Syntheses and characterization of four heterometallic Ln-Co or Ln-Ni heptanuclear clusters with glycine as ligand

The self-assemble of Ln(ClO4)(3) (Ln = Pr, Gd), M(ClO4)2 (M = Co, Ni) and glycine provides four new heptanuclear clusters {LnM(6)} and two of them were successfully characterized by X-ray structural analyses. Na[PrCo6(Gly)(12)](ClO4)(4)(H2O)(6) (1) (Gly=NH2CH2COO-) crystallizes in the rhombohedral R-3c space group (a=b=12.4998(1) angstrom, c=62.4276(9) angstrom, and Z=6). The structure of the cation may be described as a Pr3+ ion situates in the center of an octahedral cage formed by Six Co2+ atoms. Na[GdNi6(Gly)(6)(HGly)(2)(mu(3)-OH)(3) (mu(2)-OH2)(H2O)(6)](.)(ClO4)(7)(.)(H2O)(9) (2) attributes to the triclinic P-1 space group (a = 13.3868(2) angstrom, b = 15.2182(3) angstrom, c = 19.2877(1) angstrom, alpha = 86.73(0)degrees, beta = 80.430(1)degrees, gamma = 65.033(1)degrees and Z= 2). The structure of the cation may be described as a Gd3+ ion is in the center of a prism formed by six nickel atoms. Primary structure analyses of Na-4[PrCo6(Gly)(9)(mu(3)-OH)(3)(H2O)(6)](.)(ClO4)(7) (3) and Na-4[GdNi6(Gly)(9) (mu(3)-OH)(3)(H2O)(6)](.)(ClO4)(7) (4) show they also have [LnM(6)(Gly)(6)(mu(3)-OH)(3)(H2O)(6)](6+) cores. 1 and 3 represent the first successfully attempt to syntheses of heptanuclear Ln-Co clusters. The magnetic measurement reveals that 2 exhibits ferromagnetic interaction. (c) 2005 Elsevier B.V. All rights reserved.