| Abstrakt: |
The adjoined 3d–4f metallacrown (MC) molecule DyIII2MnIII6(H2shi)(Hshi)(shi)7(py)9·2py·0.7H2O, 1, where H3shi is salicylhydroxamic acid and py is pyridine, has been synthesized and characterized by FT–IR spectroscopy and single-crystal X-ray diffraction. The core of the molecule consists of two metallacrown (MC) rings, an archetypal 12-MC-4 and a collapsed 11-MC-4, that are linked through a common ring DyIII center. For the 12-MC-4 portion of 1, the heterobimetallic composition of the MC ring with one DyIII and three MnIII ions is uncommon for metallacrowns as most 12-MC-4 rings are homometallic. In addition, the 12-MC-4 binds a DyIII cation in the central cavity of the MC. The coordination environment about the central DyIII ion has a triangular dodecahedron shape, which again is atypical. For 12-MC-4 molecules with a central lanthanide ion, the central lanthanide ion typically adopts a square antiprism geometry. The ring DyIII cation of the 12-MC-4, which has a biaugmented trigonal prism shape, is shared with the collapsed 11-MC-4 and serves to join both metallacrowns. The collapsed 11-MC-4 ring is also composed of three MnIII and one DyIII ions. For one of the ring metal–metal linkages, only an oxygen atom is present, and an eleven membered ring is generated. In addition, the DyIII center and one of the MnIII centers bind to ring oxygen atoms on the opposite side of the MC ring; thus, the potential cavity of the MC is collapsed, and the MC does not bind a central metal ion as is customary. [ABSTRACT FROM AUTHOR] |
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