Family of Carboxylate- and Nitrate-diphenoxo Triply Bridged Dinuclear Ni(II)Ln(III) Complexes (Ln = Eu, Gd, Tb, Ho, Er, Y): Synthesis, Experimental and Theoretical Magneto-Structural Studies, and Single-Molecule Magnet Behavior

Enrique Colacio, Jose Ruiz, Antonio J. Mota, Maria A. Palacios, Eduard Cremades, Eliseo Ruiz, Fraser J. White, Euan K. Brechin

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Seven acetate-diphenoxo triply bridged M-II-Ln(III) complexes (M-II = Ni-II and Ln(III) = Gd, Tb, Ho, Er, and Y; M-II = Zn-II and Ln(III) = Ho-III and Er-III) of formula [M(mu-L)(mu-OAc)Ln(NO3)(2)], one nitrate-diphenoxo triply bridged Ni-II-Tb-III complex, [Ni(mu-L)(mu-NO3)Tb(NO3)(2)]center dot 2CH(3)OH, and two diphenoxo doubly bridged Ni-II-Ln(III) complexes (Ln(III) = Eu, Gd) of formula [Ni(H2O)(mu-L)Ln(NO3)(3)]center dot 2CH(3)OH have been prepared in one pot reaction from the compartmental ligan d N,N',N ''-trimethyl-N,N ''-bis (2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H2L). Moreover, Ni-II-Ln(III) complexes bearing benzoate or 9-anthracenecarboxylate bridging groups of formula [Ni(mu-L)(mu-BzO)Dy(NO3)(2)] and [Ni(mu-L)(mu-9-An)Dy(9-An)(NO3)(2)]3 center dot CH3CN have also been successfully synthesized. In acetate-diphenoxo triply bridged complexes, the acetate bridging group forces the structure to be folded with an average hinge angle in the M(mu-O-2)Ln bridging fragment of similar to 22 degrees, whereas nitrate-diphenoxo doubly bridged complexes and diphenoxo-doubly bridged complexes exhibit more planar structures with hinge angles of similar to 13 degrees and similar to 2 degrees, respectively. All Ni-II-Ln(III) complexes exhibit ferromagnetic interactions between Ni-II and Ln(III) ions and, in the case of the Gd-III complexes, the J(NiGd) coupling increases weakly but significantly with the planarity of the M-(O)(2)-Gd bridging fragment and with the increase of the Ni-O-Gd angle. Density functional theory (DFT) theoretical calculations on the (NiGdIII)-Gd-II complexes and model compounds support these magneto-structural correlations as well as the experimental J(NiGd) values, which were found to be similar to 1.38 and similar to 2.1 cm(-1) for the folded [Ni(mu-L)(mu-OAc)Gd(NO3)(2)] and planar [Ni(H2O)(mu-L)Gd(NO3)(3)]center dot 2CH(3)OH complexes, respectively. The (NiDyIII)-Dy-II complexes exhibit slow relaxation of the magnetization with Delta/k(B) energy barriers under 1000 Oe applied magnetic fields of 9.2 and 10.1 K for [Ni(mu-L)(mu-BzO)Dy(NO3)(2)] and [Ni(mu-L)(mu-9-An)Dy(9-An)(NO3)(2)]center dot 3CH(3)CN, respectively.

Original languageEnglish
Pages (from-to)5857-5868
Number of pages12
JournalInorganic Chemistry
Issue number10
Publication statusPublished - 21 May 2012

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