1 and its guest-free structure H[Co-6(phendc)(6)Cl] (1') at different blocking temperatures of 5.3 and 7.8 K, respectively. The absence of this observation for 2 raises an interesting question regarding its origin and provides a remarkable example of fine-tuning of frustrated magnetic properties via host-guest interactions.
