Structures and Magnetism of Two Novel Heptanuclear Lanthanide-Centered Trigonal Prismatic Clusters:  LnCu6(μ3-OH)3(HL)2(L)4(ClO4)2·25H2O (Ln = La, Tb; H2L = Iminodiacetic Acid)

The new heteronuclear iminodiacetic acid (H2L) complexes LnCu6(mu 3-OH)3(HL)2(L)4(ClO4)(2).25H2O with Ln = La (1) and Tb (2) have been prepared in aqueous solution and characterized by single-crystal X-ray diffraction to be isomorphous (crystallographic data for 1 and 2: hexagonal, P63/m; a = b = 12.6425(14) A, c = 24.541(5) A, Z = 2 (1); a = b = 12.5802(9) A, c = 24.285(4) A, Z = 2 (2)). Ln3+ was found to be located in the center of the trigonal prismatic cage formed by six Cu2+ ions, with a tricapped trigonal prismatic coordination environment of nine O atoms. The magnetic properties of complexes 1 and 2 have been studied. The results indicate the presence of ferromagnetic couplings between Tb3+ and Cu2+ in compound 2.