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A new family of octanuclear lanthanide compounds [Na2Ln6L8(C6H4NH2COO)2(C2H5OH)2(H2O)4(NO3)]·NO3·C2H5OH·nH2O [H2L = 2-{[(2-hydroxy-3-methoxyphenyl)methylidene]amino}benzoic acid; Ln = Dy (1) (n = 15); Tb (2), Gd (3) (n = 14); Sm (4) (n = 16)] have been prepared under hydrothermal conditions. The X-ray crystal structure analysis reveals that complexes 1-4 are isomorphous. The core of the structure is a [4 + 2] combination of an Ln4 cubane and an Ln2 unit. The two units are bridged by a nitrate ion, which is located in the center of the cluster and displays an unusual μ8-η(2):η(2):η(4) tridentate bridging mode. The magnetic studies for complex 1 show that the [Na2Dy6] unit exhibits slow magnetic relaxation behavior.

The syntheses, crystal structures and magnetic properties are described for two novel 2D heterometallic Cu(II)-Sr(II) coordination polymers {Sr(H(2)O)(6)[(Im)(4)Cu(4)(pdc)(4)Sr(H(2)O)(4)]·6H(2)O}(n) (1) and [Cu(2)(H(2)O)(2)(pdc)(2)Sr(H(2)O)(3)](n) (2) (H(3)pdc = 3,5-pyrazoledicarboxylic acid; Im = imidazole). The 1 : 1 : 1 : 5 reaction of SrCl(2)·6H(2)O, Cu(NO(3))(2)·3H(2)O, H(3)pdc and imidazole in H(2)O-EtOH at 120 °C under autogenous pressure gave 1. Complex 2 was obtained from the 1 : 1 : 1 H(3)pdc/Sr(OH)(2)·8H(2)O/Cu(NO(3))(2)·3H(2)O reaction mixture in H(2)O-EtOH under solvothermal conditions. Complex 1 can be described as a 2D grid-shaped network with the four Cu(II) ions in a saddle-like conformation. In complex 2, Sr(II) ions link metalloligands [Cu(2)(pdc)(2)(H(2)O)(2)](2-) to generate a 2D layer framework. Variable-temperature solid-state dc magnetic susceptibility studies have been performed in the temperature range 2.0-300 K for complexes 1 and 2. Antiferromagnetic Cu(II)···Cu(II) exchange interactions were found for both 1 and 2.

Two Dy compounds, [Dy2(Phen)2(CH3COO)6] (1; Phen = 1,10‐phenanthroline) and [Dy(Phen)2(NO3)3] (2), were obtained by the reactions of Phen with different dysprosium salts containing different anions, which act as bridging groups and greatly affect the coordination polyhedra of the metal ions. In the former complex, the DyIII ions are bridged by acetate anions and adopt a spherical capped square antiprismatic (C4v) coordination environment, whereas a bicapped square antiprism (D4d) was observed for 2, in which the DyIII ions are bridged by nitrate anions. Static and dynamic magnetic measurements revealed that both compounds display slow magnetic relaxation but with fast quantum tunneling of magnetization (QTM). In an applied direct‐current (dc) field, the QTM was suppressed, and two slow magnetic relaxation processes occurred for both compounds. Comparative studies on the magnetic properties indicate how the ligand field and the local geometric symmetry of the magnetic anisotropy of the DyIII center leads to differing magnetic behavior.

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