- Terbium(III) and Yttrium(III) complexes with pyridine-substituted nitronyl nitroxide radical and different β-diketonate ligands. Crystal structures and magnetic and luminescence properties
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A terbium(III) complex of nitronyl nitroxide free radical 2-(2-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro1H-imidazolyl-1-oxy-3-oxide (NIT2Py), [Tb(acac)3NIT2Py]·0.5H2O (3) (acac = acetylacetonate), was synthesized for comparison with the previously reported [Tb(hfac)3NIT2Py]·0.5C7H16 (1) (hfac = hexafluoroacetylacetonate), together with their yttrium analogues [Y(hfac)3NIT2Py]·0.5C7H16 (2) and [Y(acac)3NIT2Py]·0.5H2O (4). The crystal structures show that in all complexes the nitronyl nitroxide radical acts as a chelating ligand. Magnetic studies show that 3 like 1 exhibits slow relaxation of magnetization at low temperature, suggesting single-molecule magnet behavior. The luminescence spectra show resolved vibronic structure with the main interval decreasing from 1600 cm-1 to 1400 cm-1 between 80 and 300 K. This effect is analyzed quantitatively using experimental Raman frequencies.
- Lannes, Anthony,Intissar, Mourad,Suffren, Yan,Reber, Christian,Luneau, Dominique
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p. 9548 - 9560
(2015/02/19)
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- Crystal structure and vacuum sublimation of the product of reaction of yttrium hexafluoroacetylacetonate and copper acetylacetonate [Y(Hfa)3(H2O)2Cu(Acac)2]
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The cocrystallization of an equimolar mixture of Y(Hfa)3 (Hfa = hexafluoroacetylacetonate ion) and Cu(Acac)2 (Acac = acetylacetonate ion) from 96% EtOH gives [Y(Hfa)3(H2O)2Cu(Acac)2] crystals with the following unit cell parameters: a = 12.435, b = 19.692, c = 16.242 A, β = 111.35°, V = 3704.2 A3, Z = 4, space group P21/c. In the [Y(Hfa)3(H2O)2] molecules (the structure was determined for the first time), the central Y3+ ion is coordinated by six oxygen atoms of three hexafluoroacetylacetonate ligands and two oxygen atoms of two H2O molecules. The Y-O(Hfa) bond lengths lie in the range 2.318-2.342 A (d(av) = 2.331 A) and are close to the Y-O(H2O) bond lengths of 2.342 and 2.346 A. The Cu(Acac)2 molecules in the crystals have the same structure as does the individual Cu(Acac)2 compound. In the crystal structure, the Y(Hfa)3(H2O)2 and Cu(Acac)2 molecules are linked together by intermolecular hydrogen bonds to form zigzag chains. Heating of [Y(Hfa)3(H2O)2Cu(Acac)2] in vacuum induces ligand-exchange reaction and evolution of Cu(Hfa)2 into the gas phase.
- Kuz'mina,Kupriyanova,Troyanov
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p. 367 - 372
(2008/10/08)
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