Carbonato-bridged NiII2LnIII2(LnIII = GdIII, TbIII, DyIII) complexes generated by atmospheric CO2 fixation and their single-molecule-magnet behavior: [(4-CO3)2{NiII(3-MeOsaltn)(MeOH or H2O)LnIII(NO3)}2solvent [3-MeOsaltn = N, N -Bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato]

Soichiro Sakamoto, Takeshi Fujinami, Koshiro Nishi, Naohide Matsumoto, Naotaka Mochida, Takayuki Ishida, Yukinari Sunatsuki, Nazzareno Re

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Atmospheric CO2 fixation of [NiII(3-MeOsaltn)(H 2O)2]·2.5H2O [3-MeOsaltn = N,N′-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato], Ln III(NO3)3·6H2O, and triethylamine occurred in methanol/acetone, giving a first series of carbonato-bridged NiII2LnIII2 complexes [(μ4-CO3)2{NiII(3- MeOsaltn)(MeOH)LnIII(NO3)}2] (1Gd, 1Tb, and 1Dy). When the reaction was carried out in acetonitrile/water, it gave a second series of complexes [(μ4-CO3)2{Ni II(3-MeOsaltn)(H2O)LnIII(NO3)} 2]·2CH3CN·2H2O (2Gd, 2Tb, and 2Dy). For both series, each NiII2LnIII 2 structure can be described as two di-μ-phenoxo-bridged Ni IILnIII binuclear units bridged by two carbonato CO 32- units to form a carbonato-bridged (μ4- CO3)2{NiII2LnIII 2} structure. The high-spin NiII ion has octahedral coordination geometry, and the LnIII ion is coordinated by O 9 donor atoms from NiII(3-MeOsaltn), bidentate NO 3-, and one and two oxygen atoms of two CO 32- ions. The NO3- ion for the first series roughly lie on Ln-O(methoxy) bonds and are tilted toward the outside, while for the second series, the two oxygen atoms roughly lie on one of the Ln-O(phenoxy) bonds due to the intramolecular hydrogen bond. The temperature-dependent magnetic susceptibilities indicated a ferromagnetic interaction between the NiII and LnIII ions (Ln III = GdIII, TbIII, DyIII) for all of the complexes, with a distinctly different magnetic behavior between the two series in the lowest-temperature region due to the LnIII-Ln III magnetic interaction and/or different magnetic anisotropies of the TbIII or DyIII ion. Alternating-current susceptibility measurements under the 0 and 1000 Oe direct-current (dc) bias fields showed no magnetic relaxation for the NiII2GdIII 2 complexes but exhibited an out-of-phase signal for Ni II2TbIII2 and NiII 2DyIII2, indicative of slow relaxation of magnetization. The energy barriers, Δ/kB, for the spin flipping were estimated from the Arrhenius plot to be 12.2(7) and 6.1(3) K for 1Tb and 2Tb, respectively, and 18.1(6) and 14.5(4) K for 1Dy and 2Dy, respectively, under a dc bias field of 1000 Oe. Compound 1Dy showed relatively slow relaxation of magnetization reorientation even at zero dc applied field with Δ/kB = 6.6(4) K.

Original languageEnglish
Pages (from-to)7218-7229
Number of pages12
JournalInorganic Chemistry
Issue number12
Publication statusPublished - Jun 17 2013

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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