title: Acetato-bridged dinuclear lanthanide complexes with single molecule magnet behaviour for the Dy2 species.
abstract: Five dinuclear lanthanide complexes with formula [Ln2L2(OAc)4(MeOH)a(H2O)b] · cMeOH · dH2O (a = 2, b = 0, c = 2, d = 0, Ln = Sm (1), Gd (2), Dy (3); a = 0, b = 2, c = 4, d = 2, Ln = Tm (4)) and [Yb2L2(OAc)4(MeOH)2]·[Yb2L2(OAc)4(H2O)2] · 2H2O (5) (HL = (E)-N'-(2-hydroxybenzylidene)-2-mercaptonicotinohydrazide), have been synthesized and their crystal structures and magnetic properties are reported. All five complexes are centrosymmetric, showing a similar dinuclear core with two lanthanide ions in each complex being bridged by acetate groups in the η(1):η(2):μ2 mode. The various coordination modes of acetate groups result in two kinds of coordination geometries for Ln ions with the ones in complexes 1-4 and the Yb2 in 5 being nine-coordinated with a mono-capped square antiprism geometry, while the Yb1 ions in the other part of complex 5 are eight-coordinated with a triangular dodecahedron geometry. Magnetic susceptibility studies reveal that complex 3 shows single molecule magnet behaviour with an energy barrier of 39.1 K. In addition, comparison of the structural parameters among the similar Dy2 SMMs with a η(1):η(2):μ2 coordination mode of carboxylate groups reveals the significant role played by coordination geometry in modulating the relaxation dynamics of SMMs.
authors.affiliation: State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China. tang@ciac.ac.cn.
authors.forename: Haixia
authors.initials: H
authors.lastname: Zhang
authors.forename: Shuang-Yan
authors.initials: SY
authors.lastname: Lin
authors.forename: Shufang
authors.initials: S
authors.lastname: Xue
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Jinkui
authors.initials: J
authors.lastname: Tang