| Popis: |
Aquatris(3-cyanopentane-2, 4-dionato)scandium(III) undergoes two transformations which can be monitored by X-ray diffraction as well as solid-state NMR spectroscopy: At 145 K, the mononuclear complex shows a reversible phase transition; in agreement with the symmetry principle, this transition of the t2 type proceeds from the monoclinic room temperature phase to triclinic twins at low temperature, the twin law corresponding to a twofold rotation. Under vacuum at room temperature, the aqua ligand of the complex is irreversibly eliminated and the structure rearranges, forming a 1D chain polymer. In both phases of the mononuclear complex as well as in the polymer, the coordination polyhedra around the ScIII atom represent distorted capped trigonal prisms. Solid-state 45Sc NMR spectroscopic investigations on powder samples reveal a reversible phase transition of the monoclinic complex at low temperatures. Changes of the NMR signal line shapes for the room and low temperature complex as well as the 1D chain polymer are a fingerprint for different scandium bonding situations. |
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